Fixed Parser issue

2022-09-06 12:22:31 -07:00
268 changed files with 10063 additions and 9278 deletions
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@ -9,22 +9,22 @@
 # This also holds true for GitHub teams.

 # Rescript 
-*.res @berekuk @OAGr
-*.resi @berekuk @OAGr
+*.res @OAGr
+*.resi @OAGr

 # Typescript 
-*.tsx @Hazelfire @berekuk @OAGr 
-*.ts @Hazelfire @berekuk @OAGr
+*.tsx @Hazelfire @OAGr
+*.ts @Hazelfire @OAGr

 # Javascript
-*.js @Hazelfire @berekuk @OAGr
+*.js @Hazelfire @OAGr

 # Any opsy files
-.github/** @quinn-dougherty @berekuk @OAGr
-*.json @quinn-dougherty @Hazelfire @berekuk @OAGr
-*.y*ml @quinn-dougherty @berekuk @OAGr
-*.config.js @Hazelfire @berekuk @OAGr
-vercel.json @OAGr @berekuk @Hazelfire
+.github/** @quinn-dougherty @OAGr
+*.json @quinn-dougherty @Hazelfire @OAGr
+*.y*ml @quinn-dougherty @OAGr
+*.config.js @Hazelfire @OAGr
+netlify.toml @quinn-dougherty @OAGr @Hazelfire 

 # Documentation
 *.md @quinn-dougherty @OAGr @Hazelfire
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@ -1,4 +1,4 @@
-name: Squiggle packages checks
+name: Squiggle packages check

 on:
  push:
@ -9,40 +9,214 @@ on:
    branches:
      - master
      - develop
-
-env:
-  TURBO_TOKEN: ${{ secrets.TURBO_TOKEN }}
-  TURBO_TEAM: quantified-uncertainty
+      - reducer-dev
+      - epic-reducer-project

 jobs:
-  build-test-lint:
-    name: Build, test, lint
+  pre_check:
+    name: Precheck for skipping redundant jobs
    runs-on: ubuntu-latest
+    outputs:
+      should_skip_lang: ${{ steps.skip_lang_check.outputs.should_skip }}
+      should_skip_components: ${{ steps.skip_components_check.outputs.should_skip }}
+      should_skip_website: ${{ steps.skip_website_check.outputs.should_skip }}
+      should_skip_vscodeext: ${{ steps.skip_vscodeext_check.outputs.should_skip }}
+      should_skip_cli: ${{ steps.skip_cli_check.outputs.should_skip }}
    steps:
-      - uses: actions/checkout@v3
-      - name: Setup Node.js environment
-        uses: actions/setup-node@v3
+      - id: skip_lang_check
+        name: Check if the changes are about squiggle-lang src files
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
-          node-version: 16
-          cache: 'yarn'
-      - name: Install dependencies
-        run: yarn --frozen-lockfile
-      - name: Turbo run
-        run: npx turbo run build test lint bundle
+          paths: '["packages/squiggle-lang/**"]'
+      - id: skip_components_check
+        name: Check if the changes are about components src files
+        uses: fkirc/skip-duplicate-actions@v4.0.0
+        with:
+          paths: '["packages/components/**"]'
+      - id: skip_website_check
+        name: Check if the changes are about website src files
+        uses: fkirc/skip-duplicate-actions@v4.0.0
+        with:
+          paths: '["packages/website/**"]'
+      - id: skip_vscodeext_check
+        name: Check if the changes are about vscode extension src files
+        uses: fkirc/skip-duplicate-actions@v4.0.0
+        with:
+          paths: '["packages/vscode-ext/**"]'
+      - id: skip_cli_check
+        name: Check if the changes are about cli src files
+        uses: fkirc/skip-duplicate-actions@v4.0.0
+        with:
+          paths: '["packages/cli/**"]'

-  coverage:
-    name: Coverage
+  #  lang-lint:
+  #    name: Language lint
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ needs.pre_check.outputs.should_skip_lang != 'true' }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/squiggle-lang
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Install Dependencies
+  #        run: cd ../../ && yarn
+  #      - name: Check rescript lint
+  #        run: yarn lint:rescript
+  #      - name: Check javascript, typescript, and markdown lint
+  #        uses: creyD/prettier_action@v4.2
+  #        with:
+  #          dry: true
+  #          prettier_options: --check packages/squiggle-lang
+
+  lang-build-test-bundle:
+    name: Language build, test, and bundle
    runs-on: ubuntu-latest
+    needs: pre_check
+    if: ${{ needs.pre_check.outputs.should_skip_lang != 'true' }}
+    defaults:
+      run:
+        shell: bash
+        working-directory: packages/squiggle-lang
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 2
-      - name: Setup Node.js environment
-        uses: actions/setup-node@v2
-        with:
-          node-version: 16
-          cache: 'yarn'
-      - name: Install dependencies
-        run: yarn
-      - name: Coverage
-        run: npx turbo run coverage
+      - name: Install dependencies from monorepo level
+        run: cd ../../ && yarn
+      - name: Build rescript codebase
+        run: yarn build
+      - name: Run rescript tests
+        run: yarn test:rescript
+      - name: Run typescript tests
+        run: yarn test:ts
+      - name: Run webpack
+        run: yarn bundle
+      - name: Upload rescript coverage report
+        run: yarn coverage:rescript:ci
+      - name: Upload typescript coverage report
+        run: yarn coverage:ts:ci
+
+  #  components-lint:
+  #    name: Components lint
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ needs.pre_check.outputs.should_skip_components != 'true' }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/components
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Check javascript, typescript, and markdown lint
+  #        uses: creyD/prettier_action@v4.2
+  #        with:
+  #          dry: true
+  #          prettier_options: --check packages/components --ignore-path packages/components/.prettierignore
+  #
+  #  components-bundle-build:
+  #    name: Components bundle and build
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ (needs.pre_check.outputs.should_skip_components != 'true') || (needs.pre_check.outputs.should_skip_lang != 'true') }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/components
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Install dependencies from monorepo level
+  #        run: cd ../../ && yarn
+  #      - name: Build rescript codebase in squiggle-lang
+  #        run: cd ../squiggle-lang && yarn build
+  #      - name: Run webpack
+  #        run: yarn bundle
+  #      - name: Build storybook
+  #        run: yarn build
+
+  #  website-lint:
+  #    name: Website lint
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ needs.pre_check.outputs.should_skip_website != 'true' }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/website
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Check javascript, typescript, and markdown lint
+  #        uses: creyD/prettier_action@v4.2
+  #        with:
+  #          dry: true
+  #          prettier_options: --check packages/website
+  #
+  #  website-build:
+  #    name: Website build
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ (needs.pre_check.outputs.should_skip_website != 'true') || (needs.pre_check.outputs.should_skip_lang != 'true')  || (needs.pre_check.outputs.should_skip_components != 'true') }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/website
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Install dependencies from monorepo level
+  #        run: cd ../../ && yarn
+  #      - name: Build rescript in squiggle-lang
+  #        run: cd ../squiggle-lang && yarn build
+  #      - name: Build components
+  #        run: cd ../components && yarn build
+  #      - name: Build website assets
+  #        run: yarn build
+  #
+  #  vscode-ext-lint:
+  #    name: VS Code extension lint
+  #    runs-on: ubuntu-latest
+  #    needs: pre_check
+  #    if: ${{ needs.pre_check.outputs.should_skip_vscodeext != 'true' }}
+  #    defaults:
+  #      run:
+  #        shell: bash
+  #        working-directory: packages/vscode-ext
+  #    steps:
+  #      - uses: actions/checkout@v3
+  #      - name: Check javascript, typescript, and markdown lint
+  #        uses: creyD/prettier_action@v4.2
+  #        with:
+  #          dry: true
+  #          prettier_options: --check packages/vscode-ext
+
+  vscode-ext-build:
+    name: VS Code extension build
+    runs-on: ubuntu-latest
+    needs: pre_check
+    if: ${{ (needs.pre_check.outputs.should_skip_components != 'true') || (needs.pre_check.outputs.should_skip_lang != 'true') }} || (needs.pre_check.outputs.should_skip_vscodeext != 'true') }}
+    defaults:
+      run:
+        shell: bash
+        working-directory: packages/vscode-ext
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install dependencies from monorepo level
+        run: cd ../../ && yarn
+      - name: Build
+        run: yarn compile
+#  cli-lint:
+#    name: CLI lint
+#    runs-on: ubuntu-latest
+#    needs: pre_check
+#    if: ${{ needs.pre_check.outputs.should_skip_cli != 'true' }}
+#    defaults:
+#      run:
+#        shell: bash
+#        working-directory: packages/cli
+#    steps:
+#      - uses: actions/checkout@v3
+#      - name: Check javascript, typescript, and markdown lint
+#        uses: creyD/prettier_action@v4.2
+#        with:
+#          dry: true
+#          prettier_options: --check packages/cli
--- a/.github/workflows/release-please.yml
+++ b/.github/workflows/release-please.yml
@ -18,27 +18,27 @@ jobs:
    steps:
      - id: skip_lang_check
        name: Check if the changes are about squiggle-lang src files
-        uses: fkirc/skip-duplicate-actions@v5.2.0
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
          paths: '["packages/squiggle-lang/**"]'
      - id: skip_components_check
        name: Check if the changes are about components src files
-        uses: fkirc/skip-duplicate-actions@v5.2.0
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
          paths: '["packages/components/**"]'
      - id: skip_website_check
        name: Check if the changes are about website src files
-        uses: fkirc/skip-duplicate-actions@v5.2.0
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
          paths: '["packages/website/**"]'
      - id: skip_vscodeext_check
        name: Check if the changes are about vscode extension src files
-        uses: fkirc/skip-duplicate-actions@v5.2.0
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
          paths: '["packages/vscode-ext/**"]'
      - id: skip_cli_check
        name: Check if the changes are about cli src files
-        uses: fkirc/skip-duplicate-actions@v5.2.0
+        uses: fkirc/skip-duplicate-actions@v4.0.0
        with:
          paths: '["packages/cli/**"]'

--- a/.gitignore
+++ b/.gitignore
@ -7,9 +7,4 @@ yarn-error.log
 **/.sync.ffs_db
 .direnv
 .log
-
-.vscode
-todo.txt
 result
-shell.nix
-.turbo
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@ -1,7 +1,7 @@
 {
  "packages/cli": "0.0.3",
-  "packages/components": "0.4.1",
-  "packages/squiggle-lang": "0.4.1",
-  "packages/vscode-ext": "0.4.1",
-  "packages/website": "0.0.0"
+  "packages/components": "0.3.1",
+  "packages/squiggle-lang": "0.3.0",
+  "packages/vscode-ext": "0.3.1",
+  "packages/website": "0.3.0"
 }
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -1 +0,0 @@
-See the [Changelog.mdx page](./packages/website/docs/Changelog.mdx) for the changelog.
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@ -16,7 +16,7 @@ Squiggle is currently pre-alpha.

 # Bug reports

-Anyone (with a github account) can file an issue at any time. Please allow Slava, Sam, and Ozzie to triage, but otherwise just follow the suggestions in the issue templates.
+Anyone (with a github account) can file an issue at any time. Please allow Quinn, Sam, and Ozzie to triage, but otherwise just follow the suggestions in the issue templates.

 # Project structure

@ -28,7 +28,7 @@ Squiggle is a **monorepo** with three **packages**.

 # Deployment ops

-We use Vercel, and it should only concern Slava, Sam, and Ozzie.
+We use netlify, and it should only concern Quinn, Sam, and Ozzie.

 # Development environment, building, testing, dev server

@ -56,9 +56,9 @@ If you absolutely must, please prefix your commit message with `hotfix: `.

 Please work against `develop` branch. **Do not** work against `master`.

- For rescript code: Slava and Ozzie are reviewers
+- For rescript code: Quinn and Ozzie are reviewers
 - For js or typescript code: Sam and Ozzie are reviewers
- For ops code (i.e. yaml, package.json): Slava and Sam are reviewers
+- For ops code (i.e. yaml, package.json): Quinn and Sam are reviewers

 Autopings are set up: if you are not autopinged, you are welcome to comment, but please do not use the formal review feature, send approvals, rejections, or merges.

--- a/README.md
+++ b/README.md
@ -21,10 +21,10 @@ _An estimation language_.

 ## Our deployments

- **website/docs prod**: https://squiggle-language.com
- **website/docs staging**: https://preview.squiggle-language.com
- **components storybook prod**: https://components.squiggle-language.com
- **components storybook staging**: https://preview-components.squiggle-language.com
+- **website/docs prod**: https://squiggle-language.com [![Netlify Status](https://api.netlify.com/api/v1/badges/2139af5c-671d-473d-a9f6-66c96077d8a1/deploy-status)](https://app.netlify.com/sites/squiggle-documentation/deploys)
+- **website/docs staging**: https://develop--squiggle-documentation.netlify.app/
+- **components storybook prod**: https://squiggle-components.netlify.app/ [![Netlify Status](https://api.netlify.com/api/v1/badges/b7f724aa-6b20-4d0e-bf86-3fcd1a3e9a70/deploy-status)](https://app.netlify.com/sites/squiggle-components/deploys)
+- **components storybook staging**: https://develop--squiggle-components.netlify.app/
 - **legacy (2020) playground**: https://playground.squiggle-language.com

