Merge branch 'develop' into documentation-refactors-april

* develop: (72 commits) cases to handle with new parser. lambdas in arrays and records Note duplicate parameters Note infinite recursion Note infinite recursion Add array string and function viewers Recurse showTypes Pass showTypes and showControls in playground do not export private modules from Reducer module Allows hiding controls sam's monkeying fixed function f not bound Refactor and rename lambda in partial Make error message more descriptive Refactor and shrink effect code Make a tooltip to restrict users from log scales Add Patrial storybook and update partial bindings async Lint js Format and fix CI bugs Hotfix playground chart Real log scales ...
2022-05-03 11:07:12 -04:00 · 2022-05-03 11:07:12 -04:00 · c2155ef746
commit c2155ef746
parent b28df258e1 6112487b78
50 changed files with 1871 additions and 770 deletions
--- a/packages/components/package.json
+++ b/packages/components/package.json
@ -9,6 +9,7 @@
    "react": "^18.1.0",
    "react-ace": "^10.1.0",
    "react-dom": "^18.1.0",
+    "react-use": "^17.3.2",
    "react-vega": "^7.5.0",
    "styled-components": "^5.3.5",
    "vega": "^5.22.1",
@ -30,7 +31,7 @@
    "@testing-library/user-event": "^14.1.1",
    "@types/jest": "^27.4.0",
    "@types/lodash": "^4.14.182",
-    "@types/node": "^17.0.29",
+    "@types/node": "^17.0.31",
    "@types/react": "^18.0.3",
    "@types/react-dom": "^18.0.2",
    "@types/styled-components": "^5.1.24",
@ -38,7 +39,7 @@
    "cross-env": "^7.0.3",
    "react-scripts": "^5.0.1",
    "style-loader": "^3.3.1",
-    "ts-loader": "^9.2.9",
+    "ts-loader": "^9.3.0",
    "tsconfig-paths-webpack-plugin": "^3.5.2",
    "typescript": "^4.6.3",
    "web-vitals": "^2.1.4",
--- a/packages/components/src/SquiggleChart.js.map
+++ b/packages/components/src/SquiggleChart.js.map
--- a/packages/components/src/components/DistributionChart.tsx
+++ b/packages/components/src/components/DistributionChart.tsx
@ -1,38 +1,78 @@
 import * as React from "react";
 import _ from "lodash";
-import type { Spec } from "vega";
 import type { Distribution } from "@quri/squiggle-lang";
 import { distributionErrorToString } from "@quri/squiggle-lang";
-import { createClassFromSpec } from "react-vega";
+import { Vega, VisualizationSpec } from "react-vega";
 import * as chartSpecification from "../vega-specs/spec-distributions.json";
 import { ErrorBox } from "./ErrorBox";
+import { useSize } from "react-use";
+import {
+  linearXScale,
+  logXScale,
+  linearYScale,
+  expYScale,
+} from "./DistributionVegaScales";
 import styled from "styled-components";

-let SquiggleVegaChart = createClassFromSpec({
-  spec: chartSpecification as Spec,
-});
-
 type DistributionChartProps = {
  distribution: Distribution;
-  width: number;
+  width?: number;
  height: number;
+  /** Whether to show the user graph controls (scale etc) */
+  showControls?: boolean;
 };

 export const DistributionChart: React.FC<DistributionChartProps> = ({
  distribution,
-  width,
  height,
+  width,
+  showControls = false,
 }: DistributionChartProps) => {
+  let [isLogX, setLogX] = React.useState(false);
+  let [isExpY, setExpY] = React.useState(false);
  let shape = distribution.pointSet();
+  const [sized, _] = useSize((size) => {
    if (shape.tag === "Ok") {
-    let widthProp = width ? width - 20 : undefined;
+      let massBelow0 =
+        shape.value.continuous.some((x) => x.x <= 0) ||
+        shape.value.discrete.some((x) => x.x <= 0);
+      let spec = buildVegaSpec(isLogX, isExpY);
+      let widthProp = width ? width - 20 : size.width - 10;
+
+      // Check whether we should disable the checkbox
+      var logCheckbox = (
+        <CheckBox label="Log X scale" value={isLogX} onChange={setLogX} />
+      );
+      if (massBelow0) {
+        logCheckbox = (
+          <CheckBox
+            label="Log X scale"
+            value={isLogX}
+            onChange={setLogX}
+            disabled={true}
+            tooltip={
+              "Your distribution has mass lower than or equal to 0. Log only works on strictly positive values."
+            }
+          />
+        );
+      }
+
      var result = (
-      <SquiggleVegaChart
+        <div>
+          <Vega
+            spec={spec}
            data={{ con: shape.value.continuous, dis: shape.value.discrete }}
            width={widthProp}
            height={height}
            actions={false}
          />
+          {showControls && (
+            <div>
+              {logCheckbox}
+              <CheckBox label="Exp Y scale" value={isExpY} onChange={setExpY} />
+            </div>
+          )}
+        </div>
      );
    } else {
      var result = (
@ -41,5 +81,50 @@ export const DistributionChart: React.FC<DistributionChartProps> = ({
        </ErrorBox>
      );
    }
+
    return result;
+  });
+  return sized;
+};
+
+function buildVegaSpec(isLogX: boolean, isExpY: boolean): VisualizationSpec {
+  return {
+    ...chartSpecification,
+    scales: [
+      isLogX ? logXScale : linearXScale,
+      isExpY ? expYScale : linearYScale,
+    ],
+  } as VisualizationSpec;
+}
+
+interface CheckBoxProps {
+  label: string;
+  onChange: (x: boolean) => void;
+  value: boolean;
+  disabled?: boolean;
+  tooltip?: string;
+}
+
+const Label = styled.label<{ disabled: boolean }>`
+  ${(props) => props.disabled && "color: #999;"}
+`;
+
+export const CheckBox = ({
+  label,
+  onChange,
+  value,
+  disabled = false,
+  tooltip,
+}: CheckBoxProps) => {
+  return (
+    <span title={tooltip}>
+      <input
+        type="checkbox"
+        value={value + ""}
+        onChange={() => onChange(!value)}
+        disabled={disabled}
+      />
+      <Label disabled={disabled}>{label}</Label>
+    </span>
+  );
 };
--- a/packages/components/src/components/DistributionVegaScales.ts
+++ b/packages/components/src/components/DistributionVegaScales.ts
@ -0,0 +1,80 @@
+import type { LogScale, LinearScale, PowScale } from "vega";
+export let linearXScale: LinearScale = {
+  name: "xscale",
+  type: "linear",
+  range: "width",
+  zero: false,
+  nice: false,
+  domain: {
+    fields: [
+      {
+        data: "con",
+        field: "x",
+      },
+      {
+        data: "dis",
+        field: "x",
+      },
+    ],
+  },
+};
+export let linearYScale: LinearScale = {
+  name: "yscale",
+  type: "linear",
+  range: "height",
+  zero: true,
+  domain: {
+    fields: [
+      {
+        data: "con",
+        field: "y",
+      },
+      {
+        data: "dis",
+        field: "y",
+      },
+    ],
+  },
+};
+
+export let logXScale: LogScale = {
+  name: "xscale",
+  type: "log",
+  range: "width",
+  zero: false,
+  base: 10,
+  nice: false,
+  domain: {
+    fields: [
+      {
+        data: "con",
+        field: "x",
+      },
+      {
+        data: "dis",
+        field: "x",
+      },
+    ],
+  },
+};
+
+export let expYScale: PowScale = {
+  name: "yscale",
+  type: "pow",
+  exponent: 0.1,
+  range: "height",
+  zero: true,
+  nice: false,
+  domain: {
+    fields: [
+      {
+        data: "con",
+        field: "y",
+      },
+      {
+        data: "dis",
+        field: "y",
+      },
+    ],
+  },
+};
--- a/packages/components/src/components/SquiggleChart.tsx
+++ b/packages/components/src/components/SquiggleChart.tsx
@ -33,10 +33,18 @@ const variableBox = {
  `,
 };

-export const VariableBox: React.FC<{
+interface VariableBoxProps {
  heading: string;
  children: React.ReactNode;
-}> = ({ heading = "Error", children }) => {
+  showTypes?: boolean;
+}
+
+export const VariableBox: React.FC<VariableBoxProps> = ({
+  heading = "Error",
+  children,
+  showTypes = false,
+}: VariableBoxProps) => {
+  if (showTypes) {
    return (
      <variableBox.Component>
        <variableBox.Heading>
@ -45,6 +53,9 @@ export const VariableBox: React.FC<{
        <variableBox.Body>{children}</variableBox.Body>
      </variableBox.Component>
    );
+  } else {
+    return <>{children}</>;
+  }
 };

 let RecordKeyHeader = styled.h3``;
@ -52,27 +63,36 @@ let RecordKeyHeader = styled.h3``;
 export interface SquiggleItemProps {
  /** The input string for squiggle */
  expression: squiggleExpression;
-  width: number;
+  width?: number;
  height: number;
+  /** Whether to show type information */
+  showTypes?: boolean;
+  /** Whether to show users graph controls (scale etc) */
+  showControls?: boolean;
 }

 const SquiggleItem: React.FC<SquiggleItemProps> = ({
  expression,
  width,
  height,
+  showTypes = false,
+  showControls = false,
 }: SquiggleItemProps) => {
  switch (expression.tag) {
    case "number":
      return (
-        <VariableBox heading="Number">
+        <VariableBox heading="Number" showTypes={showTypes}>
          <NumberShower precision={3} number={expression.value} />
        </VariableBox>
      );
    case "distribution": {
      let distType = expression.value.type();
      return (
-        <VariableBox heading={`Distribution (${distType})`}>
-          {distType === "Symbolic" ? (
+        <VariableBox
+          heading={`Distribution (${distType})`}
+          showTypes={showTypes}
+        >
+          {distType === "Symbolic" && showTypes ? (
            <>
              <div>{expression.value.toString()}</div>
            </>
@ -83,47 +103,77 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
            distribution={expression.value}
            height={height}
            width={width}
+            showControls={showControls}
          />
        </VariableBox>
      );
    }
    case "string":
      return (
-        <VariableBox heading="String">{`"${expression.value}"`}</VariableBox>
+        <VariableBox
+          heading="String"
+          showTypes={showTypes}
+        >{`"${expression.value}"`}</VariableBox>
      );
    case "boolean":
      return (
-        <VariableBox heading="Boolean">
+        <VariableBox heading="Boolean" showTypes={showTypes}>
          {expression.value.toString()}
        </VariableBox>
      );
    case "symbol":
-      return <VariableBox heading="Symbol">{expression.value}</VariableBox>;
+      return (
+        <VariableBox heading="Symbol" showTypes={showTypes}>
+          {expression.value}
+        </VariableBox>
+      );
    case "call":
-      return <VariableBox heading="Call">{expression.value}</VariableBox>;
+      return (
+        <VariableBox heading="Call" showTypes={showTypes}>
+          {expression.value}
+        </VariableBox>
+      );
    case "array":
      return (
-        <VariableBox heading="Array">
+        <VariableBox heading="Array" showTypes={showTypes}>
          {expression.value.map((r) => (
-            <SquiggleItem expression={r} width={width - 20} height={50} />
+            <SquiggleItem
+              expression={r}
+              width={width !== undefined ? width - 20 : width}
+              height={50}
+              showTypes={showTypes}
+              showControls={showControls}
+            />
          ))}
        </VariableBox>
      );
    case "record":
      return (
-        <VariableBox heading="Record">
+        <VariableBox heading="Record" showTypes={showTypes}>
          {Object.entries(expression.value).map(([key, r]) => (
            <>
              <RecordKeyHeader>{key}</RecordKeyHeader>
-              <SquiggleItem expression={r} width={width - 20} height={50} />
+              <SquiggleItem
+                expression={r}
+                width={width !== undefined ? width - 20 : width}
+                height={50}
+                showTypes={showTypes}
+                showControls={showControls}
+              />
            </>
          ))}
        </VariableBox>
      );
-    default:
+    case "arraystring":
+      return (
+        <VariableBox heading="Array String" showTypes={showTypes}>
+          {expression.value.map((r) => `"${r}"`)}
+        </VariableBox>
+      );
+    case "lambda":
      return (
        <ErrorBox heading="No Viewer">
-          {"We don't currently have a working viewer for record types."}
+          There is no viewer currently available for function types.
        </ErrorBox>
      );
  }
@ -153,6 +203,10 @@ export interface SquiggleChartProps {
  bindings?: bindings;
  /** JS imported parameters */
  jsImports?: jsImports;
+  /** Whether to show type information about returns, default false */
+  showTypes?: boolean;
+  /** Whether to show graph controls (scale etc)*/
+  showControls?: boolean;
 }

 const ChartWrapper = styled.div`
@ -169,7 +223,9 @@ export const SquiggleChart: React.FC<SquiggleChartProps> = ({
  height = 60,
  bindings = defaultBindings,
  jsImports = defaultImports,
-  width = NaN,
+  width,
+  showTypes = false,
+  showControls = false,
 }: SquiggleChartProps) => {
  let samplingInputs: samplingParams = {
    sampleCount: sampleCount,
@ -186,7 +242,13 @@ export const SquiggleChart: React.FC<SquiggleChartProps> = ({
    let expression = expressionResult.value;
    onChange(expression);
    internal = (
-      <SquiggleItem expression={expression} width={width} height={height} />
+      <SquiggleItem
+        expression={expression}
+        width={width}
+        height={height}
+        showTypes={showTypes}
+        showControls={showControls}
+      />
    );
  } else {
    internal = (
--- a/packages/components/src/components/SquiggleEditor.tsx
+++ b/packages/components/src/components/SquiggleEditor.tsx
@ -40,6 +40,10 @@ export interface SquiggleEditorProps {
  bindings?: bindings;
  /** JS Imports */
  jsImports?: jsImports;
+  /** Whether to show detail about types of the returns, default false */
+  showTypes?: boolean;
+  /** Whether to give users access to graph controls */
+  showControls: boolean;
 }

 const Input = styled.div`
@ -50,7 +54,7 @@ const Input = styled.div`

 export let SquiggleEditor: React.FC<SquiggleEditorProps> = ({
  initialSquiggleString = "",
-  width = 500,
+  width,
  sampleCount,
  outputXYPoints,
  kernelWidth,
@ -61,6 +65,8 @@ export let SquiggleEditor: React.FC<SquiggleEditorProps> = ({
  onChange,
  bindings = defaultBindings,
  jsImports = defaultImports,
+  showTypes = false,
+  showControls = false,
 }: SquiggleEditorProps) => {
  let [expression, setExpression] = React.useState(initialSquiggleString);
  return (
@ -87,6 +93,8 @@ export let SquiggleEditor: React.FC<SquiggleEditorProps> = ({
        onChange={onChange}
        bindings={bindings}
        jsImports={jsImports}
+        showTypes={showTypes}
+        showControls={showControls}
      />
    </div>
  );
@ -145,6 +153,8 @@ export interface SquigglePartialProps {
  bindings?: bindings;
  /** Variables imported from js */
  jsImports?: jsImports;
+  /** Whether to give users access to graph controls */
+  showControls?: boolean;
 }

 export let SquigglePartial: React.FC<SquigglePartialProps> = ({
@ -160,6 +170,9 @@ export let SquigglePartial: React.FC<SquigglePartialProps> = ({
    xyPointLength: outputXYPoints,
  };
  let [expression, setExpression] = React.useState(initialSquiggleString);
+  let [error, setError] = React.useState<string | null>(null);
+
+  let runSquiggleAndUpdateBindings = () => {
    let squiggleResult = runPartial(
      expression,
      bindings,
@ -168,7 +181,14 @@ export let SquigglePartial: React.FC<SquigglePartialProps> = ({
    );
    if (squiggleResult.tag == "Ok") {
      if (onChange) onChange(squiggleResult.value);
+      setError(null);
+    } else {
+      setError(errorValueToString(squiggleResult.value));
    }
+  };
+
+  React.useEffect(runSquiggleAndUpdateBindings, [expression]);
+
  return (
    <div>
      <Input>
@ -180,13 +200,7 @@ export let SquigglePartial: React.FC<SquigglePartialProps> = ({
          height={20}
        />
      </Input>
-      {squiggleResult.tag == "Error" ? (
-        <ErrorBox heading="Error">
-          {errorValueToString(squiggleResult.value)}
-        </ErrorBox>
-      ) : (
-        <></>
-      )}
+      {error !== null ? <ErrorBox heading="Error">{error}</ErrorBox> : <></>}
    </div>
  );
 };
--- a/packages/components/src/components/SquigglePlayground.tsx
+++ b/packages/components/src/components/SquigglePlayground.tsx
@ -43,6 +43,8 @@ function FieldFloat(Props: FieldFloatProps) {
 interface Props {
  initialSquiggleString?: string;
  height?: number;
+  showTypes?: boolean;
+  showControls?: boolean;
 }

 interface Props2 {
@ -55,10 +57,6 @@ const ShowBox = styled.div<Props2>`
  height: ${(props) => props.height};
 `;