 ## Packages
@ -51,25 +51,7 @@ For any project in the repo, begin by running `yarn` in the top level
 yarn
 ```

-Then use `turbo` to build the specific packages or the entire monorepo:
-
-```sh
-turbo run build
-```
-
-Or:
-
-```sh
-turbo run build --filter=@quri/squiggle-components
-```
-
-You can also run specific npm scripts for the package you're working on. See `packages/*/README.md` for the details.
-
-# NixOS users
-
-This repository requires the use of bundled binaries from node_modules, which
-are not linked statically. The easiest way to get them working is to enable
-[nix-ld](https://github.com/Mic92/nix-ld).
+See `packages/*/README.md` to work with whatever project you're interested in.

 # Contributing

--- a/nix/squiggle-lang.nix
+++ b/nix/squiggle-lang.nix
@ -30,6 +30,16 @@ rec {
          patchelf --replace-needed libstdc++.so.6 $THE_SO linux/ninja.exe && echo "- replaced needed for linux/ninja.exe"
        '';
      };
+      bisect_ppx = {
+        buildInputs = common.which;
+        postInstall = ''
+          echo "PATCHELF'ING BISECT_PPX EXECUTABLE"
+          THE_LD=$(patchelf --print-interpreter $(which mkdir))
+          patchelf --set-interpreter $THE_LD bin/linux/ppx
+          patchelf --set-interpreter $THE_LD bin/linux/bisect-ppx-report
+          cp bin/linux/ppx ppx
+        '';
+      };
      gentype = {
        postInstall = ''
          mv gentype.exe ELFLESS-gentype.exe
@ -65,7 +75,6 @@ rec {
      # custom gitignore so that the flake keeps build artefacts
      mv .gitignore GITIGNORE
      sed -i /Reducer_Peggy_GeneratedParser.js/d GITIGNORE
-      sed -i /ReducerProject_IncludeParser.js/d GITIGNORE
      sed -i /\*.bs.js/d GITIGNORE
      sed -i /\*.gen.ts/d GITIGNORE
      sed -i /\*.gen.tsx/d GITIGNORE
--- a/nixos.sh
+++ b/nixos.sh
@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# This script is only relevant if you're rolling nixos.
+
+# Esy (a bisect_ppx dependency/build tool) is borked on nixos without using an FHS shell. https://github.com/esy/esy/issues/858
+# We need to patchelf rescript executables. https://github.com/NixOS/nixpkgs/issues/107375
+set -x
+
+fhsShellName="squiggle-fhs-development"
+fhsShellDotNix="{pkgs ? import <nixpkgs> {} }: (pkgs.buildFHSUserEnv { name = \"${fhsShellName}\"; targetPkgs = pkgs: [pkgs.yarn pkgs.glibc]; runScript = \"yarn\"; }).env"
+nix-shell - <<<"$fhsShellDotNix"
+
+theLd=$(patchelf --print-interpreter $(which mkdir))
+patchelf --set-interpreter $theLd ./node_modules/gentype/gentype.exe
+patchelf --set-interpreter $theLd ./node_modules/rescript/linux/*.exe
+patchelf --set-interpreter $theLd ./node_modules/bisect_ppx/ppx
+patchelf --set-interpreter $theLd ./node_modules/bisect_ppx/bisect-ppx-report
+theSo=$(find /nix/store/*$fhsShellName*/lib64 -name libstdc++.so.6 | head -n 1)
+patchelf --replace-needed libstdc++.so.6 $theSo ./node_modules/rescript/linux/ninja.exe
--- a/package.json
+++ b/package.json
@ -2,11 +2,12 @@
  "private": true,
  "name": "squiggle",
  "scripts": {
-    "nodeclean": "rm -r node_modules && rm -r packages/*/node_modules"
+    "nodeclean": "rm -r node_modules && rm -r packages/*/node_modules",
+    "format:all": "prettier --write . && cd packages/squiggle-lang && yarn format",
+    "lint:all": "prettier --check . && cd packages/squiggle-lang && yarn lint:rescript"
  },
  "devDependencies": {
-    "prettier": "^2.7.1",
-    "turbo": "^1.5.5"
+    "prettier": "^2.7.1"
  },
  "workspaces": [
    "packages/*"
--- a/packages/cli/README.md
+++ b/packages/cli/README.md
@ -20,30 +20,3 @@ Runs compilation in the current directory and all of its subdirectories.
 ### `npx squiggle-cli-experimental watch`

 Watches `.squiggleU` files in the current directory (and subdirectories) and rebuilds them when they are saved. Note that this will _not_ rebuild files when their dependencies are changed, just when they are changed directly.
-
-## Further instructions
-
-The above requires having node, npm and npx. To install the first two, see [here](https://nodejs.org/en/), to install npx, run:
-
-```
-npm install -g npx
-```
-
-Alternatively, you can run the following without the need for npx:
-
-```
-npm install squiggle-cli-experimental
-node node_modules/squiggle-cli-experimental/index.js compile
-```
-
-or you can add a script to your `package.json`, like:
-
-```
- ...
- scripts: {
-  "compile": "squiggle-cli-experimental compile"
- }
- ...
-```
-
-This can be run with `npm run compile`. `npm` knows how to reach into the node_modules directly, so it's not necessary to specify that.
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@ -7,15 +7,13 @@
  "bin": "index.js",
  "type": "module",
  "scripts": {
-    "start": "node .",
-    "lint": "prettier --check .",
-    "format": "prettier --write ."
+    "start": "node ."
  },
  "license": "MIT",
  "dependencies": {
-    "chalk": "^5.1.0",
+    "chalk": "^5.0.1",
    "chokidar": "^3.5.3",
-    "commander": "^9.4.1",
+    "commander": "^9.4.0",
    "fs": "^0.0.1-security",
    "glob": "^8.0.3",
    "indent-string": "^5.0.0"
--- a/packages/components/jest.config.js
+++ b/packages/components/jest.config.js
@ -1,6 +0,0 @@
-/** @type {import('ts-jest').JestConfigWithTsJest} */
-module.exports = {
-  preset: "ts-jest",
-  setupFilesAfterEnv: ["<rootDir>/test/setup.js"],
-  testEnvironment: "jsdom",
-};
--- a/packages/components/netlify.toml
+++ b/packages/components/netlify.toml
@ -0,0 +1,8 @@
+[build]
+    base = "packages/components/"
+    command = "cd ../squiggle-lang && yarn build && cd ../components && yarn build"
+    publish = "storybook-static/"
+    ignore = "node -e 'process.exitCode = process.env.BRANCH.includes(\"dependabot\") ? 0 : 1' && git diff --quiet $CACHED_COMMIT_REF $COMMIT_REF . ../squiggle-lang"
+
+[build.environment]
+    NETLIFY_USE_YARN = "true"
--- a/packages/components/package.json
+++ b/packages/components/package.json
@ -1,73 +1,64 @@
 {
  "name": "@quri/squiggle-components",
-  "version": "0.5.0",
+  "version": "0.4.0-alpha.1",
  "license": "MIT",
  "dependencies": {
    "@floating-ui/react-dom": "^1.0.0",
-    "@floating-ui/react-dom-interactions": "^0.10.1",
-    "@headlessui/react": "^1.7.3",
+    "@floating-ui/react-dom-interactions": "^0.9.3",
+    "@headlessui/react": "^1.6.6",
    "@heroicons/react": "^1.0.6",
-    "@hookform/resolvers": "^2.9.8",
-    "@quri/squiggle-lang": "^0.5.0",
+    "@hookform/resolvers": "^2.9.7",
+    "@quri/squiggle-lang": "^0.4.0-alpha.0",
    "@react-hook/size": "^2.1.2",
-    "@types/uuid": "^8.3.4",
    "clsx": "^1.2.1",
-    "framer-motion": "^7.5.3",
+    "framer-motion": "^7.2.1",
    "lodash": "^4.17.21",
    "react": "^18.1.0",
    "react-ace": "^10.1.0",
-    "react-hook-form": "^7.37.0",
+    "react-hook-form": "^7.34.2",
    "react-use": "^17.4.0",
    "react-vega": "^7.6.0",
-    "uuid": "^9.0.0",
    "vega": "^5.22.1",
    "vega-embed": "^6.21.0",
    "vega-lite": "^5.5.0",
-    "vscode-uri": "^3.0.6",
+    "vscode-uri": "^3.0.3",
    "yup": "^0.32.11"
  },
  "devDependencies": {
    "@babel/plugin-proposal-private-property-in-object": "^7.18.6",
-    "@storybook/addon-actions": "^6.5.12",
-    "@storybook/addon-essentials": "^6.5.12",
-    "@storybook/addon-links": "^6.5.12",
-    "@storybook/builder-webpack5": "^6.5.12",
-    "@storybook/manager-webpack5": "^6.5.12",
+    "@storybook/addon-actions": "^6.5.9",
+    "@storybook/addon-essentials": "^6.5.10",
+    "@storybook/addon-links": "^6.5.10",
+    "@storybook/builder-webpack5": "^6.5.10",
+    "@storybook/manager-webpack5": "^6.5.10",
    "@storybook/node-logger": "^6.5.9",
    "@storybook/preset-create-react-app": "^4.1.2",
-    "@storybook/react": "^6.5.12",
+    "@storybook/react": "^6.5.10",
    "@testing-library/jest-dom": "^5.16.5",
    "@testing-library/react": "^13.4.0",
    "@testing-library/user-event": "^14.4.3",
    "@types/jest": "^27.5.0",
-    "@types/lodash": "^4.14.186",
-    "@types/node": "^18.8.3",
-    "@types/react": "^18.0.21",
+    "@types/lodash": "^4.14.184",
+    "@types/node": "^18.7.15",
+    "@types/react": "^18.0.18",
    "@types/styled-components": "^5.1.26",
-    "@types/uuid": "^8.3.4",
    "@types/webpack": "^5.28.0",
-    "canvas": "^2.10.1",
    "cross-env": "^7.0.3",
-    "jest": "^29.0.3",
-    "jest-environment-jsdom": "^29.1.2",
-    "jsdom": "^20.0.1",
    "mini-css-extract-plugin": "^2.6.1",
    "postcss-cli": "^10.0.0",
-    "postcss-import": "^15.0.0",
+    "postcss-import": "^14.1.0",
    "postcss-loader": "^7.0.1",
-    "postcss-nesting": "^10.2.0",
    "react": "^18.1.0",
    "react-scripts": "^5.0.1",
    "style-loader": "^3.3.1",
    "tailwindcss": "^3.1.8",
-    "ts-jest": "^29.0.3",
-    "ts-loader": "^9.4.1",
+    "ts-loader": "^9.3.0",
    "tsconfig-paths-webpack-plugin": "^4.0.0",
-    "typescript": "^4.8.4",
-    "web-vitals": "^3.0.3",
+    "typescript": "^4.8.2",
+    "web-vitals": "^3.0.1",
    "webpack": "^5.74.0",
    "webpack-cli": "^4.10.0",
-    "webpack-dev-server": "^4.11.1"
+    "webpack-dev-server": "^4.10.0"
  },
  "peerDependencies": {
    "react": "^16.8.0 || ^17 || ^18",
@ -75,7 +66,7 @@
  },
  "scripts": {
    "start": "cross-env REACT_APP_FAST_REFRESH=false && start-storybook -p 6006 -s public",
-    "build:cjs": "rm -rf dist/src && rm -f dist/tsconfig.tsbuildinfo && tsc -b",
+    "build:cjs": "rm -rf dist/src && tsc -b",
    "build:css": "postcss ./src/styles/main.css -o ./dist/main.css",
    "build:storybook": "build-storybook -s public",
    "build": "yarn run build:cjs && yarn run build:css && yarn run build:storybook",
@ -83,10 +74,7 @@
    "all": "yarn bundle && yarn build",
    "lint": "prettier --check .",
    "format": "prettier --write .",
-    "prepack": "yarn run build:cjs && yarn run bundle",
-    "test": "jest",
-    "test:debug": "node --inspect-brk node_modules/.bin/jest --runInBand",
-    "test:profile": "node --cpu-prof node_modules/.bin/jest --runInBand"
+    "prepack": "yarn run build:cjs && yarn run bundle"
  },
  "eslintConfig": {
    "extends": [
--- a/packages/components/src/components/Alert.tsx
+++ b/packages/components/src/components/Alert.tsx
@ -24,13 +24,13 @@ export const Alert: React.FC<{
  children,
 }) => {
  return (
-    <div className={clsx("rounded-md p-4", backgroundColor)} role="status">
+    <div className={clsx("rounded-md p-4", backgroundColor)}>
      <div className="flex">
        <Icon
          className={clsx("h-5 w-5 flex-shrink-0", iconColor)}
          aria-hidden="true"
        />
-        <div className="ml-3 grow">
+        <div className="ml-3">
          <header className={clsx("text-sm font-medium", headingColor)}>
            {heading}
          </header>
--- a/packages/components/src/components/CodeEditor.tsx
+++ b/packages/components/src/components/CodeEditor.tsx
@ -5,8 +5,6 @@ import AceEditor from "react-ace";
 import "ace-builds/src-noconflict/mode-golang";
 import "ace-builds/src-noconflict/theme-github";

-import { SqLocation } from "@quri/squiggle-lang";
-
 interface CodeEditorProps {
  value: string;
  onChange: (value: string) => void;
@ -15,17 +13,15 @@ interface CodeEditorProps {
  width?: number;
  height: number;
  showGutter?: boolean;
-  errorLocations?: SqLocation[];
 }

 export const CodeEditor: FC<CodeEditorProps> = ({
  value,
  onChange,
  onSubmit,
-  height,
  oneLine = false,
  showGutter = false,
-  errorLocations = [],
+  height,
 }) => {
  const lineCount = value.split("\n").length;
  const id = useMemo(() => _.uniqueId(), []);
@ -34,11 +30,8 @@ export const CodeEditor: FC<CodeEditorProps> = ({
  const onSubmitRef = useRef<typeof onSubmit | null>(null);
  onSubmitRef.current = onSubmit;

-  const editorEl = useRef<AceEditor | null>(null);
-
  return (
    <AceEditor
-      ref={editorEl}
      value={value}
      mode="golang"
      theme="github"
@ -55,7 +48,10 @@ export const CodeEditor: FC<CodeEditorProps> = ({
      editorProps={{
        $blockScrolling: true,
      }}
-      setOptions={{}}
+      setOptions={{
+        enableBasicAutocompletion: false,
+        enableLiveAutocompletion: false,
+      }}
      commands={[
        {
          name: "submit",
@ -63,14 +59,6 @@ export const CodeEditor: FC<CodeEditorProps> = ({
          exec: () => onSubmitRef.current?.(),
        },
      ]}
-      markers={errorLocations?.map((location) => ({
-        startRow: location.start.line - 1,
-        startCol: location.start.column - 1,
-        endRow: location.end.line - 1,
-        endCol: location.end.column - 1,
-        className: "ace-error-marker",
-        type: "text",
-      }))}
    />
  );
 };
--- a/packages/components/src/components/DistributionChart.tsx
+++ b/packages/components/src/components/DistributionChart.tsx
@ -6,7 +6,6 @@ import {
  resultMap,
  SqRecord,
  environment,
-  SqDistributionTag,
 } from "@quri/squiggle-lang";
 import { Vega } from "react-vega";
 import { ErrorAlert } from "./Alert";
@ -32,7 +31,6 @@ export type DistributionChartProps = {
  environment: environment;
  width?: number;
  height: number;
-  xAxisType?: "number" | "dateTime";
 } & DistributionPlottingSettings;

 export function defaultPlot(distribution: SqDistribution): Plot {
@ -58,15 +56,14 @@ export const DistributionChart: React.FC<DistributionChartProps> = (props) => {
  } = props;
  const [sized] = useSize((size) => {
    const shapes = flattenResult(
-      plot.distributions.map((x) =>
-        resultMap(x.distribution.pointSet(environment), (pointSet) => ({
+      plot.distributions.map((x) => {
+        return resultMap(x.distribution.pointSet(environment), (pointSet) => ({
+          ...pointSet.asShape(),
          name: x.name,
          // color: x.color, // not supported yet
-          ...pointSet.asShape(),
-        }))
-      )
+        }));
+      })
    );
-
    if (shapes.tag === "Error") {
      return (
        <ErrorAlert heading="Distribution Error">
@ -75,40 +72,18 @@ export const DistributionChart: React.FC<DistributionChartProps> = (props) => {
      );
    }

-    // if this is a sample set, include the samples
-    const samples: number[] = [];
-    for (const { distribution } of plot?.distributions) {
-      if (distribution.tag === SqDistributionTag.SampleSet) {
-        samples.push(...distribution.value());
-      }
-    }
+    const spec = buildVegaSpec(props);

-    const domain = shapes.value.flatMap((shape) =>
-      shape.discrete.concat(shape.continuous)
-    );
-
-    const spec = buildVegaSpec({
-      ...props,
-      minX: props.minX ?? Math.min(...domain.map((x) => x.x)),
-      maxX: props.minX ?? Math.max(...domain.map((x) => x.x)),
-      maxY: Math.max(...domain.map((x) => x.y)),
-    });
-
-    // I think size.width is sometimes not finite due to the component not being in a visible context
-    // This occurs during testing
-    let widthProp = width
-      ? width
-      : Number.isFinite(size.width)
-      ? size.width
-      : 400;
+    let widthProp = width ? width : size.width;
    if (widthProp < 20) {
      console.warn(
        `Width of Distribution is set to ${widthProp}, which is too small`
      );
      widthProp = 20;
    }
-
-    const vegaData = { data: shapes.value, samples };
+    const domain = shapes.value.flatMap((shape) =>
+      shape.discrete.concat(shape.continuous)
+    );

    return (
      <div style={{ width: widthProp }}>
@ -119,7 +94,7 @@ export const DistributionChart: React.FC<DistributionChartProps> = (props) => {
        ) : (
          <Vega
            spec={spec}
-            data={vegaData}
+            data={{ data: shapes.value, domain }}
            width={widthProp - 10}
            height={height}
            actions={actions}
--- a/packages/components/src/components/FunctionChart.tsx
+++ b/packages/components/src/components/FunctionChart.tsx
@ -1,15 +1,9 @@
 import * as React from "react";
-import {
-  SqLambda,
-  environment,
-  SqValueTag,
-  SqError,
-} from "@quri/squiggle-lang";
+import { SqLambda, environment, SqValueTag } from "@quri/squiggle-lang";
 import { FunctionChart1Dist } from "./FunctionChart1Dist";
 import { FunctionChart1Number } from "./FunctionChart1Number";
 import { DistributionPlottingSettings } from "./DistributionChart";
-import { MessageAlert } from "./Alert";
-import { SquiggleErrorAlert } from "./SquiggleErrorAlert";
+import { ErrorAlert, MessageAlert } from "./Alert";

 export type FunctionChartSettings = {
  start: number;
@ -25,25 +19,6 @@ interface FunctionChartProps {
  height: number;
 }

-const FunctionCallErrorAlert = ({ error }: { error: SqError }) => {
-  const [expanded, setExpanded] = React.useState(false);
-  if (expanded) {
-  }
-  return (
-    <MessageAlert heading="Function Display Failed">
-      <div className="space-y-2">
-        <span
-          className="underline decoration-dashed cursor-pointer"
-          onClick={() => setExpanded(!expanded)}
-        >
-          {expanded ? "Hide" : "Show"} error details
-        </span>
-        {expanded ? <SquiggleErrorAlert error={error} /> : null}
-      </div>
-    </MessageAlert>
-  );
-};
-
 export const FunctionChart: React.FC<FunctionChartProps> = ({
  fn,
  chartSettings,
@ -51,8 +26,7 @@ export const FunctionChart: React.FC<FunctionChartProps> = ({
  distributionPlotSettings,
  height,
 }) => {
-  console.log(fn.parameters().length);
-  if (fn.parameters().length !== 1) {
+  if (fn.parameters.length > 1) {
    return (
      <MessageAlert heading="Function Display Not Supported">
        Only functions with one parameter are displayed.
@ -73,7 +47,9 @@ export const FunctionChart: React.FC<FunctionChartProps> = ({
  const validResult = getValidResult();

  if (validResult.tag === "Error") {
-    return <FunctionCallErrorAlert error={validResult.value} />;
+    return (
+      <ErrorAlert heading="Error">{validResult.value.toString()}</ErrorAlert>
+    );
  }

  switch (validResult.value.tag) {
--- a/packages/components/src/components/SquiggleChart.tsx
+++ b/packages/components/src/components/SquiggleChart.tsx
@ -2,21 +2,23 @@ import * as React from "react";
 import {
  SqValue,
  environment,
-  SqProject,
  defaultEnvironment,
+  resultMap,
+  SqValueTag,
 } from "@quri/squiggle-lang";
 import { useSquiggle } from "../lib/hooks";
 import { SquiggleViewer } from "./SquiggleViewer";
 import { JsImports } from "../lib/jsImports";
-import { getValueToRender } from "../lib/utility";

-export type SquiggleChartProps = {
+export interface SquiggleChartProps {
  /** The input string for squiggle */
-  code: string;
+  code?: string;
  /** Allows to re-run the code if code hasn't changed */
  executionId?: number;
  /** If the output requires monte carlo sampling, the amount of samples */
  sampleCount?: number;
+  /** The amount of points returned to draw the distribution */
+  environment?: environment;
  /** If the result is a function, where the function domain starts */
  diagramStart?: number;
  /** If the result is a function, where the function domain ends */
@ -24,7 +26,7 @@ export type SquiggleChartProps = {
  /** If the result is a function, the amount of stops sampled */
  diagramCount?: number;
  /** When the squiggle code gets reevaluated */
-  onChange?(expr: SqValue | undefined, sourceName: string): void;
+  onChange?(expr: SqValue | undefined): void;
  /** CSS width of the element */
  width?: number;
  height?: number;
@ -46,35 +48,24 @@ export type SquiggleChartProps = {
  minX?: number;
  /** Specify the upper bound of the x scale */
  maxX?: number;
-  /** Whether the x-axis should be dates or numbers */
-  xAxisType?: "number" | "dateTime";
  /** Whether to show vega actions to the user, so they can copy the chart spec */
  distributionChartActions?: boolean;
  enableLocalSettings?: boolean;
-} & (StandaloneExecutionProps | ProjectExecutionProps);
+}

-// Props needed for a standalone execution
-type StandaloneExecutionProps = {
-  project?: undefined;
-  continues?: undefined;
-  /** The amount of points returned to draw the distribution, not needed if using a project */
-  environment?: environment;
-};
-
-// Props needed when executing inside a project.
-type ProjectExecutionProps = {
-  environment?: undefined;
-  /** The project that this execution is part of */
-  project: SqProject;
-  /** What other squiggle sources from the project to continue. Default [] */
-  continues?: string[];
-};
 const defaultOnChange = () => {};
 const defaultImports: JsImports = {};

-export const splitSquiggleChartSettings = (props: SquiggleChartProps) => {
-  const {
+export const SquiggleChart: React.FC<SquiggleChartProps> = React.memo(
+  ({
+    code = "",
+    executionId = 0,
+    environment,
+    onChange = defaultOnChange, // defaultOnChange must be constant, don't move its definition here
+    height = 200,
+    jsImports = defaultImports,
    showSummary = false,
+    width,
    logX = false,
    expY = false,
    diagramStart = 0,
@ -85,72 +76,47 @@ export const splitSquiggleChartSettings = (props: SquiggleChartProps) => {
    maxX,
    color,
    title,
-    xAxisType = "number",
    distributionChartActions,
-  } = props;
-
-  const distributionPlotSettings = {
-    showSummary,
-    logX,
-    expY,
-    format: tickFormat,
-    minX,
-    maxX,
-    color,
-    title,
-    xAxisType,
-    actions: distributionChartActions,
-  };
-
-  const chartSettings = {
-    start: diagramStart,
-    stop: diagramStop,
-    count: diagramCount,
-  };
-
-  return { distributionPlotSettings, chartSettings };
-};
-
-export const SquiggleChart: React.FC<SquiggleChartProps> = React.memo(
-  (props) => {
-    const { distributionPlotSettings, chartSettings } =
-      splitSquiggleChartSettings(props);
-
-    const {
+    enableLocalSettings = false,
+  }) => {
+    const { result, bindings } = useSquiggle({
      code,
-      jsImports = defaultImports,
-      onChange = defaultOnChange, // defaultOnChange must be constant, don't move its definition here
-      executionId = 0,
-      width,
-      height = 200,
-      enableLocalSettings = false,
-      continues,
-      project,
      environment,
-    } = props;
-
-    const resultAndBindings = useSquiggle({
-      environment,
-      continues,
-      project,
-      code,
      jsImports,
      onChange,
      executionId,
    });

-    const valueToRender = getValueToRender(resultAndBindings);
+    const distributionPlotSettings = {
+      showSummary,
+      logX,
+      expY,
+      format: tickFormat,
+      minX,
+      maxX,
+      color,
+      title,
+      actions: distributionChartActions,
+    };
+
+    const chartSettings = {
+      start: diagramStart,
+      stop: diagramStop,
+      count: diagramCount,
+    };
+
+    const resultToRender = resultMap(result, (value) =>
+      value.tag === SqValueTag.Void ? bindings.asValue() : value
+    );

    return (
      <SquiggleViewer
-        result={valueToRender}
+        result={resultToRender}
        width={width}
        height={height}
        distributionPlotSettings={distributionPlotSettings}
        chartSettings={chartSettings}
-        environment={
-          project ? project.getEnvironment() : environment ?? defaultEnvironment
-        }
+        environment={environment ?? defaultEnvironment}
        enableLocalSettings={enableLocalSettings}
      />
    );
--- a/packages/components/src/components/SquiggleEditor.tsx
+++ b/packages/components/src/components/SquiggleEditor.tsx
@ -1,29 +1,20 @@
 import React from "react";
 import { CodeEditor } from "./CodeEditor";
 import { SquiggleContainer } from "./SquiggleContainer";
-import {
-  splitSquiggleChartSettings,
-  SquiggleChartProps,
-} from "./SquiggleChart";
-import { useMaybeControlledValue, useSquiggle } from "../lib/hooks";
-import { JsImports } from "../lib/jsImports";
-import { defaultEnvironment, SqLocation, SqProject } from "@quri/squiggle-lang";
-import { SquiggleViewer } from "./SquiggleViewer";
-import { getErrorLocations, getValueToRender } from "../lib/utility";
+import { SquiggleChart, SquiggleChartProps } from "./SquiggleChart";
+import { useMaybeControlledValue } from "../lib/hooks";

 const WrappedCodeEditor: React.FC<{
  code: string;
  setCode: (code: string) => void;
-  errorLocations?: SqLocation[];
-}> = ({ code, setCode, errorLocations }) => (
-  <div className="border border-grey-200 p-2 m-4" data-testid="squiggle-editor">
+}> = ({ code, setCode }) => (
+  <div className="border border-grey-200 p-2 m-4">
    <CodeEditor
      value={code}
      onChange={setCode}
      oneLine={true}
      showGutter={false}
      height={20}
-      errorLocations={errorLocations}
    />
  </div>
 );
@ -33,9 +24,6 @@ export type SquiggleEditorProps = SquiggleChartProps & {
  onCodeChange?: (code: string) => void;
 };

-const defaultOnChange = () => {};
-const defaultImports: JsImports = {};
-
 export const SquiggleEditor: React.FC<SquiggleEditorProps> = (props) => {
  const [code, setCode] = useMaybeControlledValue({
    value: props.code,
@ -43,50 +31,11 @@ export const SquiggleEditor: React.FC<SquiggleEditorProps> = (props) => {
    onChange: props.onCodeChange,
  });

-  const { distributionPlotSettings, chartSettings } =
-    splitSquiggleChartSettings(props);
-
-  const {
-    environment,
-    jsImports = defaultImports,
-    onChange = defaultOnChange, // defaultOnChange must be constant, don't move its definition here
-    executionId = 0,
-    width,
-    height = 200,
-    enableLocalSettings = false,
-    continues,
-    project,
-  } = props;
-
-  const resultAndBindings = useSquiggle({
-    environment,
-    continues,
-    code,
-    project,
-    jsImports,
-    onChange,
-    executionId,
-  });
-
-  const valueToRender = getValueToRender(resultAndBindings);
-  const errorLocations = getErrorLocations(resultAndBindings.result);
-
+  let chartProps = { ...props, code };
  return (
    <SquiggleContainer>
-      <WrappedCodeEditor
-        code={code}
-        setCode={setCode}
-        errorLocations={errorLocations}
-      />
-      <SquiggleViewer
-        result={valueToRender}
-        width={width}
-        height={height}
-        distributionPlotSettings={distributionPlotSettings}
-        chartSettings={chartSettings}
-        environment={environment ?? defaultEnvironment}
-        enableLocalSettings={enableLocalSettings}
-      />
+      <WrappedCodeEditor code={code} setCode={setCode} />
+      <SquiggleChart {...chartProps} />
    </SquiggleContainer>
  );
 };
--- a/packages/components/src/components/SquiggleErrorAlert.tsx
+++ b/packages/components/src/components/SquiggleErrorAlert.tsx
@ -1,4 +1,4 @@
-import { SqError, SqFrame } from "@quri/squiggle-lang";
+import { SqError } from "@quri/squiggle-lang";
 import React from "react";
 import { ErrorAlert } from "./Alert";

@ -6,39 +6,6 @@ type Props = {
  error: SqError;
 };

-const StackTraceFrame: React.FC<{ frame: SqFrame }> = ({ frame }) => {
-  const location = frame.location();
-  return (
-    <div>
-      {frame.name()}
-      {location
-        ? ` at line ${location.start.line}, column ${location.start.column}`
-        : ""}
-    </div>
-  );
-};
-
-const StackTrace: React.FC<Props> = ({ error }) => {
-  const frames = error.getFrameArray();
-  return frames.length ? (
-    <div>
-      <div className="font-medium">Stack trace:</div>
-      <div className="ml-4">
-        {frames.map((frame, i) => (
-          <StackTraceFrame frame={frame} key={i} />
-        ))}
-      </div>
-    </div>
-  ) : null;
-};
-
 export const SquiggleErrorAlert: React.FC<Props> = ({ error }) => {
-  return (
-    <ErrorAlert heading="Error">
-      <div className="space-y-4">
-        <div>{error.toString()}</div>
-        <StackTrace error={error} />
-      </div>
-    </ErrorAlert>
-  );
+  return <ErrorAlert heading="Error">{error.toString()}</ErrorAlert>;
 };
--- a/packages/components/src/components/SquigglePlayground.tsx
+++ b/packages/components/src/components/SquigglePlayground.tsx
@ -8,11 +8,7 @@ import React, {
 } from "react";
 import { useForm, UseFormRegister, useWatch } from "react-hook-form";
 import * as yup from "yup";
-import {
-  useMaybeControlledValue,
-  useRunnerState,
-  useSquiggle,
-} from "../lib/hooks";
+import { useMaybeControlledValue, useRunnerState } from "../lib/hooks";
 import { yupResolver } from "@hookform/resolvers/yup";
 import {
  ChartSquareBarIcon,
@ -28,9 +24,9 @@ import {
 } from "@heroicons/react/solid";
 import clsx from "clsx";

-import { environment, SqProject } from "@quri/squiggle-lang";
+import { environment } from "@quri/squiggle-lang";

-import { SquiggleChartProps } from "./SquiggleChart";
+import { SquiggleChart, SquiggleChartProps } from "./SquiggleChart";
 import { CodeEditor } from "./CodeEditor";
 import { JsonEditor } from "./JsonEditor";
 import { ErrorAlert, SuccessAlert } from "./Alert";
@ -44,8 +40,6 @@ import { HeadedSection } from "./ui/HeadedSection";
 import { defaultTickFormat } from "../lib/distributionSpecBuilder";
 import { Button } from "./ui/Button";
 import { JsImports } from "../lib/jsImports";
-import { getErrorLocations, getValueToRender } from "../lib/utility";
-import { SquiggleViewer } from "./SquiggleViewer";

 type PlaygroundProps = SquiggleChartProps & {
  /** The initial squiggle string to put in the playground */
@ -182,7 +176,7 @@ const RunControls: React.FC<{
  const CurrentPlayIcon = isRunning ? RefreshIcon : PlayIcon;

  return (
-    <div className="flex space-x-1 items-center" data-testid="autorun-controls">
+    <div className="flex space-x-1 items-center">
      {autorunMode ? null : (
        <button onClick={run}>
          <CurrentPlayIcon
@ -251,8 +245,6 @@ export const SquigglePlayground: FC<PlaygroundProps> = ({
  onSettingsChange,
  showEditor = true,
  showShareButton = false,
-  continues,
-  project,
 }) => {
  const [code, setCode] = useMaybeControlledValue({
    value: controlledCode,
@ -290,7 +282,7 @@ export const SquigglePlayground: FC<PlaygroundProps> = ({
    onSettingsChange?.(vars);
  }, [vars, onSettingsChange]);

-  const environment: environment = useMemo(
+  const env: environment = useMemo(
    () => ({
      sampleCount: Number(vars.sampleCount),
      xyPointLength: Number(vars.xyPointLength),
@ -307,53 +299,26 @@ export const SquigglePlayground: FC<PlaygroundProps> = ({
    executionId,
  } = useRunnerState(code);

-  const resultAndBindings = useSquiggle({
-    environment,
-    continues,
-    code: renderedCode,
-    project,
-    jsImports: imports,
-    executionId,
-  });
-
-  const valueToRender = getValueToRender(resultAndBindings);
-
  const squiggleChart =
    renderedCode === "" ? null : (
      <div className="relative">
        {isRunning ? (
          <div className="absolute inset-0 bg-white opacity-0 animate-semi-appear" />
        ) : null}
-        <SquiggleViewer
-          result={valueToRender}
-          environment={environment}
-          height={vars.chartHeight || 150}
-          distributionPlotSettings={{
-            showSummary: vars.showSummary ?? false,
-            logX: vars.logX ?? false,
-            expY: vars.expY ?? false,
-            format: vars.tickFormat,
-            minX: vars.minX,
-            maxX: vars.maxX,
-            title: vars.title,
-            actions: vars.distributionChartActions,
-          }}
-          chartSettings={{
-            start: vars.diagramStart ?? 0,
-            stop: vars.diagramStop ?? 10,
-            count: vars.diagramCount ?? 20,
-          }}
+        <SquiggleChart
+          code={renderedCode}
+          executionId={executionId}
+          environment={env}
+          {...vars}
+          jsImports={imports}
          enableLocalSettings={true}
        />
      </div>
    );

-  const errorLocations = getErrorLocations(resultAndBindings.result);
-
  const firstTab = vars.showEditor ? (
-    <div className="border border-slate-200" data-testid="squiggle-editor">
+    <div className="border border-slate-200">
      <CodeEditor
-        errorLocations={errorLocations}
        value={code}
        onChange={setCode}
        onSubmit={run}
@ -403,9 +368,7 @@ export const SquigglePlayground: FC<PlaygroundProps> = ({
      >
        {tabs}
      </div>
-      <div className="w-1/2 p-2 pl-4" data-testid="playground-result">
-        {squiggleChart}
-      </div>
+      <div className="w-1/2 p-2 pl-4">{squiggleChart}</div>
    </div>
  );

--- a/packages/components/src/components/SquiggleViewer/ExpressionViewer.tsx
+++ b/packages/components/src/components/SquiggleViewer/ExpressionViewer.tsx
@ -2,7 +2,7 @@ import React, { useContext } from "react";
 import { SqDistributionTag, SqValue, SqValueTag } from "@quri/squiggle-lang";
 import { NumberShower } from "../NumberShower";
 import { DistributionChart, defaultPlot, makePlot } from "../DistributionChart";
-import { FunctionChart } from "../FunctionChart";
+import { FunctionChart, FunctionChartSettings } from "../FunctionChart";
 import clsx from "clsx";
 import { VariableBox } from "./VariableBox";
 import { ItemSettingsMenu } from "./ItemSettingsMenu";
@ -135,6 +135,29 @@ export const ExpressionViewer: React.FC<Props> = ({ value, width }) => {
          {() => value.value.toString()}
        </VariableBox>
      );
+    case SqValueTag.Symbol:
+      return (
+        <VariableBox value={value} heading="Symbol">
+          {() => (
+            <>
+              <span className="text-slate-500 mr-2">Undefined Symbol:</span>
+              <span className="text-slate-600">{value.value}</span>
+            </>
+          )}
+        </VariableBox>
+      );
+    case SqValueTag.Call:
+      return (
+        <VariableBox value={value} heading="Call">
+          {() => value.value}
+        </VariableBox>
+      );
+    case SqValueTag.ArrayString:
+      return (
+        <VariableBox value={value} heading="Array String">
+          {() => value.value.map((r) => `"${r}"`).join(", ")}
+        </VariableBox>
+      );
    case SqValueTag.Date:
      return (
        <VariableBox value={value} heading="Date">
@ -219,6 +242,24 @@ export const ExpressionViewer: React.FC<Props> = ({ value, width }) => {
        </VariableBox>
      );
    }
+    case SqValueTag.Module: {
+      return (
+        <VariableList value={value} heading="Module">
+          {(_) =>
+            value.value
+              .entries()
+              .filter(([key, _]) => !key.match(/^(__result__)$/))
+              .map(([key, r]) => (
+                <ExpressionViewer
+                  key={key}
+                  value={r}
+                  width={width !== undefined ? width - 20 : width}
+                />
+              ))
+          }
+        </VariableList>
+      );
+    }
    case SqValueTag.Record:
      const plot = makePlot(value.value);
      if (plot) {
@ -298,9 +339,7 @@ export const ExpressionViewer: React.FC<Props> = ({ value, width }) => {
          {() => (
            <div>
              <span>No display for type: </span>{" "}
-              <span className="font-semibold text-slate-600">
-                {(value as { tag: string }).tag}
-              </span>
+              <span className="font-semibold text-slate-600">{value.tag}</span>
            </div>
          )}
        </VariableList>
--- a/packages/components/src/components/SquiggleViewer/VariableBox.tsx
+++ b/packages/components/src/components/SquiggleViewer/VariableBox.tsx
@ -1,4 +1,4 @@
-import { SqValue } from "@quri/squiggle-lang";
+import { SqValue, SqValueLocation } from "@quri/squiggle-lang";
 import React, { useContext, useReducer } from "react";
 import { Tooltip } from "../ui/Tooltip";
 import { LocalItemSettings, MergedItemSettings } from "./utils";
@ -45,7 +45,7 @@ export const VariableBox: React.FC<VariableBoxProps> = ({
    : location.path.items[location.path.items.length - 1];

  return (
-    <div role={isTopLevel ? "status" : undefined}>
+    <div>
      <header className="inline-flex space-x-1">
        <Tooltip text={heading}>
          <span
@ -70,7 +70,7 @@ export const VariableBox: React.FC<VariableBoxProps> = ({
        <div className="flex w-full">
          {location.path.items.length ? (
            <div
-              className="shrink-0 border-l-2 border-slate-200 hover:border-indigo-600 w-4 cursor-pointer"
+              className="border-l-2 border-slate-200 hover:border-indigo-600 w-4 cursor-pointer"
              onClick={toggleCollapsed}
            ></div>
          ) : null}
--- a/packages/components/src/index.ts
+++ b/packages/components/src/index.ts
@ -1,4 +1,3 @@
-export { SqProject } from "@quri/squiggle-lang/";
 export { SquiggleChart } from "./components/SquiggleChart";
 export { SquiggleEditor } from "./components/SquiggleEditor";
 export { SquigglePlayground } from "./components/SquigglePlayground";
--- a/packages/components/src/lib/distributionSpecBuilder.ts
+++ b/packages/components/src/lib/distributionSpecBuilder.ts
@ -1,5 +1,5 @@
 import { VisualizationSpec } from "react-vega";
-import type { LogScale, LinearScale, PowScale, TimeScale } from "vega";
+import type { LogScale, LinearScale, PowScale } from "vega";

 export type DistributionChartSpecOptions = {
  /** Set the x scale to be logarithmic by deault */
@ -14,21 +14,26 @@ export type DistributionChartSpecOptions = {
  title?: string;
  /** The formatting of the ticks */
  format?: string;
-  /** Whether the x-axis should be dates or numbers */
-  xAxisType?: "number" | "dateTime";
 };

-/** X Scales */
-export const linearXScale: LinearScale = {
+export let linearXScale: LinearScale = {
  name: "xscale",
  clamp: true,
  type: "linear",
  range: "width",
  zero: false,
  nice: false,
+  domain: { data: "domain", field: "x" },
+};
+export let linearYScale: LinearScale = {
+  name: "yscale",
+  type: "linear",
+  range: "height",
+  zero: true,
+  domain: { data: "domain", field: "y" },
 };

-export const logXScale: LogScale = {
+export let logXScale: LogScale = {
  name: "xscale",
  type: "log",
  range: "width",
@ -36,104 +41,60 @@ export const logXScale: LogScale = {
  base: 10,
  nice: false,
  clamp: true,
+  domain: { data: "domain", field: "x" },
 };

-export const timeXScale: TimeScale = {
-  name: "xscale",
-  clamp: true,
-  type: "time",
-  range: "width",
-  nice: false,
-};
-
-/** Y Scales */
-export const linearYScale: LinearScale = {
-  name: "yscale",
-  type: "linear",
-  range: "height",
-  zero: true,
-};
-
-export const expYScale: PowScale = {
+export let expYScale: PowScale = {
  name: "yscale",
  type: "pow",
  exponent: 0.1,
  range: "height",
  zero: true,
  nice: false,
+  domain: { data: "domain", field: "y" },
 };

 export const defaultTickFormat = ".9~s";
-export const timeTickFormat = "%b %d, %Y %H:%M";
-const width = 500;

 export function buildVegaSpec(
-  specOptions: DistributionChartSpecOptions & { maxY: number }
+  specOptions: DistributionChartSpecOptions
 ): VisualizationSpec {
  const {
+    format = defaultTickFormat,
    title,
    minX,
    maxX,
    logX,
    expY,
-    xAxisType = "number",
-    maxY,
  } = specOptions;

-  const dateTime = xAxisType === "dateTime";
+  let xScale = logX ? logXScale : linearXScale;
+  if (minX !== undefined && Number.isFinite(minX)) {
+    xScale = { ...xScale, domainMin: minX };
+  }

-  // some fallbacks
-  const format = specOptions?.format
-    ? specOptions.format
-    : dateTime
-    ? timeTickFormat
-    : defaultTickFormat;
+  if (maxX !== undefined && Number.isFinite(maxX)) {
+    xScale = { ...xScale, domainMax: maxX };
+  }

-  let xScale = dateTime ? timeXScale : logX ? logXScale : linearXScale;
-
-  xScale = {
-    ...xScale,
-    domain: [minX ?? 0, maxX ?? 1],
-    domainMin: minX,
-    domainMax: maxX,
-  };
-
-  let yScale = expY ? expYScale : linearYScale;
-  yScale = { ...yScale, domain: [0, maxY ?? 1], domainMin: 0, domainMax: maxY };
-
-  const spec: VisualizationSpec = {
+  let spec: VisualizationSpec = {
    $schema: "https://vega.github.io/schema/vega/v5.json",
    description: "Squiggle plot chart",
-    width: width,
+    width: 500,
    height: 100,
    padding: 5,
-    data: [{ name: "data" }, { name: "domain" }, { name: "samples" }],
-    signals: [
+    data: [
      {
-        name: "hover",
-        value: null,
-        on: [
-          { events: "mouseover", update: "datum" },
-          { events: "mouseout", update: "null" },
-        ],
+        name: "data",
      },
      {
-        name: "position",
-        value: "[0, 0]",
-        on: [
-          { events: "mousemove", update: "xy() " },
-          { events: "mouseout", update: "null" },
-        ],
-      },
-      {
-        name: "position_scaled",
-        value: null,
-        update: "isArray(position) ? invert('xscale', position[0]) : ''",
+        name: "domain",
      },
    ],
+    signals: [],
    scales: [
      xScale,
-      yScale,
+      expY ? expYScale : linearYScale,
      {
        name: "color",
        type: "ordinal",
@ -154,7 +115,7 @@ export function buildVegaSpec(
        domainColor: "#fff",
        domainOpacity: 0.0,
        format: format,
-        tickCount: dateTime ? 3 : 10,
+        tickCount: 10,
        labelOverlap: "greedy",
      },
    ],
@ -271,16 +232,13 @@ export function buildVegaSpec(
                    },
                    size: [{ value: 100 }],
                    tooltip: {
-                      signal: dateTime
-                        ? "{ probability: datum.y, value: datetime(datum.x) }"
-                        : "{ probability: datum.y, value: datum.x }",
+                      signal: "{ probability: datum.y, value: datum.x }",
                    },
                  },
                  update: {
                    x: {
                      scale: "xscale",
                      field: "x",
-                      offset: 0.5, // if this is not included, the circles are slightly left of center.
                    },
                    y: {
                      scale: "yscale",
@ -297,69 +255,6 @@ export function buildVegaSpec(
          },
        ],
      },
-
-      {
-        name: "sampleset",
-        type: "rect",
-        from: { data: "samples" },
-        encode: {
-          enter: {
-            x: { scale: "xscale", field: "data" },
-            width: { value: 0.1 },
-
-            y: { value: 25, offset: { signal: "height" } },
-            height: { value: 5 },
-          },
-        },
-      },
-      {
-        type: "text",
-        name: "announcer",
-        interactive: false,
-        encode: {
-          enter: {
-            x: { signal: String(width), offset: 1 }, // vega would prefer its internal ` "width" ` variable, but that breaks the squiggle playground. Just setting it to the same var as used elsewhere in the spec achieves the same result.
-            fill: { value: "black" },
-            fontSize: { value: 20 },
-            align: { value: "right" },
-          },
-          update: {
-            text: {
-              signal: dateTime
-                ? "position_scaled ? utcyear(position_scaled) + '-' + utcmonth(position_scaled) + '-' + utcdate(position_scaled) + 'T' + utchours(position_scaled)+':' +utcminutes(position_scaled) : ''"
-                : "position_scaled ? format(position_scaled, ',.4r')  : ''",
-            },
-          },
-        },
-      },
-      {
-        type: "rule",
-        interactive: false,
-        encode: {
-          enter: {
-            x: { value: 0 },
-            y: { scale: "yscale", value: 0 },
-
-            y2: {
-              signal: "height",
-              offset: 2,
-            },
-            strokeDash: { value: [5, 5] },
-          },
-
-          update: {
-            x: {
-              signal:
-                "position ? position[0] < 0 ? null : position[0] > width ? null : position[0]: null",
-            },
-
-            opacity: {
-              signal:
-                "position ? position[0] < 0 ? 0 : position[0] > width ? 0 : 1 : 0",
-            },
-          },
-        },
-      },
    ],
    legends: [
      {
--- a/packages/components/src/lib/hooks/useSquiggle.ts
+++ b/packages/components/src/lib/hooks/useSquiggle.ts
@ -1,97 +1,42 @@
-import {
-  result,
-  SqError,
-  SqProject,
-  SqRecord,
-  SqValue,
-  environment,
-} from "@quri/squiggle-lang";
+import { environment, SqProject, SqValue } from "@quri/squiggle-lang";
 import { useEffect, useMemo } from "react";
 import { JsImports, jsImportsToSquiggleCode } from "../jsImports";
-import * as uuid from "uuid";

 type SquiggleArgs = {
-  environment?: environment;
  code: string;
  executionId?: number;
  jsImports?: JsImports;
-  project?: SqProject;
-  continues?: string[];
-  onChange?: (expr: SqValue | undefined, sourceName: string) => void;
+  environment?: environment;
+  onChange?: (expr: SqValue | undefined) => void;
 };

-export type ResultAndBindings = {
-  result: result<SqValue, SqError>;
-  bindings: SqRecord;
-};
-
-const importSourceName = (sourceName: string) => "imports-" + sourceName;
-const defaultContinues = [];
-
-export const useSquiggle = (args: SquiggleArgs): ResultAndBindings => {
-  const project = useMemo(() => {
-    if (args.project) {
-      return args.project;
-    } else {
-      const p = SqProject.create();
-      if (args.environment) {
-        p.setEnvironment(args.environment);
-      }
-      return p;
-    }
-  }, [args.project, args.environment]);
-
-  const sourceName = useMemo(() => uuid.v4(), []);
-
-  const env = project.getEnvironment();
-  const continues = args.continues || defaultContinues;
-
+export const useSquiggle = (args: SquiggleArgs) => {
  const result = useMemo(
    () => {
-      project.setSource(sourceName, args.code);
-      let fullContinues = continues;
+      const project = SqProject.create();
+      project.setSource("main", args.code);
+      if (args.environment) {
+        project.setEnvironment(args.environment);
+      }
      if (args.jsImports && Object.keys(args.jsImports).length) {
        const importsSource = jsImportsToSquiggleCode(args.jsImports);
-        project.setSource(importSourceName(sourceName), importsSource);
-        fullContinues = continues.concat(importSourceName(sourceName));
+        project.setSource("imports", importsSource);
+        project.setContinues("main", ["imports"]);
      }
-      project.setContinues(sourceName, fullContinues);
-      project.run(sourceName);
-      const result = project.getResult(sourceName);
-      const bindings = project.getBindings(sourceName);
+      project.run("main");
+      const result = project.getResult("main");
+      const bindings = project.getBindings("main");
      return { result, bindings };
    },
-    // This complains about executionId not being used inside the function body.
-    // This is on purpose, as executionId simply allows you to run the squiggle
-    // code again
    // eslint-disable-next-line react-hooks/exhaustive-deps
-    [
-      args.code,
-      args.jsImports,
-      args.executionId,
-      sourceName,
-      continues,
-      project,
-      env,
-    ]
+    [args.code, args.environment, args.jsImports, args.executionId]
  );

  const { onChange } = args;

  useEffect(() => {
-    onChange?.(
-      result.result.tag === "Ok" ? result.result.value : undefined,
-      sourceName
-    );
-  }, [result, onChange, sourceName]);
-
-  useEffect(() => {
-    return () => {
-      project.removeSource(sourceName);
-      if (project.getSource(importSourceName(sourceName)))
-        project.removeSource(importSourceName(sourceName));
-    };
-  }, [project, sourceName]);
+    onChange?.(result.result.tag === "Ok" ? result.result.value : undefined);
+  }, [result, onChange]);

  return result;
 };
--- a/packages/components/src/lib/plotParser.ts
+++ b/packages/components/src/lib/plotParser.ts
@ -1,11 +1,5 @@
 import * as yup from "yup";
-import {
-  SqValue,
-  SqValueTag,
-  SqDistribution,
-  result,
-  SqRecord,
-} from "@quri/squiggle-lang";
+import { SqDistribution, result, SqRecord } from "@quri/squiggle-lang";

 export type LabeledDistribution = {
  name: string;
@ -27,55 +21,48 @@ function ok<a, b>(x: a): result<a, b> {

 const schema = yup
  .object()
-  .noUnknown()
  .strict()
+  .noUnknown()
  .shape({
-    distributions: yup
-      .array()
-      .required()
-      .of(
-        yup.object().required().shape({
-          name: yup.string().required(),
-          distribution: yup.mixed().required(),
-        })
-      ),
+    distributions: yup.object().shape({
+      tag: yup.mixed().oneOf(["array"]),
+      value: yup
+        .array()
+        .of(
+          yup.object().shape({
+            tag: yup.mixed().oneOf(["record"]),
+            value: yup.object({
+              name: yup.object().shape({
+                tag: yup.mixed().oneOf(["string"]),
+                value: yup.string().required(),
+              }),
+              // color: yup
+              //   .object({
+              //     tag: yup.mixed().oneOf(["string"]),
+              //     value: yup.string().required(),
+              //   })
+              //   .default(undefined),
+              distribution: yup.object({
+                tag: yup.mixed().oneOf(["distribution"]),
+                value: yup.mixed(),
+              }),
+            }),
+          })
+        )
+        .required(),
+    }),
  });

-type JsonObject =
-  | string
-  | { [key: string]: JsonObject }
-  | JsonObject[]
-  | SqDistribution;
-
-function toJson(val: SqValue): JsonObject {
-  if (val.tag === SqValueTag.String) {
-    return val.value;
-  } else if (val.tag === SqValueTag.Record) {
-    return toJsonRecord(val.value);
-  } else if (val.tag === SqValueTag.Array) {
-    return val.value.getValues().map(toJson);
-  } else if (val.tag === SqValueTag.Distribution) {
-    return val.value;
-  } else {
-    throw new Error("Could not parse object of type " + val.tag);
-  }
-}
-
-function toJsonRecord(val: SqRecord): JsonObject {
-  let recordObject: JsonObject = {};
-  val.entries().forEach(([key, value]) => (recordObject[key] = toJson(value)));
-  return recordObject;
-}
-
 export function parsePlot(record: SqRecord): result<Plot, string> {
  try {
-    const plotRecord = schema.validateSync(toJsonRecord(record));
-    if (plotRecord.distributions) {
-      return ok({ distributions: plotRecord.distributions.map((x) => x) });
-    } else {
-      // I have no idea why yup's typings thinks this is possible
-      return error("no distributions field. Should never get here");
-    }
+    const plotRecord = schema.validateSync(record);
+    return ok({
+      distributions: plotRecord.distributions.value.map((x) => ({
+        name: x.value.name.value,
+        // color: x.value.color?.value, // not supported yet
+        distribution: x.value.distribution.value,
+      })),
+    });
  } catch (e) {
    const message = e instanceof Error ? e.message : "Unknown error";
    return error(message);
--- a/packages/components/src/lib/utility.ts
+++ b/packages/components/src/lib/utility.ts
@ -1,5 +1,4 @@
-import { result, resultMap, SqValueTag } from "@quri/squiggle-lang";
-import { ResultAndBindings } from "./hooks/useSquiggle";
+import { result } from "@quri/squiggle-lang";

 export function flattenResult<a, b>(x: result<a, b>[]): result<a[], b> {
  if (x.length === 0) {
@ -36,18 +35,3 @@ export function all(arr: boolean[]): boolean {
 export function some(arr: boolean[]): boolean {
  return arr.reduce((x, y) => x || y, false);
 }
-
-export function getValueToRender({ result, bindings }: ResultAndBindings) {
-  return resultMap(result, (value) =>
-    value.tag === SqValueTag.Void ? bindings.asValue() : value
-  );
-}
-
-export function getErrorLocations(result: ResultAndBindings["result"]) {
-  if (result.tag === "Error") {
-    const location = result.value.location();
-    return location ? [location] : [];
-  } else {
-    return [];
-  }
-}
--- a/packages/components/src/stories/SquiggleChart.stories.mdx
+++ b/packages/components/src/stories/SquiggleChart.stories.mdx
@ -79,22 +79,6 @@ could be continuous, discrete or mixed.
  </Story>
 </Canvas>

-### Date Distribution
-
-<Canvas>
-  <Story
-    name="Date Distribution"
-    args={{
-      code: "mx(1661819770311, 1661829770311, 1661839770311)",
-      width,
-      xAxisType: "dateTime",
-      width,
-    }}
-  >
-    {Template.bind({})}
-  </Story>
-</Canvas>
-
 ## Mixed distributions

 <Canvas>
--- a/packages/components/src/stories/SquigglePartial.stories.mdx
+++ b/packages/components/src/stories/SquigglePartial.stories.mdx
@ -0,0 +1,51 @@
+import { SquigglePartial, SquiggleEditor } from "../components/SquiggleEditor";
+import { useState } from "react";
+import { Canvas, Meta, Story, Props } from "@storybook/addon-docs";
+
+<Meta title="Squiggle/SquigglePartial" component={SquigglePartial} />
+
+export const Template = (props) => <SquigglePartial {...props} />;
+
+# Squiggle Partial
+
+A Squiggle Partial is an editor that does not return a graph to the user, but
+instead returns bindings that can be used by further Squiggle Editors.
+
+<Canvas>
+  <Story
+    name="Standalone"
+    args={{
+      defaultCode: "x = normal(5,2)",
+    }}
+  >
+    {Template.bind({})}
+  </Story>
+</Canvas>
+
+<Canvas>
+  <Story
+    name="With Editor"
+    args={{
+      initialPartialString: "x = normal(5,2)",
+      initialEditorString: "x",
+    }}
+  >
+    {(props) => {
+      let [bindings, setBindings] = useState({});
+      return (
+        <>
+          <SquigglePartial
+            {...props}
+            defaultCode={props.initialPartialString}
+            onChange={setBindings}
+          />
+          <SquiggleEditor
+            {...props}
+            defaultCode={props.initialEditorString}
+            bindings={bindings}
+          />
+        </>
+      );
+    }}
+  </Story>
+</Canvas>
--- a/packages/components/src/styles/main.css
+++ b/packages/components/src/styles/main.css
@ -22,8 +22,3 @@ but this line is still necessary for proper initialization of `--tw-*` variables
 .ace_cursor {
  border-left: 2px solid !important;
 }
-
-.ace-error-marker {
-  position: absolute;
-  border-bottom: 1px solid red;
-}
--- a/packages/components/test/autorun.test.tsx
+++ b/packages/components/test/autorun.test.tsx
@ -1,55 +0,0 @@
-import { render, screen, waitFor, within } from "@testing-library/react";
-import userEvent from "@testing-library/user-event";
-import * as React from "react";
-import "@testing-library/jest-dom";
-import { SquigglePlayground } from "../src/index";
-
-test("Autorun is default", async () => {
-  render(<SquigglePlayground code="70*30" />);
-  await waitFor(() =>
-    expect(screen.getByTestId("playground-result")).toHaveTextContent("2100")
-  );
-});
-
-test("Autorun can be switched off", async () => {
-  const user = userEvent.setup();
-  render(<SquigglePlayground code="70*30" />);
-
-  expect(screen.getByTestId("autorun-controls")).toHaveTextContent("Autorun");
-
-  await waitFor(() =>
-    expect(screen.getByTestId("playground-result")).toHaveTextContent("2100")
-  );
-
-  await user.click(screen.getByText("Autorun")); // disable
-  expect(screen.getByTestId("autorun-controls")).toHaveTextContent("Paused");
-  expect(screen.getByTestId("autorun-controls")).not.toHaveTextContent(
-    "Autorun"
-  );
-
-  await user.click(screen.getByText("Paused")); // enable autorun again
-  expect(screen.getByTestId("autorun-controls")).toHaveTextContent("Autorun");
-
-  // we should replace the code here, but it's hard to update react-ace state via user events: https://github.com/securingsincity/react-ace/issues/923
-  // ...or replace react-ace with something else
-
-  // TODO:
-
-  /*
-  const editor = screen
-    .getByTestId("squiggle-editor")
-    .querySelector(".ace_editor") as HTMLElement;
-  editor.focus();
-  //   await user.clear(editor);
-  await userEvent.paste("40*40"); // https://github.com/securingsincity/react-ace/issues/923#issuecomment-755502696
-  screen.debug(editor);
-
-  // this makes the tests slower, but it's hard to test otherwise that the code _didn't_ execute
-  await new Promise((r) => setTimeout(r, 300));
-  expect(screen.getByTestId("playground-result")).toHaveTextContent("2100"); // still the old value
-
-  await waitFor(() =>
-    expect(screen.getByTestId("playground-result")).toHaveTextContent("1600")
-  );
-*/
-});
--- a/packages/components/test/basic.test.tsx
+++ b/packages/components/test/basic.test.tsx
@ -1,53 +0,0 @@
-import { render, screen } from "@testing-library/react";
-import React from "react";
-import "@testing-library/jest-dom";
-import {
-  SquiggleChart,
-  SquiggleEditor,
-  SquigglePlayground,
-} from "../src/index";
-import { SqProject } from "@quri/squiggle-lang";
-
-test("Chart logs nothing on render", async () => {
-  const { unmount } = render(<SquiggleChart code={"normal(0, 1)"} />);
-  unmount();
-
-  expect(console.log).not.toBeCalled();
-  expect(console.warn).not.toBeCalled();
-  expect(console.error).not.toBeCalled();
-});
-
-test("Editor logs nothing on render", async () => {
-  const { unmount } = render(<SquiggleEditor code={"normal(0, 1)"} />);
-  unmount();
-
-  expect(console.log).not.toBeCalled();
-  expect(console.warn).not.toBeCalled();
-  expect(console.error).not.toBeCalled();
-});
-
-test("Project dependencies work in editors", async () => {
-  const project = SqProject.create();
-
-  render(<SquiggleEditor code={"x = 1"} project={project} />);
-  const source = project.getSourceIds()[0];
-  const { container } = render(
-    <SquiggleEditor code={"x + 1"} project={project} continues={[source]} />
-  );
-  expect(container).toHaveTextContent("2");
-});
-
-test("Project dependencies work in playgrounds", async () => {
-  const project = SqProject.create();
-  project.setSource("depend", "x = 1");
-
-  render(
-    <SquigglePlayground
-      code={"x + 1"}
-      project={project}
-      continues={["depend"]}
-    />
-  );
-  // We must await here because SquigglePlayground loads results asynchronously
-  expect(await screen.findByRole("status")).toHaveTextContent("2");
-});
--- a/packages/components/test/cleanup.test.tsx
+++ b/packages/components/test/cleanup.test.tsx
@ -1,39 +0,0 @@
-import { render } from "@testing-library/react";
-import React from "react";
-import "@testing-library/jest-dom";
-import { SquiggleChart } from "../src/index";
-import { SqProject } from "@quri/squiggle-lang";
-
-test("Creates and cleans up source", async () => {
-  const project = SqProject.create();
-
-  const { unmount } = render(
-    <SquiggleChart code={"normal(0, 1)"} project={project} />
-  );
-
-  expect(project.getSourceIds().length).toBe(1);
-
-  const sourceId = project.getSourceIds()[0];
-  expect(project.getSource(sourceId)).toBe("normal(0, 1)");
-
-  unmount();
-  expect(project.getSourceIds().length).toBe(0);
-  expect(project.getSource(sourceId)).toBe(undefined);
-});
-
-test("Creates and cleans up source and imports", async () => {
-  const project = SqProject.create();
-
-  const { unmount } = render(
-    <SquiggleChart
-      code={"normal($x, 1)"}
-      project={project}
-      jsImports={{ x: 3 }}
-    />
-  );
-
-  expect(project.getSourceIds().length).toBe(2);
-
-  unmount();
-  expect(project.getSourceIds()).toStrictEqual([]);
-});
--- a/packages/components/test/setup.js
+++ b/packages/components/test/setup.js
@ -1,8 +0,0 @@
-global.console = {
-  ...console,
-  log: jest.fn(console.log),
-  debug: jest.fn(console.debug),
-  info: jest.fn(console.info),
-  warn: jest.fn(console.warn),
-  error: jest.fn(console.error),
-};
--- a/packages/components/vercel.json
+++ b/packages/components/vercel.json
@ -1,4 +0,0 @@
-{
-  "buildCommand": "cd ../.. && npx turbo run build --filter=@quri/squiggle-components",
-  "outputDirectory": "storybook-static"
-}
--- a/packages/squiggle-lang/.gitignore
+++ b/packages/squiggle-lang/.gitignore
@ -23,4 +23,3 @@ coverage
 .nyc_output/
 src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.js
 src/rescript/Reducer/Reducer_Peggy/helpers.js
-src/rescript/ReducerProject/ReducerProject_IncludeParser.js
--- a/packages/squiggle-lang/.prettierignore
+++ b/packages/squiggle-lang/.prettierignore
@ -3,8 +3,6 @@ lib
 *.bs.js
 *.gen.tsx
 .nyc_output/
-coverage/
+_coverage/
 .cache/
 Reducer_Peggy_GeneratedParser.js
-ReducerProject_IncludeParser.js
-src/rescript/Reducer/Reducer_Peggy/helpers.js
--- a/packages/squiggle-lang/tests/Distributions/Dotwise_test.res
+++ b/packages/squiggle-lang/tests/Distributions/Dotwise_test.res
@ -32,29 +32,25 @@ describe("dotSubtract", () => {
 */
  Skip.test("mean of normal minus exponential (property)", () => {
    assert_(
-      property2(
-        float_(),
-        floatRange(1e-5, 1e5),
-        (mean, rate) => {
-          // We limit ourselves to stdev=1 so that the integral is trivial
-          let dotDifference = DistributionOperation.Constructors.pointwiseSubtract(
-            ~env,
-            mkNormal(mean, 1.0),
-            mkExponential(rate),
+      property2(float_(), floatRange(1e-5, 1e5), (mean, rate) => {
+        // We limit ourselves to stdev=1 so that the integral is trivial
+        let dotDifference = DistributionOperation.Constructors.pointwiseSubtract(
+          ~env,
+          mkNormal(mean, 1.0),
+          mkExponential(rate),
+        )
+        let meanResult = E.R2.bind(DistributionOperation.Constructors.mean(~env), dotDifference)
+        // according to algebra or random variables,
+        let meanAnalytical =
+          mean -.
+          SymbolicDist.Exponential.mean({rate: rate})->E.R2.toExn(
+            "On trusted input this should never happen",
          )
-          let meanResult = E.R2.bind(DistributionOperation.Constructors.mean(~env), dotDifference)
-          // according to algebra or random variables,
-          let meanAnalytical =
-            mean -.
-            SymbolicDist.Exponential.mean({rate: rate})->E.R2.toExn(
-              "On trusted input this should never happen",
-            )
-          switch meanResult {
-          | Ok(meanValue) => abs_float(meanValue -. meanAnalytical) /. abs_float(meanValue) < 1e-2 // 1% relative error
-          | Error(err) => err === DistributionTypes.OperationError(DivisionByZeroError)
-          }
-        },
-      ),
+        switch meanResult {
+        | Ok(meanValue) => abs_float(meanValue -. meanAnalytical) /. abs_float(meanValue) < 1e-2 // 1% relative error
+        | Error(err) => err === DistributionTypes.OperationError(DivisionByZeroError)
+        }
+      }),
    )
    pass
  })
--- a/packages/squiggle-lang/tests/Distributions/Invariants/AlgebraicCombination_test.res
+++ b/packages/squiggle-lang/tests/Distributions/Invariants/AlgebraicCombination_test.res
@ -40,60 +40,51 @@ let algebraicPower = algebraicPower(~env)

 describe("(Algebraic) addition of distributions", () => {
  describe("mean", () => {
-    test(
-      "normal(mean=5) + normal(mean=20)",
-      () => {
-        normalDist5
-        ->algebraicAdd(normalDist20)
+    test("normal(mean=5) + normal(mean=20)", () => {
+      normalDist5
+      ->algebraicAdd(normalDist20)
+      ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
+      ->E.R2.fmap(run)
+      ->E.R2.fmap(toFloat)
+      ->E.R.toExn("Expected float", _)
+      ->expect
+      ->toBe(Some(2.5e1))
+    })
+
+    test("uniform(low=9, high=10) + beta(alpha=2, beta=5)", () => {
+      // let uniformMean = (9.0 +. 10.0) /. 2.0
+      // let betaMean = 1.0 /. (1.0 +. 5.0 /. 2.0)
+      let received =
+        uniformDist
+        ->algebraicAdd(betaDist)
        ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
        ->E.R2.fmap(run)
        ->E.R2.fmap(toFloat)
        ->E.R.toExn("Expected float", _)
-        ->expect
-        ->toBe(Some(2.5e1))
-      },
-    )
-
-    test(
-      "uniform(low=9, high=10) + beta(alpha=2, beta=5)",
-      () => {
-        // let uniformMean = (9.0 +. 10.0) /. 2.0
-        // let betaMean = 1.0 /. (1.0 +. 5.0 /. 2.0)
-        let received =
-          uniformDist
-          ->algebraicAdd(betaDist)
-          ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
-        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // sometimes it works with ~digits=2.
-        | Some(x) => x->expect->toBeSoCloseTo(9.786831807237022, ~digits=1) // (uniformMean +. betaMean)
-        }
-      },
-    )
-    test(
-      "beta(alpha=2, beta=5) + uniform(low=9, high=10)",
-      () => {
-        // let uniformMean = (9.0 +. 10.0) /. 2.0
-        // let betaMean = 1.0 /. (1.0 +. 5.0 /. 2.0)
-        let received =
-          betaDist
-          ->algebraicAdd(uniformDist)
-          ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
-        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // sometimes it works with ~digits=2.
-        | Some(x) => x->expect->toBeSoCloseTo(9.784290207736126, ~digits=1) // (uniformMean +. betaMean)
-        }
-      },
-    )
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // sometimes it works with ~digits=2.
+      | Some(x) => x->expect->toBeSoCloseTo(9.786831807237022, ~digits=1) // (uniformMean +. betaMean)
+      }
+    })
+    test("beta(alpha=2, beta=5) + uniform(low=9, high=10)", () => {
+      // let uniformMean = (9.0 +. 10.0) /. 2.0
+      // let betaMean = 1.0 /. (1.0 +. 5.0 /. 2.0)
+      let received =
+        betaDist
+        ->algebraicAdd(uniformDist)
+        ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // sometimes it works with ~digits=2.
+      | Some(x) => x->expect->toBeSoCloseTo(9.784290207736126, ~digits=1) // (uniformMean +. betaMean)
+      }
+    })
  })
  describe("pdf", () => {
    // TEST IS WRONG. SEE STDEV ADDITION EXPRESSION.
@ -131,282 +122,247 @@ describe("(Algebraic) addition of distributions", () => {
        }
      },
    )
-    test(
-      "(normal(mean=10) + normal(mean=10)).pdf(1.9e1)",
-      () => {
-        let received =
-          normalDist20