-const MyComponent = styled.div`
-  color: ${(props) => props.theme.colors.main};
-`;
-
 interface TitleProps {
  readonly maxHeight: number;
 }
@ -74,13 +72,15 @@ const Display = styled.div<TitleProps>`

 const Row = styled.div`
  display: grid;
-  grid-template-columns: 1fr 1fr;
+  grid-template-columns: 50% 50%;
 `;
 const Col = styled.div``;

 let SquigglePlayground: FC<Props> = ({
  initialSquiggleString = "",
  height = 300,
+  showTypes = false,
+  showControls = false,
 }: Props) => {
  let [squiggleString, setSquiggleString] = useState(initialSquiggleString);
  let [sampleCount, setSampleCount] = useState(1000);
@ -112,6 +112,8 @@ let SquigglePlayground: FC<Props> = ({
              diagramCount={diagramCount}
              pointDistLength={pointDistLength}
              height={150}
+              showTypes={showTypes}
+              showControls={showControls}
            />
          </Display>
        </Col>
--- 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={{
+      initialSquiggleString: "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}
+            initialSquiggleString={props.initialPartialString}
+            onChange={setBindings}
+          />
+          <SquiggleEditor
+            {...props}
+            initialSquiggleString={props.initialEditorString}
+            bindings={bindings}
+          />
+        </>
+      );
+    }}
+  </Story>
+</Canvas>
--- a/packages/components/src/vega-specs/spec-distributions.json
+++ b/packages/components/src/vega-specs/spec-distributions.json
@ -3,7 +3,6 @@
  "description": "A basic area chart example",
  "width": 500,
  "height": 100,
-  "autosize": "fit",
  "padding": 5,
  "data": [
    {
@ -13,72 +12,8 @@
      "name": "dis"
    }
  ],
-  "signals": [
-    {
-      "name": "xscale",
-      "description": "The transform of the x scale",
-      "value": false,
-      "bind": {
-        "input": "checkbox",
-        "name": "log x scale"
-      }
-    },
-    {
-      "name": "yscale",
-      "description": "The transform of the y scale",
-      "value": false,
-      "bind": {
-        "input": "checkbox",
-        "name": "log y scale"
-      }
-    }
-  ],
-  "scales": [
-    {
-      "name": "xscale",
-      "type": "pow",
-      "exponent": {
-        "signal": "xscale ? 0.1 : 1"
-      },
-      "range": "width",
-      "zero": false,
-      "nice": false,
-      "domain": {
-        "fields": [
-          {
-            "data": "con",
-            "field": "x"
-          },
-          {
-            "data": "dis",
-            "field": "x"
-          }
-        ]
-      }
-    },
-    {
-      "name": "yscale",
-      "type": "pow",
-      "exponent": {
-        "signal": "yscale ? 0.1 : 1"
-      },
-      "range": "height",
-      "nice": true,
-      "zero": true,
-      "domain": {
-        "fields": [
-          {
-            "data": "con",
-            "field": "y"
-          },
-          {
-            "data": "dis",
-            "field": "y"
-          }
-        ]
-      }
-    }
-  ],
+  "signals": [],
+  "scales": [],
  "axes": [
    {
      "orient": "bottom",
--- 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 +1,142 @@
+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((:$setBindings {} :y 1))")
+  // Then it answers the bindings for the next statement when reduced
+  testMacroEval([], eBindStatement(eBindings([]), exampleStatementY), "Ok({y: 1})")
+  // Now let's feed a binding to see what happens
+  testMacro(
+    [],
+    eBindStatement(eBindings([("x", EvNumber(2.))]), exampleStatementX),
+    "Ok((:$setBindings {x: 2} :y 2))",
+  )
+  // An expression does not return a binding, thus error
+  testMacro([], eBindStatement(eBindings([]), exampleExpression), "Error(Assignment expected)")
+  // When bindings from previous statement are missing the context is injected. This must be the first statement of a block
+  testMacro(
+    [("z", EvNumber(99.))],
+    eBindStatementDefault(exampleStatementY),
+    "Ok((:$setBindings {z: 99} :y 1))",
+  )
+})
+
+describe("bindExpression", () => {
+  // x is simply bound in the expression
+  testMacro([], eBindExpression(eBindings([("x", EvNumber(2.))]), eSymbol("x")), "Ok(2)")
+  // When an let statement is the end expression then bindings are returned
+  testMacro(
+    [],
+    eBindExpression(eBindings([("x", EvNumber(2.))]), exampleStatementY),
+    "Ok((:$exportBindings (:$setBindings {x: 2} :y 1)))",
+  )
+  // Now let's reduce that expression
+  testMacroEval(
+    [],
+    eBindExpression(eBindings([("x", EvNumber(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", EvNumber(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((:$$bindExpression (:$$block 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((:$$bindExpression (:$let :z (:$$block (:$$block :y)))))",
+  )
+  testMacroEval(
+    [],
+    eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
+    "Ok({z: :y})",
+  )
+  // Empty block
+  testMacro([], eBlock(list{}), "Ok(:undefined block)") //TODO: should be an error
+  //   :$$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 (:$$block (:$let :y (:add :x 1)) :y)))",
+  )
+  MyOnly.testMacroEval(
+    [("x", EvNumber(1.))],
+    eBlock(list{
+      eBlock(list{
+        eLetStatement("y", eFunction("add", list{eSymbol("x"), eNumber(1.)})),
+        eSymbol("y"),
+      }),
+    }),
+    "Ok(2)",
+  )
+})
+
+describe("lambda", () => {
+  // assign a lambda to a variable
+  let lambdaExpression = eFunction("$$lambda", list{eArrayString(["y"]), exampleExpressionY})
+  testMacro([], lambdaExpression, "Ok(lambda(y=>internal))")
+  // call a lambda
+  let callLambdaExpression = list{lambdaExpression, eNumber(1.)}->ExpressionT.EList
+  testMacro([], callLambdaExpression, "Ok(((:$$lambda [y] :y) 1))")
+  testMacroEval([], callLambdaExpression, "Ok(1)")
+  // Parameters shadow the outer scope
+  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(1)")
+  // When not shadowed by the parameters, the outer scope variables are available
+  let lambdaExpression = eFunction(
+    "$$lambda",
+    list{eArrayString(["z"]), eFunction("add", list{eSymbol("y"), eSymbol("z")})},
+  )
+  let callLambdaExpression = eList(list{lambdaExpression, eNumber(1.)})
+  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(667)")
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_Expression/Reducer_Expression_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_Expression/Reducer_Expression_test.res
@ -0,0 +1,6 @@
+open Jest
+open Expect
+
+test("dummy", () => {
+  expect(true)->toBe(true)
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsEval_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsEval_test.res
@ -1,5 +1,5 @@
 open ReducerInterface.ExpressionValue
-module MathJs = Reducer.MathJs
+module MathJs = Reducer_MathJs
 module ErrorValue = Reducer.ErrorValue

 open Jest
--- a/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsParse_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_MathJs/Reducer_MathJsParse_test.res
@ -1,4 +1,4 @@
-module Parse = Reducer.MathJs.Parse
+module Parse = Reducer_MathJs.Parse
 module Result = Belt.Result

 open Jest
@ -18,8 +18,14 @@ module MySkip = {
    Skip.test(desc, () => expectParseToBe(expr, answer))
 }

+module MyOnly = {
+  let testParse = (expr, answer) => Only.test(expr, () => expectParseToBe(expr, answer))
+  let testDescriptionParse = (desc, expr, answer) =>
+    Only.test(desc, () => expectParseToBe(expr, answer))
+}
+
 describe("MathJs parse", () => {
-  describe("literals operators paranthesis", () => {
+  describe("literals operators parenthesis", () => {
    testParse("1", "1")
    testParse("'hello'", "'hello'")
    testParse("true", "true")
@ -40,15 +46,15 @@ describe("MathJs parse", () => {
  })

  describe("functions", () => {
-    MySkip.testParse("identity(x) = x", "???")
-    MySkip.testParse("identity(x)", "???")
+    testParse("identity(x) = x", "identity = (x) => x")
+    testParse("identity(x)", "identity(x)")
  })

  describe("arrays", () => {
    testDescriptionParse("empty", "[]", "[]")
    testDescriptionParse("define", "[0, 1, 2]", "[0, 1, 2]")
    testDescriptionParse("define with strings", "['hello', 'world']", "['hello', 'world']")
-    MySkip.testParse("range(0, 4)", "range(0, 4)")
+    testParse("range(0, 4)", "range(0, 4)")
    testDescriptionParse("index", "([0,1,2])[1]", "([0, 1, 2])[1]")
  })

@ -58,11 +64,6 @@ describe("MathJs parse", () => {
  })

  describe("comments", () => {
-    MySkip.testDescriptionParse("define", "# This is a comment", "???")
-  })
-
-  describe("if statement", () => {
-    // TODO Tertiary operator instead
-    MySkip.testDescriptionParse("define", "if (true) { 1 } else { 0 }", "???")
+    testDescriptionParse("define", "1 # This is a comment", "1")
  })
 })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_TestHelpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_TestHelpers.res
@ -1,40 +1,31 @@
-module Expression = Reducer.Expression
+module ExpressionT = Reducer_Expression_T
 module ExpressionValue = ReducerInterface.ExpressionValue
+module ErrorValue = Reducer_ErrorValue

 open Jest
 open Expect

+let unwrapRecord = rValue =>
+  rValue->Belt.Result.flatMap(value =>
+    switch value {
+    | ExpressionValue.EvRecord(aRecord) => Ok(aRecord)
+    | _ => ErrorValue.RETodo("TODO: External bindings must be returned")->Error
+    }
+  )
+
 let expectParseToBe = (expr: string, answer: string) =>
-  Reducer.parse(expr)->Expression.toStringResult->expect->toBe(answer)
-
-let expectParseOuterToBe = (expr: string, answer: string) =>
-  Reducer.parseOuter(expr)->Expression.toStringResult->expect->toBe(answer)
-
-let expectParsePartialToBe = (expr: string, answer: string) =>
-  Reducer.parsePartial(expr)->Expression.toStringResult->expect->toBe(answer)
+  Reducer.parse(expr)->ExpressionT.toStringResult->expect->toBe(answer)

 let expectEvalToBe = (expr: string, answer: string) =>
  Reducer.evaluate(expr)->ExpressionValue.toStringResult->expect->toBe(answer)

 let expectEvalBindingsToBe = (expr: string, bindings: Reducer.externalBindings, answer: string) =>
-  Reducer.evaluateUsingExternalBindings(expr, bindings)
+  Reducer.evaluateUsingOptions(expr, ~externalBindings=Some(bindings), ~environment=None)
  ->ExpressionValue.toStringResult
  ->expect
  ->toBe(answer)

-let expectEvalPartialBindingsToBe = (
-  expr: string,
-  bindings: Reducer.externalBindings,
-  answer: string,
-) =>
-  Reducer.evaluatePartialUsingExternalBindings(expr, bindings)
-  ->ExpressionValue.toStringResultRecord
-  ->expect
-  ->toBe(answer)
-
 let testParseToBe = (expr, answer) => test(expr, () => expectParseToBe(expr, answer))
-let testParseOuterToBe = (expr, answer) => test(expr, () => expectParseOuterToBe(expr, answer))
-let testParsePartialToBe = (expr, answer) => test(expr, () => expectParsePartialToBe(expr, answer))
 let testDescriptionParseToBe = (desc, expr, answer) =>
  test(desc, () => expectParseToBe(expr, answer))