-          ->Ok
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        let calculated =
-          normalDist10
-          ->algebraicAdd(normalDist10)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        switch received {
-        | None =>
-          "this branch occurs when the dispatch to Jstat on trusted input fails."
-          ->expect
-          ->toBe("never")
-        | Some(x) =>
-          switch calculated {
-          | None => "algebraicAdd has"->expect->toBe("failed")
-          | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=1)
-          }
-        }
-      },
-    )
-    test(
-      "(uniform(low=9, high=10) + beta(alpha=2, beta=5)).pdf(10)",
-      () => {
-        let received =
-          uniformDist
-          ->algebraicAdd(betaDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
+    test("(normal(mean=10) + normal(mean=10)).pdf(1.9e1)", () => {
+      let received =
+        normalDist20
+        ->Ok
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      let calculated =
+        normalDist10
+        ->algebraicAdd(normalDist10)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      switch received {
+      | None =>
+        "this branch occurs when the dispatch to Jstat on trusted input fails."
+        ->expect
+        ->toBe("never")
+      | Some(x) =>
+        switch calculated {
        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // sometimes it works with ~digits=4.
-        // This value was calculated by a python script
-        | Some(x) => x->expect->toBeSoCloseTo(0.979023, ~digits=0)
+        | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=1)
        }
-      },
-    )
-    test(
-      "(beta(alpha=2, beta=5) + uniform(low=9, high=10)).pdf(10)",
-      () => {
-        let received =
-          betaDist
-          ->algebraicAdd(uniformDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
-        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic.
-        | Some(x) => x->expect->toBeSoCloseTo(0.979023, ~digits=0)
-        }
-      },
-    )
+      }
+    })
+    test("(uniform(low=9, high=10) + beta(alpha=2, beta=5)).pdf(10)", () => {
+      let received =
+        uniformDist
+        ->algebraicAdd(betaDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // sometimes it works with ~digits=4.
+      // This value was calculated by a python script
+      | Some(x) => x->expect->toBeSoCloseTo(0.979023, ~digits=0)
+      }
+    })
+    test("(beta(alpha=2, beta=5) + uniform(low=9, high=10)).pdf(10)", () => {
+      let received =
+        betaDist
+        ->algebraicAdd(uniformDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic.
+      | Some(x) => x->expect->toBeSoCloseTo(0.979023, ~digits=0)
+      }
+    })
  })
  describe("cdf", () => {
-    testAll(
-      "(normal(mean=5) + normal(mean=5)).cdf (imprecise)",
-      list{6e0, 8e0, 1e1, 1.2e1},
-      x => {
-        let received =
-          normalDist10
-          ->Ok
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        let calculated =
-          normalDist5
-          ->algebraicAdd(normalDist5)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
+    testAll("(normal(mean=5) + normal(mean=5)).cdf (imprecise)", list{6e0, 8e0, 1e1, 1.2e1}, x => {
+      let received =
+        normalDist10
+        ->Ok
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      let calculated =
+        normalDist5
+        ->algebraicAdd(normalDist5)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten

-        switch received {
-        | None =>
-          "this branch occurs when the dispatch to Jstat on trusted input fails."
-          ->expect
-          ->toBe("never")
-        | Some(x) =>
-          switch calculated {
-          | None => "algebraicAdd has"->expect->toBe("failed")
-          | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=0)
-          }
-        }
-      },
-    )
-    test(
-      "(normal(mean=10) + normal(mean=10)).cdf(1.25e1)",
-      () => {
-        let received =
-          normalDist20
-          ->Ok
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        let calculated =
-          normalDist10
-          ->algebraicAdd(normalDist10)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        switch received {
-        | None =>
-          "this branch occurs when the dispatch to Jstat on trusted input fails."
-          ->expect
-          ->toBe("never")
-        | Some(x) =>
-          switch calculated {
-          | None => "algebraicAdd has"->expect->toBe("failed")
-          | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=2)
-          }
-        }
-      },
-    )
-    test(
-      "(uniform(low=9, high=10) + beta(alpha=2, beta=5)).cdf(10)",
-      () => {
-        let received =
-          uniformDist
-          ->algebraicAdd(betaDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
+      switch received {
+      | None =>
+        "this branch occurs when the dispatch to Jstat on trusted input fails."
+        ->expect
+        ->toBe("never")
+      | Some(x) =>
+        switch calculated {
        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // The value was calculated externally using a python script
-        | Some(x) => x->expect->toBeSoCloseTo(0.71148, ~digits=1)
+        | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=0)
        }
-      },
-    )
-    test(
-      "(beta(alpha=2, beta=5) + uniform(low=9, high=10)).cdf(10)",
-      () => {
-        let received =
-          betaDist
-          ->algebraicAdd(uniformDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
+      }
+    })
+    test("(normal(mean=10) + normal(mean=10)).cdf(1.25e1)", () => {
+      let received =
+        normalDist20
+        ->Ok
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      let calculated =
+        normalDist10
+        ->algebraicAdd(normalDist10)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      switch received {
+      | None =>
+        "this branch occurs when the dispatch to Jstat on trusted input fails."
+        ->expect
+        ->toBe("never")
+      | Some(x) =>
+        switch calculated {
        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // The value was calculated externally using a python script
-        | Some(x) => x->expect->toBeSoCloseTo(0.71148, ~digits=1)
+        | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=2)
        }
-      },
-    )
+      }
+    })
+    test("(uniform(low=9, high=10) + beta(alpha=2, beta=5)).cdf(10)", () => {
+      let received =
+        uniformDist
+        ->algebraicAdd(betaDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // The value was calculated externally using a python script
+      | Some(x) => x->expect->toBeSoCloseTo(0.71148, ~digits=1)
+      }
+    })
+    test("(beta(alpha=2, beta=5) + uniform(low=9, high=10)).cdf(10)", () => {
+      let received =
+        betaDist
+        ->algebraicAdd(uniformDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // The value was calculated externally using a python script
+      | Some(x) => x->expect->toBeSoCloseTo(0.71148, ~digits=1)
+      }
+    })
  })

  describe("inv", () => {
-    testAll(
-      "(normal(mean=5) + normal(mean=5)).inv (imprecise)",
-      list{5e-2, 4.2e-3, 9e-3},
-      x => {
-        let received =
-          normalDist10
-          ->Ok
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        let calculated =
-          normalDist5
-          ->algebraicAdd(normalDist5)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
+    testAll("(normal(mean=5) + normal(mean=5)).inv (imprecise)", list{5e-2, 4.2e-3, 9e-3}, x => {
+      let received =
+        normalDist10
+        ->Ok
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      let calculated =
+        normalDist5
+        ->algebraicAdd(normalDist5)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten

-        switch received {
-        | None =>
-          "this branch occurs when the dispatch to Jstat on trusted input fails."
-          ->expect
-          ->toBe("never")
-        | Some(x) =>
-          switch calculated {
-          | None => "algebraicAdd has"->expect->toBe("failed")
-          | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=-1)
-          }
-        }
-      },
-    )
-    test(
-      "(normal(mean=10) + normal(mean=10)).inv(1e-1)",
-      () => {
-        let received =
-          normalDist20
-          ->Ok
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        let calculated =
-          normalDist10
-          ->algebraicAdd(normalDist10)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toOption
-          ->E.O.flatten
-        switch received {
-        | None =>
-          "this branch occurs when the dispatch to Jstat on trusted input fails."
-          ->expect
-          ->toBe("never")
-        | Some(x) =>
-          switch calculated {
-          | None => "algebraicAdd has"->expect->toBe("failed")
-          | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=-1)
-          }
-        }
-      },
-    )
-    test(
-      "(uniform(low=9, high=10) + beta(alpha=2, beta=5)).inv(2e-2)",
-      () => {
-        let received =
-          uniformDist
-          ->algebraicAdd(betaDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
+      switch received {
+      | None =>
+        "this branch occurs when the dispatch to Jstat on trusted input fails."
+        ->expect
+        ->toBe("never")
+      | Some(x) =>
+        switch calculated {
        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // sometimes it works with ~digits=2.
-        | Some(x) => x->expect->toBeSoCloseTo(9.179319623146968, ~digits=0)
+        | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=-1)
        }
-      },
-    )
-    test(
-      "(beta(alpha=2, beta=5) + uniform(low=9, high=10)).inv(2e-2)",
-      () => {
-        let received =
-          betaDist
-          ->algebraicAdd(uniformDist)
-          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
-          ->E.R2.fmap(run)
-          ->E.R2.fmap(toFloat)
-          ->E.R.toExn("Expected float", _)
-        switch received {
+      }
+    })
+    test("(normal(mean=10) + normal(mean=10)).inv(1e-1)", () => {
+      let received =
+        normalDist20
+        ->Ok
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      let calculated =
+        normalDist10
+        ->algebraicAdd(normalDist10)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toOption
+        ->E.O.flatten
+      switch received {
+      | None =>
+        "this branch occurs when the dispatch to Jstat on trusted input fails."
+        ->expect
+        ->toBe("never")
+      | Some(x) =>
+        switch calculated {
        | None => "algebraicAdd has"->expect->toBe("failed")
-        // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
-        // sometimes it works with ~digits=2.
-        | Some(x) => x->expect->toBeSoCloseTo(9.190872365862756, ~digits=0)
+        | Some(y) => x->expect->toBeSoCloseTo(y, ~digits=-1)
        }
-      },
-    )
+      }
+    })
+    test("(uniform(low=9, high=10) + beta(alpha=2, beta=5)).inv(2e-2)", () => {
+      let received =
+        uniformDist
+        ->algebraicAdd(betaDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // sometimes it works with ~digits=2.
+      | Some(x) => x->expect->toBeSoCloseTo(9.179319623146968, ~digits=0)
+      }
+    })
+    test("(beta(alpha=2, beta=5) + uniform(low=9, high=10)).inv(2e-2)", () => {
+      let received =
+        betaDist
+        ->algebraicAdd(uniformDist)
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
+        ->E.R2.fmap(run)
+        ->E.R2.fmap(toFloat)
+        ->E.R.toExn("Expected float", _)
+      switch received {
+      | None => "algebraicAdd has"->expect->toBe("failed")
+      // This is nondeterministic, we could be in a situation where ci fails but you click rerun and it passes, which is bad.
+      // sometimes it works with ~digits=2.
+      | Some(x) => x->expect->toBeSoCloseTo(9.190872365862756, ~digits=0)
+      }
+    })
  })
 })
--- a/packages/squiggle-lang/tests/Distributions/Invariants/Means_test.res
+++ b/packages/squiggle-lang/tests/Distributions/Invariants/Means_test.res
@ -3,7 +3,7 @@ This is the most basic file in our invariants family of tests.

 Validate that the addition of means equals the mean of the addition, similar for subtraction and multiplication. 

-Details in https://squiggle-language.com/docs/internal/invariants/
+Details in https://develop--squiggle-documentation.netlify.app/docs/internal/invariants/

 Note: epsilon of 1e3 means the invariants are, in general, not being satisfied. 
 */
@ -87,22 +87,14 @@ describe("Means are invariant", () => {
    let testAddInvariant = (t1, t2) =>
      E.R.liftM2(testAdditionMean, t1, t2)->E.R.toExn("Means were not invariant", _)

-    testAll(
-      "with two of the same distribution",
-      distributions,
-      dist => {
-        testAddInvariant(dist, dist)
-      },
-    )
+    testAll("with two of the same distribution", distributions, dist => {
+      testAddInvariant(dist, dist)
+    })

-    testAll(
-      "with two different distributions",
-      pairsOfDifferentDistributions,
-      dists => {
-        let (dist1, dist2) = dists
-        testAddInvariant(dist1, dist2)
-      },
-    )
+    testAll("with two different distributions", pairsOfDifferentDistributions, dists => {
+      let (dist1, dist2) = dists
+      testAddInvariant(dist1, dist2)
+    })

    testAll(
      "with two different distributions in swapped order",
@ -124,22 +116,14 @@ describe("Means are invariant", () => {
    let testSubtractInvariant = (t1, t2) =>
      E.R.liftM2(testSubtractionMean, t1, t2)->E.R.toExn("Means were not invariant", _)

-    testAll(
-      "with two of the same distribution",
-      distributions,
-      dist => {
-        testSubtractInvariant(dist, dist)
-      },
-    )
+    testAll("with two of the same distribution", distributions, dist => {
+      testSubtractInvariant(dist, dist)
+    })

-    testAll(
-      "with two different distributions",
-      pairsOfDifferentDistributions,
-      dists => {
-        let (dist1, dist2) = dists
-        testSubtractInvariant(dist1, dist2)
-      },
-    )
+    testAll("with two different distributions", pairsOfDifferentDistributions, dists => {
+      let (dist1, dist2) = dists
+      testSubtractInvariant(dist1, dist2)
+    })

    testAll(
      "with two different distributions in swapped order",
@ -161,22 +145,14 @@ describe("Means are invariant", () => {
    let testMultiplicationInvariant = (t1, t2) =>
      E.R.liftM2(testMultiplicationMean, t1, t2)->E.R.toExn("Means were not invariant", _)

-    testAll(
-      "with two of the same distribution",
-      distributions,
-      dist => {
-        testMultiplicationInvariant(dist, dist)
-      },
-    )
+    testAll("with two of the same distribution", distributions, dist => {
+      testMultiplicationInvariant(dist, dist)
+    })

-    testAll(
-      "with two different distributions",
-      pairsOfDifferentDistributions,
-      dists => {
-        let (dist1, dist2) = dists
-        testMultiplicationInvariant(dist1, dist2)
-      },
-    )
+    testAll("with two different distributions", pairsOfDifferentDistributions, dists => {
+      let (dist1, dist2) = dists
+      testMultiplicationInvariant(dist1, dist2)
+    })

    testAll(
      "with two different distributions in swapped order",
--- a/packages/squiggle-lang/tests/Distributions/Scoring/KlDivergence_test.res
+++ b/packages/squiggle-lang/tests/Distributions/Scoring/KlDivergence_test.res
@ -17,9 +17,10 @@ describe("klDivergence: continuous -> continuous -> float", () => {
      let answer =
        uniformMakeR(lowAnswer, highAnswer)->E.R2.errMap(s => DistributionTypes.ArgumentError(s))
      let prediction =
-        uniformMakeR(lowPrediction, highPrediction)->E.R2.errMap(
-          s => DistributionTypes.ArgumentError(s),
-        )
+        uniformMakeR(
+          lowPrediction,
+          highPrediction,
+        )->E.R2.errMap(s => DistributionTypes.ArgumentError(s))
      // integral along the support of the answer of answer.pdf(x) times log of prediction.pdf(x) divided by answer.pdf(x) dx
      let analyticalKl = Js.Math.log((highPrediction -. lowPrediction) /. (highAnswer -. lowAnswer))
      let kl = E.R.liftJoin2(klDivergence, prediction, answer)
@ -182,9 +183,9 @@ describe("combineAlongSupportOfSecondArgument0", () => {
    let answer =
      uniformMakeR(lowAnswer, highAnswer)->E.R2.errMap(s => DistributionTypes.ArgumentError(s))
    let prediction =
-      uniformMakeR(lowPrediction, highPrediction)->E.R2.errMap(
-        s => DistributionTypes.ArgumentError(s),
-      )
+      uniformMakeR(lowPrediction, highPrediction)->E.R2.errMap(s => DistributionTypes.ArgumentError(
+        s,
+      ))
    let answerWrapped = E.R.fmap(a => run(FromDist(#ToDist(ToPointSet), a)), answer)
    let predictionWrapped = E.R.fmap(a => run(FromDist(#ToDist(ToPointSet), a)), prediction)

--- a/packages/squiggle-lang/tests/Distributions/Symbolic_test.res
+++ b/packages/squiggle-lang/tests/Distributions/Symbolic_test.res
@ -3,7 +3,7 @@ open Expect
 open TestHelpers

 // TODO: use Normal.make (but preferably after teh new validation dispatch is in)
-let mkNormal = (mean, stdev) => DistributionTypes.Symbolic(#Normal({mean, stdev}))
+let mkNormal = (mean, stdev) => DistributionTypes.Symbolic(#Normal({mean: mean, stdev: stdev}))

 describe("(Symbolic) normalize", () => {
  testAll("has no impact on normal distributions", list{-1e8, -1e-2, 0.0, 1e-4, 1e16}, mean => {
@ -47,7 +47,10 @@ describe("(Symbolic) mean", () => {
    tup => {
      let (low, medium, high) = tup
      let meanValue = run(
-        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Triangular({low, medium, high}))),
+        FromDist(
+          #ToFloat(#Mean),
+          DistributionTypes.Symbolic(#Triangular({low: low, medium: medium, high: high})),
+        ),
      )
      meanValue->unpackFloat->expect->toBeCloseTo((low +. medium +. high) /. 3.0) // https://www.statology.org/triangular-distribution/
    },
@ -60,7 +63,7 @@ describe("(Symbolic) mean", () => {
    tup => {
      let (alpha, beta) = tup
      let meanValue = run(
-        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Beta({alpha, beta}))),
+        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Beta({alpha: alpha, beta: beta}))),
      )
      meanValue->unpackFloat->expect->toBeCloseTo(1.0 /. (1.0 +. beta /. alpha)) // https://en.wikipedia.org/wiki/Beta_distribution#Mean
    },
@ -81,8 +84,8 @@ describe("(Symbolic) mean", () => {
      let (mean, stdev) = tup
      let betaDistribution = SymbolicDist.Beta.fromMeanAndStdev(mean, stdev)
      let meanValue =
-        betaDistribution->E.R2.fmap(
-          d => run(FromDist(#ToFloat(#Mean), d->DistributionTypes.Symbolic)),
+        betaDistribution->E.R2.fmap(d =>
+          run(FromDist(#ToFloat(#Mean), d->DistributionTypes.Symbolic))
        )
      switch meanValue {
      | Ok(value) => value->unpackFloat->expect->toBeCloseTo(mean)
@ -97,7 +100,7 @@ describe("(Symbolic) mean", () => {
    tup => {
      let (mu, sigma) = tup
      let meanValue = run(
-        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Lognormal({mu, sigma}))),
+        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Lognormal({mu: mu, sigma: sigma}))),
      )
      meanValue->unpackFloat->expect->toBeCloseTo(Js.Math.exp(mu +. sigma ** 2.0 /. 2.0)) // https://brilliant.org/wiki/log-normal-distribution/
    },
@ -109,7 +112,7 @@ describe("(Symbolic) mean", () => {
    tup => {
      let (low, high) = tup
      let meanValue = run(
-        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Uniform({low, high}))),
+        FromDist(#ToFloat(#Mean), DistributionTypes.Symbolic(#Uniform({low: low, high: high}))),
      )
      meanValue->unpackFloat->expect->toBeCloseTo((low +. high) /. 2.0) // https://en.wikipedia.org/wiki/Continuous_uniform_distribution#Moments
    },
--- a/packages/squiggle-lang/tests/E/splitContinuousAndDiscrete_test.res
+++ b/packages/squiggle-lang/tests/E/splitContinuousAndDiscrete_test.res
@ -9,28 +9,22 @@ let prepareInputs = (ar, minWeight) =>
 describe("Continuous and discrete splits", () => {
  makeTest(
    "is empty, with no common elements",
-    prepareInputs([1.33455, 1.432, 2.0], 2),
+    prepareInputs([1.432, 1.33455, 2.0], 2),
    ([1.33455, 1.432, 2.0], []),
  )

  makeTest(
    "only stores 3.5 as discrete when minWeight is 3",
-    prepareInputs([1.33455, 1.432, 2.0, 2.0, 3.5, 3.5, 3.5], 3),
+    prepareInputs([1.432, 1.33455, 2.0, 2.0, 3.5, 3.5, 3.5], 3),
    ([1.33455, 1.432, 2.0, 2.0], [(3.5, 3.0)]),
  )

  makeTest(
    "doesn't store 3.5 as discrete when minWeight is 5",
-    prepareInputs([1.33455, 1.432, 2.0, 2.0, 3.5, 3.5, 3.5], 5),
+    prepareInputs([1.432, 1.33455, 2.0, 2.0, 3.5, 3.5, 3.5], 5),
    ([1.33455, 1.432, 2.0, 2.0, 3.5, 3.5, 3.5], []),
  )

-  makeTest(
-    "more general test",
-    prepareInputs([10., 10., 11., 11., 11., 12., 13., 13., 13., 13., 13., 14.], 3),
-    ([10., 10., 12., 14.], [(11., 3.), (13., 5.)]),
-  )
-
  let makeDuplicatedArray = count => {
    let arr = Belt.Array.range(1, count) |> E.A.fmap(float_of_int)
    let sorted = arr |> Belt.SortArray.stableSortBy(_, compare)
--- a/packages/squiggle-lang/tests/Lodash_test.res
+++ b/packages/squiggle-lang/tests/Lodash_test.res
@ -0,0 +1,20 @@
+open Jest
+open Expect
+
+let makeTest = (~only=false, str, item1, item2) =>
+  only
+    ? Only.test(str, () => expect(item1)->toEqual(item2))
+    : test(str, () => expect(item1)->toEqual(item2))
+
+describe("Lodash", () =>
+  describe("Lodash", () => {
+    makeTest("min", Lodash.min([1, 3, 4]), 1)
+    makeTest("max", Lodash.max([1, 3, 4]), 4)
+    makeTest("uniq", Lodash.uniq([1, 3, 4, 4]), [1, 3, 4])
+    makeTest(
+      "countBy",
+      Lodash.countBy([1, 3, 4, 4], r => r),
+      Js.Dict.fromArray([("1", 1), ("3", 1), ("4", 2)]),
+    )
+  })
+)
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Bindings/Reducer_Bindings_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Bindings/Reducer_Bindings_test.res
@ -1,50 +1,27 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Bindings = Reducer_Bindings
-module Namespace = Reducer_Namespace

 open Jest
 open Expect
 open Expect.Operators

-describe("Bindings", () => {
-  let value = Reducer_T.IEvNumber(1967.0)
-  let bindings = Bindings.make()->Bindings.set("value", value)
+describe("Name Space", () => {
+  let value = InternalExpressionValue.IEvNumber(1967.0)
+  let nameSpace = Bindings.emptyNameSpace->Bindings.set("value", value)
  test("get", () => {
-    expect(bindings->Bindings.get("value")) == Some(value)
+    expect(Bindings.get(nameSpace, "value")) == Some(value)
  })

-  test("get nonexisting value", () => {
-    expect(bindings->Bindings.get("nosuchvalue")) == None
+  test("chain and get", () => {
+    let mainNameSpace = Bindings.emptyNameSpace->Bindings.chainTo([nameSpace])
+    expect(Bindings.get(mainNameSpace, "value")) == Some(value)
  })

-  test("get on extended", () => {
-    expect(bindings->Bindings.extend->Bindings.get("value")) == Some(value)
-  })
-
-  test("locals", () => {
-    expect(bindings->Bindings.locals->Namespace.get("value")) == Some(value)
-  })
-
-  test("locals on extendeed", () => {
-    expect(bindings->Bindings.extend->Bindings.locals->Namespace.get("value")) == None
-  })
-
-  describe("extend", () => {
-    let value2 = Reducer_T.IEvNumber(5.)
-    let extendedBindings = bindings->Bindings.extend->Bindings.set("value", value2)
-
-    test(
-      "get on extended",
-      () => {
-        expect(extendedBindings->Bindings.get("value")) == Some(value2)
-      },
-    )
-
-    test(
-      "get on original",
-      () => {
-        expect(bindings->Bindings.get("value")) == Some(value)
-      },
-    )
+  test("chain and set", () => {
+    let mainNameSpace0 = Bindings.emptyNameSpace->Bindings.chainTo([nameSpace])
+    let mainNameSpace =
+      mainNameSpace0->Bindings.set("value", InternalExpressionValue.IEvNumber(1968.0))
+    expect(Bindings.get(mainNameSpace, "value")) == Some(InternalExpressionValue.IEvNumber(1968.0))
  })
 })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res
@ -0,0 +1,146 @@
+open Jest
+// open Expect
+
+open Reducer_Expression_ExpressionBuilder
+open Reducer_TestMacroHelpers
+module ExpressionT = Reducer_Expression_T
+
+let exampleExpression = eNumber(1.)
+let exampleExpressionY = eSymbol("y")
+let exampleStatementY = eLetStatement("y", eNumber(1.))
+let exampleStatementX = eLetStatement("y", eSymbol("x"))
+let exampleStatementZ = eLetStatement("z", eSymbol("y"))
+
+// If it is not a macro then it is not expanded
+testMacro([], exampleExpression, "Ok(1)")
+
+describe("bindStatement", () => {
+  // A statement is bound by the bindings created by the previous statement
+  testMacro(
+    [],
+    eBindStatement(eBindings([]), exampleStatementY),
+    "Ok((:$_setBindings_$ @{} :y 1) context: @{})",
+  )
+  // Then it answers the bindings for the next statement when reduced
+  testMacroEval([], eBindStatement(eBindings([]), exampleStatementY), "Ok(@{y: 1})")
+  // Now let's feed a binding to see what happens
+  testMacro(
+    [],
+    eBindStatement(eBindings([("x", IEvNumber(2.))]), exampleStatementX),
+    "Ok((:$_setBindings_$ @{x: 2} :y 2) context: @{x: 2})",
+  )
+  // An expression does not return a binding, thus error
+  testMacro([], eBindStatement(eBindings([]), exampleExpression), "Assignment expected")
+  // When bindings from previous statement are missing the context is injected. This must be the first statement of a block
+  testMacro(
+    [("z", IEvNumber(99.))],
+    eBindStatementDefault(exampleStatementY),
+    "Ok((:$_setBindings_$ @{z: 99} :y 1) context: @{z: 99})",
+  )
+})
+
+describe("bindExpression", () => {
+  // x is simply bound in the expression
+  testMacro(
+    [],
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), eSymbol("x")),
+    "Ok(2 context: @{x: 2})",
+  )
+  // When an let statement is the end expression then bindings are returned
+  testMacro(
+    [],
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), exampleStatementY),
+    "Ok((:$_exportBindings_$ (:$_setBindings_$ @{x: 2} :y 1)) context: @{x: 2})",
+  )
+  // Now let's reduce that expression
+  testMacroEval(
+    [],
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), exampleStatementY),
+    "Ok(@{x: 2,y: 1})",
+  )
+  // When bindings are missing the context is injected. This must be the first and last statement of a block
+  testMacroEval(
+    [("z", IEvNumber(99.))],
+    eBindExpressionDefault(exampleStatementY),
+    "Ok(@{y: 1,z: 99})",
+  )
+})
+
+describe("block", () => {
+  // Block with a single expression
+  testMacro([], eBlock(list{exampleExpression}), "Ok((:$$_bindExpression_$$ 1))")
+  testMacroEval([], eBlock(list{exampleExpression}), "Ok(1)")
+  // Block with a single statement
+  testMacro([], eBlock(list{exampleStatementY}), "Ok((:$$_bindExpression_$$ (:$_let_$ :y 1)))")
+  testMacroEval([], eBlock(list{exampleStatementY}), "Ok(@{y: 1})")
+  // Block with a statement and an expression
+  testMacro(
+    [],
+    eBlock(list{exampleStatementY, exampleExpressionY}),
+    "Ok((:$$_bindExpression_$$ (:$$_bindStatement_$$ (:$_let_$ :y 1)) :y))",
+  )
+  testMacroEval([], eBlock(list{exampleStatementY, exampleExpressionY}), "Ok(1)")
+  // Block with a statement and another statement
+  testMacro(
+    [],
+    eBlock(list{exampleStatementY, exampleStatementZ}),
+    "Ok((:$$_bindExpression_$$ (:$$_bindStatement_$$ (:$_let_$ :y 1)) (:$_let_$ :z :y)))",
+  )
+  testMacroEval([], eBlock(list{exampleStatementY, exampleStatementZ}), "Ok(@{y: 1,z: 1})")
+  // Block inside a block
+  testMacro([], eBlock(list{eBlock(list{exampleExpression})}), "Ok((:$$_bindExpression_$$ {1}))")
+  testMacroEval([], eBlock(list{eBlock(list{exampleExpression})}), "Ok(1)")
+  // Block assigned to a variable
+  testMacro(
+    [],
+    eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
+    "Ok((:$$_bindExpression_$$ (:$_let_$ :z {{:y}})))",
+  )
+  testMacroEval(
+    [],
+    eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
+    "Ok(@{z: :y})",
+  )
+  // Empty block
+  testMacro([], eBlock(list{}), "Ok(:undefined block)") //TODO: should be an error
+  //   :$$_block_$$ (:$$_block_$$ (:$_let_$ :y (:add :x 1)) :y)"
+  testMacro(
+    [],
+    eBlock(list{
+      eBlock(list{
+        eLetStatement("y", eFunction("add", list{eSymbol("x"), eNumber(1.)})),
+        eSymbol("y"),
+      }),
+    }),
+    "Ok((:$$_bindExpression_$$ {(:$_let_$ :y (:add :x 1)); :y}))",
+  )
+  testMacroEval(
+    [("x", IEvNumber(1.))],
+    eBlock(list{
+      eBlock(list{
+        eLetStatement("y", eFunction("add", list{eSymbol("x"), eNumber(1.)})),
+        eSymbol("y"),
+      }),
+    }),
+    "Ok(2)",
+  )
+})
+
+describe("lambda", () => {
+  // assign a lambda to a variable
+  let lambdaExpression = eFunction("$$_lambda_$$", list{eArrayString(["y"]), exampleExpressionY})
+  testMacro([], lambdaExpression, "Ok(lambda(y=>internal code))")
+  // call a lambda
+  let callLambdaExpression = list{lambdaExpression, eNumber(1.)}->ExpressionT.EList
+  testMacro([], callLambdaExpression, "Ok(((:$$_lambda_$$ [y] :y) 1))")
+  testMacroEval([], callLambdaExpression, "Ok(1)")
+  // Parameters shadow the outer scope
+  testMacroEval([("y", IEvNumber(666.))], callLambdaExpression, "Ok(1)")
+  // When not shadowed by the parameters, the outer scope variables are available
+  let lambdaExpression = eFunction(
+    "$$_lambda_$$",
+    list{eArrayString(["z"]), eFunction("add", list{eSymbol("y"), eSymbol("z")})},
+  )
+  let callLambdaExpression = eList(list{lambdaExpression, eNumber(1.)})
+  testMacroEval([("y", IEvNumber(666.))], callLambdaExpression, "Ok(667)")
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn_test.res
@ -0,0 +1,41 @@
+module ExpressionValue = ReducerInterface.InternalExpressionValue
+module Expression = Reducer_Expression
+
+open Jest
+open Expect
+
+let expectEvalToBe = (sourceCode: string, answer: string) =>
+  Expression.BackCompatible.evaluateString(sourceCode)
+  ->ExpressionValue.toStringResult
+  ->expect
+  ->toBe(answer)
+
+let testEval = (expr, answer) => test(expr, () => expectEvalToBe(expr, answer))
+
+describe("builtin", () => {
+  // All MathJs operators and functions are available for string, number and boolean
+  // .e.g + - / * > >= < <= == /= not and or
+  // See https://mathjs.org/docs/expressions/syntax.html
+  // See https://mathjs.org/docs/reference/functions.html
+  testEval("-1", "Ok(-1)")
+  testEval("1-1", "Ok(0)")
+  testEval("2>1", "Ok(true)")
+  testEval("concat('a','b')", "Ok('ab')")
+})
+
+describe("builtin exception", () => {
+  //It's a pity that MathJs does not return error position
+  test("MathJs Exception", () =>
+    expectEvalToBe("testZadanga(1)", "Error(JS Exception: Error: Undefined function testZadanga)")
+  )
+})
+
+describe("error reporting from collection functions", () => {
+  testEval("arr=[1,2,3]; map(arr, {|x| x*2})", "Ok([2,4,6])")
+  testEval(
+    "arr = [normal(3,2)]; map(arr, zarathsuzaWasHere)",
+    "Error(zarathsuzaWasHere is not defined)",
+  )
+  // FIXME: returns "Error(Function not found: map(Array,Symbol))"
+  // Actually this error is correct but not informative
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Helpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Helpers.res
@ -0,0 +1,17 @@
+// Reducer_Helpers
+module ErrorValue = Reducer_ErrorValue
+module InternalExpressionValue = ReducerInterface.InternalExpressionValue
+module Bindings = Reducer_Bindings
+
+let removeDefaultsInternal = (iev: InternalExpressionValue.t) => {
+  switch iev {
+  | InternalExpressionValue.IEvBindings(nameSpace) =>
+    Bindings.removeOther(
+      nameSpace,
+      ReducerInterface.StdLib.internalStdLib,
+    )->InternalExpressionValue.IEvBindings
+  | value => value
+  }
+}
+
+let rRemoveDefaultsInternal = r => Belt.Result.map(r, removeDefaultsInternal)
--- a/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsEval_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsEval_test.res
@ -0,0 +1,31 @@
+module MathJs = Reducer_MathJs
+module ErrorValue = Reducer_ErrorValue
+
+open Jest
+open ExpectJs
+
+describe("eval", () => {
+  test("Number", () => expect(MathJs.Eval.eval("1"))->toEqual(Ok(IEvNumber(1.))))
+  test("Number expr", () => expect(MathJs.Eval.eval("1-1"))->toEqual(Ok(IEvNumber(0.))))
+  test("String", () => expect(MathJs.Eval.eval("'hello'"))->toEqual(Ok(IEvString("hello"))))
+  test("String expr", () =>
+    expect(MathJs.Eval.eval("concat('hello ','world')"))->toEqual(Ok(IEvString("hello world")))
+  )
+  test("Boolean", () => expect(MathJs.Eval.eval("true"))->toEqual(Ok(IEvBool(true))))