@ -42,34 +33,16 @@ let testEvalToBe = (expr, answer) => test(expr, () => expectEvalToBe(expr, answe
 let testDescriptionEvalToBe = (desc, expr, answer) => test(desc, () => expectEvalToBe(expr, answer))
 let testEvalBindingsToBe = (expr, bindingsList, answer) =>
  test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-  test(expr, () => expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))

 module MySkip = {
  let testParseToBe = (expr, answer) => Skip.test(expr, () => expectParseToBe(expr, answer))
-  let testParseOuterToBe = (expr, answer) =>
-    Skip.test(expr, () => expectParseOuterToBe(expr, answer))
-  let testParsePartialToBe = (expr, answer) =>
-    Skip.test(expr, () => expectParsePartialToBe(expr, answer))
  let testEvalToBe = (expr, answer) => Skip.test(expr, () => expectEvalToBe(expr, answer))
  let testEvalBindingsToBe = (expr, bindingsList, answer) =>
    Skip.test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-  let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-    Skip.test(expr, () =>
-      expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer)
-    )
 }
 module MyOnly = {
  let testParseToBe = (expr, answer) => Only.test(expr, () => expectParseToBe(expr, answer))
-  let testParseOuterToBe = (expr, answer) =>
-    Only.test(expr, () => expectParseOuterToBe(expr, answer))
-  let testParsePartialToBe = (expr, answer) =>
-    Only.test(expr, () => expectParsePartialToBe(expr, answer))
  let testEvalToBe = (expr, answer) => Only.test(expr, () => expectEvalToBe(expr, answer))
  let testEvalBindingsToBe = (expr, bindingsList, answer) =>
    Only.test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-  let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-    Only.test(expr, () =>
-      expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer)
-    )
 }
--- a/packages/squiggle-lang/tests/Reducer/Reducer_TestMacroHelpers.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_TestMacroHelpers.res
@ -0,0 +1,82 @@
+open Jest
+open Expect
+
+module Bindings = Reducer_Expression_Bindings
+module Expression = Reducer_Expression
+module ExpressionValue = ReducerInterface_ExpressionValue
+module ExpressionWithContext = Reducer_ExpressionWithContext
+module Macro = Reducer_Expression_Macro
+module T = Reducer_Expression_T
+
+let testMacro_ = (
+  tester,
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedCode: string,
+) => {
+  let bindings = Belt.Map.String.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.expandMacroCall(
+      bindings,
+      ExpressionValue.defaultEnvironment,
+      Expression.reduceExpression,
+    )
+    ->ExpressionWithContext.toStringResult
+    ->expect
+    ->toEqual(expectedCode)
+  )
+}
+
+let testMacroEval_ = (
+  tester,
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedValue: string,
+) => {
+  let bindings = Belt.Map.String.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.doMacroCall(bindings, ExpressionValue.defaultEnvironment, Expression.reduceExpression)
+    ->ExpressionValue.toStringResult
+    ->expect
+    ->toEqual(expectedValue)
+  )
+}
+
+let testMacro = (
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedExpr: string,
+) => testMacro_(test, bindArray, expr, expectedExpr)
+let testMacroEval = (
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedValue: string,
+) => testMacroEval_(test, bindArray, expr, expectedValue)
+
+module MySkip = {
+  let testMacro = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Skip.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Skip.test, bindArray, expr, expectedValue)
+}
+
+module MyOnly = {
+  let testMacro = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Only.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Only.test, bindArray, expr, expectedValue)
+}
--- a/packages/squiggle-lang/tests/Reducer/Reducer_debugging_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_debugging_test.res
@ -0,0 +1,16 @@
+open Jest
+open Reducer_TestHelpers
+
+/*
+    You can wrap around any expression with inspect(expr) to log the value of that expression.
+    This is useful for debugging. inspect(expr) returns the value of expr, but also prints it out.
+
+    There is a second version of inspect that takes a label, which will print out the label and the value.
+
+    inspectPerformace(expr, label) will print out the value of expr, the label, and the time it took to evaluate expr.
+*/
+describe("Debugging", () => {
+  testEvalToBe("inspect(1)", "Ok(1)")
+  testEvalToBe("inspect(1, \"one\")", "Ok(1)")
+  testEvalToBe("inspectPerformance(1, \"one\")", "Ok(1)")
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_externalBindings_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_externalBindings_test.res
@ -1,60 +1,63 @@
+// TODO: Reimplement with usual parse
 open Jest
 open Reducer_TestHelpers

-describe("Parse for Bindings", () => {
-  testParseOuterToBe("x", "Ok((:$$bindExpression (:$$bindings) :x))")
-  testParseOuterToBe("x+1", "Ok((:$$bindExpression (:$$bindings) (:add :x 1)))")
-  testParseOuterToBe(
-    "y = x+1; y",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) :y))",
-  )
-})
+// describe("Parse for Bindings", () => {
+//   testParseOuterToBe("x", "Ok((:$$bindExpression (:$$bindings) :x))")
+//   testParseOuterToBe("x+1", "Ok((:$$bindExpression (:$$bindings) (:add :x 1)))")
+//   testParseOuterToBe(
+//     "y = x+1; y",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) :y))",
+//   )
+// })

-describe("Parse Partial", () => {
-  testParsePartialToBe(
-    "x",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) :x) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y=x",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y :x)) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y=x+1",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y = x+1; z = y",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$let :z :y)) (:$exportVariablesExpression)))",
-  )
-})
+// describe("Parse Partial", () => {
+//   testParsePartialToBe(
+//     "x",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) :x) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y=x",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y :x)) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y=x+1",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y = x+1; z = y",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$let :z :y)) (:$exportVariablesExpression)))",
+//   )
+// })

 describe("Eval with Bindings", () => {
  testEvalBindingsToBe("x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(1)")
  testEvalBindingsToBe("x+1", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(2)")
+  testParseToBe("y = x+1; y", "Ok((:$$block (:$$block (:$let :y (:add :x 1)) :y)))")
  testEvalBindingsToBe("y = x+1; y", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(2)")
+  testEvalBindingsToBe("y = x+1", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1,y: 2})")
 })

 /*
    Partial code is a partial code fragment that is cut out from a larger code.
    Therefore it does not end with an expression.
 */
-describe("Eval Partial", () => {
-  testEvalPartialBindingsToBe(
-    //   A partial cannot end with an expression
-    "x",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Error(Assignment expected)",
-  )
-  testEvalPartialBindingsToBe("y=x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1, y: 1})")
-  testEvalPartialBindingsToBe(
-    "y=x+1",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Ok({x: 1, y: 2})",
-  )
-  testEvalPartialBindingsToBe(
-    "y = x+1; z = y",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Ok({x: 1, y: 2, z: 2})",
-  )
-})
+// describe("Eval Partial", () => {
+//   testEvalPartialBindingsToBe(
+//     //   A partial cannot end with an expression
+//     "x",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Error(Assignment expected)",
+//   )
+//   testEvalPartialBindingsToBe("y=x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1,y: 1})")
+//   testEvalPartialBindingsToBe(
+//     "y=x+1",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Ok({x: 1,y: 2})",
+//   )
+//   testEvalPartialBindingsToBe(
+//     "y = x+1; z = y",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Ok({x: 1,y: 2,z: 2})",
+//   )
+// })
--- a/packages/squiggle-lang/tests/Reducer/Reducer_functionAssignment_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_functionAssignment_test.res
@ -0,0 +1,12 @@
+open Jest
+open Reducer_TestHelpers
+
+describe("Parse function assignment", () => {
+  testParseToBe("f(x)=x", "Ok((:$$block (:$let :f (:$$lambda [x] (:$$block :x)))))")
+  testParseToBe("f(x)=2*x", "Ok((:$$block (:$let :f (:$$lambda [x] (:$$block (:multiply 2 :x))))))")
+  //MathJs does not allow blocks in function definitions
+})
+
+describe("Evaluate function assignment", () => {
+  testEvalToBe("f(x)=x; f(1)", "Ok(1)")
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_functionTricks_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_functionTricks_test.res
@ -0,0 +1,77 @@
+open Jest
+open Reducer_TestHelpers
+
+describe("Arity check", () => {
+  testEvalToBe("f(x,y) = x + y; f(1,2)", "Ok(3)")
+  testEvalToBe(
+    "f(x,y) = x + y; f(1)",
+    "Error(2 arguments expected. Instead 1 argument(s) were passed.)",
+  )
+  testEvalToBe(
+    "f(x,y) = x + y; f(1,2,3)",
+    "Error(2 arguments expected. Instead 3 argument(s) were passed.)",
+  )
+  testEvalToBe(
+    "f(x,y)=x+y; f(1,2,3,4)",
+    "Error(2 arguments expected. Instead 4 argument(s) were passed.)",
+  )
+  testEvalToBe(
+    "f(x,y)=x+y; f(1)",
+    "Error(2 arguments expected. Instead 1 argument(s) were passed.)",
+  )
+  testEvalToBe(
+    "f(x,y)=x(y); f(f)",
+    "Error(2 arguments expected. Instead 1 argument(s) were passed.)",
+  )
+  testEvalToBe("f(x)=x; f(f)", "Ok(lambda(x=>internal code))")
+  testEvalToBe(
+    "f(x,y)=x(y); f(z)",
+    "Error(2 arguments expected. Instead 1 argument(s) were passed.)",
+  )
+})
+
+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(2 is not a function)")
+  testEvalToBe("f(x)=x(1); f(2)", "Error(2 is not a function)")
+})
+
+describe("call and bindings", () => {
+  testEvalToBe("f(x)=x+1", "Ok({f: lambda(x=>internal code)})")
+  testEvalToBe("f(x)=x+1; f(1)", "Ok(2)")
+  testEvalToBe("f=1;y=2", "Ok({f: 1,y: 2})")
+  testEvalToBe("f(x)=x+1; y=f(1)", "Ok({f: lambda(x=>internal code),y: 2})")
+  testEvalToBe("f(x)=x+1; y=f(1); f(1)", "Ok(2)")
+  testEvalToBe("f(x)=x+1; y=f(1); z=f(1)", "Ok({f: lambda(x=>internal code),y: 2,z: 2})")
+  testEvalToBe(
+    "f(x)=x+1; g(x)=f(x)+1",
+    "Ok({f: lambda(x=>internal code),g: lambda(x=>internal code)})",
+  )
+  testParseToBe(
+    "f=99; g(x)=f; g(2)",
+    "Ok((:$$block (:$$block (:$let :f 99) (:$let :g (:$$lambda [x] (:$$block :f))) (: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)",
+    "Ok({f: lambda(x=>internal code),g: lambda(x=>internal code),y: 4})",
+  )
+  testEvalToBe("f(x)=x+1; g(x)=f(x)+1; g(2)", "Ok(4)")
+})
+
+describe("function trics", () => {
+  testParseToBe(
+    "f(x)=f(y)=2; f(2)",
+    "Ok((:$$block (:$$block (:$let :f (:$$lambda [x] (:$$block (:$let :f (:$$lambda [y] (:$$block 2)))))) (:f 2))))",
+  )
+  testEvalToBe("f(x)=f(y)=2; f(2)", "Ok({f: lambda(y=>internal code),x: 2})")
+  testEvalToBe("y=2;g(x)=y+1;g(2)", "Ok(3)")
+  testEvalToBe("y=2;g(x)=inspect(y)+1", "Ok({g: lambda(x=>internal code),y: 2})")
+  MySkip.testEvalToBe("f(x) = x(x); f(f)", "????") // TODO: Infinite loop. Any solution? Catching proper exception or timeout?
+  MySkip.testEvalToBe("f(x, x)=x+x; f(1,2)", "????") // TODO: Duplicate parameters
+  MySkip.testEvalToBe("myadd(x,y)=x+y; z=[add]; z[0](3,2)", "????") //TODO: to fix with new parser
+  MySkip.testEvalToBe("myaddd(x,y)=x+y; z={x: add}; z.x(3,2)", "????") //TODO: to fix with new parser
+})
--- a/packages/squiggle-lang/tests/Reducer/Reducer_test.res
+++ b/packages/squiggle-lang/tests/Reducer/Reducer_test.res
@ -10,46 +10,39 @@ describe("reducer using mathjs parse", () => {
  // Those tests toString that we are converting mathjs parse tree to what we need

  describe("expressions", () => {
-    testParseToBe("1", "Ok(1)")
-    testParseToBe("(1)", "Ok(1)")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2*3", "Ok((:add 1 (:multiply 2 3)))")
+    testParseToBe("1", "Ok((:$$block 1))")
+    testParseToBe("(1)", "Ok((:$$block 1))")
+    testParseToBe("1+2", "Ok((:$$block (:add 1 2)))")
+    testParseToBe("1+2*3", "Ok((:$$block (:add 1 (:multiply 2 3))))")
  })
  describe("arrays", () => {
    //Note. () is a empty list in Lisp
    //  The only builtin structure in Lisp is list. There are no arrays
    //  [1,2,3] becomes (1 2 3)
-    testDescriptionParseToBe("empty", "[]", "Ok(())")
-    testParseToBe("[1, 2, 3]", "Ok((1 2 3))")
-    testParseToBe("['hello', 'world']", "Ok(('hello' 'world'))")
-    testDescriptionParseToBe("index", "([0,1,2])[1]", "Ok((:$atIndex (0 1 2) (1)))")
+    testDescriptionParseToBe("empty", "[]", "Ok((:$$block ()))")
+    testParseToBe("[1, 2, 3]", "Ok((:$$block (1 2 3)))")
+    testParseToBe("['hello', 'world']", "Ok((:$$block ('hello' 'world')))")
+    testDescriptionParseToBe("index", "([0,1,2])[1]", "Ok((:$$block (:$atIndex (0 1 2) (1))))")
  })
  describe("records", () => {
-    testDescriptionParseToBe("define", "{a: 1, b: 2}", "Ok((:$constructRecord (('a' 1) ('b' 2))))")
+    testDescriptionParseToBe(
+      "define",
+      "{a: 1, b: 2}",
+      "Ok((:$$block (:$constructRecord (('a' 1) ('b' 2)))))",
+    )
    testDescriptionParseToBe(
      "use",
      "{a: 1, b: 2}.a",
-      "Ok((:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a')))",
+      "Ok((:$$block (:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a'))))",
    )
  })
  describe("multi-line", () => {
-    testParseToBe("1; 2", "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) 1) 2))")
-    testParseToBe(
-      "1+1; 2+1",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:add 1 1)) (:add 2 1)))",
-    )
+    testParseToBe("1; 2", "Ok((:$$block (:$$block 1 2)))")
+    testParseToBe("1+1; 2+1", "Ok((:$$block (:$$block (:add 1 1) (:add 2 1))))")
  })
  describe("assignment", () => {
-    testParseToBe(
-      "x=1; x",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :x 1)) :x))",
-    )
-    testParseToBe(
-      "x=1+1; x+1",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :x (:add 1 1))) (:add :x 1)))",
-    )
+    testParseToBe("x=1; x", "Ok((:$$block (:$$block (:$let :x 1) :x)))")
+    testParseToBe("x=1+1; x+1", "Ok((:$$block (:$$block (:$let :x (:add 1 1)) (:add :x 1))))")
  })
 })

@ -91,7 +84,7 @@ describe("eval", () => {
    testEvalToBe("x=1; y=x+1; y+1", "Ok(3)")
    testEvalToBe("1; x=1", "Error(Assignment expected)")
    testEvalToBe("1; 1", "Error(Assignment expected)")
-    testEvalToBe("x=1; x=1", "Error(Expression expected)")
+    testEvalToBe("x=1; x=1", "Ok({x: 1})")
  })
 })

--- a/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_Distribution_test.res
+++ b/packages/squiggle-lang/tests/ReducerInterface/ReducerInterface_Distribution_test.res
@ -119,27 +119,34 @@ 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((:$$block (:pow (:normal 5 2) (:normal 5 1))))")
+    testParse("3 ^ normal(5,1)", "Ok((:$$block (:pow 3 (:normal 5 1))))")
+    testParse("normal(5,2) ^ 3", "Ok((:$$block (:pow (:normal 5 2) 3)))")
  })
  describe("subtraction", () => {
-    testParse("10 - normal(5,1)", "Ok((:subtract 10 (:normal 5 1)))")
-    testParse("normal(5,1) - 10", "Ok((:subtract (:normal 5 1) 10))")
+    testParse("10 - normal(5,1)", "Ok((:$$block (:subtract 10 (:normal 5 1))))")
+    testParse("normal(5,1) - 10", "Ok((:$$block (:subtract (:normal 5 1) 10)))")
  })
  describe("pointwise arithmetic expressions", () => {
    testParse(~skip=true, "normal(5,2) .+ normal(5,1)", "Ok((:dotAdd (:normal 5 2) (:normal 5 1)))")
    testParse(
      ~skip=true,
      "normal(5,2) .- normal(5,1)",
-      "Ok((:dotSubtract (:normal 5 2) (:normal 5 1)))",
+      "Ok((:$$block (:dotSubtract (:normal 5 2) (:normal 5 1))))",
+      // TODO: !!! returns "Ok((:$$block (:dotPow (:normal 5 2) (:normal 5 1))))"
    )
-    testParse("normal(5,2) .* normal(5,1)", "Ok((:dotMultiply (:normal 5 2) (:normal 5 1)))")
-    testParse("normal(5,2) ./ normal(5,1)", "Ok((:dotDivide (:normal 5 2) (:normal 5 1)))")
-    testParse("normal(5,2) .^ normal(5,1)", "Ok((:dotPow (:normal 5 2) (:normal 5 1)))")
+    testParse(
+      "normal(5,2) .* normal(5,1)",
+      "Ok((:$$block (:dotMultiply (:normal 5 2) (:normal 5 1))))",
+    )
+    testParse(
+      "normal(5,2) ./ normal(5,1)",
+      "Ok((:$$block (:dotDivide (:normal 5 2) (:normal 5 1))))",
+    )
+    testParse("normal(5,2) .^ normal(5,1)", "Ok((:$$block (: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((:$$block (: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/package.json
+++ b/packages/squiggle-lang/package.json
@ -4,7 +4,9 @@
  "homepage": "https://squiggle-language.com",
  "license": "MIT",
  "scripts": {
-    "build": "rescript build -with-deps && tsc",
+    "build": "yarn build:rescript && yarn build:typescript",
+    "build:rescript": "rescript build -with-deps",
+    "build:typescript": "tsc",
    "bundle": "webpack",
    "start": "rescript build -w -with-deps",
    "clean": "rescript clean && rm -r dist",
@ -55,7 +57,7 @@
    "nyc": "^15.1.0",
    "reanalyze": "^2.19.0",
    "ts-jest": "^27.1.4",
-    "ts-loader": "^9.2.8",
+    "ts-loader": "^9.3.0",
    "ts-node": "^10.7.0",
    "typescript": "^4.6.3",
    "webpack": "^5.72.0",
--- a/packages/squiggle-lang/src/js/distribution.ts
+++ b/packages/squiggle-lang/src/js/distribution.ts
@ -3,7 +3,7 @@ import {
  genericDist,
  continuousShape,
  discreteShape,
-  samplingParams,
+  environment,
  distributionError,
  toPointSet,
  distributionErrorToString,
@ -51,9 +51,9 @@ export type shape = {

 export class Distribution {
  t: genericDist;
-  env: samplingParams;
+  env: environment;

-  constructor(t: genericDist, env: samplingParams) {
+  constructor(t: genericDist, env: environment) {
    this.t = t;
    this.env = env;
    return this;
--- a/packages/squiggle-lang/src/js/index.ts
+++ b/packages/squiggle-lang/src/js/index.ts
@ -1,8 +1,10 @@
 import * as _ from "lodash";
 import {
  samplingParams,
-  evaluateUsingExternalBindings,
+  environment,
+  defaultEnvironment,
  evaluatePartialUsingExternalBindings,
+  evaluateUsingOptions,
  externalBindings,
  expressionValue,
  errorValue,
@ -11,6 +13,7 @@ export {
  makeSampleSetDist,
  errorValueToString,
  distributionErrorToString,
+  distributionError,
 } from "../rescript/TypescriptInterface.gen";
 export type {
  samplingParams,
@ -26,9 +29,9 @@ import {
  convertRawToTypescript,
 } from "./rescript_interop";
 import { result, resultMap, tag, tagged } from "./types";
-import { Distribution } from "./distribution";
+import { Distribution, shape } from "./distribution";

-export { Distribution, squiggleExpression, result, resultMap };
+export { Distribution, squiggleExpression, result, resultMap, shape };

 export let defaultSamplingInputs: samplingParams = {
  sampleCount: 10000,
@ -38,33 +41,34 @@ export let defaultSamplingInputs: samplingParams = {
 export function run(
  squiggleString: string,
  bindings?: externalBindings,
-  samplingInputs?: samplingParams,
+  environment?: environment,
  imports?: jsImports
 ): result<squiggleExpression, errorValue> {
  let b = bindings ? bindings : defaultBindings;
  let i = imports ? imports : defaultImports;
-  let si: samplingParams = samplingInputs
-    ? samplingInputs
-    : defaultSamplingInputs;
-
-  let result: result<expressionValue, errorValue> =
-    evaluateUsingExternalBindings(squiggleString, mergeImports(b, i));
-  return resultMap(result, (x) => createTsExport(x, si));
+  let e = environment ? environment : defaultEnvironment;
+  let res: result<expressionValue, errorValue> = evaluateUsingOptions(
+    { externalBindings: mergeImports(b, i), environment: e },
+    squiggleString
+  );
+  return resultMap(res, (x) => createTsExport(x, e));
 }

 // Run Partial. A partial is a block of code that doesn't return a value
 export function runPartial(
  squiggleString: string,
  bindings?: externalBindings,
-  _samplingInputs?: samplingParams,
+  environment?: environment,
  imports?: jsImports
 ): result<externalBindings, errorValue> {
  let b = bindings ? bindings : defaultBindings;
  let i = imports ? imports : defaultImports;
+  let e = environment ? environment : defaultEnvironment;

  return evaluatePartialUsingExternalBindings(
    squiggleString,
-    mergeImports(b, i)
+    mergeImports(b, i),
+    e
  );
 }

@ -88,7 +92,7 @@ export let defaultBindings: externalBindings = {};

 function createTsExport(
  x: expressionValue,
-  sampEnv: samplingParams
+  environment: environment
 ): squiggleExpression {
  switch (x.tag) {
    case "EvArray":
@ -107,7 +111,10 @@ function createTsExport(
              return tag(
                "record",
                _.mapValues(arrayItem.value, (recordValue: unknown) =>
-                  convertRawToTypescript(recordValue as rescriptExport, sampEnv)
+                  convertRawToTypescript(
+                    recordValue as rescriptExport,
+                    environment
+                  )
                )
              );
            case "EvArray":
@ -115,20 +122,24 @@ function createTsExport(
              return tag(
                "array",
                y.map((childArrayItem) =>
-                  convertRawToTypescript(childArrayItem, sampEnv)
+                  convertRawToTypescript(childArrayItem, environment)
                )
              );
            default:
-              return createTsExport(arrayItem, sampEnv);
+              return createTsExport(arrayItem, environment);
          }
        })
      );
+    case "EvArrayString":
+      return tag("arraystring", x.value);
    case "EvBool":
      return tag("boolean", x.value);
    case "EvCall":
      return tag("call", x.value);
+    case "EvLambda":
+      return tag("lambda", x.value);
    case "EvDistribution":
-      return tag("distribution", new Distribution(x.value, sampEnv));
+      return tag("distribution", new Distribution(x.value, environment));
    case "EvNumber":
      return tag("number", x.value);
    case "EvRecord":
@ -136,7 +147,7 @@ function createTsExport(
      let result: tagged<"record", { [key: string]: squiggleExpression }> = tag(
        "record",
        _.mapValues(x.value, (x: unknown) =>
-          convertRawToTypescript(x as rescriptExport, sampEnv)
+          convertRawToTypescript(x as rescriptExport, environment)
        )
      );
      return result;
--- a/packages/squiggle-lang/src/js/rescript_interop.ts
+++ b/packages/squiggle-lang/src/js/rescript_interop.ts
@ -3,10 +3,11 @@ import {
  mixedShape,
  sampleSetDist,
  genericDist,
-  samplingParams,
+  environment,
  symbolicDist,
  discreteShape,
  continuousShape,
+  lambdaValue,
 } from "../rescript/TypescriptInterface.gen";
 import { Distribution } from "./distribution";
 import { tagged, tag } from "./types";
@ -19,31 +20,39 @@ export type rescriptExport =
      _0: rescriptExport[];
    }
  | {
-      TAG: 1; // EvBool
+      TAG: 1; // EvString
+      _0: string[];
+    }
+  | {
+      TAG: 2; // EvBool
      _0: boolean;
    }
  | {
-      TAG: 2; // EvCall
+      TAG: 3; // EvCall
      _0: string;
    }
  | {
-      TAG: 3; // EvDistribution
+      TAG: 4; // EvDistribution
      _0: rescriptDist;
    }
  | {
-      TAG: 4; // EvNumber
+      TAG: 5; // EvLambda
+      _0: lambdaValue;
+    }
+  | {
+      TAG: 6; // EvNumber
      _0: number;
    }
  | {
-      TAG: 5; // EvRecord
+      TAG: 7; // EvRecord
      _0: { [key: string]: rescriptExport };
    }
  | {
-      TAG: 6; // EvString
+      TAG: 8; // EvString
      _0: string;
    }
  | {
-      TAG: 7; // EvSymbol
+      TAG: 9; // EvSymbol
      _0: string;
    };

@ -70,7 +79,9 @@ export type squiggleExpression =
  | tagged<"symbol", string>
  | tagged<"string", string>
  | tagged<"call", string>
+  | tagged<"lambda", lambdaValue>
  | tagged<"array", squiggleExpression[]>
+  | tagged<"arraystring", string[]>
  | tagged<"boolean", boolean>
  | tagged<"distribution", Distribution>
  | tagged<"number", number>
@ -78,36 +89,40 @@ export type squiggleExpression =

 export function convertRawToTypescript(
  result: rescriptExport,
-  sampEnv: samplingParams
+  environment: environment
 ): squiggleExpression {
  switch (result.TAG) {
    case 0: // EvArray
      return tag(
        "array",
-        result._0.map((x) => convertRawToTypescript(x, sampEnv))
+        result._0.map((x) => convertRawToTypescript(x, environment))
      );
-    case 1: // EvBool
+    case 1: // EvArrayString
+      return tag("arraystring", result._0);
+    case 2: // EvBool
      return tag("boolean", result._0);
-    case 2: // EvCall
+    case 3: // EvCall
      return tag("call", result._0);
-    case 3: // EvDistribution
+    case 4: // EvDistribution
      return tag(
        "distribution",
        new Distribution(
          convertRawDistributionToGenericDist(result._0),
-          sampEnv
+          environment
        )
      );
-    case 4: // EvNumber
+    case 5: // EvDistribution
+      return tag("lambda", result._0);
+    case 6: // EvNumber
      return tag("number", result._0);
-    case 5: // EvRecord
+    case 7: // EvRecord
      return tag(
        "record",
-        _.mapValues(result._0, (x) => convertRawToTypescript(x, sampEnv))
+        _.mapValues(result._0, (x) => convertRawToTypescript(x, environment))
      );
-    case 6: // EvString
+    case 8: // EvString
      return tag("string", result._0);
-    case 7: // EvSymbol
+    case 9: // EvSymbol
      return tag("symbol", result._0);
  }
 }
@ -141,15 +156,15 @@ export type jsValue =

 export function jsValueToBinding(value: jsValue): rescriptExport {
  if (typeof value === "boolean") {
-    return { TAG: 1, _0: value as boolean };
+    return { TAG: 2, _0: value as boolean };
  } else if (typeof value === "string") {
-    return { TAG: 6, _0: value as string };
+    return { TAG: 8, _0: value as string };
  } else if (typeof value === "number") {
-    return { TAG: 4, _0: value as number };
+    return { TAG: 6, _0: value as number };
  } else if (Array.isArray(value)) {
    return { TAG: 0, _0: value.map(jsValueToBinding) };
  } else {
    // Record
-    return { TAG: 5, _0: _.mapValues(value, jsValueToBinding) };
+    return { TAG: 7, _0: _.mapValues(value, jsValueToBinding) };
  }
 }
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res
@ -9,6 +9,11 @@ type env = {
  xyPointLength: int,
 }

+let defaultEnv = {
+  sampleCount: 10000,
+  xyPointLength: 10000,
+}
+
 type outputType =
  | Dist(genericDist)
  | Float(float)
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi
@ -4,6 +4,9 @@ type env = {
  xyPointLength: int,
 }

+@genType
+let defaultEnv: env
+
 open DistributionTypes

@genType
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
@ -114,6 +114,7 @@ module DistributionOperation = {
    | ToFloat(#Mean) => `mean`
    | ToFloat(#Pdf(r)) => `pdf(${E.Float.toFixed(r)})`
    | ToFloat(#Sample) => `sample`
+    | ToFloat(#IntegralSum) => `integralSum`
    | ToDist(Normalize) => `normalize`
    | ToDist(ToPointSet) => `toPointSet`
    | ToDist(ToSampleSet(r)) => `toSampleSet(${E.I.toString(r)})`
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer.res
@ -1,15 +1,11 @@
-module Dispatch = Reducer_Dispatch
 module ErrorValue = Reducer_ErrorValue
 module Expression = Reducer_Expression
-module Extra = Reducer_Extra
-module Js = Reducer_Js
-module MathJs = Reducer_MathJs

-type expressionValue = Reducer_Expression.expressionValue
-type externalBindings = Expression.externalBindings
-let evaluate = Expression.eval
-let evaluateUsingExternalBindings = Expression.evalUsingExternalBindings
-let evaluatePartialUsingExternalBindings = Expression.evalPartialUsingExternalBindings
+type environment = ReducerInterface_ExpressionValue.environment
+type errorValue = Reducer_ErrorValue.errorValue
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+let evaluate = Expression.evaluate
+let evaluateUsingOptions = Expression.evaluateUsingOptions
+let evaluatePartialUsingExternalBindings = Expression.evaluatePartialUsingExternalBindings
 let parse = Expression.parse
-let parseOuter = Expression.parseOuter
-let parsePartial = Expression.parsePartial
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer.resi
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer.resi
@ -1,26 +1,28 @@
-module Dispatch = Reducer_Dispatch
 module ErrorValue = Reducer_ErrorValue
 module Expression = Reducer_Expression
-module Extra = Reducer_Extra
-module Js = Reducer_Js
-module MathJs = Reducer_MathJs

+@genType
+type environment = ReducerInterface_ExpressionValue.environment
+@genType
+type errorValue = Reducer_ErrorValue.errorValue
@genType
 type expressionValue = ReducerInterface_ExpressionValue.expressionValue
@genType
 type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+
@genType
-let evaluate: string => result<expressionValue, Reducer_ErrorValue.errorValue>
-@genType
-let evaluateUsingExternalBindings: (
+let evaluateUsingOptions: (
+  ~environment: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.environment>,
+  ~externalBindings: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.externalBindings>,
  string,
-  externalBindings,
-) => result<expressionValue, Reducer_ErrorValue.errorValue>
+) => result<expressionValue, errorValue>
@genType
 let evaluatePartialUsingExternalBindings: (
  string,
-  externalBindings,
-) => result<externalBindings, Reducer_ErrorValue.errorValue>
-let parse: string => result<Expression.expression, ErrorValue.errorValue>
-let parseOuter: string => result<Expression.expression, ErrorValue.errorValue>
-let parsePartial: string => result<Expression.expression, ErrorValue.errorValue>
+  QuriSquiggleLang.ReducerInterface_ExpressionValue.externalBindings,
+  QuriSquiggleLang.ReducerInterface_ExpressionValue.environment,
+) => result<externalBindings, errorValue>
+@genType
+let evaluate: string => result<expressionValue, errorValue>
+
+let parse: string => result<Expression.expression, errorValue>
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
@ -1,5 +1,6 @@
 module ExternalLibrary = ReducerInterface.ExternalLibrary
 module MathJs = Reducer_MathJs
+module Bindings = Reducer_Expression_Bindings
 open ReducerInterface.ExpressionValue
 open Reducer_ErrorValue