+  test("Boolean expr", () => expect(MathJs.Eval.eval("2>1"))->toEqual(Ok(IEvBool(true))))
+})
+
+describe("errors", () => {
+  // All those errors propagete up and are returned by the resolver
+  test("unknown function", () =>
+    expect(MathJs.Eval.eval("testZadanga()"))->toEqual(
+      Error(ErrorValue.REJavaScriptExn(Some("Undefined function testZadanga"), Some("Error"))),
+    )
+  )
+
+  test("unknown answer type", () =>
+    expect(MathJs.Eval.eval("1+1i"))->toEqual(
+      Error(ErrorValue.RETodo("Unhandled MathJs literal type: object")),
+    )
+  )
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Namespace_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Namespace_test.res
@ -1,62 +0,0 @@
-@@warning("-44")
-module Namespace = Reducer_Namespace
-
-open Jest
-open Expect
-open Expect.Operators
-
-let makeValue = (v: float) => v->Reducer_T.IEvNumber
-
-describe("Namespace", () => {
-  let value = makeValue(5.)
-  let v2 = makeValue(2.)
-  let ns = Namespace.make()->Namespace.set("value", value)
-
-  test("get", () => {
-    expect(ns->Namespace.get("value")) == Some(value)
-  })
-
-  test("get nonexisting value", () => {
-    expect(ns->Namespace.get("nosuchvalue")) == None
-  })
-
-  test("set", () => {
-    let ns2 = ns->Namespace.set("v2", v2)
-    expect(ns2->Namespace.get("v2")) == Some(v2)
-  })
-
-  test("immutable", () => {
-    let _ = ns->Namespace.set("v2", Reducer_T.IEvNumber(2.))
-    expect(ns->Namespace.get("v2")) == None
-  })
-
-  describe("merge many", () => {
-    let x1 = makeValue(10.)
-    let x2 = makeValue(20.)
-    let x3 = makeValue(30.)
-    let x4 = makeValue(40.)
-    let ns1 = Namespace.make()->Namespace.set("x1", x1)->Namespace.set("x2", x2)
-    let ns2 = Namespace.make()->Namespace.set("x3", x3)->Namespace.set("x4", x4)
-
-    let nsMerged = Namespace.mergeMany([ns, ns1, ns2])
-
-    test(
-      "merge many 1",
-      () => {
-        expect(nsMerged->Namespace.get("x1")) == Some(x1)
-      },
-    )
-    test(
-      "merge many 2",
-      () => {
-        expect(nsMerged->Namespace.get("x4")) == Some(x4)
-      },
-    )
-    test(
-      "merge many 3",
-      () => {
-        expect(nsMerged->Namespace.get("value")) == Some(value)
-      },
-    )
-  })
-})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_Parse_test.res
@ -3,231 +3,346 @@ open Reducer_Peggy_TestHelpers

 describe("Peggy parse", () => {
  describe("float", () => {
-    testParse("1.", "{1}")
-    testParse("1.1", "{1.1}")
-    testParse(".1", "{0.1}")
-    testParse("0.1", "{0.1}")
-    testParse("1e1", "{10}")
-    testParse("1e-1", "{0.1}")
-    testParse(".1e1", "{1}")
-    testParse("0.1e1", "{1}")
+    testParse("1.", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("1.1", "{(::$_endOfOuterBlock_$ () 1.1)}")
+    testParse(".1", "{(::$_endOfOuterBlock_$ () 0.1)}")
+    testParse("0.1", "{(::$_endOfOuterBlock_$ () 0.1)}")
+    testParse("1e1", "{(::$_endOfOuterBlock_$ () 10)}")
+    testParse("1e-1", "{(::$_endOfOuterBlock_$ () 0.1)}")
+    testParse(".1e1", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("0.1e1", "{(::$_endOfOuterBlock_$ () 1)}")
  })

  describe("literals operators parenthesis", () => {
-    testParse("1", "{1}")
-    testParse("'hello'", "{'hello'}")
-    testParse("true", "{true}")
-    testParse("1+2", "{(:add 1 2)}")
-    testParse("add(1,2)", "{(:add 1 2)}")
-    testParse("(1)", "{1}")
-    testParse("(1+2)", "{(:add 1 2)}")
+    // Note that there is always an outer block. Otherwise, external bindings are ignrored at the first statement
+    testParse("1", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("'hello'", "{(::$_endOfOuterBlock_$ () 'hello')}")
+    testParse("true", "{(::$_endOfOuterBlock_$ () true)}")
+    testParse("1+2", "{(::$_endOfOuterBlock_$ () (::add 1 2))}")
+    testParse("add(1,2)", "{(::$_endOfOuterBlock_$ () (::add 1 2))}")
+    testParse("(1)", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("(1+2)", "{(::$_endOfOuterBlock_$ () (::add 1 2))}")
  })

  describe("unary", () => {
-    testParse("-1", "{(:unaryMinus 1)}")
-    testParse("!true", "{(:not true)}")
-    testParse("1 + -1", "{(:add 1 (:unaryMinus 1))}")
-    testParse("-a[0]", "{(:unaryMinus (:$_atIndex_$ :a 0))}")
-    testParse("!a[0]", "{(:not (:$_atIndex_$ :a 0))}")
+    testParse("-1", "{(::$_endOfOuterBlock_$ () (::unaryMinus 1))}")
+    testParse("!true", "{(::$_endOfOuterBlock_$ () (::not true))}")
+    testParse("1 + -1", "{(::$_endOfOuterBlock_$ () (::add 1 (::unaryMinus 1)))}")
+    testParse("-a[0]", "{(::$_endOfOuterBlock_$ () (::unaryMinus (::$_atIndex_$ :a 0)))}")
+    testParse("!a[0]", "{(::$_endOfOuterBlock_$ () (::not (::$_atIndex_$ :a 0)))}")
  })

  describe("multiplicative", () => {
-    testParse("1 * 2", "{(:multiply 1 2)}")
-    testParse("1 / 2", "{(:divide 1 2)}")
-    testParse("1 * 2 * 3", "{(:multiply (:multiply 1 2) 3)}")
-    testParse("1 * 2 / 3", "{(:divide (:multiply 1 2) 3)}")
-    testParse("1 / 2 * 3", "{(:multiply (:divide 1 2) 3)}")
-    testParse("1 / 2 / 3", "{(:divide (:divide 1 2) 3)}")
-    testParse("1 * 2 + 3 * 4", "{(:add (:multiply 1 2) (:multiply 3 4))}")
-    testParse("1 * 2 - 3 * 4", "{(:subtract (:multiply 1 2) (:multiply 3 4))}")
-    testParse("1 * 2 .+ 3 * 4", "{(:dotAdd (:multiply 1 2) (:multiply 3 4))}")
-    testParse("1 * 2 .- 3 * 4", "{(:dotSubtract (:multiply 1 2) (:multiply 3 4))}")
-    testParse("1 * 2 + 3 .* 4", "{(:add (:multiply 1 2) (:dotMultiply 3 4))}")
-    testParse("1 * 2 + 3 / 4", "{(:add (:multiply 1 2) (:divide 3 4))}")
-    testParse("1 * 2 + 3 ./ 4", "{(:add (:multiply 1 2) (:dotDivide 3 4))}")
-    testParse("1 * 2 - 3 .* 4", "{(:subtract (:multiply 1 2) (:dotMultiply 3 4))}")
-    testParse("1 * 2 - 3 / 4", "{(:subtract (:multiply 1 2) (:divide 3 4))}")
-    testParse("1 * 2 - 3 ./ 4", "{(:subtract (:multiply 1 2) (:dotDivide 3 4))}")
-    testParse("1 * 2 - 3 * 4^5", "{(:subtract (:multiply 1 2) (:multiply 3 (:pow 4 5)))}")
+    testParse("1 * 2", "{(::$_endOfOuterBlock_$ () (::multiply 1 2))}")
+    testParse("1 / 2", "{(::$_endOfOuterBlock_$ () (::divide 1 2))}")
+    testParse("1 * 2 * 3", "{(::$_endOfOuterBlock_$ () (::multiply (::multiply 1 2) 3))}")
+    testParse("1 * 2 / 3", "{(::$_endOfOuterBlock_$ () (::divide (::multiply 1 2) 3))}")
+    testParse("1 / 2 * 3", "{(::$_endOfOuterBlock_$ () (::multiply (::divide 1 2) 3))}")
+    testParse("1 / 2 / 3", "{(::$_endOfOuterBlock_$ () (::divide (::divide 1 2) 3))}")
+    testParse(
+      "1 * 2 + 3 * 4",
+      "{(::$_endOfOuterBlock_$ () (::add (::multiply 1 2) (::multiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 - 3 * 4",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::multiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 .+ 3 * 4",
+      "{(::$_endOfOuterBlock_$ () (::dotAdd (::multiply 1 2) (::multiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 .- 3 * 4",
+      "{(::$_endOfOuterBlock_$ () (::dotSubtract (::multiply 1 2) (::multiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 + 3 .* 4",
+      "{(::$_endOfOuterBlock_$ () (::add (::multiply 1 2) (::dotMultiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 + 3 / 4",
+      "{(::$_endOfOuterBlock_$ () (::add (::multiply 1 2) (::divide 3 4)))}",
+    )
+    testParse(
+      "1 * 2 + 3 ./ 4",
+      "{(::$_endOfOuterBlock_$ () (::add (::multiply 1 2) (::dotDivide 3 4)))}",
+    )
+    testParse(
+      "1 * 2 - 3 .* 4",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::dotMultiply 3 4)))}",
+    )
+    testParse(
+      "1 * 2 - 3 / 4",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::divide 3 4)))}",
+    )
+    testParse(
+      "1 * 2 - 3 ./ 4",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::dotDivide 3 4)))}",
+    )
+    testParse(
+      "1 * 2 - 3 * 4^5",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::multiply 3 (::pow 4 5))))}",
+    )
    testParse(
      "1 * 2 - 3 * 4^5^6",
-      "{(:subtract (:multiply 1 2) (:multiply 3 (:pow (:pow 4 5) 6)))}",
+      "{(::$_endOfOuterBlock_$ () (::subtract (::multiply 1 2) (::multiply 3 (::pow (::pow 4 5) 6))))}",
+    )
+    testParse(
+      "1 * -a[-2]",
+      "{(::$_endOfOuterBlock_$ () (::multiply 1 (::unaryMinus (::$_atIndex_$ :a (::unaryMinus 2)))))}",
    )
-    testParse("1 * -a[-2]", "{(:multiply 1 (:unaryMinus (:$_atIndex_$ :a (:unaryMinus 2))))}")
  })

  describe("multi-line", () => {
-    testParse("x=1; 2", "{:x = {1}; 2}")
-    testParse("x=1; y=2", "{:x = {1}; :y = {2}}")
+    testParse("x=1; 2", "{:x = {1}; (::$_endOfOuterBlock_$ () 2)}")
+    testParse("x=1; y=2", "{:x = {1}; :y = {2}; (::$_endOfOuterBlock_$ () ())}")
  })

  describe("variables", () => {
-    testParse("x = 1", "{:x = {1}}")
-    testParse("x", "{:x}")
-    testParse("x = 1; x", "{:x = {1}; :x}")
+    testParse("x = 1", "{:x = {1}; (::$_endOfOuterBlock_$ () ())}")
+    testParse("x", "{(::$_endOfOuterBlock_$ () :x)}")
+    testParse("x = 1; x", "{:x = {1}; (::$_endOfOuterBlock_$ () :x)}")
  })

  describe("functions", () => {
-    testParse("identity(x) = x", "{:identity = {|:x| {:x}}}") // Function definitions become lambda assignments
-    testParse("identity(x)", "{(:identity :x)}")
+    testParse("identity(x) = x", "{:identity = {|:x| {:x}}; (::$_endOfOuterBlock_$ () ())}") // Function definitions become lambda assignments
+    testParse("identity(x)", "{(::$_endOfOuterBlock_$ () (::identity :x))}")
  })

  describe("arrays", () => {
-    testParse("[]", "{[]}")
-    testParse("[0, 1, 2]", "{[0; 1; 2]}")
-    testParse("['hello', 'world']", "{['hello'; 'world']}")
-    testParse("([0,1,2])[1]", "{(:$_atIndex_$ [0; 1; 2] 1)}")
+    testParse("[]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$))}")
+    testParse("[0, 1, 2]", "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ 0 1 2))}")
+    testParse(
+      "['hello', 'world']",
+      "{(::$_endOfOuterBlock_$ () (::$_constructArray_$ 'hello' 'world'))}",
+    )
+    testParse(
+      "([0,1,2])[1]",
+      "{(::$_endOfOuterBlock_$ () (::$_atIndex_$ (::$_constructArray_$ 0 1 2) 1))}",
+    )
  })

  describe("records", () => {
-    testParse("{a: 1, b: 2}", "{{'a': 1, 'b': 2}}")
-    testParse("{1+0: 1, 2+0: 2}", "{{(:add 1 0): 1, (:add 2 0): 2}}") // key can be any expression
-    testParse("record.property", "{(:$_atIndex_$ :record 'property')}")
+    testParse(
+      "{a: 1, b: 2}",
+      "{(::$_endOfOuterBlock_$ () (::$_constructRecord_$ ('a': 1 'b': 2)))}",
+    )
+    testParse(
+      "{1+0: 1, 2+0: 2}",
+      "{(::$_endOfOuterBlock_$ () (::$_constructRecord_$ ((::add 1 0): 1 (::add 2 0): 2)))}",
+    ) // key can be any expression
+    testParse("record.property", "{(::$_endOfOuterBlock_$ () (::$_atIndex_$ :record 'property'))}")
  })

  describe("post operators", () => {
    //function call, array and record access are post operators with higher priority than unary operators
-    testParse("a==!b(1)", "{(:equal :a (:not (:b 1)))}")
-    testParse("a==!b[1]", "{(:equal :a (:not (:$_atIndex_$ :b 1)))}")
-    testParse("a==!b.one", "{(:equal :a (:not (:$_atIndex_$ :b 'one')))}")
+    testParse("a==!b(1)", "{(::$_endOfOuterBlock_$ () (::equal :a (::not (::b 1))))}")
+    testParse("a==!b[1]", "{(::$_endOfOuterBlock_$ () (::equal :a (::not (::$_atIndex_$ :b 1))))}")
+    testParse(
+      "a==!b.one",
+      "{(::$_endOfOuterBlock_$ () (::equal :a (::not (::$_atIndex_$ :b 'one'))))}",
+    )
  })

  describe("comments", () => {
-    testParse("1 # This is a line comment", "{1}")
-    testParse("1 // This is a line comment", "{1}")
-    testParse("1 /* This is a multi line comment */", "{1}")
-    testParse("/* This is a multi line comment */ 1", "{1}")
+    testParse("1 # This is a line comment", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("1 // This is a line comment", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("1 /* This is a multi line comment */", "{(::$_endOfOuterBlock_$ () 1)}")
+    testParse("/* This is a multi line comment */ 1", "{(::$_endOfOuterBlock_$ () 1)}")
    testParse(
      `
  /* This is 
  a multi line 
  comment */
  1`,
-      "{1}",
+      "{(::$_endOfOuterBlock_$ () 1)}",
    )
  })

  describe("ternary operator", () => {
-    testParse("true ? 2 : 3", "{(::$$_ternary_$$ true 2 3)}")
+    testParse("true ? 2 : 3", "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ true 2 3))}")
    testParse(
      "false ? 2 : false ? 4 : 5",
-      "{(::$$_ternary_$$ false 2 (::$$_ternary_$$ false 4 5))}",
+      "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ false 2 (::$$_ternary_$$ false 4 5)))}",
    ) // nested ternary
  })

  describe("if then else", () => {
-    testParse("if true then 2 else 3", "{(::$$_ternary_$$ true {2} {3})}")
-    testParse("if false then {2} else {3}", "{(::$$_ternary_$$ false {2} {3})}")
+    testParse(
+      "if true then 2 else 3",
+      "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ true {2} {3}))}",
+    )
+    testParse(
+      "if false then {2} else {3}",
+      "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ false {2} {3}))}",
+    )
    testParse(
      "if false then {2} else if false then {4} else {5}",
-      "{(::$$_ternary_$$ false {2} (::$$_ternary_$$ false {4} {5}))}",
+      "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ false {2} (::$$_ternary_$$ false {4} {5})))}",
    ) //nested if
  })

  describe("logical", () => {
-    testParse("true || false", "{(:or true false)}")
-    testParse("true && false", "{(:and true false)}")
-    testParse("a * b + c", "{(:add (:multiply :a :b) :c)}") // for comparison
-    testParse("a && b || c", "{(:or (:and :a :b) :c)}")
-    testParse("a && b || c && d", "{(:or (:and :a :b) (:and :c :d))}")
-    testParse("a && !b || c", "{(:or (:and :a (:not :b)) :c)}")
-    testParse("a && b==c || d", "{(:or (:and :a (:equal :b :c)) :d)}")
-    testParse("a && b!=c || d", "{(:or (:and :a (:unequal :b :c)) :d)}")
-    testParse("a && !(b==c) || d", "{(:or (:and :a (:not (:equal :b :c))) :d)}")
-    testParse("a && b>=c || d", "{(:or (:and :a (:largerEq :b :c)) :d)}")
-    testParse("a && !(b>=c) || d", "{(:or (:and :a (:not (:largerEq :b :c))) :d)}")
-    testParse("a && b<=c || d", "{(:or (:and :a (:smallerEq :b :c)) :d)}")
-    testParse("a && b>c || d", "{(:or (:and :a (:larger :b :c)) :d)}")
-    testParse("a && b<c || d", "{(:or (:and :a (:smaller :b :c)) :d)}")
-    testParse("a && b<c[i] || d", "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c :i))) :d)}")
-    testParse("a && b<c.i || d", "{(:or (:and :a (:smaller :b (:$_atIndex_$ :c 'i'))) :d)}")
-    testParse("a && b<c(i) || d", "{(:or (:and :a (:smaller :b (:c :i))) :d)}")
-    testParse("a && b<1+2 || d", "{(:or (:and :a (:smaller :b (:add 1 2))) :d)}")
-    testParse("a && b<1+2*3 || d", "{(:or (:and :a (:smaller :b (:add 1 (:multiply 2 3)))) :d)}")
+    testParse("true || false", "{(::$_endOfOuterBlock_$ () (::or true false))}")
+    testParse("true && false", "{(::$_endOfOuterBlock_$ () (::and true false))}")
+    testParse("a * b + c", "{(::$_endOfOuterBlock_$ () (::add (::multiply :a :b) :c))}") // for comparison
+    testParse("a && b || c", "{(::$_endOfOuterBlock_$ () (::or (::and :a :b) :c))}")
+    testParse("a && b || c && d", "{(::$_endOfOuterBlock_$ () (::or (::and :a :b) (::and :c :d)))}")
+    testParse("a && !b || c", "{(::$_endOfOuterBlock_$ () (::or (::and :a (::not :b)) :c))}")
+    testParse("a && b==c || d", "{(::$_endOfOuterBlock_$ () (::or (::and :a (::equal :b :c)) :d))}")
+    testParse(
+      "a && b!=c || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::unequal :b :c)) :d))}",
+    )
+    testParse(
+      "a && !(b==c) || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::not (::equal :b :c))) :d))}",
+    )
+    testParse(
+      "a && b>=c || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::largerEq :b :c)) :d))}",
+    )
+    testParse(
+      "a && !(b>=c) || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::not (::largerEq :b :c))) :d))}",
+    )
+    testParse(
+      "a && b<=c || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smallerEq :b :c)) :d))}",
+    )
+    testParse("a && b>c || d", "{(::$_endOfOuterBlock_$ () (::or (::and :a (::larger :b :c)) :d))}")
+    testParse(
+      "a && b<c || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b :c)) :d))}",
+    )
+    testParse(
+      "a && b<c[i] || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::$_atIndex_$ :c :i))) :d))}",
+    )
+    testParse(
+      "a && b<c.i || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::$_atIndex_$ :c 'i'))) :d))}",
+    )
+    testParse(
+      "a && b<c(i) || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::c :i))) :d))}",
+    )
+    testParse(
+      "a && b<1+2 || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::add 1 2))) :d))}",
+    )
+    testParse(
+      "a && b<1+2*3 || d",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::add 1 (::multiply 2 3)))) :d))}",
+    )
    testParse(
      "a && b<1+2*-3+4 || d",
-      "{(:or (:and :a (:smaller :b (:add (:add 1 (:multiply 2 (:unaryMinus 3))) 4))) :d)}",
+      "{(::$_endOfOuterBlock_$ () (::or (::and :a (::smaller :b (::add (::add 1 (::multiply 2 (::unaryMinus 3))) 4))) :d))}",
    )
    testParse(
      "a && b<1+2*3 || d ? true : false",
-      "{(::$$_ternary_$$ (:or (:and :a (:smaller :b (:add 1 (:multiply 2 3)))) :d) true false)}",
+      "{(::$_endOfOuterBlock_$ () (::$$_ternary_$$ (::or (::and :a (::smaller :b (::add 1 (::multiply 2 3)))) :d) true false))}",
    )
  })

  describe("pipe", () => {
-    testParse("1 -> add(2)", "{(:add 1 2)}")
-    testParse("-1 -> add(2)", "{(:add (:unaryMinus 1) 2)}")
-    testParse("-a[1] -> add(2)", "{(:add (:unaryMinus (:$_atIndex_$ :a 1)) 2)}")
-    testParse("-f(1) -> add(2)", "{(:add (:unaryMinus (:f 1)) 2)}")
-    testParse("1 + 2 -> add(3)", "{(:add 1 (:add 2 3))}")
-    testParse("1 -> add(2) * 3", "{(:multiply (:add 1 2) 3)}")
-    testParse("1 -> subtract(2)", "{(:subtract 1 2)}")
-    testParse("-1 -> subtract(2)", "{(:subtract (:unaryMinus 1) 2)}")
-    testParse("1 -> subtract(2) * 3", "{(:multiply (:subtract 1 2) 3)}")
+    testParse("1 -> add(2)", "{(::$_endOfOuterBlock_$ () (::add 1 2))}")
+    testParse("-1 -> add(2)", "{(::$_endOfOuterBlock_$ () (::add (::unaryMinus 1) 2))}")
+    testParse(
+      "-a[1] -> add(2)",
+      "{(::$_endOfOuterBlock_$ () (::add (::unaryMinus (::$_atIndex_$ :a 1)) 2))}",
+    )
+    testParse("-f(1) -> add(2)", "{(::$_endOfOuterBlock_$ () (::add (::unaryMinus (::f 1)) 2))}")
+    testParse("1 + 2 -> add(3)", "{(::$_endOfOuterBlock_$ () (::add 1 (::add 2 3)))}")
+    testParse("1 -> add(2) * 3", "{(::$_endOfOuterBlock_$ () (::multiply (::add 1 2) 3))}")
+    testParse("1 -> subtract(2)", "{(::$_endOfOuterBlock_$ () (::subtract 1 2))}")
+    testParse("-1 -> subtract(2)", "{(::$_endOfOuterBlock_$ () (::subtract (::unaryMinus 1) 2))}")
+    testParse(
+      "1 -> subtract(2) * 3",
+      "{(::$_endOfOuterBlock_$ () (::multiply (::subtract 1 2) 3))}",
+    )
  })

  describe("elixir pipe", () => {
    //handled together with -> so there is no need for seperate tests
-    testParse("1 |> add(2)", "{(:add 1 2)}")
+    testParse("1 |> add(2)", "{(::$_endOfOuterBlock_$ () (::add 1 2))}")
  })

  describe("to", () => {
-    testParse("1 to 2", "{(:credibleIntervalToDistribution 1 2)}")
-    testParse("-1 to -2", "{(:credibleIntervalToDistribution (:unaryMinus 1) (:unaryMinus 2))}") // lower than unary
+    testParse("1 to 2", "{(::$_endOfOuterBlock_$ () (::credibleIntervalToDistribution 1 2))}")
+    testParse(
+      "-1 to -2",
+      "{(::$_endOfOuterBlock_$ () (::credibleIntervalToDistribution (::unaryMinus 1) (::unaryMinus 2)))}",
+    ) // lower than unary
    testParse(
      "a[1] to a[2]",
-      "{(:credibleIntervalToDistribution (:$_atIndex_$ :a 1) (:$_atIndex_$ :a 2))}",
+      "{(::$_endOfOuterBlock_$ () (::credibleIntervalToDistribution (::$_atIndex_$ :a 1) (::$_atIndex_$ :a 2)))}",
    ) // lower than post
    testParse(
      "a.p1 to a.p2",
-      "{(:credibleIntervalToDistribution (:$_atIndex_$ :a 'p1') (:$_atIndex_$ :a 'p2'))}",
+      "{(::$_endOfOuterBlock_$ () (::credibleIntervalToDistribution (::$_atIndex_$ :a 'p1') (::$_atIndex_$ :a 'p2')))}",
    ) // lower than post
-    testParse("1 to 2 + 3", "{(:credibleIntervalToDistribution 1 (:add 2 3))}")
+    testParse(
+      "1 to 2 + 3",
+      "{(::$_endOfOuterBlock_$ () (::add (::credibleIntervalToDistribution 1 2) 3))}",
+    ) // higher than binary operators
    testParse(
      "1->add(2) to 3->add(4) -> add(4)",
-      "{(:credibleIntervalToDistribution (:add 1 2) (:add (:add 3 4) 4))}",
+      "{(::$_endOfOuterBlock_$ () (::credibleIntervalToDistribution (::add 1 2) (::add (::add 3 4) 4)))}",
    ) // lower than chain
  })

  describe("inner block", () => {
    // inner blocks are 0 argument lambdas. They can be used whenever a value is required.
    // Like lambdas they have a local scope.
-    testParse("x={y=1; y}; x", "{:x = {:y = {1}; :y}; :x}")
+    testParse("x={y=1; y}; x", "{:x = {:y = {1}; :y}; (::$_endOfOuterBlock_$ () :x)}")
  })

  describe("lambda", () => {
-    testParse("{|x| x}", "{{|:x| :x}}")
-    testParse("f={|x| x}", "{:f = {|:x| :x}}")
-    testParse("f(x)=x", "{:f = {|:x| {:x}}}") // Function definitions are lambda assignments
-    testParse("f(x)=x ? 1 : 0", "{:f = {|:x| {(::$$_ternary_$$ :x 1 0)}}}") // Function definitions are lambda assignments
+    testParse("{|x| x}", "{(::$_endOfOuterBlock_$ () {|:x| {:x}})}")
+    testParse("f={|x| x}", "{:f = {{|:x| {:x}}}; (::$_endOfOuterBlock_$ () ())}")
+    testParse("f(x)=x", "{:f = {|:x| {:x}}; (::$_endOfOuterBlock_$ () ())}") // Function definitions are lambda assignments
+    testParse(
+      "f(x)=x ? 1 : 0",
+      "{:f = {|:x| {(::$$_ternary_$$ :x 1 0)}}; (::$_endOfOuterBlock_$ () ())}",
+    ) // Function definitions are lambda assignments
  })

  describe("Using lambda as value", () => {
    testParse(
      "myadd(x,y)=x+y; z=myadd; z",
-      "{:myadd = {|:x,:y| {(:add :x :y)}}; :z = {:myadd}; :z}",
+      "{:myadd = {|:x,:y| {(::add :x :y)}}; :z = {:myadd}; (::$_endOfOuterBlock_$ () :z)}",
    )
    testParse(
      "myadd(x,y)=x+y; z=[myadd]; z",
-      "{:myadd = {|:x,:y| {(:add :x :y)}}; :z = {[:myadd]}; :z}",
+      "{:myadd = {|:x,:y| {(::add :x :y)}}; :z = {(::$_constructArray_$ :myadd)}; (::$_endOfOuterBlock_$ () :z)}",
    )
    testParse(
      "myaddd(x,y)=x+y; z={x: myaddd}; z",
-      "{:myaddd = {|:x,:y| {(:add :x :y)}}; :z = {{'x': :myaddd}}; :z}",
+      "{:myaddd = {|:x,:y| {(::add :x :y)}}; :z = {(::$_constructRecord_$ ('x': :myaddd))}; (::$_endOfOuterBlock_$ () :z)}",
+    )
+    testParse("f({|x| x+1})", "{(::$_endOfOuterBlock_$ () (::f {|:x| {(::add :x 1)}}))}")
+    testParse(
+      "map(arr, {|x| x+1})",
+      "{(::$_endOfOuterBlock_$ () (::map :arr {|:x| {(::add :x 1)}}))}",
+    )
+    testParse(
+      "map([1,2,3], {|x| x+1})",
+      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ 1 2 3) {|:x| {(::add :x 1)}}))}",
+    )
+    testParse(
+      "[1,2,3]->map({|x| x+1})",
+      "{(::$_endOfOuterBlock_$ () (::map (::$_constructArray_$ 1 2 3) {|:x| {(::add :x 1)}}))}",
    )
-    testParse("f({|x| x+1})", "{(:f {|:x| (:add :x 1)})}")
-    testParse("map(arr, {|x| x+1})", "{(:map :arr {|:x| (:add :x 1)})}")
-    testParse("map([1,2,3], {|x| x+1})", "{(:map [1; 2; 3] {|:x| (:add :x 1)})}")
-    testParse("[1,2,3]->map({|x| x+1})", "{(:map [1; 2; 3] {|:x| (:add :x 1)})}")
  })
  describe("unit", () => {
-    testParse("1m", "{(:fromUnit_m 1)}")
-    testParse("1M", "{(:fromUnit_M 1)}")
-    testParse("1m+2cm", "{(:add (:fromUnit_m 1) (:fromUnit_cm 2))}")
+    testParse("1m", "{(::$_endOfOuterBlock_$ () (::fromUnit_m 1))}")
+    testParse("1M", "{(::$_endOfOuterBlock_$ () (::fromUnit_M 1))}")
+    testParse("1m+2cm", "{(::$_endOfOuterBlock_$ () (::add (::fromUnit_m 1) (::fromUnit_cm 2)))}")
  })
  describe("Module", () => {
-    testParse("x", "{:x}")
-    testParse("Math.pi", "{:Math.pi}")
+    testParse("x", "{(::$_endOfOuterBlock_$ () :x)}")
+    testParse("Math.pi", "{(::$_endOfOuterBlock_$ () :Math.pi)}")
  })
 })

@ -236,19 +351,19 @@ describe("parsing new line", () => {
    `
 a + 
 b`,
-    "{(:add :a :b)}",
+    "{(::$_endOfOuterBlock_$ () (::add :a :b))}",
  )
  testParse(
    `
 x=
 1`,
-    "{:x = {1}}",
+    "{:x = {1}; (::$_endOfOuterBlock_$ () ())}",
  )
  testParse(
    `
 x=1
 y=2`,
-    "{:x = {1}; :y = {2}}",
+    "{:x = {1}; :y = {2}; (::$_endOfOuterBlock_$ () ())}",
  )
  testParse(
    `
@ -256,7 +371,7 @@ describe("parsing new line", () => {
  y=2;
  y }
 x`,
-    "{:x = {:y = {2}; :y}; :x}",
+    "{:x = {:y = {2}; :y}; (::$_endOfOuterBlock_$ () :x)}",
  )
  testParse(
    `
@ -264,7 +379,7 @@ describe("parsing new line", () => {
  y=2
  y }
 x`,
-    "{:x = {:y = {2}; :y}; :x}",
+    "{:x = {:y = {2}; :y}; (::$_endOfOuterBlock_$ () :x)}",
  )
  testParse(
    `
@ -273,7 +388,7 @@ describe("parsing new line", () => {
  y 
  }
 x`,
-    "{:x = {:y = {2}; :y}; :x}",
+    "{:x = {:y = {2}; :y}; (::$_endOfOuterBlock_$ () :x)}",
  )
  testParse(
    `
@ -281,7 +396,7 @@ describe("parsing new line", () => {
 y=2
 z=3
 `,
-    "{:x = {1}; :y = {2}; :z = {3}}",
+    "{:x = {1}; :y = {2}; :z = {3}; (::$_endOfOuterBlock_$ () ())}",
  )
  testParse(
    `
@ -292,7 +407,7 @@ describe("parsing new line", () => {
  x+y+z
 }
 `,
-    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}}",
+    "{:f = {:x = {1}; :y = {2}; :z = {3}; (::add (::add :x :y) :z)}; (::$_endOfOuterBlock_$ () ())}",
  )
  testParse(
    `
@ -305,7 +420,7 @@ describe("parsing new line", () => {
 g=f+4
 g
 `,
-    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; :g}",
+    "{:f = {:x = {1}; :y = {2}; :z = {3}; (::add (::add :x :y) :z)}; :g = {(::add :f 4)}; (::$_endOfOuterBlock_$ () :g)}",
  )
  testParse(
    `
@ -327,7 +442,7 @@ describe("parsing new line", () => {
  p ->
  q 
 `,
-    "{:f = {:x = {1}; :y = {2}; :z = {3}; (:add (:add :x :y) :z)}; :g = {(:add :f 4)}; (:q (:p (:h :g)))}",
+    "{:f = {:x = {1}; :y = {2}; :z = {3}; (::add (::add :x :y) :z)}; :g = {(::add :f 4)}; (::$_endOfOuterBlock_$ () (::q (::p (::h :g))))}",
  )
  testParse(
    `
@ -336,7 +451,7 @@ describe("parsing new line", () => {
  c |>
  d 
 `,
-    "{(:d (:c (:b :a)))}",
+    "{(::$_endOfOuterBlock_$ () (::d (::c (::b :a))))}",
  )
  testParse(
    `
@ -346,6 +461,6 @@ describe("parsing new line", () => {
  d +
  e
 `,
-    "{(:add (:d (:c (:b :a))) :e)}",
+    "{(::$_endOfOuterBlock_$ () (::add (::d (::c (::b :a))) :e))}",
  )
 })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_TestHelpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_TestHelpers.res
@ -1,5 +1,6 @@
 module Expression = Reducer_Expression
 module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.InternalExpressionValue
 module Parse = Reducer_Peggy_Parse
 module Result = Belt.Result
 module ToExpression = Reducer_Peggy_ToExpression
@ -9,12 +10,12 @@ open Jest
 open Expect

 let expectParseToBe = (expr, answer) =>
-  Parse.parse(expr, "test")->Parse.toStringResult->expect->toBe(answer)
+  Parse.parse(expr)->Parse.toStringResult->expect->toBe(answer)

 let testParse = (expr, answer) => test(expr, () => expectParseToBe(expr, answer))

-let expectExpressionToBe = (expr, answer, ~v="_", ()) => {
-  let rExpr = Parse.parse(expr, "test")->Result.map(ToExpression.fromNode)
+let expectToExpressionToBe = (expr, answer, ~v="_", ()) => {
+  let rExpr = Parse.parse(expr)->Result.map(ToExpression.fromNode)
  let a1 = rExpr->ExpressionT.toStringResultOkless

  if v == "_" {
@ -22,24 +23,24 @@ let expectExpressionToBe = (expr, answer, ~v="_", ()) => {
  } else {
    let a2 =
      rExpr
-      ->E.R2.errMap(e => e->SqError.fromParseError)
      ->Result.flatMap(expr => Expression.BackCompatible.evaluate(expr))
-      ->Reducer_Value.toStringResultOkless
+      ->Reducer_Helpers.rRemoveDefaultsInternal
+      ->ExpressionValue.toStringResultOkless
    (a1, a2)->expect->toEqual((answer, v))
  }
 }

 let testToExpression = (expr, answer, ~v="_", ()) =>
-  test(expr, () => expectExpressionToBe(expr, answer, ~v, ()))
+  test(expr, () => expectToExpressionToBe(expr, answer, ~v, ()))

 module MyOnly = {
  let testParse = (expr, answer) => Only.test(expr, () => expectParseToBe(expr, answer))
  let testToExpression = (expr, answer, ~v="_", ()) =>
-    Only.test(expr, () => expectExpressionToBe(expr, answer, ~v, ()))
+    Only.test(expr, () => expectToExpressionToBe(expr, answer, ~v, ()))
 }

 module MySkip = {
  let testParse = (expr, answer) => Skip.test(expr, () => expectParseToBe(expr, answer))
  let testToExpression = (expr, answer, ~v="_", ()) =>
-    Skip.test(expr, () => expectExpressionToBe(expr, answer, ~v, ()))
+    Skip.test(expr, () => expectToExpressionToBe(expr, answer, ~v, ()))
 }
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_outerBlock_test.res
@ -1,12 +1,23 @@
+module Bindings = Reducer_Bindings
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+
 open Jest
 open Reducer_Peggy_TestHelpers

-// Note: these tests aren't useful anymore since outer block macro got deleted.
-// Probably can be removed or folded into other Peggy tests.
 describe("Peggy Outer Block", () => {
-  testToExpression("1", "1", ~v="1", ())
-  testToExpression("x=1", "x = {1}", ~v="()", ())
-  testToExpression("x=1; y=2", "x = {1}; y = {2}", ~v="()", ())
-  testToExpression("x=1; 2", "x = {1}; 2", ~v="2", ())
-  testToExpression("x={a=1; a}; x", "x = {a = {1}; a}; x", ~v="1", ())
+  testToExpression("1", "{(:$_endOfOuterBlock_$ () 1)}", ~v="1", ())
+  testToExpression("x=1", "{(:$_let_$ :x {1}); (:$_endOfOuterBlock_$ () ())}", ~v="()", ())
+  testToExpression(
+    "x=1; y=2",
+    "{(:$_let_$ :x {1}); (:$_let_$ :y {2}); (:$_endOfOuterBlock_$ () ())}",
+    ~v="()",
+    (),
+  )
+  testToExpression("x=1; 2", "{(:$_let_$ :x {1}); (:$_endOfOuterBlock_$ () 2)}", ~v="2", ())
+  testToExpression(
+    "x={a=1; a}; x",
+    "{(:$_let_$ :x {(:$_let_$ :a {1}); :a}); (:$_endOfOuterBlock_$ () :x)}",
+    ~v="1",
+    (),
+  )
 })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res
@ -1,4 +1,5 @@
 module Bindings = Reducer_Bindings
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue

 open Jest
 open Reducer_Peggy_TestHelpers
@ -6,121 +7,202 @@ open Reducer_Peggy_TestHelpers
 describe("Peggy to Expression", () => {
  describe("literals operators parenthesis", () => {
    // Note that there is always an outer block. Otherwise, external bindings are ignored at the first statement
-    testToExpression("1", "1", ~v="1", ())
-    testToExpression("'hello'", "'hello'", ~v="'hello'", ())
-    testToExpression("true", "true", ~v="true", ())
-    testToExpression("1+2", "(add)(1, 2)", ~v="3", ())
-    testToExpression("add(1,2)", "(add)(1, 2)", ~v="3", ())
-    testToExpression("(1)", "1", ())
-    testToExpression("(1+2)", "(add)(1, 2)", ())
+    testToExpression("1", "{(:$_endOfOuterBlock_$ () 1)}", ~v="1", ())
+    testToExpression("'hello'", "{(:$_endOfOuterBlock_$ () 'hello')}", ~v="'hello'", ())
+    testToExpression("true", "{(:$_endOfOuterBlock_$ () true)}", ~v="true", ())
+    testToExpression("1+2", "{(:$_endOfOuterBlock_$ () (:add 1 2))}", ~v="3", ())
+    testToExpression("add(1,2)", "{(:$_endOfOuterBlock_$ () (:add 1 2))}", ~v="3", ())
+    testToExpression("(1)", "{(:$_endOfOuterBlock_$ () 1)}", ())
+    testToExpression("(1+2)", "{(:$_endOfOuterBlock_$ () (:add 1 2))}", ())
  })

  describe("unary", () => {
-    testToExpression("-1", "(unaryMinus)(1)", ~v="-1", ())
-    testToExpression("!true", "(not)(true)", ~v="false", ())
-    testToExpression("1 + -1", "(add)(1, (unaryMinus)(1))", ~v="0", ())
-    testToExpression("-a[0]", "(unaryMinus)(($_atIndex_$)(a, 0))", ())
+    testToExpression("-1", "{(:$_endOfOuterBlock_$ () (:unaryMinus 1))}", ~v="-1", ())
+    testToExpression("!true", "{(:$_endOfOuterBlock_$ () (:not true))}", ~v="false", ())
+    testToExpression("1 + -1", "{(:$_endOfOuterBlock_$ () (:add 1 (:unaryMinus 1)))}", ~v="0", ())
+    testToExpression("-a[0]", "{(:$_endOfOuterBlock_$ () (:unaryMinus (:$_atIndex_$ :a 0)))}", ())
  })

  describe("multi-line", () => {
-    testToExpression("x=1; 2", "x = {1}; 2", ~v="2", ())
-    testToExpression("x=1; y=2", "x = {1}; y = {2}", ())
+    testToExpression("x=1; 2", "{(:$_let_$ :x {1}); (:$_endOfOuterBlock_$ () 2)}", ~v="2", ())
+    testToExpression(
+      "x=1; y=2",
+      "{(:$_let_$ :x {1}); (:$_let_$ :y {2}); (:$_endOfOuterBlock_$ () ())}",
+      (),
+    )
  })

  describe("variables", () => {
-    testToExpression("x = 1", "x = {1}", ())
-    testToExpression("x", "x", ~v="Error(x is not defined)", ()) //TODO: value should return error
-    testToExpression("x = 1; x", "x = {1}; x", ~v="1", ())
+    testToExpression("x = 1", "{(:$_let_$ :x {1}); (:$_endOfOuterBlock_$ () ())}", ())