@ -11,7 +12,7 @@ open Reducer_ErrorValue

 exception TestRescriptException

-let callInternal = (call: functionCall): result<'b, errorValue> => {
+let callInternal = (call: functionCall, _environment): result<'b, errorValue> => {
  let callMathJs = (call: functionCall): result<'b, errorValue> =>
    switch call {
    | ("javascriptraise", [msg]) => Js.Exn.raiseError(toString(msg)) // For Tests
@ -20,12 +21,12 @@ let callInternal = (call: functionCall): result<'b, errorValue> => {
    }

  let constructRecord = arrayOfPairs => {
-    Belt.Array.map(arrayOfPairs, pairValue => {
+    Belt.Array.map(arrayOfPairs, pairValue =>
      switch pairValue {
      | EvArray([EvString(key), valueValue]) => (key, valueValue)
      | _ => ("wrong key type", pairValue->toStringWithType->EvString)
      }
-    })
+    )
    ->Js.Dict.fromArray
    ->EvRecord
    ->Ok
@ -43,16 +44,58 @@ let callInternal = (call: functionCall): result<'b, errorValue> => {
    | None => RERecordPropertyNotFound("Record property not found", sIndex)->Error
    }

+  let inspect = (value: expressionValue) => {
+    Js.log(value->toString)
+    value->Ok
+  }
+
+  let inspectLabel = (value: expressionValue, label: string) => {
+    Js.log(`${label}: ${value->toString}`)
+    value->Ok
+  }
+
+  /*
+    NOTE: This function is cancelled. The related issue is
+    https://github.com/webpack/webpack/issues/13435
+ */
+  let inspectPerformance = (value: expressionValue, label: string) => {
+    // let _ = %raw("{performance} = require('perf_hooks')")
+    // let start = %raw(`performance.now()`)
+    // let finish = %raw(`performance.now()`)
+    // let performance = finish - start
+    // Js.log(`${label}: ${value->toString} performance: ${Js.String.make(performance)}ms`)
+    // TODO find a way of failing the hook gracefully, also needs a block parameter
+    Js.log(`${label}: ${value->toString}`)
+    value->Ok
+  }
+
+  let doSetBindings = (
+    externalBindings: externalBindings,
+    symbol: string,
+    value: expressionValue,
+  ) => {
+    Bindings.fromExternalBindings(externalBindings)
+    ->Belt.Map.String.set(symbol, value)
+    ->Bindings.toExternalBindings
+    ->EvRecord
+    ->Ok
+  }
+
+  let doExportBindings = (externalBindings: externalBindings) => EvRecord(externalBindings)->Ok
+
  switch call {
-  // | ("$constructRecord", pairArray)
-  // | ("$atIndex", [EvArray(anArray), EvNumber(fIndex)]) => arrayAtIndex(anArray, fIndex)
-  // | ("$atIndex", [EvRecord(aRecord), EvString(sIndex)]) => recordAtIndex(aRecord, sIndex)
-  | ("$constructRecord", [EvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
  | ("$atIndex", [EvArray(aValueArray), EvArray([EvNumber(fIndex)])]) =>
    arrayAtIndex(aValueArray, fIndex)
  | ("$atIndex", [EvRecord(dict), EvArray([EvString(sIndex)])]) => recordAtIndex(dict, sIndex)
  | ("$atIndex", [obj, index]) =>
    (toStringWithType(obj) ++ "??~~~~" ++ toStringWithType(index))->EvString->Ok
+  | ("$constructRecord", [EvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
+  | ("inspect", [value, EvString(label)]) => inspectLabel(value, label)
+  | ("inspect", [value]) => inspect(value)
+  | ("inspectPerformance", [value, EvString(label)]) => inspectPerformance(value, label)
+  | ("$setBindings", [EvRecord(externalBindings), EvSymbol(symbol), value]) =>
+    doSetBindings(externalBindings, symbol, value)
+  | ("$exportBindings", [EvRecord(externalBindings)]) => doExportBindings(externalBindings)
  | call => callMathJs(call)
  }
 }
@ -60,12 +103,12 @@ let callInternal = (call: functionCall): result<'b, errorValue> => {
 /*
  Reducer uses Result monad while reducing expressions
 */
-let dispatch = (call: functionCall): result<expressionValue, errorValue> =>
+let dispatch = (call: functionCall, environment): result<expressionValue, errorValue> =>
  try {
    let (fn, args) = call
    // There is a bug that prevents string match in patterns
    // So we have to recreate a copy of the string
-    ExternalLibrary.dispatch((Js.String.make(fn), args), callInternal)
+    ExternalLibrary.dispatch((Js.String.make(fn), args), environment, callInternal)
  } catch {
  | Js.Exn.Error(obj) => REJavaScriptExn(Js.Exn.message(obj), Js.Exn.name(obj))->Error
  | _ => RETodo("unhandled rescript exception")->Error
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros.res
@ -3,120 +3,170 @@
  they take expressions as parameters and return a new expression.
  Macros are used to define language building blocks. They are like Lisp macros.
 */
+module Bindings = Reducer_Expression_Bindings
 module ExpressionT = Reducer_Expression_T
 module ExpressionValue = ReducerInterface.ExpressionValue
+module ExpressionWithContext = Reducer_ExpressionWithContext
 module Result = Belt.Result
+open Reducer_Expression_ExpressionBuilder

-open Reducer_ErrorValue
-
+type environment = ExpressionValue.environment
+type errorValue = Reducer_ErrorValue.errorValue
 type expression = ExpressionT.expression
-
-type reducerFn = (
-  expression,
-  ExpressionT.bindings,
-) => result<ExpressionValue.expressionValue, errorValue>
+type expressionValue = ExpressionValue.expressionValue
+type expressionWithContext = ExpressionWithContext.expressionWithContext

 let dispatchMacroCall = (
-  list: list<expression>,
+  macroExpression: expression,
  bindings: ExpressionT.bindings,
-  reduceExpression: reducerFn,
-): result<expression, 'e> => {
-  let rec replaceSymbols = (expression: expression, bindings: ExpressionT.bindings): result<
-    expression,
-    errorValue,
-  > =>
-    switch expression {
-    | ExpressionT.EValue(EvSymbol(aSymbol)) =>
-      switch bindings->Belt.Map.String.get(aSymbol) {
-      | Some(boundExpression) => boundExpression->Ok
-      | None => RESymbolNotFound(aSymbol)->Error
-      }
-    | ExpressionT.EValue(_) => expression->Ok
-    | ExpressionT.EBindings(_) => expression->Ok
-    | ExpressionT.EList(list) => {
-        let racc = list->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
-          racc->Result.flatMap(acc => {
-            each
-            ->replaceSymbols(bindings)
-            ->Result.flatMap(newNode => {
-              acc->Belt.List.add(newNode)->Ok
-            })
-          })
-        )
-        racc->Result.map(acc => acc->ExpressionT.EList)
-      }
-    }
-
-  let doBindStatement = (statement: expression, bindings: ExpressionT.bindings) => {
+  environment,
+  reduceExpression: ExpressionT.reducerFn,
+): result<expressionWithContext, errorValue> => {
+  let doBindStatement = (bindingExpr: expression, statement: expression, environment) =>
    switch statement {
-    | ExpressionT.EList(list{
-        ExpressionT.EValue(EvCall("$let")),
-        ExpressionT.EValue(EvSymbol(aSymbol)),
-        expressionToReduce,
-      }) => {
-        let rNewExpressionToReduce = replaceSymbols(expressionToReduce, bindings)
+    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), symbolExpr, statement}) => {
+        let rExternalBindingsValue = reduceExpression(bindingExpr, bindings, environment)

-        let rNewValue =
-          rNewExpressionToReduce->Result.flatMap(newExpressionToReduce =>
-            reduceExpression(newExpressionToReduce, bindings)
-          )
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)

-        let rNewExpression = rNewValue->Result.map(newValue => ExpressionT.EValue(newValue))
-        rNewExpression->Result.map(newExpression =>
-          Belt.Map.String.set(bindings, aSymbol, newExpression)->ExpressionT.EBindings
+          // Js.log(
+          //   `bindStatement ${Bindings.toString(newBindings)}<==${ExpressionT.toString(
+          //       bindingExpr,
+          //     )} statement: $let ${ExpressionT.toString(symbolExpr)}=${ExpressionT.toString(
+          //       statement,
+          //     )}`,
+          // )
+
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement->Result.map(newStatement =>
+            ExpressionWithContext.withContext(
+              eFunction(
+                "$setBindings",
+                list{newBindings->Bindings.toExternalBindings->eRecord, symbolExpr, newStatement},
+              ),
+              newBindings,
            )
+          )
+        })
      }
    | _ => REAssignmentExpected->Error
    }
-  }

-  let doExportVariableExpression = (bindings: ExpressionT.bindings) => {
-    let emptyDictionary: Js.Dict.t<ExpressionValue.expressionValue> = Js.Dict.empty()
-    let reducedBindings = bindings->Belt.Map.String.keep((_key, value) =>
-      switch value {
-      | ExpressionT.EValue(_) => true
-      | _ => false
-      }
+  let doBindExpression = (bindingExpr: expression, statement: expression, environment): result<
+    expressionWithContext,
+    errorValue,
+  > =>
+    switch statement {
+    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), symbolExpr, statement}) => {
+        let rExternalBindingsValue = reduceExpression(bindingExpr, bindings, environment)
+
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement->Result.map(newStatement =>
+            ExpressionWithContext.withContext(
+              eFunction(
+                "$exportBindings",
+                list{
+                  eFunction(
+                    "$setBindings",
+                    list{
+                      newBindings->Bindings.toExternalBindings->eRecord,
+                      symbolExpr,
+                      newStatement,
+                    },
+                  ),
+                },
+              ),
+              newBindings,
+            )
          )
-    let externalBindings = reducedBindings->Belt.Map.String.reduce(emptyDictionary, (
-      acc,
-      key,
-      expressionValue,
-    ) => {
-      let value = switch expressionValue {
-      | EValue(aValue) => aValue
-      | _ => EvSymbol("internal")
-      }
-      Js.Dict.set(acc, key, value)
-      acc
        })
-    externalBindings->ExpressionValue.EvRecord->ExpressionT.EValue->Ok
+      }
+    | _ => {
+        let rExternalBindingsValue: result<expressionValue, errorValue> = reduceExpression(
+          bindingExpr,
+          bindings,
+          environment,
+        )
+
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement->Result.map(newStatement =>
+            ExpressionWithContext.withContext(newStatement, newBindings)
+          )
+        })
+      }
    }

-  let doBindExpression = (expression: expression, bindings: ExpressionT.bindings) =>
-    switch expression {
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), ..._}) =>
-      REExpressionExpected->Error
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$exportVariablesExpression"))}) =>
-      doExportVariableExpression(bindings)
-    | _ => replaceSymbols(expression, bindings)
+  let doBlock = (exprs: list<expression>, _bindings: ExpressionT.bindings, _environment): result<
+    expressionWithContext,
+    errorValue,
+  > => {
+    let exprsArray = Belt.List.toArray(exprs)
+    let maxIndex = Js.Array2.length(exprsArray) - 1
+    let newStatement = exprsArray->Js.Array2.reducei((acc, statement, index) =>
+      if index == 0 {
+        if index == maxIndex {
+          eBindExpressionDefault(statement)
+        } else {
+          eBindStatementDefault(statement)
+        }
+      } else if index == maxIndex {
+        eBindExpression(acc, statement)
+      } else {
+        eBindStatement(acc, statement)
+      }
+    , eSymbol("undefined block"))
+    ExpressionWithContext.noContext(newStatement)->Ok
  }

-  switch list {
-  | list{ExpressionT.EValue(EvCall("$$bindings"))} => bindings->ExpressionT.EBindings->Ok
+  let doLambdaDefinition = (
+    bindings: ExpressionT.bindings,
+    parameters: array<string>,
+    lambdaDefinition: ExpressionT.expression,
+  ) =>
+    ExpressionWithContext.noContext(
+      eLambda(parameters, bindings->Bindings.toExternalBindings, lambdaDefinition),
+    )->Ok

+  let expandExpressionList = (aList, bindings: ExpressionT.bindings, environment): result<
+    expressionWithContext,
+    errorValue,
+  > =>
+    switch aList {
    | list{
        ExpressionT.EValue(EvCall("$$bindStatement")),
-      ExpressionT.EBindings(bindings),
+        bindingExpr: ExpressionT.expression,
        statement,
      } =>
-    doBindStatement(statement, bindings)
+      doBindStatement(bindingExpr, statement, environment)
+    | list{ExpressionT.EValue(EvCall("$$bindStatement")), statement} =>
+      // bindings of the context are used when there is no binding expression
+      doBindStatement(eRecord(Bindings.toExternalBindings(bindings)), statement, environment)
    | list{
        ExpressionT.EValue(EvCall("$$bindExpression")),
-      ExpressionT.EBindings(bindings),
+        bindingExpr: ExpressionT.expression,
        expression,
      } =>
-    doBindExpression(expression, bindings)
-  | _ => list->ExpressionT.EList->Ok
+      doBindExpression(bindingExpr, expression, environment)
+    | list{ExpressionT.EValue(EvCall("$$bindExpression")), expression} =>
+      // bindings of the context are used when there is no binding expression
+      doBindExpression(eRecord(Bindings.toExternalBindings(bindings)), expression, environment)
+    | list{ExpressionT.EValue(EvCall("$$block")), ...exprs} => doBlock(exprs, bindings, environment)
+    | list{
+        ExpressionT.EValue(EvCall("$$lambda")),
+        ExpressionT.EValue(EvArrayString(parameters)),
+        lambdaDefinition,
+      } =>
+      doLambdaDefinition(bindings, parameters, lambdaDefinition)
+    | _ => ExpressionWithContext.noContext(ExpressionT.EList(aList))->Ok
+    }
+
+  switch macroExpression {
+  | EList(aList) => expandExpressionList(aList, bindings, environment)
+  | _ => ExpressionWithContext.noContext(macroExpression)->Ok
  }
 }
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res
@ -1,15 +1,17 @@
@genType
 type errorValue =
+  | REArityError(option<string>, int, int) //TODO: Binding a lambda to a variable should record the variable name in lambda for error reporting
  | REArrayIndexNotFound(string, int)
  | REAssignmentExpected
+  | REDistributionError(DistributionTypes.error)
  | REExpressionExpected
  | REFunctionExpected(string)
  | REJavaScriptExn(option<string>, option<string>) // Javascript Exception
  | REMacroNotFound(string)
+  | RENotAFunction(string)
  | RERecordPropertyNotFound(string, string)
  | RESymbolNotFound(string)
  | RESyntaxError(string)
-  | REDistributionError(DistributionTypes.error)
  | RETodo(string) // To do

 type t = errorValue
@ -17,6 +19,10 @@ type t = errorValue
@genType
 let errorToString = err =>
  switch err {
+  | REArityError(_oFnName, arity, usedArity) =>
+    `${Js.String.make(arity)} arguments expected. Instead ${Js.String.make(
+        usedArity,
+      )} argument(s) were passed.`
  | REArrayIndexNotFound(msg, index) => `${msg}: ${Js.String.make(index)}`
  | REAssignmentExpected => "Assignment expected"
  | REExpressionExpected => "Expression expected"
@ -35,6 +41,7 @@ let errorToString = err =>
      answer
    }
  | REMacroNotFound(macro) => `Macro not found: ${macro}`
+  | RENotAFunction(valueString) => `${valueString} is not a function`
  | RERecordPropertyNotFound(msg, index) => `${msg}: ${index}`
  | RESymbolNotFound(symbolName) => `${symbolName} is not defined`
  | RESyntaxError(desc) => `Syntax Error: ${desc}`
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res
@ -1,35 +1,22 @@
+module Bindings = Reducer_Expression_Bindings
 module BuiltIn = Reducer_Dispatch_BuiltIn
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionValue = ReducerInterface.ExpressionValue
 module Extra = Reducer_Extra
+module Lambda = Reducer_Expression_Lambda
+module Macro = Reducer_Expression_Macro
 module MathJs = Reducer_MathJs
 module Result = Belt.Result
 module T = Reducer_Expression_T
-open Reducer_ErrorValue

+type environment = ReducerInterface_ExpressionValue.environment
+type errorValue = Reducer_ErrorValue.errorValue
 type expression = T.expression
-type expressionValue = ExpressionValue.expressionValue
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type internalCode = ReducerInterface_ExpressionValue.internalCode
 type t = expression

-/*
-  Shows the expression as text of expression
-*/
-let rec toString = expression =>
-  switch expression {
-  | T.EBindings(_) => "$$bound"
-  | T.EList(aList) =>
-    `(${Belt.List.map(aList, aValue => toString(aValue))
-      ->Extra.List.interperse(" ")
-      ->Belt.List.toArray
-      ->Js.String.concatMany("")})`
-  | EValue(aValue) => ExpressionValue.toString(aValue)
-  }
-
-let toStringResult = codeResult =>
-  switch codeResult {
-  | Ok(a) => `Ok(${toString(a)})`
-  | Error(m) => `Error(${Js.String.make(m)})`
-  }
-
 /*
  Converts a MathJs code to expression
 */
@ -39,148 +26,115 @@ let parse_ = (expr: string, parser, converter): result<t, errorValue> =>
 let parse = (mathJsCode: string): result<t, errorValue> =>
  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromNode)

-let parsePartial = (mathJsCode: string): result<t, errorValue> =>
-  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromPartialNode)
-
-let parseOuter = (mathJsCode: string): result<t, errorValue> =>
-  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromOuterNode)
-
-let defaultBindings: T.bindings = Belt.Map.String.empty
-
 /*
  Recursively evaluate/reduce the expression (Lisp AST)
 */
-let rec reduceExpression = (expression: t, bindings: T.bindings): result<expressionValue, 'e> => {
-  /*
-    Macros are like functions but instead of taking values as parameters,
-    they take expressions as parameters and return a new expression.
-    Macros are used to define language building blocks. They are like Lisp macros.
- */
-  let doMacroCall = (list: list<t>, bindings: T.bindings): result<t, 'e> =>
-    Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(list, bindings, reduceExpression)
+let rec reduceExpression = (expression: t, bindings: T.bindings, environment: environment): result<
+  expressionValue,
+  'e,
+> => {
+  // Js.log(`reduce: ${T.toString(expression)} bindings: ${bindings->Bindings.toString}`)
+  switch expression {
+  | T.EValue(value) => value->Ok
+  | T.EList(list) =>
+    switch list {
+    | list{EValue(EvCall(fName)), ..._args} =>
+      switch Macro.isMacroName(fName) {
+      // A macro expands then reduces itself
+      | true => Macro.doMacroCall(expression, bindings, environment, reduceExpression)
+      | false => reduceExpressionList(list, bindings, environment)
+      }
+    | _ => reduceExpressionList(list, bindings, environment)
+    }
+  }
+}
+
+and reduceExpressionList = (
+  expressions: list<t>,
+  bindings: T.bindings,
+  environment: environment,
+): result<expressionValue, 'e> => {
+  let racc: result<list<expressionValue>, 'e> = expressions->Belt.List.reduceReverse(Ok(list{}), (
+    racc,
+    each: expression,
+  ) =>
+    racc->Result.flatMap(acc => {
+      each
+      ->reduceExpression(bindings, environment)
+      ->Result.map(newNode => {
+        acc->Belt.List.add(newNode)
+      })
+    })
+  )
+  racc->Result.flatMap(acc => acc->reduceValueList(environment))
+}

 /*
    After reducing each level of expression(Lisp AST), we have a value list to evaluate
 */
-  let reduceValueList = (valueList: list<expressionValue>): result<expressionValue, 'e> =>
+and reduceValueList = (valueList: list<expressionValue>, environment): result<
+  expressionValue,
+  'e,
+> =>
  switch valueList {
-    | list{EvCall(fName), ...args} => (fName, args->Belt.List.toArray)->BuiltIn.dispatch
-    | _ => valueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
-    }
+  | list{EvCall(fName), ...args} => (fName, args->Belt.List.toArray)->BuiltIn.dispatch(environment)

-  let rec seekMacros = (expression: t, bindings: T.bindings): result<t, 'e> =>
-    switch expression {
-    | T.EValue(_value) => expression->Ok
-    | T.EBindings(_value) => expression->Ok
-    | T.EList(list) => {
-        let racc: result<list<t>, 'e> = list->Belt.List.reduceReverse(Ok(list{}), (
-          racc,
-          each: expression,
-        ) =>
-          racc->Result.flatMap(acc => {
-            each
-            ->seekMacros(bindings)
-            ->Result.flatMap(newNode => {
-              acc->Belt.List.add(newNode)->Ok
-            })
-          })
-        )
-        racc->Result.flatMap(acc => acc->doMacroCall(bindings))
-      }
-    }
-
-  let rec reduceExpandedExpression = (expression: t): result<expressionValue, 'e> =>
-    switch expression {
-    | T.EValue(value) => value->Ok
-    | T.EList(list) => {
-        let racc: result<list<expressionValue>, 'e> = list->Belt.List.reduceReverse(Ok(list{}), (
-          racc,
-          each: expression,
-        ) =>
-          racc->Result.flatMap(acc => {
-            each
-            ->reduceExpandedExpression
-            ->Result.flatMap(newNode => {
-              acc->Belt.List.add(newNode)->Ok
-            })
-          })
-        )
-        racc->Result.flatMap(acc => acc->reduceValueList)
-      }
-    | EBindings(_bindings) => RETodo("Error: Bindings cannot be reduced to values")->Error
-    }
-
-  let rExpandedExpression: result<t, 'e> = expression->seekMacros(bindings)
-  rExpandedExpression->Result.flatMap(expandedExpression =>
-    expandedExpression->reduceExpandedExpression
+  | list{EvLambda(lamdaCall), ...args} =>
+    Lambda.doLambdaCall(lamdaCall, args, environment, reduceExpression)
+  | _ =>
+    valueList
+    ->Lambda.checkIfReduced
+    ->Result.flatMap(reducedValueList =>
+      reducedValueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
    )
  }

-let evalUsingExternalBindingsExpression_ = (aExpression, bindings): result<expressionValue, 'e> =>
-  reduceExpression(aExpression, bindings)
+let evalUsingBindingsExpression_ = (aExpression, bindings, environment): result<
+  expressionValue,
+  'e,
+> => reduceExpression(aExpression, bindings, environment)

-/*
-  Evaluates MathJs code via Reducer using bindings and answers the result.
-  When bindings are used, the code is a partial code as if it is cut from a larger code.
-  Therefore all statements are assignments.
-*/
-let evalPartialUsingExternalBindings_ = (codeText: string, bindings: T.bindings) => {
-  parsePartial(codeText)->Result.flatMap(expression =>
-    expression->evalUsingExternalBindingsExpression_(bindings)
-  )
+let evaluateUsingOptions = (
+  ~environment: option<ReducerInterface_ExpressionValue.environment>,
+  ~externalBindings: option<ReducerInterface_ExpressionValue.externalBindings>,
+  code: string,
+): result<expressionValue, errorValue> => {
+  let anEnvironment = switch environment {
+  | Some(env) => env
+  | None => ReducerInterface_ExpressionValue.defaultEnvironment
  }

-/*
-  Evaluates MathJs code via Reducer using bindings and answers the result.
-  When bindings are used, the code is a partial code as if it is cut from a larger code.
-  Therefore all statments are assignments.
-*/
-let evalOuterWBindings_ = (codeText: string, bindings: T.bindings) => {
-  parseOuter(codeText)->Result.flatMap(expression =>
-    expression->evalUsingExternalBindingsExpression_(bindings)
-  )
+  let anExternalBindings = switch externalBindings {
+  | Some(bindings) => bindings
+  | None => ReducerInterface_ExpressionValue.defaultExternalBindings
+  }
+
+  let bindings = anExternalBindings->Bindings.fromExternalBindings
+
+  parse(code)->Result.flatMap(expr => evalUsingBindingsExpression_(expr, bindings, anEnvironment))
 }