+    testToExpression("x", "{(:$_endOfOuterBlock_$ () :x)}", ~v="Error(x is not defined)", ()) //TODO: value should return error
+    testToExpression("x = 1; x", "{(:$_let_$ :x {1}); (:$_endOfOuterBlock_$ () :x)}", ~v="1", ())
  })

  describe("functions", () => {
-    testToExpression("identity(x) = x", "identity = {|x| {x}}", ()) // Function definitions become lambda assignments
-    testToExpression("identity(x)", "(identity)(x)", ()) // Note value returns error properly
+    testToExpression(
+      "identity(x) = x",
+      "{(:$_let_$ :identity (:$$_lambda_$$ [x] {:x})); (:$_endOfOuterBlock_$ () ())}",
+      (),
+    ) // Function definitions become lambda assignments
+    testToExpression("identity(x)", "{(:$_endOfOuterBlock_$ () (:identity :x))}", ()) // Note value returns error properly
    testToExpression(
      "f(x) = x> 2 ? 0 : 1; f(3)",
-      "f = {|x| {(larger)(x, 2) ? (0) : (1)}}; (f)(3)",
+      "{(:$_let_$ :f (:$$_lambda_$$ [x] {(:$$_ternary_$$ (:larger :x 2) 0 1)})); (:$_endOfOuterBlock_$ () (:f 3))}",
      ~v="0",
      (),
    )
  })

  describe("arrays", () => {
-    testToExpression("[]", "[]", ~v="[]", ())
-    testToExpression("[0, 1, 2]", "[0, 1, 2]", ~v="[0,1,2]", ())
-    testToExpression("['hello', 'world']", "['hello', 'world']", ~v="['hello','world']", ())
-    testToExpression("([0,1,2])[1]", "($_atIndex_$)([0, 1, 2], 1)", ~v="1", ())
+    testToExpression("[]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$))}", ~v="[]", ())
+    testToExpression(
+      "[0, 1, 2]",
+      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 0 1 2))}",
+      ~v="[0,1,2]",
+      (),
+    )
+    testToExpression(
+      "['hello', 'world']",
+      "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 'hello' 'world'))}",
+      ~v="['hello','world']",
+      (),
+    )
+    testToExpression(
+      "([0,1,2])[1]",
+      "{(:$_endOfOuterBlock_$ () (:$_atIndex_$ (:$_constructArray_$ 0 1 2) 1))}",
+      ~v="1",
+      (),
+    )
  })

  describe("records", () => {
-    testToExpression("{a: 1, b: 2}", "{'a': 1, 'b': 2}", ~v="{a: 1,b: 2}", ())
-    testToExpression("{1+0: 1, 2+0: 2}", "{(add)(1, 0): 1, (add)(2, 0): 2}", ()) // key can be any expression
-    testToExpression("record.property", "($_atIndex_$)(record, 'property')", ())
+    testToExpression(
+      "{a: 1, b: 2}",
+      "{(:$_endOfOuterBlock_$ () (:$_constructRecord_$ (('a' 1) ('b' 2))))}",
+      ~v="{a: 1,b: 2}",
+      (),
+    )
+    testToExpression(
+      "{1+0: 1, 2+0: 2}",
+      "{(:$_endOfOuterBlock_$ () (:$_constructRecord_$ (((:add 1 0) 1) ((:add 2 0) 2))))}",
+      (),
+    ) // key can be any expression
+    testToExpression(
+      "record.property",
+      "{(:$_endOfOuterBlock_$ () (:$_atIndex_$ :record 'property'))}",
+      (),
+    )
    testToExpression(
      "record={property: 1}; record.property",
-      "record = {{'property': 1}}; ($_atIndex_$)(record, 'property')",
+      "{(:$_let_$ :record {(:$_constructRecord_$ (('property' 1)))}); (:$_endOfOuterBlock_$ () (:$_atIndex_$ :record 'property'))}",
      ~v="1",
      (),
    )
  })

  describe("comments", () => {
-    testToExpression("1 # This is a line comment", "1", ~v="1", ())
-    testToExpression("1 // This is a line comment", "1", ~v="1", ())
-    testToExpression("1 /* This is a multi line comment */", "1", ~v="1", ())
-    testToExpression("/* This is a multi line comment */ 1", "1", ~v="1", ())
-  })
-
-  describe("ternary operator", () => {
-    testToExpression("true ? 1 : 0", "true ? (1) : (0)", ~v="1", ())
-    testToExpression("false ? 1 : 0", "false ? (1) : (0)", ~v="0", ())
-    testToExpression("true ? 1 : false ? 2 : 0", "true ? (1) : (false ? (2) : (0))", ~v="1", ()) // nested ternary
-    testToExpression("false ? 1 : false ? 2 : 0", "false ? (1) : (false ? (2) : (0))", ~v="0", ()) // nested ternary
-    describe(
-      "ternary bindings",
-      () => {
-        testToExpression(
-          // expression binding
-          "f(a) = a > 5 ? 1 : 0; f(6)",
-          "f = {|a| {(larger)(a, 5) ? (1) : (0)}}; (f)(6)",
-          ~v="1",
-          (),
-        )
-        testToExpression(
-          // when true binding
-          "f(a) = a > 5 ? a : 0; f(6)",
-          "f = {|a| {(larger)(a, 5) ? (a) : (0)}}; (f)(6)",
-          ~v="6",
-          (),
-        )
-        testToExpression(
-          // when false binding
-          "f(a) = a < 5 ? 1 : a; f(6)",
-          "f = {|a| {(smaller)(a, 5) ? (1) : (a)}}; (f)(6)",
-          ~v="6",
-          (),
-        )
-      },
+    testToExpression("1 # This is a line comment", "{(:$_endOfOuterBlock_$ () 1)}", ~v="1", ())
+    testToExpression("1 // This is a line comment", "{(:$_endOfOuterBlock_$ () 1)}", ~v="1", ())
+    testToExpression(
+      "1 /* This is a multi line comment */",
+      "{(:$_endOfOuterBlock_$ () 1)}",
+      ~v="1",
+      (),
+    )
+    testToExpression(
+      "/* This is a multi line comment */ 1",
+      "{(:$_endOfOuterBlock_$ () 1)}",
+      ~v="1",
+      (),
    )
  })

+  describe("ternary operator", () => {
+    testToExpression(
+      "true ? 1 : 0",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ true 1 0))}",
+      ~v="1",
+      (),
+    )
+    testToExpression(
+      "false ? 1 : 0",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ false 1 0))}",
+      ~v="0",
+      (),
+    )
+    testToExpression(
+      "true ? 1 : false ? 2 : 0",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ true 1 (:$$_ternary_$$ false 2 0)))}",
+      ~v="1",
+      (),
+    ) // nested ternary
+    testToExpression(
+      "false ? 1 : false ? 2 : 0",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ false 1 (:$$_ternary_$$ false 2 0)))}",
+      ~v="0",
+      (),
+    ) // nested ternary
+    describe("ternary bindings", () => {
+      testToExpression(
+        // expression binding
+        "f(a) = a > 5 ? 1 : 0; f(6)",
+        "{(:$_let_$ :f (:$$_lambda_$$ [a] {(:$$_ternary_$$ (:larger :a 5) 1 0)})); (:$_endOfOuterBlock_$ () (:f 6))}",
+        ~v="1",
+        (),
+      )
+      testToExpression(
+        // when true binding
+        "f(a) = a > 5 ? a : 0; f(6)",
+        "{(:$_let_$ :f (:$$_lambda_$$ [a] {(:$$_ternary_$$ (:larger :a 5) :a 0)})); (:$_endOfOuterBlock_$ () (:f 6))}",
+        ~v="6",
+        (),
+      )
+      testToExpression(
+        // when false binding
+        "f(a) = a < 5 ? 1 : a; f(6)",
+        "{(:$_let_$ :f (:$$_lambda_$$ [a] {(:$$_ternary_$$ (:smaller :a 5) 1 :a)})); (:$_endOfOuterBlock_$ () (:f 6))}",
+        ~v="6",
+        (),
+      )
+    })
+  })
+
  describe("if then else", () => {
-    testToExpression("if true then 2 else 3", "true ? ({2}) : ({3})", ())
-    testToExpression("if true then {2} else {3}", "true ? ({2}) : ({3})", ())
+    testToExpression(
+      "if true then 2 else 3",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ true {2} {3}))}",
+      (),
+    )
+    testToExpression(
+      "if true then {2} else {3}",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ true {2} {3}))}",
+      (),
+    )
    testToExpression(
      "if false then {2} else if false then {4} else {5}",
-      "false ? ({2}) : (false ? ({4}) : ({5}))",
+      "{(:$_endOfOuterBlock_$ () (:$$_ternary_$$ false {2} (:$$_ternary_$$ false {4} {5})))}",
      (),
    ) //nested if
  })

  describe("pipe", () => {
-    testToExpression("1 -> add(2)", "(add)(1, 2)", ~v="3", ())
-    testToExpression("-1 -> add(2)", "(add)((unaryMinus)(1), 2)", ~v="1", ()) // note that unary has higher priority naturally
-    testToExpression("1 -> add(2) * 3", "(multiply)((add)(1, 2), 3)", ~v="9", ())
+    testToExpression("1 -> add(2)", "{(:$_endOfOuterBlock_$ () (:add 1 2))}", ~v="3", ())
+    testToExpression(
+      "-1 -> add(2)",
+      "{(:$_endOfOuterBlock_$ () (:add (:unaryMinus 1) 2))}",
+      ~v="1",
+      (),
+    ) // note that unary has higher priority naturally
+    testToExpression(
+      "1 -> add(2) * 3",
+      "{(:$_endOfOuterBlock_$ () (:multiply (:add 1 2) 3))}",
+      ~v="9",
+      (),
+    )
  })

  describe("elixir pipe", () => {
-    testToExpression("1 |> add(2)", "(add)(1, 2)", ~v="3", ())
+    testToExpression("1 |> add(2)", "{(:$_endOfOuterBlock_$ () (:add 1 2))}", ~v="3", ())
  })

  // see testParse for priorities of to and credibleIntervalToDistribution
@ -130,28 +212,44 @@ describe("Peggy to Expression", () => {
    // Like lambdas they have a local scope.
    testToExpression(
      "y=99; x={y=1; y}",
-      "y = {99}; x = {y = {1}; y}",
-      // "{(:$_let_$ :y {99}); (:$_let_$ :x {(:$_let_$ :y {1}); :y}); (:$_endOfOuterBlock_$ () ())}",
+      "{(:$_let_$ :y {99}); (:$_let_$ :x {(:$_let_$ :y {1}); :y}); (:$_endOfOuterBlock_$ () ())}",
      (),
    )
  })

  describe("lambda", () => {
-    testToExpression("{|x| x}", "{|x| x}", ~v="lambda(x=>internal code)", ())
-    testToExpression("f={|x| x}", "f = {|x| x}", ())
-    testToExpression("f(x)=x", "f = {|x| {x}}", ()) // Function definitions are lambda assignments
-    testToExpression("f(x)=x ? 1 : 0", "f = {|x| {x ? (1) : (0)}}", ())
+    testToExpression(
+      "{|x| x}",
+      "{(:$_endOfOuterBlock_$ () (:$$_lambda_$$ [x] {:x}))}",
+      ~v="lambda(x=>internal code)",
+      (),
+    )
+    testToExpression(
+      "f={|x| x}",
+      "{(:$_let_$ :f {(:$$_lambda_$$ [x] {:x})}); (:$_endOfOuterBlock_$ () ())}",
+      (),
+    )
+    testToExpression(
+      "f(x)=x",
+      "{(:$_let_$ :f (:$$_lambda_$$ [x] {:x})); (:$_endOfOuterBlock_$ () ())}",
+      (),
+    ) // Function definitions are lambda assignments
+    testToExpression(
+      "f(x)=x ? 1 : 0",
+      "{(:$_let_$ :f (:$$_lambda_$$ [x] {(:$$_ternary_$$ :x 1 0)})); (:$_endOfOuterBlock_$ () ())}",
+      (),
+    )
  })

  describe("module", () => {
    // testToExpression("Math.pi", "{:Math.pi}", ~v="3.141592653589793", ())
    // Only.test("stdlibrary", () => {
-    //  SquiggleLibrary_StdLib.stdLib
+    //  ReducerInterface_StdLib.internalStdLib
    //  ->IEvBindings
-    //  ->Reducer_Value.toString
+    //  ->InternalExpressionValue.toString
    //  ->expect
    //  ->toBe("")
    // })
-    testToExpression("Math.pi", "Math.pi", ~v="3.141592653589793", ())
+    testToExpression("Math.pi", "{(:$_endOfOuterBlock_$ () :Math.pi)}", ~v="3.141592653589793", ())
  })
 })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_void_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_void_test.res
@ -3,17 +3,22 @@ open Reducer_Peggy_TestHelpers

 describe("Peggy void", () => {
  //literal
-  testToExpression("()", "()", ~v="()", ())
+  testToExpression("()", "{(:$_endOfOuterBlock_$ () ())}", ~v="()", ())
  testToExpression(
    "fn()=1",
-    "fn = {|_| {1}}",
+    "{(:$_let_$ :fn (:$$_lambda_$$ [_] {1})); (:$_endOfOuterBlock_$ () ())}",
    // ~v="@{fn: lambda(_=>internal code)}",
    (),
  )
-  testToExpression("fn()=1; fn()", "fn = {|_| {1}}; (fn)(())", ~v="1", ())
+  testToExpression(
+    "fn()=1; fn()",
+    "{(:$_let_$ :fn (:$$_lambda_$$ [_] {1})); (:$_endOfOuterBlock_$ () (:fn ()))}",
+    ~v="1",
+    (),
+  )
  testToExpression(
    "fn(a)=(); call fn(1)",
-    "fn = {|a| {()}}; _ = {(fn)(1)}",
+    "{(:$_let_$ :fn (:$$_lambda_$$ [a] {()})); (:$_let_$ :_ {(:fn 1)}); (:$_endOfOuterBlock_$ () ())}",
    // ~v="@{_: (),fn: lambda(a=>internal code)}",
    (),
  )
--- a/packages/squiggle-lang/tests/Reducer/Reducer_TestHelpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_TestHelpers.res
@ -1,5 +1,7 @@
+module ErrorValue = Reducer_ErrorValue
 module Expression = Reducer_Expression
 module ExpressionT = Reducer_Expression_T
+module InternalExpressionValue = ReducerInterface.InternalExpressionValue

 open Jest
 open Expect
@ -7,8 +9,8 @@ open Expect
 let unwrapRecord = rValue =>
  rValue->Belt.Result.flatMap(value =>
    switch value {
-    | Reducer_T.IEvRecord(aRecord) => Ok(aRecord)
-    | _ => SqError.Message.RETodo("TODO: Internal bindings must be returned")->Error
+    | InternalExpressionValue.IEvRecord(aRecord) => Ok(aRecord)
+    | _ => ErrorValue.RETodo("TODO: Internal bindings must be returned")->Error
    }
  )

@ -16,13 +18,17 @@ let expectParseToBe = (code: string, answer: string) =>
  Expression.BackCompatible.parse(code)->ExpressionT.toStringResult->expect->toBe(answer)

 let expectEvalToBe = (code: string, answer: string) =>
-  Expression.BackCompatible.evaluateString(code)->Reducer_Value.toStringResult->expect->toBe(answer)
+  Expression.BackCompatible.evaluateString(code)
+  ->Reducer_Helpers.rRemoveDefaultsInternal
+  ->InternalExpressionValue.toStringResult
+  ->expect
+  ->toBe(answer)

 let expectEvalError = (code: string) =>
  Expression.BackCompatible.evaluateString(code)
-  ->Reducer_Value.toStringResult
+  ->InternalExpressionValue.toStringResult
  ->expect
-  ->toMatch("Error\\(")
+  ->toMatch("Error\(")

 let testParseToBe = (expr, answer) => test(expr, () => expectParseToBe(expr, answer))
 let testDescriptionParseToBe = (desc, expr, answer) =>
--- a/packages/squiggle-lang/tests/Reducer/Reducer_TestMacroHelpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_TestMacroHelpers.res
@ -0,0 +1,88 @@
+open Jest
+open Expect
+
+module Bindings = Reducer_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
+module Expression = Reducer_Expression
+module ExpressionWithContext = Reducer_ExpressionWithContext
+module InternalExpressionValue = ReducerInterface.InternalExpressionValue
+module Macro = Reducer_Expression_Macro
+module ProjectAccessorsT = ReducerProject_ProjectAccessors_T
+module T = Reducer_Expression_T
+
+let testMacro_ = (
+  tester,
+  bindArray: array<(string, InternalExpressionValue.t)>,
+  expr: T.expression,
+  expectedCode: string,
+) => {
+  let bindings = Bindings.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.expandMacroCall(
+      bindings,
+      ProjectAccessorsT.identityAccessors,
+      Expression.reduceExpressionInProject,
+    )
+    ->ExpressionWithContext.toStringResult
+    ->expect
+    ->toEqual(expectedCode)
+  )
+}
+
+let testMacroEval_ = (
+  tester,
+  bindArray: array<(string, InternalExpressionValue.t)>,
+  expr: T.expression,
+  expectedValue: string,
+) => {
+  let bindings = Bindings.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.doMacroCall(
+      bindings,
+      ProjectAccessorsT.identityAccessors,
+      Expression.reduceExpressionInProject,
+    )
+    ->InternalExpressionValue.toStringResult
+    ->expect
+    ->toEqual(expectedValue)
+  )
+}
+
+let testMacro = (
+  bindArray: array<(string, InternalExpressionValue.t)>,
+  expr: T.expression,
+  expectedExpr: string,
+) => testMacro_(test, bindArray, expr, expectedExpr)
+let testMacroEval = (
+  bindArray: array<(string, InternalExpressionValue.t)>,
+  expr: T.expression,
+  expectedValue: string,
+) => testMacroEval_(test, bindArray, expr, expectedValue)
+
+module MySkip = {
+  let testMacro = (
+    bindArray: array<(string, InternalExpressionValue.t)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Skip.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, InternalExpressionValue.t)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Skip.test, bindArray, expr, expectedValue)
+}
+
+module MyOnly = {
+  let testMacro = (
+    bindArray: array<(string, InternalExpressionValue.t)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Only.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, InternalExpressionValue.t)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Only.test, bindArray, expr, expectedValue)
+}
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_Compile_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_Compile_test.res
@ -0,0 +1,52 @@
+module Expression = Reducer_Expression
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+module Bindings = Reducer_Bindings
+module T = Reducer_Type_T
+module TypeCompile = Reducer_Type_Compile
+
+open Jest
+open Expect
+
+let myIevEval = (aTypeSourceCode: string) =>
+  TypeCompile.ievFromTypeExpression(aTypeSourceCode, Expression.reduceExpressionInProject)
+let myIevEvalToString = (aTypeSourceCode: string) =>
+  myIevEval(aTypeSourceCode)->InternalExpressionValue.toStringResult
+
+let myIevExpectEqual = (aTypeSourceCode, answer) =>
+  expect(myIevEvalToString(aTypeSourceCode))->toEqual(answer)
+
+let myIevTest = (test, aTypeSourceCode, answer) =>
+  test(aTypeSourceCode, () => myIevExpectEqual(aTypeSourceCode, answer))
+
+let myTypeEval = (aTypeSourceCode: string) =>
+  TypeCompile.fromTypeExpression(aTypeSourceCode, Expression.reduceExpressionInProject)
+let myTypeEvalToString = (aTypeSourceCode: string) => myTypeEval(aTypeSourceCode)->T.toStringResult
+
+let myTypeExpectEqual = (aTypeSourceCode, answer) =>
+  expect(myTypeEvalToString(aTypeSourceCode))->toEqual(answer)
+
+let myTypeTest = (test, aTypeSourceCode, answer) =>
+  test(aTypeSourceCode, () => myTypeExpectEqual(aTypeSourceCode, answer))
+
+//   | ItTypeIdentifier(string)
+myTypeTest(test, "number", "number")
+myTypeTest(test, "(number)", "number")
+//   | ItModifiedType({modifiedType: iType})
+myIevTest(test, "number<-min(0)", "Ok({min: 0,typeIdentifier: #number,typeTag: 'typeIdentifier'})")
+myTypeTest(test, "number<-min(0)", "number<-min(0)")
+//   | ItTypeOr({typeOr: array<iType>})
+myTypeTest(test, "number | string", "(number | string)")
+//   | ItTypeFunction({inputs: array<iType>, output: iType})
+myTypeTest(test, "number => number => number", "(number => number => number)")
+//   | ItTypeArray({element: iType})
+myIevTest(test, "[number]", "Ok({element: #number,typeTag: 'typeArray'})")
+myTypeTest(test, "[number]", "[number]")
+//   | ItTypeTuple({elements: array<iType>})
+myTypeTest(test, "[number, string]", "[number, string]")
+//   | ItTypeRecord({properties: Belt.Map.String.t<iType>})
+myIevTest(
+  test,
+  "{age: number, name: string}",
+  "Ok({properties: {age: #number,name: #string},typeTag: 'typeRecord'})",
+)
+myTypeTest(test, "{age: number, name: string}", "{age: number, name: string}")
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res
@ -0,0 +1,42 @@
+module Bindings = Reducer_Bindings
+module ErrorValue = Reducer_ErrorValue
+module Expression = Reducer_Expression
+module ExpressionT = Reducer_Expression_T
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+module ProjectAccessorsT = ReducerProject_ProjectAccessors_T
+module T = Reducer_Type_T
+module TypeChecker = Reducer_Type_TypeChecker
+
+open Jest
+open Expect
+
+let checkArgumentsSourceCode = (aTypeSourceCode: string, sourceCode: string): result<
+  'v,
+  ErrorValue.t,
+> => {
+  let reducerFn = Expression.reduceExpressionInProject
+  let rResult =
+    Expression.BackCompatible.parse(sourceCode)->Belt.Result.flatMap(expr =>
+      reducerFn(expr, Bindings.emptyBindings, ProjectAccessorsT.identityAccessors)
+    )
+  rResult->Belt.Result.flatMap(result =>
+    switch result {
+    | IEvArray(args) => TypeChecker.checkArguments(aTypeSourceCode, args, reducerFn)
+    | _ => Js.Exn.raiseError("Arguments has to be an array")
+    }
+  )
+}
+
+let myCheckArguments = (aTypeSourceCode: string, sourceCode: string): string =>
+  switch checkArgumentsSourceCode(aTypeSourceCode, sourceCode) {
+  | Ok(_) => "Ok"
+  | Error(error) => ErrorValue.errorToString(error)
+  }
+
+let myCheckArgumentsExpectEqual = (aTypeSourceCode, sourceCode, answer) =>
+  expect(myCheckArguments(aTypeSourceCode, sourceCode))->toEqual(answer)
+
+let myCheckArgumentsTest = (test, aTypeSourceCode, sourceCode, answer) =>
+  test(aTypeSourceCode, () => myCheckArgumentsExpectEqual(aTypeSourceCode, sourceCode, answer))
+
+myCheckArgumentsTest(test, "number=>number=>number", "[1,2]", "Ok")
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res
@ -0,0 +1,73 @@
+module Expression = Reducer_Expression
+module ExpressionT = Reducer_Expression_T
+module ErrorValue = Reducer_ErrorValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+module Bindings = Reducer_Bindings
+module T = Reducer_Type_T
+module TypeChecker = Reducer_Type_TypeChecker
+module ProjectAccessorsT = ReducerProject_ProjectAccessors_T
+
+open Jest
+open Expect
+
+// In development, you are expected to use TypeChecker.isTypeOf(aTypeSourceCode, result, reducerFn).
+// isTypeOfSourceCode is written to use strings instead of expression values.
+
+let isTypeOfSourceCode = (aTypeSourceCode: string, sourceCode: string): result<
+  'v,
+  ErrorValue.t,
+> => {
+  let reducerFn = Expression.reduceExpressionInProject
+  let rResult =
+    Expression.BackCompatible.parse(sourceCode)->Belt.Result.flatMap(expr =>
+      reducerFn(expr, Bindings.emptyBindings, ProjectAccessorsT.identityAccessors)
+    )
+  rResult->Belt.Result.flatMap(result => TypeChecker.isTypeOf(aTypeSourceCode, result, reducerFn))
+}
+
+let myTypeCheck = (aTypeSourceCode: string, sourceCode: string): string =>
+  switch isTypeOfSourceCode(aTypeSourceCode, sourceCode) {
+  | Ok(_) => "Ok"
+  | Error(error) => ErrorValue.errorToString(error)
+  }
+
+let myTypeCheckExpectEqual = (aTypeSourceCode, sourceCode, answer) =>
+  expect(myTypeCheck(aTypeSourceCode, sourceCode))->toEqual(answer)
+
+let myTypeCheckTest = (test, aTypeSourceCode, sourceCode, answer) =>
+  test(aTypeSourceCode, () => myTypeCheckExpectEqual(aTypeSourceCode, sourceCode, answer))
+
+myTypeCheckTest(test, "number", "1", "Ok")
+myTypeCheckTest(test, "number", "'2'", "Expected type: number but got: '2'")
+myTypeCheckTest(test, "string", "3", "Expected type: string but got: 3")
+myTypeCheckTest(test, "string", "'a'", "Ok")
+myTypeCheckTest(test, "[number]", "[1,2,3]", "Ok")
+myTypeCheckTest(test, "[number]", "['a','a','a']", "Expected type: number but got: 'a'")
+myTypeCheckTest(test, "[number]", "[1,'a',3]", "Expected type: number but got: 'a'")
+myTypeCheckTest(test, "[number, string]", "[1,'a']", "Ok")
+myTypeCheckTest(test, "[number, string]", "[1, 2]", "Expected type: string but got: 2")
+myTypeCheckTest(
+  test,
+  "[number, string, string]",
+  "[1,'a']",
+  "Expected type: [number, string, string] but got: [1,'a']",
+)
+myTypeCheckTest(
+  test,
+  "[number, string]",
+  "[1,'a', 3]",
+  "Expected type: [number, string] but got: [1,'a',3]",
+)
+myTypeCheckTest(test, "{age: number, name: string}", "{age: 1, name: 'a'}", "Ok")
+myTypeCheckTest(
+  test,
+  "{age: number, name: string}",
+  "{age: 1, name: 'a', job: 'IT'}",
+  "Expected type: {age: number, name: string} but got: {age: 1,job: 'IT',name: 'a'}",
+)
+myTypeCheckTest(test, "number | string", "1", "Ok")
+myTypeCheckTest(test, "date | string", "1", "Expected type: (date | string) but got: 1")
+myTypeCheckTest(test, "number<-min(10)", "10", "Ok")
+myTypeCheckTest(test, "number<-min(10)", "0", "Expected type: number<-min(10) but got: 0")
+myTypeCheckTest(test, "any", "0", "Ok")
+myTypeCheckTest(test, "any", "'a'", "Ok")
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Type/Reducer_Type_switch_replacement_test.res
@ -0,0 +1,127 @@
+open Jest
+open Expect
+
+module DispatchT = Reducer_Dispatch_T
+module Expression = Reducer_Expression
+module ExpressionT = Reducer_Expression_T
+module ProjectAccessorsT = ReducerProject_ProjectAccessors_T
+module ProjectReducerFnT = ReducerProject_ReducerFn_T
+module TypeChecker = Reducer_Type_TypeChecker
+module TypeCompile = Reducer_Type_Compile
+
+open ReducerInterface_InternalExpressionValue
+
+type errorValue = Reducer_ErrorValue.errorValue
+
+// Let's build a function to replace switch statements
+// In dispatchChainPiece, we execute an return the result of execution if there is a type match.
+// Otherwise we return None so that the call chain can continue.
+// So we want to build a function like
+// dispatchChainPiece = (call: functionCall, accessors): option<result<internalExpressionValue, errorValue>>
+// Use accessors.environment to get the environment finally.
+
+// Now lets make the dispatchChainPiece itself.
+// Note that I am not passing the reducer to the dispatchChainPiece as an argument because it is in the context anyway.
+// Keep in mind that reducerFn is necessary for map/reduce so dispatchChainPiece should have a reducerFn in context.
+
+let makeMyDispatchChainPiece = (reducer: ProjectReducerFnT.t): DispatchT.dispatchChainPiece => {
+  // Let's have a pure implementations
+  module Implementation = {
+    let stringConcat = (a: string, b: string): string => Js.String2.concat(a, b)
+    let arrayConcat = (
+      a: Js.Array2.t<internalExpressionValue>,
+      b: Js.Array2.t<internalExpressionValue>,
+    ): Js.Array2.t<internalExpressionValue> => Js.Array2.concat(a, b)
+    let plot = _r => "yey, plotted"
+  }
+
+  let extractStringString = args =>
+    switch args {
+    | [IEvString(a), IEvString(b)] => (a, b)
+    | _ => raise(Reducer_Exception.ImpossibleException("extractStringString developer error"))
+    }
+
+  let extractArrayArray = args =>
+    switch args {
+    | [IEvArray(a), IEvArray(b)] => (a, b)
+    | _ => raise(Reducer_Exception.ImpossibleException("extractArrayArray developer error"))
+    }
+
+  // Let's bridge the pure implementation to expression values
+  module Bridge = {
+    let stringConcat: DispatchT.genericIEvFunction = (args, _accessors: ProjectAccessorsT.t) => {
+      let (a, b) = extractStringString(args)
+      Implementation.stringConcat(a, b)->IEvString->Ok
+    }
+    let arrayConcat: DispatchT.genericIEvFunction = (args, _accessors: ProjectAccessorsT.t) => {
+      let (a, b) = extractArrayArray(args)
+      Implementation.arrayConcat(a, b)->IEvArray->Ok
+    }
+    let plot: DispatchT.genericIEvFunction = (args, _accessors: ProjectAccessorsT.t) => {
+      switch args {
+      // Just assume that we are doing the business of extracting and converting the deep record
+      | [IEvRecord(_)] => Implementation.plot({"title": "This is a plot"})->IEvString->Ok
+      | _ => raise(Reducer_Exception.ImpossibleException("plot developer error"))
+      }
+    }
+  }
+
+  // concat functions are to illustrate polymoprhism. And the plot function is to illustrate complex types
+  let jumpTable = [
+    (
+      "concat",
+      TypeCompile.fromTypeExpressionExn("string=>string=>string", reducer),
+      Bridge.stringConcat,
+    ),
+    (
+      "concat",
+      TypeCompile.fromTypeExpressionExn("[any]=>[any]=>[any]", reducer),
+      Bridge.arrayConcat,
+    ),
+    (
+      "plot",
+      TypeCompile.fromTypeExpressionExn(
+        // Nested complex types are available
+        // records {property: type}
+        // arrays [type]
+        // tuples [type, type]
+        // <- type contracts are available naturally and they become part of dispatching
+        // Here we are not enumerating the possibilities because type checking has a dedicated test
+        "{title: string, line: {width: number, color: string}}=>string",
+        reducer,
+      ),
+      Bridge.plot,
+    ),
+  ]
+
+  //Here we are creating a dispatchChainPiece function that will do the actual dispatch from the jumpTable
+  Reducer_Dispatch_ChainPiece.makeFromTypes(jumpTable)
+}
+
+// And finally, let's write a library dispatch for our external library
+// Exactly the same as the one used in real life
+let _dispatch = (
+  call: functionCall,
+  accessors: ProjectAccessorsT.t,
+  reducer: ProjectReducerFnT.t,
+  chain,
+): result<internalExpressionValue, 'e> => {
+  let dispatchChainPiece = makeMyDispatchChainPiece(reducer)
+  dispatchChainPiece(call, accessors)->E.O2.defaultFn(() => chain(call, accessors, reducer))
+}
+
+// What is important about this implementation?
+// A) Exactly the same function jump table can be used to create type guarded lambda functions
+// Guarded lambda functions will be the basis of the next version of Squiggle
+// B) Complicated recursive record types are not a problem.
+
+describe("Type Dispatch", () => {
+  let reducerFn = Expression.reduceExpressionInProject
+  let dispatchChainPiece = makeMyDispatchChainPiece(reducerFn)
+  test("stringConcat", () => {
+    let call: functionCall = ("concat", [IEvString("hello"), IEvString("world")])
+
+    let result = dispatchChainPiece(call, ProjectAccessorsT.identityAccessors)
+    expect(result)->toEqual(Some(Ok(IEvString("helloworld"))))
+  })
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Value_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Value_test.res
@ -1,14 +0,0 @@
-open Jest
-open Expect
-
-describe("ExpressionValue", () => {
-  test("argsToString", () =>
-    expect([IEvNumber(1.), IEvString("a")]->Reducer_Value.argsToString)->toBe("1,'a'")
-  )
-
-  test("toStringFunctionCall", () =>
-    expect(("fn", [IEvNumber(1.), IEvString("a")])->Reducer_Value.toStringFunctionCall)->toBe(
-      "fn(1,'a')",
-    )
-  )
-})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_constructArray_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_constructArray_test.res
@ -2,11 +2,11 @@ open Jest
 open Reducer_Peggy_TestHelpers

 describe("Construct Array", () => {
-  testToExpression("[1,2]", "[1, 2]", ~v="[1,2]", ())
-  testToExpression("[]", "[]", ~v="[]", ())
+  testToExpression("[1,2]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$ 1 2))}", ~v="[1,2]", ())
+  testToExpression("[]", "{(:$_endOfOuterBlock_$ () (:$_constructArray_$))}", ~v="[]", ())
  testToExpression(
    "f(x)=x; g(x)=x; [f, g]",
-    "f = {|x| {x}}; g = {|x| {x}}; [f, g]",
+    "{(:$_let_$ :f (:$$_lambda_$$ [x] {:x})); (:$_let_$ :g (:$$_lambda_$$ [x] {:x})); (:$_endOfOuterBlock_$ () (:$_constructArray_$ :f :g))}",
    ~v="[lambda(x=>internal code),lambda(x=>internal code)]",
    (),
  )
--- a/packages/squiggle-lang/tests/Reducer/Reducer_functionAssignment_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_functionAssignment_test.res
@ -2,15 +2,17 @@ open Jest
 open Reducer_TestHelpers

 describe("Parse function assignment", () => {
-  testParseToBe("f(x)=x", "Ok(f = {|x| {x}})")
-  testParseToBe("f(x)=2*x", "Ok(f = {|x| {(multiply)(2, x)}})")
+  testParseToBe(
+    "f(x)=x",
+    "Ok({(:$_let_$ :f (:$$_lambda_$$ [x] {:x})); (:$_endOfOuterBlock_$ () ())})",
+  )
+  testParseToBe(
+    "f(x)=2*x",
+    "Ok({(:$_let_$ :f (:$$_lambda_$$ [x] {(:multiply 2 :x)})); (:$_endOfOuterBlock_$ () ())})",
+  )
  //MathJs does not allow blocks in function definitions
 })

 describe("Evaluate function assignment", () => {
  testEvalToBe("f(x)=x; f(1)", "Ok(1)")
 })
-
-describe("Shadowing", () => {
-  testEvalToBe("x = 5; f(y) = x*y; x = 6; f(2)", "Ok(10)")
-})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_functionTricks_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_functionTricks_test.res
@ -34,7 +34,7 @@ describe("symbol not defined", () => {
  testEvalToBe("f(x)=x(y); f(f)", "Error(y is not defined)")
  testEvalToBe("f(x)=x; f(f)", "Ok(lambda(x=>internal code))")
  testEvalToBe("f(x)=x(y); f(z)", "Error(z is not defined)")
-  testEvalToBe("f(x)=x(y); f(2)", "Error(y is not defined)")
+  testEvalToBe("f(x)=x(y); f(2)", "Error(2 is not a function)")
  testEvalToBe("f(x)=x(1); f(2)", "Error(2 is not a function)")
 })

@ -46,7 +46,10 @@ describe("call and bindings", () => {
  testEvalToBe("f(x)=x+1; y=f(1); f(1)", "Ok(2)")
  testEvalToBe("f(x)=x+1; y=f(1); z=f(1); z", "Ok(2)")
  testEvalToBe("f(x)=x+1; g(x)=f(x)+1; g(0)", "Ok(2)")
-  testParseToBe("f=99; g(x)=f; g(2)", "Ok(f = {99}; g = {|x| {f}}; (g)(2))")
+  testParseToBe(
+    "f=99; g(x)=f; g(2)",
+    "Ok({(:$_let_$ :f {99}); (:$_let_$ :g (:$$_lambda_$$ [x] {:f})); (:$_endOfOuterBlock_$ () (:g 2))})",
+  )
  testEvalToBe("f=99; g(x)=f; g(2)", "Ok(99)")
  testEvalToBe("f(x)=x; g(x)=f(x); g(2)", "Ok(2)")
  testEvalToBe("f(x)=x+1; g(x)=f(x)+1; y=g(2); y", "Ok(4)")
--- a/packages/squiggle-lang/tests/Reducer/Reducer_mapReduce_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_mapReduce_test.res
@ -5,7 +5,3 @@ Skip.describe("map reduce (sam)", () => {
  testEvalToBe("addone(x)=x+1; map(2, addone)", "Error???")
  testEvalToBe("addone(x)=x+1; map(2, {x: addone})", "Error???")
 })
-
-describe("map", () => {
-  testEvalToBe("arr=[1,2,3]; map(arr, {|x| x*2})", "Ok([2,4,6])")
-})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_ternaryOperator_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_ternaryOperator_test.res
@ -2,7 +2,10 @@ open Jest
 open Reducer_TestHelpers

 describe("Parse ternary operator", () => {
-  testParseToBe("true ? 'YES' : 'NO'", "Ok(true ? ('YES') : ('NO'))")
+  testParseToBe(
+    "true ? 'YES' : 'NO'",
+    "Ok({(:$_endOfOuterBlock_$ () (:$$_ternary_$$ true 'YES' 'NO'))})",
+  )
 })

 describe("Evaluate ternary operator", () => {
--- a/packages/squiggle-lang/tests/Reducer/Reducer_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_test.res
@ -2,29 +2,19 @@ open Jest
 open Reducer_TestHelpers

 describe("eval", () => {
+  // All MathJs operators and functions are builtin for string, float and boolean
+  // .e.g + - / * > >= < <= == /= not and or
+  // See https://mathjs.org/docs/reference/functions.html
  describe("expressions", () => {
    testEvalToBe("1", "Ok(1)")
-    testEvalToBe("-1", "Ok(-1)")
-    testEvalToBe("1-1", "Ok(0)")
    testEvalToBe("1+2", "Ok(3)")
    testEvalToBe("(1+2)*3", "Ok(9)")
    testEvalToBe("2>1", "Ok(true)")
    testEvalToBe("concat('a ', 'b')", "Ok('a b')")
-    testEvalToBe("concat([3,4], [5,6,7])", "Ok([3,4,5,6,7])")
    testEvalToBe("log(10)", "Ok(2.302585092994046)")
-    testEvalToBe("Math.cos(10)", "Ok(-0.8390715290764524)")
+    testEvalToBe("cos(10)", "Ok(-0.8390715290764524)")
    // TODO more built ins
  })
-
-  describe("missing function", () => {
-    testEvalToBe("testZadanga(1)", "Error(testZadanga is not defined)")
-
-    testEvalToBe(
-      "arr = [normal(3,2)]; map(arr, zarathsuzaWasHere)",
-      "Error(zarathsuzaWasHere is not defined)",
-    )
-  })
-
  describe("arrays", () => {
    test("empty array", () => expectEvalToBe("[]", "Ok([])"))
    testEvalToBe("[1, 2, 3]", "Ok([1,2,3])")
@ -37,16 +27,14 @@ describe("eval", () => {
    test("index", () => expectEvalToBe("r = {a: 1}; r.a", "Ok(1)"))
    test("index", () => expectEvalToBe("r = {a: 1}; r.b", "Error(Record property not found: b)"))
    testEvalError("{a: 1}.b") // invalid syntax
-    test(
-      "always the same property ending",
-      () =>
-        expectEvalToBe(
-          `{
+    test("always the same property ending", () =>
+      expectEvalToBe(
+        `{
      a: 1, 
      b: 2,
    }`,
-          "Ok({a: 1,b: 2})",
-        ),
+        "Ok({a: 1,b: 2})",
+      )
    )
  })

@ -62,10 +50,6 @@ describe("eval", () => {
    testEvalError("1; 1")
    testEvalToBe("x=1; x=1; x", "Ok(1)")
  })
-
-  describe("blocks", () => {
-    testEvalToBe("x = { y = { z = 5; z * 2 }; y + 3 }; x", "Ok(13)")
-  })
 })

 describe("test exceptions", () => {
@ -80,33 +64,3 @@ describe("test exceptions", () => {
  //   "Error(TODO: unhandled rescript exception)",
  // )
 })
-
-describe("stacktraces", () => {
-  test("nested calls", () => {
-    open Expect
-
-    let error =
-      Expression.BackCompatible.evaluateString(`
-  f(x) = {
-    y = "a"
-    x + y
-  }
-  g = {|x| f(x)}
-  h(x) = g(x)
-  h(5)
-`)
-      ->E.R.getError
-      ->E.O2.toExn("oops")
-      ->SqError.toStringWithStackTrace
-
-    expect(
-      error,
-    )->toBe(`Error: There are function matches for add(), but with different arguments: [add(number, number)]; [add(distribution, number)]; [add(number, distribution)]; [add(distribution, distribution)]; [add(date, duration)]; [add(duration, duration)]
-Stack trace:
-  f at line 4, column 5
-  g at line 6, column 12
-  h at line 7, column 10
-  <top> at line 8, column 3
-`)
-  })
-})
--- a/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_Distribution_test.res
+++ b/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_Distribution_test.res
@ -23,7 +23,7 @@ describe("eval on distribution functions", () => {
    testEval("-normal(5,2)", "Ok(Normal(-5,2))")
  })
  describe("to", () => {
-    testEval("5 to 2", "Error(Error: Low value must be less than high value.)")
+    testEval("5 to 2", "Error(TODO: Low value must be less than high value.)")
    testEval("to(2,5)", "Ok(Lognormal(1.1512925464970227,0.27853260523016377))")
    testEval("to(-2,2)", "Ok(Normal(0,1.2159136638235384))")
  })
@ -98,7 +98,6 @@ describe("eval on distribution functions", () => {
      "log(normal(5,2), normal(10,1))",
      "Error(Distribution Math Error: Logarithm of input error: First input must be completely greater than 0)",
    )
-    testEval("log(2, SampleSet.fromDist(0.0001 to 5))", "Ok(Sample Set Distribution)") // log with low values, see https://github.com/quantified-uncertainty/squiggle/issues/1098
    testEval("log(uniform(5,8))", "Ok(Sample Set Distribution)")
    testEval("log10(uniform(5,8))", "Ok(Sample Set Distribution)")
  })
@ -120,28 +119,40 @@ describe("eval on distribution functions", () => {

 describe("parse on distribution functions", () => {
  describe("power", () => {
-    testParse("normal(5,2) ^ normal(5,1)", "Ok((pow)((normal)(5, 2), (normal)(5, 1)))")
-    testParse("3 ^ normal(5,1)", "Ok((pow)(3, (normal)(5, 1)))")
-    testParse("normal(5,2) ^ 3", "Ok((pow)((normal)(5, 2), 3))")
+    testParse(
+      "normal(5,2) ^ normal(5,1)",
+      "Ok({(:$_endOfOuterBlock_$ () (:pow (:normal 5 2) (:normal 5 1)))})",
+    )
+    testParse("3 ^ normal(5,1)", "Ok({(:$_endOfOuterBlock_$ () (:pow 3 (:normal 5 1)))})")
+    testParse("normal(5,2) ^ 3", "Ok({(:$_endOfOuterBlock_$ () (:pow (:normal 5 2) 3))})")
  })
  describe("subtraction", () => {
-    testParse("10 - normal(5,1)", "Ok((subtract)(10, (normal)(5, 1)))")
-    testParse("normal(5,1) - 10", "Ok((subtract)((normal)(5, 1), 10))")
+    testParse("10 - normal(5,1)", "Ok({(:$_endOfOuterBlock_$ () (:subtract 10 (:normal 5 1)))})")
+    testParse("normal(5,1) - 10", "Ok({(:$_endOfOuterBlock_$ () (:subtract (:normal 5 1) 10))})")
  })
  describe("pointwise arithmetic expressions", () => {
    testParse(~skip=true, "normal(5,2) .+ normal(5,1)", "Ok((:dotAdd (:normal 5 2) (:normal 5 1)))")
    testParse(
      ~skip=true,
      "normal(5,2) .- normal(5,1)",
-      "Ok((:$$_block_$$ (:dotSubtract (:normal 5 2) (:normal 5 1))))",
+      "Ok((:$_endOfOuterBlock_$ () (:$$_block_$$ (:dotSubtract (:normal 5 2) (:normal 5 1)))))",
      // TODO: !!! returns "Ok({(:dotPow (:normal 5 2) (:normal 5 1))})"
    )
-    testParse("normal(5,2) .* normal(5,1)", "Ok((dotMultiply)((normal)(5, 2), (normal)(5, 1)))")
-    testParse("normal(5,2) ./ normal(5,1)", "Ok((dotDivide)((normal)(5, 2), (normal)(5, 1)))")
-    testParse("normal(5,2) .^ normal(5,1)", "Ok((dotPow)((normal)(5, 2), (normal)(5, 1)))")
+    testParse(
+      "normal(5,2) .* normal(5,1)",
+      "Ok({(:$_endOfOuterBlock_$ () (:dotMultiply (:normal 5 2) (:normal 5 1)))})",
+    )
+    testParse(
+      "normal(5,2) ./ normal(5,1)",
+      "Ok({(:$_endOfOuterBlock_$ () (:dotDivide (:normal 5 2) (:normal 5 1)))})",
+    )
+    testParse(
+      "normal(5,2) .^ normal(5,1)",
+      "Ok({(:$_endOfOuterBlock_$ () (:dotPow (:normal 5 2) (:normal 5 1)))})",
+    )
  })
  describe("equality", () => {
-    testParse("5 == normal(5,2)", "Ok((equal)(5, (normal)(5, 2)))")
+    testParse("5 == normal(5,2)", "Ok({(:$_endOfOuterBlock_$ () (:equal 5 (:normal 5 2)))})")
  })
  describe("pointwise adding two normals", () => {
    testParse(~skip=true, "normal(5,2) .+ normal(5,1)", "Ok((:dotAdd (:normal 5 2) (:normal 5 1)))")
--- a/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_ExpressionValue_test.res
+++ b/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_ExpressionValue_test.res
@ -0,0 +1,11 @@
+open ReducerInterface.InternalExpressionValue
+open Jest
+open Expect
+
+describe("ExpressionValue", () => {
+  test("argsToString", () => expect([IEvNumber(1.), IEvString("a")]->argsToString)->toBe("1,'a'"))
+
+  test("toStringFunctionCall", () =>
+    expect(("fn", [IEvNumber(1.), IEvString("a")])->toStringFunctionCall)->toBe("fn(1,'a')")
+  )
+})
--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_includes_test.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_includes_test.res
@ -1,5 +1,7 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
+module Bindings = Reducer_Bindings

 open Jest
 open Expect
@ -25,14 +27,15 @@ x=1`,
    let mainIncludes = Project.getIncludes(project, "main")
    switch mainIncludes {
    | Ok(includes) => expect(includes) == ["common"]
-    | Error(error) => fail(error->SqError.toString)
+    | Error(error) => fail(error->Reducer_ErrorValue.errorToString)
    }
  })
+  let internalProject = project->Project.T.Private.castToInternalProject
  test("past chain", () => {
-    expect(project->Project.getPastChain("main")) == ["common"]
+    expect(Project.Private.getPastChain(internalProject, "main")) == ["common"]
  })
  test("import as variables", () => {
-    expect(project->Project.Private.getIncludesAsVariables("main")) == []
+    expect(Project.Private.getIncludesAsVariables(internalProject, "main")) == []
  })
 })

@ -60,20 +63,24 @@ x=1`,
    let mainIncludes = Project.getIncludes(project, "main")
    switch mainIncludes {
    | Ok(includes) => expect(includes) == ["common", "myModule"]
-    | Error(error) => fail(error->SqError.toString)
+    | Error(error) => fail(error->Reducer_ErrorValue.errorToString)
    }
  })

+  let internalProject = project->Project.T.Private.castToInternalProject
+
  test("direct past chain", () => {
-    expect(project->Project.Private.getPastChain("main")) == ["common"]
+    expect(Project.Private.getPastChain(internalProject, "main")) == ["common"]
  })

  test("direct includes", () => {
-    expect(project->Project.Private.getDirectIncludes("main")) == ["common"]
+    expect(Project.Private.getDirectIncludes(internalProject, "main")) == ["common"]
  })

  test("include as variables", () => {
-    expect(project->Project.Private.getIncludesAsVariables("main")) == [("myVariable", "myModule")]
+    expect(Project.Private.getIncludesAsVariables(internalProject, "main")) == [
+        ("myVariable", "myModule"),
+      ]
  })
 })

@ -99,13 +106,16 @@ x=1`,
    let mainIncludes = Project.getIncludes(project, "main")
    switch mainIncludes {
    | Ok(includes) => expect(includes) == ["common", "common2", "myModule"]
-    | Error(error) => fail(error->SqError.toString)
+    | Error(error) => fail(error->Reducer_ErrorValue.errorToString)
    }
  })
+  let internalProject = project->Project.T.Private.castToInternalProject
  test("direct past chain", () => {
    expect(Project.getPastChain(project, "main")) == ["common", "common2"]
  })
  test("include as variables", () => {
-    expect(project->Project.Private.getIncludesAsVariables("main")) == [("myVariable", "myModule")]
+    expect(Project.Private.getIncludesAsVariables(internalProject, "main")) == [
+        ("myVariable", "myModule"),
+      ]
  })
 })
--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_test.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_test.res
@ -1,4 +1,5 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
 module Bindings = Reducer_Bindings

@ -6,16 +7,29 @@ open Jest
 open Expect
 open Expect.Operators

+// test("", () => expect(1)->toBe(1))
+
 let runFetchResult = (project, sourceId) => {
  Project.run(project, sourceId)
-  Project.getResult(project, sourceId)->Reducer_Value.toStringResult
+  Project.getResult(project, sourceId)->InternalExpressionValue.toStringResult
 }

 let runFetchFlatBindings = (project, sourceId) => {
  Project.run(project, sourceId)
-  Project.getBindings(project, sourceId)->Reducer_Value.toStringRecord
+  Project.getBindings(project, sourceId)
+  ->Bindings.removeResult
+  ->InternalExpressionValue.toStringBindings
 }

+test("setting continuation", () => {
+  let project = Project.createProject()
+  let privateProject = project->Project.T.Private.castToInternalProject
+  let sampleBindings = Bindings.emptyBindings->Bindings.set("test", IEvVoid)
+  Project.Private.setContinuation(privateProject, "main", sampleBindings)
+  let answer = Project.Private.getContinuation(privateProject, "main")
+  expect(answer)->toBe(sampleBindings)
+})
+
 test("test result true", () => {
  let project = Project.createProject()
  Project.setSource(project, "main", "true")
@ -37,7 +51,7 @@ test("test library", () => {
 test("test bindings", () => {
  let project = Project.createProject()
  Project.setSource(project, "variables", "myVariable=666")
-  runFetchFlatBindings(project, "variables")->expect->toBe("{myVariable: 666}")
+  runFetchFlatBindings(project, "variables")->expect->toBe("@{myVariable: 666}")
 })

 describe("project1", () => {
@ -45,6 +59,7 @@ describe("project1", () => {
  Project.setSource(project, "first", "x=1")
  Project.setSource(project, "main", "x")
  Project.setContinues(project, "main", ["first"])
+  let internalProject = project->Project.T.Private.castToInternalProject

  test("runOrder", () => {
    expect(Project.getRunOrder(project)) == ["first", "main"]
@ -63,17 +78,17 @@ describe("project1", () => {
  })

  test("past chain first", () => {
-    expect(ReducerProject.getPastChain(project, "first")) == []
+    expect(Project.Private.getPastChain(internalProject, "first")) == []
  })
  test("past chain main", () => {
-    expect(ReducerProject.getPastChain(project, "main")) == ["first"]
+    expect(Project.Private.getPastChain(internalProject, "main")) == ["first"]
  })

  test("test result", () => {
    runFetchResult(project, "main")->expect->toBe("Ok(1)")
  })
  test("test bindings", () => {
-    runFetchFlatBindings(project, "first")->expect->toBe("{x: 1}")
+    runFetchFlatBindings(project, "first")->expect->toBe("@{x: 1}")
  })
 })

@ -83,7 +98,7 @@ describe("project2", () => {
  Project.setContinues(project, "second", ["first"])
  Project.setSource(project, "first", "x=1")
  Project.setSource(project, "second", "y=2")
-  Project.setSource(project, "main", "z=3;y")
+  Project.setSource(project, "main", "y")

  test("runOrder", () => {
    expect(Project.getRunOrder(project)) == ["first", "second", "main"]
@ -107,27 +122,7 @@ describe("project2", () => {
    runFetchResult(project, "main")->expect->toBe("Ok(2)")
  })
  test("test bindings", () => {
-    // bindings from continues are not exposed!
-    runFetchFlatBindings(project, "main")->expect->toBe("{z: 3}")
-  })
-})
-
-describe("removing sources", () => {
-  let project = Project.createProject()
-  Project.setContinues(project, "main", ["second"])
-  Project.setContinues(project, "second", ["first"])
-  Project.setSource(project, "first", "x=1")
-  Project.setSource(project, "second", "y=2")
-  Project.setSource(project, "main", "y")
-
-  Project.removeSource(project, "main")
-
-  test("project doesn't have source", () => {
-    expect(Project.getSource(project, "main")) == None
-  })
-
-  test("dependents get updated", () => {
-    expect(Project.getDependents(project, "second")) == []
+    runFetchFlatBindings(project, "main")->expect->toBe("@{x: 1,y: 2}")
  })
 })

@ -157,7 +152,7 @@ describe("project with include", () => {
  )
  Project.parseIncludes(project, "second") //The only way of setting includes

-  Project.setSource(project, "main", "z=3; y")
+  Project.setSource(project, "main", "y")

  test("runOrder", () => {
    expect(Project.getRunOrder(project)) == ["common", "first", "second", "main"]
@ -183,8 +178,7 @@ describe("project with include", () => {
    runFetchResult(project, "main")->expect->toBe("Ok(2)")
  })
  test("test bindings", () => {
-    // bindings from continues are not exposed!
-    runFetchFlatBindings(project, "main")->expect->toBe("{z: 3}")
+    runFetchFlatBindings(project, "main")->expect->toBe("@{common: 0,x: 1,y: 2}")
  })
 })

--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_1_test.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_1_test.res
@ -1,4 +1,5 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
 module Bindings = Reducer_Bindings

@ -11,34 +12,32 @@ describe("ReducerProject Tutorial", () => {
    /*
 Case "Running a single source". 
 */
-    test(
-      "run",
-      () => {
-        /* Let's start with running a single source and getting Result as well as the Bindings 
+    test("run", () => {
+      /* Let's start with running a single source and getting Result as well as the Bindings 
       First you need to create a project. A project is a collection of sources. 
       Project takes care of the dependencies between the sources, correct compilation and run order. 
-       You can run any source in the project. It will be compiled and run if it hasn't happened already; otherwise already existing results will be presented.
+       You can run any source in the project. It will be compiled and run if it is not already done else already existing results will be presented.
       The dependencies will be automatically compiled and run. So you don't need to worry about that in a multi source project.
       In summary you issue a run command on the whole project or on a specific source to ensure that there is a result for that source.
 */
-        let project = Project.createProject()
-        /* Every source has a name. This is used for debugging, dependencies and error messages. */
-        project->Project.setSource("main", "1 + 2")
-        /* Let's run "main" source. */
-        project->Project.run("main")
-        /* Now you have a result for "main" source. 
+      let project = Project.createProject()
+      /* Every source has a name. This is used for debugging, dependencies and error messages. */
+      Project.setSource(project, "main", "1 + 2")
+      /* Let's run "main" source. */
+      project->Project.run("main")
+      /* Now you have a result for "main" source. 
       Running one by one is necessary for UI to navigate among the sources and to see the results by source. 
       And you're free to run any source you want. 
       You will look at the results of this source and you don't want to run the others if not required.
 */

-        /* However, you could also run the whole project.
+      /* However, you could also run the whole project.
       If you have all the sources, you can always run the whole project. 
       Dependencies and recompiling on demand will be taken care of by the project. 
 */
-        project->Project.runAll
+      project->Project.runAll

-        /* Either with run or runAll you executed the project. 
+      /* Either with run or runAll you executed the project. 
       You can get the result of a specific source by calling getResult for that source. 
       You can get the bindings of a specific source by calling getBindings for that source. 
       If there is any runtime error, getResult will return the error.
@ -46,59 +45,53 @@ Case "Running a single source".
       Note that getResult returns None if the source has not been run.
       Getting None means you have forgotten to run the source.
 */
-        let result = project->Project.getResult("main")
-        let bindings = project->Project.getBindings("main")
+      let result = project->Project.getResult("main")
+      let bindings = project->Project.getBindings("main")->Bindings.removeResult

-        /* Let's display the result and bindings */
-        (result->Reducer_Value.toStringResult, bindings->Reducer_Value.toStringRecord)->expect ==
-          ("Ok(3)", "{}")
-        /* You've got 3 with empty bindings. */
-      },
-    )
+      /* Let's display the result and bindings */
+      (
+        result->InternalExpressionValue.toStringResult,
+        bindings->InternalExpressionValue.toStringBindings,
+      )->expect == ("Ok(3)", "@{}")
+      /* You've got 3 with empty bindings. */
+    })

-    test(
-      "run summary",
-      () => {
-        let project = Project.createProject()
-        project->Project.setSource("main", "1 + 2")
-        project->Project.runAll
-        let result = project->Project.getResult("main")
-        let bindings = project->Project.getBindings("main")
-        /* Now you have external bindings and external result. */
-        (
-          result->Reducer_Value.toStringResult,
-          bindings->Reducer_T.IEvRecord->Reducer_Value.toString,
-        )->expect == ("Ok(3)", "{}")
-      },
-    )
+    test("run summary", () => {
+      let project = Project.createProject()
+      Project.setSource(project, "main", "1 + 2")
+      Project.runAll(project)
+      let result = Project.getResult(project, "main")
+      let bindings = Project.getBindings(project, "main")->Bindings.removeResult
+      /* Now you have external bindings and external result. */
+      (
+        result->InternalExpressionValue.toStringResult,
+        bindings->InternalExpressionValue.IEvBindings->InternalExpressionValue.toString,
+      )->expect == ("Ok(3)", "@{}")
+    })

-    test(
-      "run with an environment",
-      () => {
-        /* Running the source code like above allows you to set a custom environment */
-        let project = Project.createProject()
+    test("run with an environment", () => {
+      /* Running the source code like above allows you to set a custom environment */
+      let project = Project.createProject()

-        /* Optional. Set your custom environment anytime before running */
-        project->Project.setEnvironment(Reducer_Context.defaultEnvironment)
+      /* Optional. Set your custom environment anytime before running */
+      Project.setEnvironment(project, InternalExpressionValue.defaultEnvironment)

-        project->Project.setSource("main", "1 + 2")
-        project->Project.runAll
-        let result = project->Project.getResult("main")
-        let _bindings = project->Project.getBindings("main")
-        result->Reducer_Value.toStringResult->expect == "Ok(3)"
-      },
-    )
+      Project.setSource(project, "main", "1 + 2")
+      Project.runAll(project)
+      let result = Project.getResult(project, "main")
+      let _bindings = Project.getBindings(project, "main")
+      result->InternalExpressionValue.toStringResult->expect == "Ok(3)"
+    })

-    test(
-      "shortcut",
-      () => {
-        /* If you are running single source without includes and you don't need a custom environment, you can use the shortcut. */
-        /* Examples above was to prepare you for the multi source tutorial. */
-        let (result, bindings) = Project.evaluate("1+2")
-        (result->Reducer_Value.toStringResult, bindings->Reducer_Value.toStringRecord)->expect ==
-          ("Ok(3)", "{}")
-      },
-    )
+    test("shortcut", () => {
+      /* If you are running single source without includes and you don't need a custom environment, you can use the shortcut. */
+      /* Examples above was to prepare you for the multi source tutorial. */
+      let (result, bindings) = Project.evaluate("1+2")
+      (
+        result->InternalExpressionValue.toStringResult,
+        bindings->Bindings.removeResult->InternalExpressionValue.toStringBindings,
+      )->expect == ("Ok(3)", "@{}")
+    })
  })
 })

--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_2_multisource_test.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_2_multisource_test.res
@ -1,4 +1,5 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
 module Bindings = Reducer_Bindings

@ -10,104 +11,102 @@ describe("ReducerProject Tutorial", () => {
  describe("Multi source", () => {
    /*
     Case "Running multiple sources" */
-    test(
-      "Chaining",
-      () => {
-        let project = Project.createProject()
-        /* This time let's add 3 sources and chain them together */
-        project->Project.setSource("source1", "x=1")
+    test("Chaining", () => {
+      let project = Project.createProject()
+      /* This time let's add 3 sources and chain them together */
+      Project.setSource(project, "source1", "x=1")

-        project->Project.setSource("source2", "y=x+1")
-        /* To run, source2 depends on source1 */
-        project->Project.setContinues("source2", ["source1"])
+      Project.setSource(project, "source2", "y=2")
+      /* To run, source2 depends on source1 */
+      Project.setContinues(project, "source2", ["source1"])

-        project->Project.setSource("source3", "z=y+1")
-        /* To run, source3 depends on source2 */
-        project->Project.setContinues("source3", ["source2"])
+      Project.setSource(project, "source3", "z=3")
+      /* To run, source3 depends on source2 */
+      Project.setContinues(project, "source3", ["source2"])

-        /* Now we can run the project */
-        project->Project.runAll
+      /* Now we can run the project */
+      Project.runAll(project)

-        /* And let's check the result and bindings of source3 */
-        let result3 = project->Project.getResult("source3")
-        let bindings3 = project->Project.getBindings("source3")
+      /* And let's check the result and bindings of source3 */
+      let result3 = Project.getResult(project, "source3")
+      let bindings3 = Project.getBindings(project, "source3")->Bindings.removeResult

-        (result3->Reducer_Value.toStringResult, bindings3->Reducer_Value.toStringRecord)->expect ==
-          ("Ok(())", "{z: 3}")
-      },
-    )
+      (
+        result3->InternalExpressionValue.toStringResult,
+        bindings3->InternalExpressionValue.toStringBindings,
+      )->expect == ("Ok(())", "@{x: 1,y: 2,z: 3}")
+    })

-    test(
-      "Depending",
-      () => {
-        /* Instead of chaining the sources, we could have a dependency tree */
-        /* The point here is that any source can depend on multiple sources */
-        let project = Project.createProject()
+    test("Depending", () => {
+      /* Instead of chaining the sources, we could have a dependency tree */
+      /* The point here is that any source can depend on multiple sources */
+      let project = Project.createProject()

-        /* This time source1 and source2 are not depending on anything */
-        project->Project.setSource("source1", "x=1")
-        project->Project.setSource("source2", "y=2")
+      /* This time source1 and source2 are not depending on anything */
+      Project.setSource(project, "source1", "x=1")
+      Project.setSource(project, "source2", "y=2")

-        project->Project.setSource("source3", "z=x+y")
-        /* To run, source3 depends on source1 and source3 together */
-        project->Project.setContinues("source3", ["source1", "source2"])
+      Project.setSource(project, "source3", "z=3")
+      /* To run, source3 depends on source1 and source3 together */
+      Project.setContinues(project, "source3", ["source1", "source2"])

-        /* Now we can run the project */
-        project->Project.runAll
+      /* Now we can run the project */
+      Project.runAll(project)

-        /* And let's check the result and bindings of source3 */
-        let result3 = project->Project.getResult("source3")
-        let bindings3 = project->Project.getBindings("source3")
+      /* And let's check the result and bindings of source3 */
+      let result3 = Project.getResult(project, "source3")
+      let bindings3 = Project.getBindings(project, "source3")->Bindings.removeResult

-        (result3->Reducer_Value.toStringResult, bindings3->Reducer_Value.toStringRecord)->expect ==
-          ("Ok(())", "{z: 3}")
-      },
-    )
+      (
+        result3->InternalExpressionValue.toStringResult,
+        bindings3->InternalExpressionValue.toStringBindings,
+      )->expect == ("Ok(())", "@{x: 1,y: 2,z: 3}")
+    })

-    test(
-      "Intro to including",
-      () => {
-        /* Though it would not be practical for a storybook, 
+    test("Intro to including", () => {
+      /* Though it would not be practical for a storybook, 
        let's write the same project above with includes.
        You will see that parsing includes is setting the dependencies the same way as before. */
-        let project = Project.createProject()
+      let project = Project.createProject()

-        /* This time source1 and source2 are not depending on anything */
-        project->Project.setSource("source1", "x=1")
-        project->Project.setSource("source2", "y=2")
+      /* This time source1 and source2 are not depending on anything */
+      Project.setSource(project, "source1", "x=1")
+      Project.setSource(project, "source2", "y=2")

-        project->Project.setSource(
-          "source3",
-          `
+      Project.setSource(
+        project,
+        "source3",
+        `
      #include "source1"
      #include "source2"
-      z=x+y`,
-        )
-        /* We need to parse the includes to set the dependencies */
-        project->Project.parseIncludes("source3")
+      z=3`,
+      )
+      /* We need to parse the includes to set the dependencies */
+      Project.parseIncludes(project, "source3")

-        /* Now we can run the project */
-        project->Project.runAll
+      /* Now we can run the project */
+      Project.runAll(project)

-        /* And let's check the result and bindings of source3 
+      /* And let's check the result and bindings of source3 
      This time you are getting all the variables because we are including the other sources 
      Behind the scenes parseIncludes is setting the dependencies */
-        let result3 = project->Project.getResult("source3")
-        let bindings3 = project->Project.getBindings("source3")
+      let result3 = Project.getResult(project, "source3")
+      let bindings3 = Project.getBindings(project, "source3")->Bindings.removeResult

-        (result3->Reducer_Value.toStringResult, bindings3->Reducer_Value.toStringRecord)->expect ==
-          ("Ok(())", "{z: 3}")
-        /*
+      (
+        result3->InternalExpressionValue.toStringResult,
+        bindings3->InternalExpressionValue.toStringBindings,
+      )->expect == ("Ok(())", "@{x: 1,y: 2,z: 3}")
+      /*
      Doing it like this is too verbose for a storybook 
      But I hope you have seen the relation of setContinues and parseIncludes */
-        /*
+      /*
         Dealing with includes needs more. 
         - There are parse errors
         - There are cyclic includes
         - And the depended source1 and source2 is not already there in the project
         - If you knew the includes before hand there would not be point of the include directive.
         More on those on the next section. */
-      },
-    )
+    })
  })
 })
--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_3_includes_test.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_3_includes_test.res
@ -1,4 +1,5 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
 module Bindings = Reducer_Bindings

@ -15,7 +16,8 @@ Here we will finally proceed to a real life scenario. */
    /* Here we investigate the details about parseIncludes, before setting up a real life scenario in the next section. */
    /* Everything happens inside a project, so let's have a project */
    let project = Project.createProject()
-    project->Project.setSource(
+    Project.setSource(
+      project,
      "main",
      `
    #include "common"
@ -23,151 +25,133 @@ Here we will finally proceed to a real life scenario. */
    `,
    )
    /* We need to parse includes after changing the source */
-    project->Project.parseIncludes("main")
-    test(
-      "getDependencies",
-      () => {
-        /* Parse includes has set the dependencies */
-        project->Project.getDependencies("main")->expect == ["common"]
-        /* If there were no includes than there would be no dependencies */
-        /* However if there was a syntax error at includes then would be no dependencies also */
-        /* Therefore looking at dependencies is not the right way to load includes */
-        /* getDependencies does not distinguish between setContinues or parseIncludes */
-      },
-    )
-    test(
-      "getIncludes",
-      () => {
-        /* Parse includes has set the includes */
-        switch project->Project.getIncludes("main") {
-        | Ok(includes) => includes->expect == ["common"]
-        | Error(err) => err->SqError.toString->fail
-        }
-        /* If the includes cannot be parsed then you get a syntax error.
+    Project.parseIncludes(project, "main")
+    test("getDependencies", () => {
+      /* Parse includes has set the dependencies */
+      Project.getDependencies(project, "main")->expect == ["common"]
+      /* If there were no includes than there would be no dependencies */
+      /* However if there was a syntax error at includes then would be no dependencies also */
+      /* Therefore looking at dependencies is not the right way to load includes */
+      /* getDependencies does not distinguish between setContinues or parseIncludes */
+    })
+    test("getIncludes", () => {
+      /* Parse includes has set the includes */
+      switch Project.getIncludes(project, "main") {
+      | Ok(includes) => includes->expect == ["common"]
+      | Error(err) => err->Reducer_ErrorValue.errorToString->fail
+      }
+      /* If the includes cannot be parsed then you get a syntax error.
      Otherwise you get the includes.
      If there is no syntax error then you can load that file and use setSource to add it to the project.
      And so on recursively... */
-      },
-    )
-    test(
-      "getDependents",
-      () => {
-        /* For any reason, you are able to query what other sources
+    })
+    test("getDependents", () => {
+      /* For any reason, you are able to query what other sources
        include or depend on the current source.
        But you don't need to use this to execute the projects.
        It is provided for completeness of information. */
-        project->Project.getDependents("main")->expect == []
-        /* Nothing is depending on or including main */
-      },
-    )
+      Project.getDependents(project, "main")->expect == []
+      /* Nothing is depending on or including main */
+    })

-    describe(
-      "Real Like",
-      () => {
-        /* Now let's look at recursive and possibly cyclic includes */