 /*
  Evaluates MathJs code and bindings via Reducer and answers the result
 */
-let eval = (codeText: string) => {
-  parse(codeText)->Result.flatMap(expression =>
-    expression->evalUsingExternalBindingsExpression_(defaultBindings)
+let evaluate = (code: string): result<expressionValue, errorValue> => {
+  evaluateUsingOptions(~environment=None, ~externalBindings=None, code)
+}
+let eval = evaluate
+let evaluatePartialUsingExternalBindings = (
+  code: string,
+  externalBindings: ReducerInterface_ExpressionValue.externalBindings,
+  environment: ReducerInterface_ExpressionValue.environment,
+): result<externalBindings, errorValue> => {
+  let rAnswer = evaluateUsingOptions(
+    ~environment=Some(environment),
+    ~externalBindings=Some(externalBindings),
+    code,
  )
+  switch rAnswer {
+  | Ok(EvRecord(externalBindings)) => Ok(externalBindings)
+  | Ok(_) =>
+    Error(Reducer_ErrorValue.RESyntaxError(`Partials must end with an assignment or record`))
+  | Error(err) => err->Error
  }
-
-type externalBindings = ReducerInterface.ExpressionValue.externalBindings //Js.Dict.t<expressionValue>
-
-let externalBindingsToBindings = (externalBindings: externalBindings): T.bindings => {
-  let keys = Js.Dict.keys(externalBindings)
-  keys->Belt.Array.reduce(defaultBindings, (acc, key) => {
-    let value = Js.Dict.unsafeGet(externalBindings, key)
-    acc->Belt.Map.String.set(key, T.EValue(value))
-  })
-}
-/*
-  Evaluates code with external bindings. External bindings are a record of expression values.
-*/
-let evalUsingExternalBindings = (code: string, externalBindings: externalBindings) => {
-  let bindings = externalBindings->externalBindingsToBindings
-  evalOuterWBindings_(code, bindings)
-}
-
-/*
-  Evaluates code with external bindings. External bindings are a record of expression values.
-  The code is a partial code as if it is cut from a larger code. Therefore all statments are assignments.
-*/
-let evalPartialUsingExternalBindings = (code: string, externalBindings: externalBindings): result<
-  externalBindings,
-  'e,
-> => {
-  let bindings = externalBindings->externalBindingsToBindings
-  let answer = evalPartialUsingExternalBindings_(code, bindings)
-  answer->Result.flatMap(answer =>
-    switch answer {
-    | EvRecord(aRecord) => Ok(aRecord)
-    | _ => RETodo("TODO: External bindings must be returned")->Error
-    }
-  )
 }
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_ExpressionWithContext.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_ExpressionWithContext.res
@ -0,0 +1,45 @@
+module Bindings = Reducer_Expression_Bindings
+module ErrorValue = Reducer_ErrorValue
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Result = Belt.Result
+
+type bindings = ExpressionT.bindings
+type context = bindings
+type environment = ExpressionValue.environment
+type errorValue = Reducer_ErrorValue.errorValue
+type expression = ExpressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type reducerFn = ExpressionT.reducerFn
+
+type expressionWithContext =
+  | ExpressionWithContext(expression, context)
+  | ExpressionNoContext(expression)
+
+let callReducer = (
+  expressionWithContext: expressionWithContext,
+  bindings: bindings,
+  environment: environment,
+  reducer: reducerFn,
+): result<expressionValue, errorValue> =>
+  switch expressionWithContext {
+  | ExpressionNoContext(expr) => reducer(expr, bindings, environment)
+  | ExpressionWithContext(expr, context) => reducer(expr, context, environment)
+  }
+
+let withContext = (expression, context) => ExpressionWithContext(expression, context)
+let noContext = expression => ExpressionNoContext(expression)
+
+let toString = expressionWithContext =>
+  switch expressionWithContext {
+  | ExpressionNoContext(expr) => ExpressionT.toString(expr)
+  | ExpressionWithContext(expr, context) =>
+    `${ExpressionT.toString(expr)} context: ${Bindings.toString(context)}`
+  }
+
+let toStringResult = rExpressionWithContext =>
+  switch rExpressionWithContext {
+  | Ok(expressionWithContext) => `Ok(${toString(expressionWithContext)})`
+  | Error(errorValue) => ErrorValue.errorToString(errorValue)
+  }
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Bindings.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Bindings.res
@ -0,0 +1,85 @@
+module ErrorValue = Reducer_ErrorValue
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Result = Belt.Result
+
+type errorValue = Reducer_ErrorValue.errorValue
+type expression = ExpressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+
+let defaultBindings: ExpressionT.bindings = Belt.Map.String.empty
+
+let fromExternalBindings = (externalBindings: externalBindings): ExpressionT.bindings => {
+  let keys = Js.Dict.keys(externalBindings)
+  keys->Belt.Array.reduce(defaultBindings, (acc, key) => {
+    let value = Js.Dict.unsafeGet(externalBindings, key)
+    acc->Belt.Map.String.set(key, value)
+  })
+}
+
+let toExternalBindings = (bindings: ExpressionT.bindings): externalBindings => {
+  let keys = Belt.Map.String.keysToArray(bindings)
+  keys->Belt.Array.reduce(Js.Dict.empty(), (acc, key) => {
+    let value = bindings->Belt.Map.String.getExn(key)
+    Js.Dict.set(acc, key, value)
+    acc
+  })
+}
+
+let fromValue = (aValue: expressionValue) =>
+  switch aValue {
+  | EvRecord(externalBindings) => fromExternalBindings(externalBindings)
+  | _ => defaultBindings
+  }
+
+let externalFromArray = anArray => Js.Dict.fromArray(anArray)
+
+let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")
+
+let rec replaceSymbols = (bindings: ExpressionT.bindings, expression: expression): result<
+  expression,
+  errorValue,
+> =>
+  switch expression {
+  | ExpressionT.EValue(value) =>
+    replaceSymbolOnValue(bindings, value)->Result.map(evValue => evValue->ExpressionT.EValue)
+  | ExpressionT.EList(list) =>
+    switch list {
+    | list{EValue(EvCall(fName)), ..._args} =>
+      switch isMacroName(fName) {
+      // A macro reduces itself so we dont dive in it
+      | true => expression->Ok
+      | false => replaceSymbolsOnExpressionList(bindings, list)
+      }
+    | _ => replaceSymbolsOnExpressionList(bindings, list)
+    }
+  }
+
+and replaceSymbolsOnExpressionList = (bindings, list) => {
+  let racc = list->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
+    racc->Result.flatMap(acc => {
+      replaceSymbols(bindings, each)->Result.flatMap(newNode => {
+        acc->Belt.List.add(newNode)->Ok
+      })
+    })
+  )
+  racc->Result.map(acc => acc->ExpressionT.EList)
+}
+and replaceSymbolOnValue = (bindings, evValue: expressionValue) =>
+  switch evValue {
+  | EvSymbol(symbol) => Belt.Map.String.getWithDefault(bindings, symbol, evValue)->Ok
+  | EvCall(symbol) => Belt.Map.String.getWithDefault(bindings, symbol, evValue)->checkIfCallable
+  | _ => evValue->Ok
+  }
+and checkIfCallable = (evValue: expressionValue) =>
+  switch evValue {
+  | EvCall(_) | EvLambda(_) => evValue->Ok
+  | _ => ErrorValue.RENotAFunction(ExpressionValue.toString(evValue))->Error
+  }
+
+let toString = (bindings: ExpressionT.bindings) =>
+  bindings->toExternalBindings->ExpressionValue.EvRecord->ExpressionValue.toString
+
+let externalBindingsToString = (externalBindings: externalBindings) =>
+  externalBindings->ExpressionValue.EvRecord->ExpressionValue.toString
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_ExpressionBuilder.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_ExpressionBuilder.res
@ -0,0 +1,66 @@
+module BBindings = Reducer_Expression_Bindings
+module BErrorValue = Reducer_ErrorValue
+module BExpressionT = Reducer_Expression_T
+module BExpressionValue = ReducerInterface.ExpressionValue
+
+type errorValue = BErrorValue.errorValue
+type expression = BExpressionT.expression
+type internalCode = ReducerInterface_ExpressionValue.internalCode
+
+external castExpressionToInternalCode: expression => internalCode = "%identity"
+
+let eArray = anArray => anArray->BExpressionValue.EvArray->BExpressionT.EValue
+
+let eArrayString = anArray => anArray->BExpressionValue.EvArrayString->BExpressionT.EValue
+
+let eBindings = (anArray: array<(string, BExpressionValue.expressionValue)>) =>
+  anArray->Js.Dict.fromArray->EvRecord->BExpressionT.EValue
+
+let eBool = aBool => aBool->BExpressionValue.EvBool->BExpressionT.EValue
+
+let eCall = (name: string): expression => name->BExpressionValue.EvCall->BExpressionT.EValue
+
+let eFunction = (fName: string, lispArgs: list<expression>): expression => {
+  let fn = fName->eCall
+  list{fn, ...lispArgs}->BExpressionT.EList
+}
+
+let eLambda = (
+  parameters: array<string>,
+  context: BExpressionValue.externalBindings,
+  expr: expression,
+) => {
+  // Js.log(`eLambda context ${BBindings.externalBindingsToString(context)}`)
+  BExpressionValue.EvLambda({
+    parameters: parameters,
+    context: context,
+    body: expr->castExpressionToInternalCode,
+  })->BExpressionT.EValue
+}
+
+let eNumber = aNumber => aNumber->BExpressionValue.EvNumber->BExpressionT.EValue
+
+let eRecord = aRecord => aRecord->BExpressionValue.EvRecord->BExpressionT.EValue
+
+let eString = aString => aString->BExpressionValue.EvString->BExpressionT.EValue
+
+let eSymbol = (name: string): expression => name->BExpressionValue.EvSymbol->BExpressionT.EValue
+
+let eList = (list: list<expression>): expression => list->BExpressionT.EList
+
+let eBlock = (exprs: list<expression>): expression => eFunction("$$block", exprs)
+
+let eLetStatement = (symbol: string, valueExpression: expression): expression =>
+  eFunction("$let", list{eSymbol(symbol), valueExpression})
+
+let eBindStatement = (bindingExpr: expression, letStatement: expression): expression =>
+  eFunction("$$bindStatement", list{bindingExpr, letStatement})
+
+let eBindStatementDefault = (letStatement: expression): expression =>
+  eFunction("$$bindStatement", list{letStatement})
+
+let eBindExpression = (bindingExpr: expression, expression: expression): expression =>
+  eFunction("$$bindExpression", list{bindingExpr, expression})
+
+let eBindExpressionDefault = (expression: expression): expression =>
+  eFunction("$$bindExpression", list{expression})
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res
@ -0,0 +1,60 @@
+module Bindings = Reducer_Expression_Bindings
+module ErrorValue = Reducer_ErrorValue
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Result = Belt.Result
+
+type environment = ReducerInterface_ExpressionValue.environment
+type expression = ExpressionT.expression
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type internalCode = ReducerInterface_ExpressionValue.internalCode
+
+external castInternalCodeToExpression: internalCode => expression = "%identity"
+
+let checkArity = (lambdaValue: ExpressionValue.lambdaValue, args: list<expressionValue>) => {
+  let argsLength = Belt.List.length(args)
+  let parametersLength = Js.Array2.length(lambdaValue.parameters)
+  if argsLength !== parametersLength {
+    ErrorValue.REArityError(None, parametersLength, argsLength)->Error
+  } else {
+    args->Ok
+  }
+}
+
+let checkIfReduced = (args: list<expressionValue>) =>
+  args->Belt.List.reduceReverse(Ok(list{}), (rAcc, arg) =>
+    rAcc->Result.flatMap(acc =>
+      switch arg {
+      | EvSymbol(symbol) => ErrorValue.RESymbolNotFound(symbol)->Error
+      | _ => list{arg, ...acc}->Ok
+      }
+    )
+  )
+
+let applyParametersToLambda = (
+  lambdaValue: ExpressionValue.lambdaValue,
+  args,
+  environment,
+  reducer: ExpressionT.reducerFn,
+): result<expressionValue, 'e> => {
+  checkArity(lambdaValue, args)->Result.flatMap(args =>
+    checkIfReduced(args)->Result.flatMap(args => {
+      let expr = castInternalCodeToExpression(lambdaValue.body)
+      let parameterList = lambdaValue.parameters->Belt.List.fromArray
+      let zippedParameterList = parameterList->Belt.List.zip(args)
+      let bindings = Belt.List.reduce(
+        zippedParameterList,
+        lambdaValue.context->Bindings.fromExternalBindings,
+        (acc, (variable, variableValue)) => acc->Belt.Map.String.set(variable, variableValue),
+      )
+      let newExpression = ExpressionBuilder.eBlock(list{expr})
+      reducer(newExpression, bindings, environment)
+    })
+  )
+}
+
+let doLambdaCall = (lambdaValue: ExpressionValue.lambdaValue, args, environment, reducer) => {
+  applyParametersToLambda(lambdaValue, args, environment, reducer)
+}
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Macro.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Macro.res
@ -0,0 +1,44 @@
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module ExpressionWithContext = Reducer_ExpressionWithContext
+module Result = Belt.Result
+
+type environment = ExpressionValue.environment
+type expression = ExpressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+type expressionWithContext = ExpressionWithContext.expressionWithContext
+
+let expandMacroCall = (
+  macroExpression: expression,
+  bindings: ExpressionT.bindings,
+  environment: environment,
+  reduceExpression: ExpressionT.reducerFn,
+): result<expressionWithContext, 'e> =>
+  Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(
+    macroExpression,
+    bindings,
+    environment,
+    reduceExpression,
+  )
+
+let doMacroCall = (
+  macroExpression: expression,
+  bindings: ExpressionT.bindings,
+  environment: environment,
+  reduceExpression: ExpressionT.reducerFn,
+): result<expressionValue, 'e> =>
+  expandMacroCall(
+    macroExpression,
+    bindings,
+    environment,
+    reduceExpression,
+  )->Result.flatMap(expressionWithContext =>
+    ExpressionWithContext.callReducer(
+      expressionWithContext,
+      bindings,
+      environment,
+      reduceExpression,
+    )
+  )
+
+let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res
@ -1,5 +1,3 @@
-open ReducerInterface.ExpressionValue
-
 /*
  An expression is a Lisp AST. An expression is either a primitive value or a list of expressions.
  In the case of a list of expressions (e1, e2, e3, ...eN), the semantic is
@ -8,8 +6,51 @@ open ReducerInterface.ExpressionValue
  A Lisp AST contains only expressions/primitive values to apply to their left.
  The act of defining the semantics of a functional language is to write it in terms of Lisp AST.
 */
+module Extra = Reducer_Extra
+module ExpressionValue = ReducerInterface.ExpressionValue
+
+type expressionValue = ExpressionValue.expressionValue
+type environment = ExpressionValue.environment
+
 type rec expression =
  | EList(list<expression>) // A list to map-reduce
  | EValue(expressionValue) // Irreducible built-in value. Reducer should not know the internals. External libraries are responsible
-  | EBindings(bindings) // let/def kind of statements return bindings
-and bindings = Belt.Map.String.t<expression>
+and bindings = Belt.Map.String.t<expressionValue>
+
+type reducerFn = (
+  expression,
+  bindings,
+  environment,
+) => result<expressionValue, Reducer_ErrorValue.errorValue>
+
+/*
+  Converts the expression to String
+*/
+let rec toString = expression =>
+  switch expression {
+  | EList(aList) =>
+    `(${Belt.List.map(aList, aValue => toString(aValue))
+      ->Extra.List.interperse(" ")
+      ->Belt.List.toArray
+      ->Js.String.concatMany("")})`
+  | EValue(aValue) => ExpressionValue.toString(aValue)
+  }
+
+let toStringResult = codeResult =>
+  switch codeResult {
+  | Ok(a) => `Ok(${toString(a)})`
+  | Error(m) => `Error(${Reducer_ErrorValue.errorToString(m)})`
+  }
+
+let inspect = (expr: expression): expression => {
+  Js.log(toString(expr))
+  expr
+}
+
+let inspectResult = (r: result<expression, Reducer_ErrorValue.errorValue>): result<
+  expression,
+  Reducer_ErrorValue.errorValue,
+> => {
+  Js.log(toStringResult(r))
+  r
+}
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Js/Reducer_Js_Gate.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Js/Reducer_Js_Gate.res
@ -8,11 +8,10 @@ external castString: unit => string = "%identity"
 /*
  As JavaScript returns us any type, we need to type check and cast type propertype before using it
 */
-let jsToEv = (jsValue): result<expressionValue, errorValue> => {
+let jsToEv = (jsValue): result<expressionValue, errorValue> =>
  switch Js.typeof(jsValue) {
  | "boolean" => jsValue->castBool->EvBool->Ok
  | "number" => jsValue->castNumber->EvNumber->Ok
  | "string" => jsValue->castString->EvString->Ok
  | other => RETodo(`Unhandled MathJs literal type: ${Js.String.make(other)}`)->Error
  }
-}
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_MathJs/Reducer_MathJs_Parse.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_MathJs/Reducer_MathJs_Parse.res
@ -11,11 +11,10 @@ type block = {"node": node}
 type blockNode = {...node, "blocks": array<block>}
 //conditionalNode
 type constantNode = {...node, "value": unit}
-//functionAssignmentNode
+type functionAssignmentNode = {...node, "name": string, "params": array<string>, "expr": node}
 type indexNode = {...node, "dimensions": array<node>}
 type objectNode = {...node, "properties": Js.Dict.t<node>}
 type accessorNode = {...node, "object": node, "index": indexNode, "name": string}
-
 type parenthesisNode = {...node, "content": node}
 //rangeNode
 //relationalNode
@ -33,6 +32,7 @@ external castAssignmentNodeWAccessor: node => assignmentNodeWAccessor = "%identi
 external castAssignmentNodeWIndex: node => assignmentNodeWIndex = "%identity"
 external castBlockNode: node => blockNode = "%identity"
 external castConstantNode: node => constantNode = "%identity"
+external castFunctionAssignmentNode: node => functionAssignmentNode = "%identity"
 external castFunctionNode: node => functionNode = "%identity"
 external castIndexNode: node => indexNode = "%identity"
 external castObjectNode: node => objectNode = "%identity"
@ -59,6 +59,7 @@ type mathJsNode =
  | MjAssignmentNode(assignmentNode)
  | MjBlockNode(blockNode)
  | MjConstantNode(constantNode)
+  | MjFunctionAssignmentNode(functionAssignmentNode)
  | MjFunctionNode(functionNode)
  | MjIndexNode(indexNode)
  | MjObjectNode(objectNode)
@ -82,6 +83,7 @@ let castNodeType = (node: node) => {
  | "AssignmentNode" => node->decideAssignmentNode
  | "BlockNode" => node->castBlockNode->MjBlockNode->Ok
  | "ConstantNode" => node->castConstantNode->MjConstantNode->Ok
+  | "FunctionAssignmentNode" => node->castFunctionAssignmentNode->MjFunctionAssignmentNode->Ok
  | "FunctionNode" => node->castFunctionNode->MjFunctionNode->Ok
  | "IndexNode" => node->castIndexNode->MjIndexNode->Ok
  | "ObjectNode" => node->castObjectNode->MjObjectNode->Ok
@ -118,6 +120,10 @@ let rec toString = (mathJsNode: mathJsNode): string => {
    ->Extra.Array.interperse(", ")
    ->Js.String.concatMany("")

+  let toStringFunctionAssignmentNode = (faNode: functionAssignmentNode): string => {
+    let paramNames = Js.Array2.toString(faNode["params"])
+    `${faNode["name"]} = (${paramNames}) => ${toStringMathJsNode(faNode["expr"])}`
+  }
  let toStringFunctionNode = (fnode: functionNode): string =>
    `${fnode->nameOfFunctionNode}(${fnode["args"]->toStringNodeArray})`

@ -152,6 +158,7 @@ let rec toString = (mathJsNode: mathJsNode): string => {
    `${aNode["object"]->toStringSymbolNode} = ${aNode["value"]->toStringMathJsNode}`
  | MjBlockNode(bNode) => `{${bNode["blocks"]->toStringBlocks}}`
  | MjConstantNode(cNode) => cNode["value"]->toStringValue
+  | MjFunctionAssignmentNode(faNode) => faNode->toStringFunctionAssignmentNode
  | MjFunctionNode(fNode) => fNode->toStringFunctionNode
  | MjIndexNode(iNode) => iNode->toStringIndexNode
  | MjObjectNode(oNode) => oNode->toStringObjectNode
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_MathJs/Reducer_MathJs_ToExpression.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_MathJs/Reducer_MathJs_ToExpression.res
@ -1,45 +1,35 @@
+/* * WARNING. DO NOT EDIT, BEAUTIFY, COMMENT ON OR REFACTOR THIS CODE. 
+We will stop using MathJs parser and
+this whole file will go to trash
+**/
 module ErrorValue = Reducer_ErrorValue
-module ExpressionValue = ReducerInterface.ExpressionValue
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
 module JavaScript = Reducer_Js
 module Parse = Reducer_MathJs_Parse
 module Result = Belt.Result