-        /* There is no function provided to load the include files.
+    describe("Real Like", () => {
+      /* Now let's look at recursive and possibly cyclic includes */
+      /* There is no function provided to load the include files.
    Because we have no idea if will it be an ordinary function or will it use promises.
    Therefore one has to write a function to load sources recursively and and setSources
    while checking for dependencies */

-        /* Let's make a dummy loader */
-        let loadSource = (sourceName: string) =>
-          switch sourceName {
-          | "source1" => "x=1"
-          | "source2" => `
+      /* Let's make a dummy loader */
+      let loadSource = (sourceName: string) =>
+        switch sourceName {
+        | "source1" => "x=1"
+        | "source2" => `
            #include "source1"
            y=2`
-          | "source3" => `
+        | "source3" => `
            #include "source2"
            z=3`
-          | _ => `source ${sourceName} not found`->Js.Exn.raiseError
-          }
+        | _ => `source ${sourceName} not found`->Js.Exn.raiseError
+        }

-        /* let's recursively load the sources */
-        let rec loadIncludesRecursively = (project, sourceName, visited) => {
-          if visited->Js.Array2.includes(sourceName) {
-            /* Oh we have already visited this source. There is an include cycle */
-            "Cyclic include ${sourceName}"->Js.Exn.raiseError
-          } else {
-            let newVisited = Js.Array2.copy(visited)
-            let _ = newVisited->Js.Array2.push(sourceName)
-            /* Let's parse the includes and dive into them */
-            Project.parseIncludes(project, sourceName)
-            let rIncludes = project->Project.getIncludes(sourceName)
-            switch rIncludes {
-            /* Maybe there is an include syntax error */
-            | Error(err) => err->SqError.toString->Js.Exn.raiseError
+      /* let's recursively load the sources */
+      let rec loadIncludesRecursively = (project, sourceName, visited) => {
+        if Js.Array2.includes(visited, sourceName) {
+          /* Oh we have already visited this source. There is an include cycle */
+          "Cyclic include ${sourceName}"->Js.Exn.raiseError
+        } else {
+          let newVisited = Js.Array2.copy(visited)
+          let _ = Js.Array2.push(newVisited, sourceName)
+          /* Let's parse the includes and dive into them */
+          Project.parseIncludes(project, sourceName)
+          let rIncludes = Project.getIncludes(project, sourceName)
+          switch rIncludes {
+          /* Maybe there is an include syntax error */
+          | Error(err) => err->Reducer_ErrorValue.errorToString->Js.Exn.raiseError

-            | Ok(includes) =>
-              includes->Belt.Array.forEach(
-                newIncludeName => {
-                  /* We have got one of the new includes.
-                   Let's load it and add it to the project */
-                  let newSource = loadSource(newIncludeName)
-                  project->Project.setSource(newIncludeName, newSource)
-                  /* The new source is loaded and added to the project. */
-                  /* Of course the new source might have includes too. */
-                  /* Let's recursively load them */
-                  project->loadIncludesRecursively(newIncludeName, newVisited)
-                },
-              )
-            }
+          | Ok(includes) =>
+            Belt.Array.forEach(includes, newIncludeName => {
+              /* We have got one of the new includes.
+               Let's load it and add it to the project */
+              let newSource = loadSource(newIncludeName)
+              Project.setSource(project, newIncludeName, newSource)
+              /* The new source is loaded and added to the project. */
+              /* Of course the new source might have includes too. */
+              /* Let's recursively load them */
+              loadIncludesRecursively(project, newIncludeName, newVisited)
+            })
          }
        }
-        /* As we have a fake source loader and a recursive include handler,
-         We can not set up a real project */
+      }
+      /* As we have a fake source loader and a recursive include handler,
+       We can not set up a real project */

-        /* * Here starts our real life project! * */
+      /* * Here starts our real life project! * */

-        let project = Project.createProject()
+      let project = Project.createProject()

-        project->Project.setSource(
-          "main",
-          `
-        #include "source1"
-        #include "source2"
+      /* main includes source3 which includes source2 which includes source1 */
+      Project.setSource(
+        project,
+        "main",
+        `
        #include "source3"
-        a = x+y+z
-        b = doubleX
-        a
+        x+y+z
        `,
-        )
-        /* Setting source requires parsing and loading the includes recursively */
-        project->loadIncludesRecursively("main", []) // Not visited yet
+      )
+      /* Setting source requires parsing and loading the includes recursively */
+      loadIncludesRecursively(project, "main", []) //No visited yet

-        /* Let's salt it more. Let's have another source in the project which also has includes */
-        /* doubleX includes source1 which is eventually included by main as well */
-        project->Project.setSource(
-          "doubleX",
-          `
+      /* Let's salt it more. Let's have another source in the project which also has includes */
+      /* doubleX includes source1 which is eventually included by main as well */
+      Project.setSource(
+        project,
+        "doubleX",
+        `
        #include "source1"
        doubleX = x * 2
        `,
-        )
-        project->loadIncludesRecursively("doubleX", [])
-        /* Remember, any time you set a source, you need to load includes recursively */
+      )
+      loadIncludesRecursively(project, "doubleX", [])
+      /* Remember, any time you set a source, you need to load includes recursively */

-        /* As doubleX is not included by main, it is not loaded recursively.
-         So we link it to the project as a dependency */
-        project->Project.setContinues("main", ["doubleX"])
+      /* As doubleX is not included by main, it is not loaded recursively.
+       So we link it to the project as a dependency */
+      Project.setContinues(project, "main", ["doubleX"])

-        /* Let's run the project */
-        project->Project.runAll
-        let result = project->Project.getResult("main")
-        let bindings = project->Project.getBindings("main")
-        /* And see the result and bindings.. */
-        test(
-          "recursive includes",
-          () => {
-            (
-              result->Reducer_Value.toStringResult,
-              bindings->Reducer_Value.toStringRecord,
-            )->expect == ("Ok(6)", "{a: 6,b: 2}")
-            /* Everything as expected */
-          },
-        )
-      },
-    )
+      /* Let's run the project */
+      Project.runAll(project)
+      let result = Project.getResult(project, "main")
+      let bindings = Project.getBindings(project, "main")
+      /* And see the result and bindings.. */
+      test("recursive includes", () => {
+        (
+          result->InternalExpressionValue.toStringResult,
+          bindings->Bindings.removeResult->InternalExpressionValue.toStringBindings,
+        )->expect == ("Ok(6)", "@{doubleX: 2,x: 1,y: 2,z: 3}")
+        /* Everything as expected */
+      })
+    })
  })

  describe("Includes myFile as myVariable", () => {
@ -182,20 +166,14 @@ Here we will finally proceed to a real life scenario. */
    `,
    )
    Project.parseIncludes(project, "main")
-    test(
-      "getDependencies",
-      () => {
-        Project.getDependencies(project, "main")->expect == ["common"]
-      },
-    )
-    test(
-      "getIncludes",
-      () => {
-        switch Project.getIncludes(project, "main") {
-        | Ok(includes) => includes->expect == ["common"]
-        | Error(err) => err->SqError.toString->fail
-        }
-      },
-    )
+    test("getDependencies", () => {
+      Project.getDependencies(project, "main")->expect == ["common"]
+    })
+    test("getIncludes", () => {
+      switch Project.getIncludes(project, "main") {
+      | Ok(includes) => includes->expect == ["common"]
+      | Error(err) => err->Reducer_ErrorValue.errorToString->fail
+      }
+    })
  })
 })
--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_4_injecting_user_values.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_4_injecting_user_values.res
@ -1,5 +1,7 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
+module Bindings = Reducer_Bindings

 open Jest
 open Expect
@ -28,7 +30,7 @@ describe("ReducerProject Tutorial", () => {
    /* We can now run the project */
    Project.runAll(project)
    let result = Project.getResult(project, "main")
-    result->Reducer_Value.toStringResult->expect == "Ok(6)"
+    result->InternalExpressionValue.toStringResult->expect == "Ok(6)"
  })
 })

--- a/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_5_calling_functions.res
+++ b/packages/squiggle-lang/tests/ReducerProject/ReducerProject_tutorial_5_calling_functions.res
@ -1,4 +1,5 @@
@@warning("-44")
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Project = ForTS_ReducerProject
 module Bindings = Reducer_Bindings

@ -30,9 +31,8 @@ describe("ReducerProject Tutorial", () => {
  })

  test("userResults", () => {
-    let userResultsAsString = Belt.Array.map(
-      userResults,
-      aResult => aResult->Reducer_Value.toStringResult,
+    let userResultsAsString = Belt.Array.map(userResults, aResult =>
+      aResult->InternalExpressionValue.toStringResult
    )
    userResultsAsString->expect == ["Ok(2)", "Ok(4)", "Ok(6)", "Ok(8)", "Ok(10)"]
  })
--- a/packages/squiggle-lang/tests/SqError_test.res
+++ b/packages/squiggle-lang/tests/SqError_test.res
@ -1,41 +0,0 @@
-open Jest
-open Expect
-
-describe("SqError.Message", () => {
-  test("toString", () =>
-    expect(SqError.Message.REOther("test error")->SqError.Message.toString)->toBe(
-      "Error: test error",
-    )
-  )
-})
-
-describe("SqError", () => {
-  test("fromMessage", () =>
-    expect(SqError.Message.REOther("test error")->SqError.fromMessage->SqError.toString)->toBe(
-      "Error: test error",
-    )
-  )
-
-  test("toStringWithStackTrace with empty stacktrace", () =>
-    expect(
-      SqError.Message.REOther("test error")->SqError.fromMessage->SqError.toStringWithStackTrace,
-    )->toBe("Error: test error")
-  )
-
-  test("toStringWithStackTrace", () => {
-    let frameStack =
-      Reducer_FrameStack.make()
-      ->Reducer_FrameStack.extend("frame1", None)
-      ->Reducer_FrameStack.extend("frame2", None)
-
-    expect(
-      SqError.Message.REOther("test error")
-      ->SqError.fromMessageWithFrameStack(frameStack)
-      ->SqError.toStringWithStackTrace,
-    )->toBe(`Error: test error
-Stack trace:
-  frame2
-  frame1
-`)
-  })
-})
--- a/packages/squiggle-lang/tests/SquiggleLibrary/SquiggleLibrary_FunctionRegistryLibrary_test.res
+++ b/packages/squiggle-lang/tests/SquiggleLibrary/SquiggleLibrary_FunctionRegistryLibrary_test.res
@ -3,17 +3,19 @@ open Expect
 open Reducer_TestHelpers

 let expectEvalToBeOk = (code: string) =>
-  Reducer_Expression.BackCompatible.evaluateString(code)->E.R.isOk->expect->toBe(true)
+  Reducer_Expression.BackCompatible.evaluateString(code)
+  ->Reducer_Helpers.rRemoveDefaultsInternal
+  ->E.R.isOk
+  ->expect
+  ->toBe(true)

 let registry = FunctionRegistry_Library.registry
 let examples = E.A.to_list(FunctionRegistry_Core.Registry.allExamples(registry))

 describe("FunctionRegistry Library", () => {
  describe("Regular tests", () => {
-    testEvalToBe("List.length([3,5,8])", "Ok(3)")
-    testEvalToBe("List.length([])", "Ok(0)")
    testEvalToBe("List.make(3, 'HI')", "Ok(['HI','HI','HI'])")
-    testEvalToBe("make(3, 'HI')", "Error(make is not defined)")
+    testEvalToBe("make(3, 'HI')", "Error(Function not found: make(Number,String))")
    testEvalToBe("List.upTo(1,3)", "Ok([1,2,3])")
    testEvalToBe("List.first([3,5,8])", "Ok(3)")
    testEvalToBe("List.last([3,5,8])", "Ok(8)")
@ -82,43 +84,25 @@ describe("FunctionRegistry Library", () => {
      "SampleSet.toList(SampleSet.mapN([SampleSet.fromList([1,2,3,4,5,6]), SampleSet.fromList([6, 5, 4, 3, 2, 1])], {|x| x[0] > x[1] ? x[0] : x[1]}))",
      "Ok([6,5,4,4,5,6])",
    )
-    testEvalToBe(
-      "SampleSet.fromList([1, 2, 3])",
-      "Error(Error: Too few samples when constructing sample set)",
-    )
-
-    testEvalToBe("Dict.merge({a: 1, b: 2}, {b: 3, c: 4, d: 5})", "Ok({a: 1,b: 3,c: 4,d: 5})")
-    testEvalToBe(
-      "Dict.mergeMany([{a: 1, b: 2}, {c: 3, d: 4}, {c: 5, e: 6}])",
-      "Ok({a: 1,b: 2,c: 5,d: 4,e: 6})",
-    )
-    testEvalToBe("Dict.keys({a: 1, b: 2})", "Ok(['a','b'])")
-    testEvalToBe("Dict.values({a: 1, b: 2})", "Ok([1,2])")
-    testEvalToBe("Dict.toList({a: 1, b: 2})", "Ok([['a',1],['b',2]])")
-    testEvalToBe("Dict.fromList([['a', 1], ['b', 2]])", "Ok({a: 1,b: 2})")
  })

  describe("Fn auto-testing", () => {
-    testAll(
-      "tests of validity",
-      examples,
-      r => {
-        expectEvalToBeOk(r)
-      },
-    )
+    testAll("tests of validity", examples, r => {
+      expectEvalToBeOk(r)
+    })

    testAll(
      "tests of type",
      E.A.to_list(
-        FunctionRegistry_Core.Registry.allExamplesWithFns(registry)->E.A2.filter(
-          ((fn, _)) => E.O.isSome(fn.output),
+        FunctionRegistry_Core.Registry.allExamplesWithFns(registry)->E.A2.filter(((fn, _)) =>
+          E.O.isSome(fn.output)
        ),
      ),
      ((fn, example)) => {
        let responseType =
          example
          ->Reducer_Expression.BackCompatible.evaluateString
-          ->E.R2.fmap(Reducer_Value.valueToValueType)
+          ->E.R2.fmap(ReducerInterface_InternalExpressionValue.valueToValueType)
        let expectedOutputType = fn.output |> E.O.toExn("")
        expect(responseType)->toEqual(Ok(expectedOutputType))
      },
--- a/packages/squiggle-lang/tests/TestHelpers.res
+++ b/packages/squiggle-lang/tests/TestHelpers.res
@ -45,12 +45,12 @@ let toExtDist: option<DistributionTypes.genericDist> => DistributionTypes.generi
 let unpackFloat = x => x->toFloat->toExtFloat
 let unpackDist = y => y->toDist->toExtDist

-let mkNormal = (mean, stdev) => DistributionTypes.Symbolic(#Normal({mean, stdev}))
-let mkBeta = (alpha, beta) => DistributionTypes.Symbolic(#Beta({alpha, beta}))
+let mkNormal = (mean, stdev) => DistributionTypes.Symbolic(#Normal({mean: mean, stdev: stdev}))
+let mkBeta = (alpha, beta) => DistributionTypes.Symbolic(#Beta({alpha: alpha, beta: beta}))
 let mkExponential = rate => DistributionTypes.Symbolic(#Exponential({rate: rate}))
-let mkUniform = (low, high) => DistributionTypes.Symbolic(#Uniform({low, high}))
-let mkCauchy = (local, scale) => DistributionTypes.Symbolic(#Cauchy({local, scale}))
-let mkLognormal = (mu, sigma) => DistributionTypes.Symbolic(#Lognormal({mu, sigma}))
+let mkUniform = (low, high) => DistributionTypes.Symbolic(#Uniform({low: low, high: high}))
+let mkCauchy = (local, scale) => DistributionTypes.Symbolic(#Cauchy({local: local, scale: scale}))
+let mkLognormal = (mu, sigma) => DistributionTypes.Symbolic(#Lognormal({mu: mu, sigma: sigma}))
 let mkDelta = x => DistributionTypes.Symbolic(#Float(x))

 let normalMake = SymbolicDist.Normal.make
--- a/packages/squiggle-lang/benchmark/Benchmark_Array.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Array.res
@ -1,80 +0,0 @@
-module Map: Benchmark_Helpers.BenchmarkTopic = {
-  let arraySize = 1000
-  let iterations = 300_000
-
-  let beltArray = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Belt.Array.map(v => v)
-    })
-  }
-
-  let jsArray2 = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Js.Array2.map(v => v)
-    })
-  }
-
-  let ocamlArray = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Array.map(v => v, _)
-    })
-  }
-
-  let runAll = () => {
-    Js.log(
-      `Mapping identity function over arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
-    )
-    Benchmark_Helpers.measure("Belt.Array.map", beltArray)
-    Benchmark_Helpers.measure("Js.Array2.map", jsArray2)
-    Benchmark_Helpers.measure("Array.map", ocamlArray)
-  }
-}
-
-module Sort: Benchmark_Helpers.BenchmarkTopic = {
-  let arraySize = 1000
-  let iterations = 30000
-
-  let jsArray2 = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    let compare = (a: float, b: float) => {
-      if a < b {
-        -1
-      } else {
-        1
-      }
-    }
-
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Js.Array2.sortInPlaceWith(compare)
-    })
-  }
-
-  let jsArray2withOcamlCompare = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Js.Array2.sortInPlaceWith(Pervasives.compare)
-    })
-  }
-
-  let ocamlArray = () => {
-    let x = Belt.Array.make(arraySize, 0.)
-    Belt.Range.forEach(1, iterations, _ => {
-      let _ = x->Array.fast_sort(compare, _)
-    })
-  }
-
-  let runAll = () => {
-    Js.log(
-      `Sorting arrays of size ${arraySize->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
-    )
-    Benchmark_Helpers.measure("Js.Array2.sort", jsArray2)
-    Benchmark_Helpers.measure("Js.Array2.sort with Ocaml compare", jsArray2withOcamlCompare)
-    Benchmark_Helpers.measure("Array.fast_sort", ocamlArray)
-  }
-}
-
-Map.runAll()
-Sort.runAll()
--- a/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Helpers.res
@ -1,11 +0,0 @@
-module type BenchmarkTopic = {
-  let runAll: unit => unit
-}
-
-let measure = (name: string, f: unit => unit) => {
-  let start = Js.Date.make()->Js.Date.valueOf
-  f()
-  let end = Js.Date.make()->Js.Date.valueOf
-  let duration = (end -. start) /. 1000.
-  Js.log2(duration, name)
-}
--- a/packages/squiggle-lang/benchmark/Benchmark_Map.res
+++ b/packages/squiggle-lang/benchmark/Benchmark_Map.res
@ -1,63 +0,0 @@
-module StringMap: Benchmark_Helpers.BenchmarkTopic = {
-  let size = 1000
-  let iterations = 10_000
-
-  let kv = Belt.Array.range(1, size)->Belt.Array.map(v => ("key" ++ v->Belt.Int.toString, v))
-
-  let beltMap = () => {
-    Belt.Range.forEach(1, iterations, _ => {
-      let m = Belt.Map.String.empty
-      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Belt.Map.String.set(k, v))
-    })
-  }
-
-  let beltMutableMap = () => {
-    Belt.Range.forEach(1, iterations, _ => {
-      let m = Belt.MutableMap.String.make()
-      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-        acc->Belt.MutableMap.String.set(k, v)
-        acc
-      })
-    })
-  }
-
-  let beltHashMap = () => {
-    Belt.Range.forEach(1, iterations, _ => {
-      let m = Belt.HashMap.String.make(~hintSize=100)
-      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-        acc->Belt.HashMap.String.set(k, v)
-        acc
-      })
-    })
-  }
-
-  let jsDict = () => {
-    Belt.Range.forEach(1, iterations, _ => {
-      let m = Js.Dict.empty()
-      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => {
-        acc->Js.Dict.set(k, v)
-        acc
-      })
-    })
-  }
-
-  let jsMap = () => {
-    Belt.Range.forEach(1, iterations, _ => {
-      let m = Js_map.make()
-      let _ = Belt.Array.reduce(kv, m, (acc, (k, v)) => acc->Js_map.set(k, v))
-    })
-  }
-
-  let runAll = () => {
-    Js.log(
-      `Filling a map with ("key{i}" => "i") key-value pairs, size ${size->Js.Int.toString} (${iterations->Js.Int.toString} iterations)`,
-    )
-    Benchmark_Helpers.measure("Belt.Map.String", beltMap)
-    Benchmark_Helpers.measure("Belt.MutableMap.String", beltMutableMap)
-    Benchmark_Helpers.measure("Belt.HashMap.String", beltHashMap)
-    Benchmark_Helpers.measure("Js.Dict", jsDict)
-    Benchmark_Helpers.measure("Js.Map", jsMap)
-  }
-}
-
-let runAll = StringMap.runAll()
--- a/packages/squiggle-lang/bsconfig.json
+++ b/packages/squiggle-lang/bsconfig.json
@ -9,11 +9,6 @@
      "dir": "__tests__",
      "type": "dev",
      "subdirs": true
-    },
-    {
-      "dir": "benchmark",
-      "type": "dev",
-      "subdirs": true
    }
  ],
  "bsc-flags": ["-bs-super-errors", "-bs-no-version-header", "-bs-g"],
@ -25,12 +20,8 @@
  ],
  "suffix": ".bs.js",
  "namespace": true,
-  "bs-dev-dependencies": [
-    "@glennsl/rescript-jest",
-    "rescript-fast-check",
-    "rescript-js-map",
-    "rescript-js-iterator"
-  ],
+  "bs-dependencies": ["bisect_ppx"],
+  "bs-dev-dependencies": ["@glennsl/rescript-jest", "rescript-fast-check"],
  "gentypeconfig": {
    "language": "typescript",
    "module": "commonjs",
@ -44,5 +35,8 @@
  "refmt": 3,
  "warnings": {
    "number": "+A-42-48-9-30-4"
-  }
+  },
+  "ppx-flags": [
+    ["../../node_modules/bisect_ppx/ppx", "--exclude-files", ".*_test\\.res$$"]
+  ]
 }
--- a/packages/squiggle-lang/jest.config.js
+++ b/packages/squiggle-lang/jest.config.js
@ -2,12 +2,13 @@
 module.exports = {
  preset: "ts-jest",
  testEnvironment: "node",
+  setupFilesAfterEnv: [
+    "<rootdir>/../../node_modules/bisect_ppx/src/runtime/js/jest.bs.js",
+  ],
  testPathIgnorePatterns: [
    ".*Fixtures.bs.js",
    "/node_modules/",
    ".*Helpers.bs.js",
    ".*Helpers.ts",
-    ".*Reducer_Type.*",
-    ".*_type_test.bs.js",
  ],
 };
--- a/packages/squiggle-lang/package.json
+++ b/packages/squiggle-lang/package.json
@ -1,6 +1,6 @@
 {
  "name": "@quri/squiggle-lang",
-  "version": "0.5.0",
+  "version": "0.4.0-alpha.0",
  "homepage": "https://squiggle-language.com",
  "license": "MIT",
  "scripts": {
@ -22,8 +22,10 @@
    "test:rescript": "jest --modulePathIgnorePatterns=__tests__/TS/*",
    "test:watch": "jest --watchAll",
    "test:fnRegistry": "jest __tests__/SquiggleLibrary/SquiggleLibrary_FunctionRegistryLibrary_test.bs.js",
-    "coverage:local": "jest --coverage && echo && echo 'Open ./coverage/lcov-report/index.html to see the detailed report.'",
-    "coverage": "jest --coverage && codecov",
+    "coverage:rescript": "rm -f *.coverage && yarn clean && BISECT_ENABLE=yes yarn build && yarn test:rescript && bisect-ppx-report html",
+    "coverage:ts": "yarn clean && yarn build && nyc --reporter=lcov yarn test:ts",
+    "coverage:rescript:ci": "yarn clean && BISECT_ENABLE=yes yarn build:rescript && yarn test:rescript && bisect-ppx-report send-to Codecov",
+    "coverage:ts:ci": "yarn coverage:ts && codecov",
    "lint:rescript": "./lint.sh",
    "lint:prettier": "prettier --check .",
    "lint": "yarn lint:rescript && yarn lint:prettier",
@ -39,32 +41,35 @@
  ],
  "author": "Quantified Uncertainty Research Institute",
  "dependencies": {
-    "@rescript/std": "^10.0.0",
+    "@rescript/std": "^9.1.4",
    "@stdlib/stats": "^0.0.13",
    "jstat": "^1.9.5",
    "lodash": "^4.17.21",
-    "mathjs": "^11.2.1",
+    "mathjs": "^11.1.0",
    "pdfast": "^0.2.0"
  },
  "devDependencies": {
    "@glennsl/rescript-jest": "^0.9.2",
+    "@istanbuljs/nyc-config-typescript": "^1.0.2",
    "@types/jest": "^27.5.0",
-    "chalk": "^5.1.0",
+    "babel-plugin-transform-es2015-modules-commonjs": "^6.26.2",
+    "bisect_ppx": "^2.7.1",
+    "chalk": "^5.0.1",
    "codecov": "^3.8.3",
-    "fast-check": "^3.1.4",
+    "fast-check": "^3.1.2",
    "gentype": "^4.5.0",
    "jest": "^27.5.1",
    "moduleserve": "^0.9.1",
+    "nyc": "^15.1.0",
    "peggy": "^2.0.1",
    "prettier": "^2.7.1",
    "reanalyze": "^2.23.0",
-    "rescript": "^10.0.0",
+    "rescript": "^9.1.4",
    "rescript-fast-check": "^1.1.1",
-    "rescript-js-map": "^1.1.0",
-    "ts-jest": "^29.0.3",
-    "ts-loader": "^9.4.1",
+    "ts-jest": "^27.1.4",
+    "ts-loader": "^9.3.0",
    "ts-node": "^10.9.1",
-    "typescript": "^4.8.4",
+    "typescript": "^4.8.2",
    "webpack": "^5.74.0",
    "webpack-cli": "^4.10.0"
  },
--- a/packages/squiggle-lang/scripts/README.md
+++ b/packages/squiggle-lang/scripts/README.md
@ -1,25 +0,0 @@
-Various scripts used for development, benchmarking and testing.
-
-None of these are bundled in the NPM package yet.
-
-# run.mjs
-
-`scripts/run.mjs` allows quick testing of Squiggle programs:
-
-```
-$ ./scripts/run.mjs '2+2'
-Running 2+2
-Ok 4
-@{__result__: 4}
-```
-
-# run-file.mjs
-
-`scripts/run-file.mjs` can be used to run and benchmark squiggle scripts stored in files:
-
-```
-$ ./scripts/run-file.mjs ./path/to/file.squiggle
-Time: 3.18 Ok
-```
-
-To see the result and bindings, add the `-o` or `--output` flag.
--- a/packages/squiggle-lang/scripts/bench-map-reduce.mjs
+++ b/packages/squiggle-lang/scripts/bench-map-reduce.mjs
@ -1,18 +0,0 @@
-#!/usr/bin/env node
-import { SqProject } from "@quri/squiggle-lang";
-import { measure } from "./lib.mjs";
-
-const maxP = 5;
-
-for (let p = 0; p <= maxP; p++) {
-  const size = Math.pow(10, p);
-  const project = SqProject.create();
-  project.setSource(
-    "main",
-    `List.upTo(1, ${size}) |> map({|x| List.upTo(1, 100) |> reduce(0, {|a,b|a+b})})`
-  );
-  const time = measure(() => {
-    project.run("main");
-  });
-  console.log(`1e${p}`, "\t", time);
-}
--- a/packages/squiggle-lang/scripts/bench-map.mjs
+++ b/packages/squiggle-lang/scripts/bench-map.mjs
@ -1,18 +0,0 @@
-#!/usr/bin/env node
-import { SqProject } from "@quri/squiggle-lang";
-import { measure } from "./lib.mjs";
-
-const maxP = 7;
-
-for (let p = 0; p <= maxP; p++) {
-  const size = Math.pow(10, p);
-  const project = SqProject.create();
-  project.setSource("list", `l = List.upTo(1,${size})`);
-  project.run("list");
-  project.setSource("map", "l |> map({|x| x})");
-  project.setContinues("map", ["list"]);
-  const time = measure(() => {
-    project.run("map");
-  });
-  console.log(`1e${p}`, "\t", time);
-}
--- a/packages/squiggle-lang/scripts/bench-sampleset-to-pointset.mjs
+++ b/packages/squiggle-lang/scripts/bench-sampleset-to-pointset.mjs
@ -1,34 +0,0 @@
-#!/usr/bin/env node
-import { SqProject } from "@quri/squiggle-lang";
-import { measure } from "./lib.mjs";
-
-const maxP = 3;
-
-const sampleCount = process.env.SAMPLE_COUNT;
-
-for (let p = 0; p <= maxP; p++) {
-  const size = Math.pow(10, p);
-  const project = SqProject.create();
-  if (sampleCount) {
-    project.setEnvironment({
-      sampleCount: Number(sampleCount),
-      xyPointLength: Number(sampleCount),
-    });
-  }
-  project.setSource(
-    "main",
-    `
-    List.upTo(1, ${size}) -> map(
-      { |x| normal(x,2) -> SampleSet.fromDist -> PointSet.fromDist }
-    )->List.last
-    `
-  );
-  const time = measure(() => {
-    project.run("main");
-  });
-  const result = project.getResult("main");
-  if (result.tag != "Ok") {
-    throw new Error("Code failed: " + result.value.toString());
-  }
-  console.log(`1e${p}`, "\t", time);
-}
--- a/packages/squiggle-lang/scripts/lib.mjs
+++ b/packages/squiggle-lang/scripts/lib.mjs
@ -1,41 +0,0 @@
-import { SqProject } from "@quri/squiggle-lang";
-
-export const measure = (cb, times = 1) => {
-  const t1 = new Date();
-
-  for (let i = 1; i <= times; i++) {
-    cb();
-  }
-  const t2 = new Date();
-  return (t2 - t1) / 1000;
-};
-
-export const red = (str) => `\x1b[31m${str}\x1b[0m`;
-export const green = (str) => `\x1b[32m${str}\x1b[0m`;
-
-export const run = (src, { output, sampleCount } = {}) => {
-  const project = SqProject.create();
-  if (sampleCount) {
-    project.setEnvironment({
-      sampleCount: Number(sampleCount),
-      xyPointLength: Number(sampleCount),
-    });
-  }
-  project.setSource("main", src);
-  const time = measure(() => project.run("main"));
-
-  const bindings = project.getBindings("main");
-  const result = project.getResult("main");
-
-  if (output) {
-    console.log("Result:", result.tag, result.value.toString());
-    console.log("Bindings:", bindings.toString());
-  }
-
-  console.log(
-    "Time:",
-    String(time),
-    result.tag === "Error" ? red(result.tag) : green(result.tag),
-    result.tag === "Error" ? result.value.toStringWithFrameStack() : ""
-  );
-};
--- a/packages/squiggle-lang/scripts/run-file.mjs
+++ b/packages/squiggle-lang/scripts/run-file.mjs
@ -1,22 +0,0 @@
-#!/usr/bin/env node
-import fs from "fs";
-
-import { Command } from "commander";
-
-import { run } from "./lib.mjs";
-
-const program = new Command();
-
-program.option("-o, --output");
-program.arguments("<string>");
-
-const options = program.parse(process.argv);
-
-const sampleCount = process.env.SAMPLE_COUNT;
-
-const src = fs.readFileSync(program.args[0], "utf-8");
-if (!src) {
-  throw new Error("Expected src");
-}
-
-run(src, { output: options.output, sampleCount });
--- a/packages/squiggle-lang/scripts/run.mjs
+++ b/packages/squiggle-lang/scripts/run.mjs
@ -1,19 +0,0 @@
-#!/usr/bin/env node
-import { run } from "./lib.mjs";
-
-import { Command } from "commander";
-
-const program = new Command();
-
-program.arguments("<string>");
-
-const options = program.parse(process.argv);
-
-const src = program.args[0];
-if (!src) {
-  throw new Error("Expected src");
-}
-
-const sampleCount = process.env.SAMPLE_COUNT;
-
-run(src, { output: true, sampleCount });
--- a/packages/squiggle-lang/src/js/SqDistribution.ts
+++ b/packages/squiggle-lang/src/js/SqDistribution.ts
@ -80,28 +80,27 @@ abstract class SqAbstractDistribution {
 }

 export class SqPointSetDistribution extends SqAbstractDistribution {
-  tag = Tag.PointSet as const;
+  tag = Tag.PointSet;

  value() {
-    return wrapPointSetDist(this.valueMethod(RSDistribution.getPointSet));
+    return this.valueMethod(RSDistribution.getPointSet);
  }
 }

 export class SqSampleSetDistribution extends SqAbstractDistribution {
-  tag = Tag.SampleSet as const;
+  tag = Tag.SampleSet;

-  value(): number[] {
+  value() {
    return this.valueMethod(RSDistribution.getSampleSet);
  }
 }

 export class SqSymbolicDistribution extends SqAbstractDistribution {
-  tag = Tag.Symbolic as const;
+  tag = Tag.Symbolic;

-  // not wrapped for TypeScript yet
-  // value() {
-  //   return this.valueMethod(RSDistribution.getSymbolic);
-  // }
+  value() {
+    return this.valueMethod(RSDistribution.getSymbolic);
+  }
 }

 const tagToClass = {
--- a/packages/squiggle-lang/src/js/SqError.ts
+++ b/packages/squiggle-lang/src/js/SqError.ts
@ -1,48 +1,17 @@
-import * as RSError from "../rescript/SqError.gen";
-import * as RSReducerT from "../rescript/Reducer/Reducer_T.gen";
-
-import * as RSFrameStack from "../rescript/Reducer/Reducer_FrameStack.gen";
-
-export { location as SqLocation } from "../rescript/Reducer/Reducer_Peggy/Reducer_Peggy_Parse.gen";
+import * as RSErrorValue from "../rescript/ForTS/ForTS_Reducer_ErrorValue.gen";

 export class SqError {
-  constructor(private _value: RSError.t) {}
+  constructor(private _value: RSErrorValue.reducerErrorValue) {}

  toString() {
-    return RSError.toString(this._value);
+    return RSErrorValue.toString(this._value);
  }

-  toStringWithStackTrace() {
-    return RSError.toStringWithStackTrace(this._value);
+  static createTodoError(v: string) {
+    return new SqError(RSErrorValue.createTodoError(v));
  }

  static createOtherError(v: string) {
-    return new SqError(RSError.createOtherError(v));
-  }
-
-  getTopFrame(): SqFrame | undefined {
-    const frame = RSFrameStack.getTopFrame(RSError.getFrameStack(this._value));
-    return frame ? new SqFrame(frame) : undefined;
-  }
-
-  getFrameArray(): SqFrame[] {
-    const frames = RSError.getFrameArray(this._value);
-    return frames.map((frame) => new SqFrame(frame));
-  }
-
-  location() {
-    return this.getTopFrame()?.location();
-  }
-}
-
-export class SqFrame {
-  constructor(private _value: RSReducerT.frame) {}
-
-  name(): string {
-    return RSFrameStack.Frame.getName(this._value);
-  }
-
-  location() {
-    return RSFrameStack.Frame.getLocation(this._value);
+    return new SqError(RSErrorValue.createOtherError(v));
  }
 }
--- a/packages/squiggle-lang/src/js/SqModule.ts
+++ b/packages/squiggle-lang/src/js/SqModule.ts
@ -0,0 +1,30 @@
+import * as RSModuleValue from "../rescript/ForTS/ForTS_SquiggleValue/ForTS_SquiggleValue_Module.gen";
+import { SqModuleValue, wrapValue } from "./SqValue";
+import { SqValueLocation } from "./SqValueLocation";
+
+export class SqModule {
+  constructor(
+    private _value: RSModuleValue.squiggleValue_Module,
+    public location: SqValueLocation
+  ) {}
+
+  entries() {
+    return RSModuleValue.getKeyValuePairs(this._value).map(
+      ([k, v]) => [k, wrapValue(v, this.location.extend(k))] as const
+    );
+  }
+
+  asValue() {
+    return new SqModuleValue(
+      RSModuleValue.toSquiggleValue(this._value),
+      this.location
+    );
+  }
+
+  get(k: string) {
+    const v = RSModuleValue.get(this._value, k);
+    return v === undefined || v === null
+      ? undefined
+      : wrapValue(v, this.location.extend(k));
+  }
+}
--- a/Show More
+++ b/Show More
				`@ -1 +0,0 @@`
				`See the [Changelog.mdx page](./packages/website/docs/Changelog.mdx) for the changelog.`