+type errorValue = ErrorValue.errorValue
 type expression = ExpressionT.expression
 type expressionValue = ExpressionValue.expressionValue
-type errorValue = ErrorValue.errorValue

-let passToFunction = (fName: string, rLispArgs): result<expression, errorValue> => {
-  let toEvCallValue = (name: string): expression => name->ExpressionValue.EvCall->ExpressionT.EValue
+let blockToNode = block => block["node"]

-  let fn = fName->toEvCallValue
-  rLispArgs->Result.flatMap(lispArgs => list{fn, ...lispArgs}->ExpressionT.EList->Ok)
-}
-
-type blockTag =
-  | ImportVariablesStatement
-  | ExportVariablesExpression
-type tagOrNode =
-  | BlockTag(blockTag)
-  | BlockNode(Parse.node)
-
-let toTagOrNode = block => BlockNode(block["node"])
-
-let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
+let rec fromInnerNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
  Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
    let fromNodeList = (nodeList: list<Parse.node>): result<list<expression>, 'e> =>
      Belt.List.reduceReverse(nodeList, Ok(list{}), (racc, currNode) =>
        racc->Result.flatMap(acc =>
-          fromNode(currNode)->Result.map(currCode => list{currCode, ...acc})
+          fromInnerNode(currNode)->Result.map(currCode => list{currCode, ...acc})
        )
      )

-    let toEvSymbolValue = (name: string): expression =>
-      name->ExpressionValue.EvSymbol->ExpressionT.EValue
-
    let caseFunctionNode = fNode => {
-      let lispArgs = fNode["args"]->Belt.List.fromArray->fromNodeList
-      passToFunction(fNode->Parse.nameOfFunctionNode, lispArgs)
+      let rLispArgs = fNode["args"]->Belt.List.fromArray->fromNodeList
+      rLispArgs->Result.map(lispArgs =>
+        ExpressionBuilder.eFunction(fNode->Parse.nameOfFunctionNode, lispArgs)
+      )
    }

    let caseObjectNode = oNode => {
@ -49,19 +39,16 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
          (key: string, value: Parse.node),
        ) =>
          racc->Result.flatMap(acc =>
-            fromNode(value)->Result.map(valueExpression => {
+            fromInnerNode(value)->Result.map(valueExpression => {
              let entryCode =
-                list{
-                  key->ExpressionValue.EvString->ExpressionT.EValue,
-                  valueExpression,
-                }->ExpressionT.EList
+                list{ExpressionBuilder.eString(key), valueExpression}->ExpressionT.EList
              list{entryCode, ...acc}
            })
          )
        )
        rargs->Result.flatMap(args =>
-          passToFunction("$constructRecord", list{ExpressionT.EList(args)}->Ok)
-        ) // $consturctRecord gets a single argument: List of key-value paiers
+          ExpressionBuilder.eFunction("$constructRecord", list{ExpressionT.EList(args)})->Ok
+        ) // $constructRecord gets a single argument: List of key-value paiers
      }

      oNode["properties"]->Js.Dict.entries->Belt.List.fromArray->fromObjectEntries
@ -73,7 +60,7 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
        Ok(list{}),
        (racc, currentPropertyMathJsNode) =>
          racc->Result.flatMap(acc =>
-            fromNode(currentPropertyMathJsNode)->Result.map(propertyCode => list{
+            fromInnerNode(currentPropertyMathJsNode)->Result.map(propertyCode => list{
              propertyCode,
              ...acc,
            })
@ -84,18 +71,41 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>

    let caseAccessorNode = (objectNode, indexNode) => {
      caseIndexNode(indexNode)->Result.flatMap(indexCode => {
-        fromNode(objectNode)->Result.flatMap(objectCode =>
-          passToFunction("$atIndex", list{objectCode, indexCode}->Ok)
+        fromInnerNode(objectNode)->Result.flatMap(objectCode =>
+          ExpressionBuilder.eFunction("$atIndex", list{objectCode, indexCode})->Ok
        )
      })
    }

+    let caseBlock = (nodesArray: array<Parse.node>): result<expression, errorValue> => {
+      let rStatements: result<list<expression>, 'a> =
+        nodesArray
+        ->Belt.List.fromArray
+        ->Belt.List.reduceReverse(Ok(list{}), (racc, currNode) =>
+          racc->Result.flatMap(acc =>
+            fromInnerNode(currNode)->Result.map(currCode => list{currCode, ...acc})
+          )
+        )
+      rStatements->Result.map(statements => ExpressionBuilder.eBlock(statements))
+    }
+
    let caseAssignmentNode = aNode => {
-      let symbol = aNode["object"]["name"]->toEvSymbolValue
-      let rValueExpression = fromNode(aNode["value"])
+      let symbolName = aNode["object"]["name"]
+      let rValueExpression = fromInnerNode(aNode["value"])
+      rValueExpression->Result.map(valueExpression =>
+        ExpressionBuilder.eLetStatement(symbolName, valueExpression)
+      )
+    }
+
+    let caseFunctionAssignmentNode = faNode => {
+      let symbol = faNode["name"]->ExpressionBuilder.eSymbol
+      let rValueExpression = fromInnerNode(faNode["expr"])
+
      rValueExpression->Result.flatMap(valueExpression => {
-        let lispArgs = list{symbol, valueExpression}->Ok
-        passToFunction("$let", lispArgs)
+        let lispParams = ExpressionBuilder.eArrayString(faNode["params"])
+        let valueBlock = ExpressionBuilder.eBlock(list{valueExpression})
+        let lambda = ExpressionBuilder.eFunction("$$lambda", list{lispParams, valueBlock})
+        ExpressionBuilder.eFunction("$let", list{symbol, lambda})->Ok
      })
    }

@ -108,88 +118,22 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
    | MjArrayNode(aNode) => caseArrayNode(aNode)
    | MjAssignmentNode(aNode) => caseAssignmentNode(aNode)
    | MjSymbolNode(sNode) => {
-        let expr: expression = toEvSymbolValue(sNode["name"])
+        let expr: expression = ExpressionBuilder.eSymbol(sNode["name"])
        let rExpr: result<expression, errorValue> = expr->Ok
        rExpr
      }
-    | MjBlockNode(bNode) => bNode["blocks"]->Belt.Array.map(toTagOrNode)->caseTagOrNodes
+    | MjBlockNode(bNode) => bNode["blocks"]->Js.Array2.map(blockToNode)->caseBlock
    | MjConstantNode(cNode) =>
      cNode["value"]->JavaScript.Gate.jsToEv->Result.flatMap(v => v->ExpressionT.EValue->Ok)
+    | MjFunctionAssignmentNode(faNode) => caseFunctionAssignmentNode(faNode)
    | MjFunctionNode(fNode) => fNode->caseFunctionNode
    | MjIndexNode(iNode) => caseIndexNode(iNode)
    | MjObjectNode(oNode) => caseObjectNode(oNode)
    | MjOperatorNode(opNode) => opNode->Parse.castOperatorNodeToFunctionNode->caseFunctionNode
-    | MjParenthesisNode(pNode) => pNode["content"]->fromNode
+    | MjParenthesisNode(pNode) => pNode["content"]->fromInnerNode
    }
    rFinalExpression
  })
-and caseTagOrNodes = (tagOrNodes): result<expression, errorValue> => {
-  let initialBindings = passToFunction("$$bindings", list{}->Ok)
-  let lastIndex = Belt.Array.length(tagOrNodes) - 1
-  tagOrNodes->Belt.Array.reduceWithIndex(initialBindings, (rPreviousBindings, tagOrNode, i) => {
-    rPreviousBindings->Result.flatMap(previousBindings => {
-      let rStatement: result<expression, errorValue> = switch tagOrNode {
-      | BlockNode(node) => fromNode(node)
-      | BlockTag(tag) =>
-        switch tag {
-        | ImportVariablesStatement => passToFunction("$importVariablesStatement", list{}->Ok)
-        | ExportVariablesExpression => passToFunction("$exportVariablesExpression", list{}->Ok)
-        }
-      }

-      let bindName = if i == lastIndex {
-        "$$bindExpression"
-      } else {
-        "$$bindStatement"
-      }
-
-      rStatement->Result.flatMap((statement: expression) => {
-        let lispArgs = list{previousBindings, statement}->Ok
-        passToFunction(bindName, lispArgs)
-      })
-    })
-  })
-}
-
-let fromPartialNode = (mathJsNode: Parse.node): result<expression, errorValue> => {
-  Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
-    let casePartialBlockNode = (bNode: Parse.blockNode) => {
-      let blocksOrTags = bNode["blocks"]->Belt.Array.map(toTagOrNode)
-      let completed = Js.Array2.concat(blocksOrTags, [BlockTag(ExportVariablesExpression)])
-      completed->caseTagOrNodes
-    }
-
-    let casePartialExpression = (node: Parse.node) => {
-      let completed = [BlockNode(node), BlockTag(ExportVariablesExpression)]
-
-      completed->caseTagOrNodes
-    }
-
-    let rFinalExpression: result<expression, errorValue> = switch typedMathJsNode {
-    | MjBlockNode(bNode) => casePartialBlockNode(bNode)
-    | _ => casePartialExpression(mathJsNode)
-    }
-    rFinalExpression
-  })
-}
-
-let fromOuterNode = (mathJsNode: Parse.node): result<expression, errorValue> => {
-  Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
-    let casePartialBlockNode = (bNode: Parse.blockNode) => {
-      let blocksOrTags = bNode["blocks"]->Belt.Array.map(toTagOrNode)
-      let completed = blocksOrTags
-      completed->caseTagOrNodes
-    }
-
-    let casePartialExpression = (node: Parse.node) => {
-      let completed = [BlockNode(node)]
-      completed->caseTagOrNodes
-    }
-
-    let rFinalExpression: result<expression, errorValue> = switch typedMathJsNode {
-    | MjBlockNode(bNode) => casePartialBlockNode(bNode)
-    | _ => casePartialExpression(mathJsNode)
-    }
-    rFinalExpression
-  })
-}
+let fromNode = (node: Parse.node): result<expression, errorValue> =>
+  fromInnerNode(node)->Result.map(expr => ExpressionBuilder.eBlock(list{expr}))
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res
@ -5,37 +5,50 @@
 module Extra_Array = Reducer_Extra_Array
 module ErrorValue = Reducer_ErrorValue

+@genType.opaque
+type internalCode = Object
+
@genType
 type rec expressionValue =
  | EvArray(array<expressionValue>)
+  | EvArrayString(array<string>)
  | EvBool(bool)
  | EvCall(string) // External function call
  | EvDistribution(DistributionTypes.genericDist)
+  | EvLambda(lambdaValue)
  | EvNumber(float)
-  | EvRecord(Js.Dict.t<expressionValue>)
+  | EvRecord(record)
  | EvString(string)
  | EvSymbol(string)
+and record = Js.Dict.t<expressionValue>
+and externalBindings = record
+and lambdaValue = {
+  parameters: array<string>,
+  context: externalBindings,
+  body: internalCode,
+}

@genType
-type externalBindings = Js.Dict.t<expressionValue>
+let defaultExternalBindings: externalBindings = Js.Dict.empty()

 type functionCall = (string, array<expressionValue>)

 let rec toString = aValue =>
  switch aValue {
+  | EvArray(anArray) => {
+      let args = anArray->Js.Array2.map(each => toString(each))->Js.Array2.toString
+      `[${args}]`
+    }
+  | EvArrayString(anArray) => {
+      let args = anArray->Js.Array2.toString
+      `[${args}]`
+    }
  | EvBool(aBool) => Js.String.make(aBool)
  | EvCall(fName) => `:${fName}`
+  | EvLambda(lambdaValue) => `lambda(${Js.Array2.toString(lambdaValue.parameters)}=>internal code)`
  | EvNumber(aNumber) => Js.String.make(aNumber)
  | EvString(aString) => `'${aString}'`
  | EvSymbol(aString) => `:${aString}`
-  | EvArray(anArray) => {
-      let args =
-        anArray
-        ->Belt.Array.map(each => toString(each))
-        ->Extra_Array.interperse(", ")
-        ->Js.String.concatMany("")
-      `[${args}]`
-    }
  | EvRecord(aRecord) => aRecord->toStringRecord
  | EvDistribution(dist) => GenericDist.toString(dist)
  }
@ -43,26 +56,27 @@ and toStringRecord = aRecord => {
  let pairs =
    aRecord
    ->Js.Dict.entries
-    ->Belt.Array.map(((eachKey, eachValue)) => `${eachKey}: ${toString(eachValue)}`)
-    ->Extra_Array.interperse(", ")
-    ->Js.String.concatMany("")
+    ->Js.Array2.map(((eachKey, eachValue)) => `${eachKey}: ${toString(eachValue)}`)
+    ->Js.Array2.toString
  `{${pairs}}`
 }

 let toStringWithType = aValue =>
  switch aValue {
+  | EvArray(_) => `Array::${toString(aValue)}`
+  | EvArrayString(_) => `ArrayString::${toString(aValue)}`
  | EvBool(_) => `Bool::${toString(aValue)}`
  | EvCall(_) => `Call::${toString(aValue)}`
+  | EvDistribution(_) => `Distribution::${toString(aValue)}`
+  | EvLambda(_) => `Lambda::${toString(aValue)}`
  | EvNumber(_) => `Number::${toString(aValue)}`
+  | EvRecord(_) => `Record::${toString(aValue)}`
  | EvString(_) => `String::${toString(aValue)}`
  | EvSymbol(_) => `Symbol::${toString(aValue)}`
-  | EvArray(_) => `Array::${toString(aValue)}`
-  | EvRecord(_) => `Record::${toString(aValue)}`
-  | EvDistribution(_) => `Distribution::${toString(aValue)}`
  }

 let argsToString = (args: array<expressionValue>): string => {
-  args->Belt.Array.map(arg => arg->toString)->Extra_Array.interperse(", ")->Js.String.concatMany("")
+  args->Js.Array2.map(arg => arg->toString)->Js.Array2.toString
 }

 let toStringFunctionCall = ((fn, args)): string => `${fn}(${argsToString(args)})`
@ -78,3 +92,9 @@ let toStringResultRecord = x =>
  | Ok(a) => `Ok(${toStringRecord(a)})`
  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
  }
+
+@genType
+type environment = DistributionOperation.env
+
+@genType
+let defaultEnvironment: environment = DistributionOperation.defaultEnv
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res
@ -14,8 +14,13 @@ type expressionValue = ExpressionValue.expressionValue
  Map external calls of Reducer
 */

-let dispatch = (call: ExpressionValue.functionCall, chain): result<expressionValue, 'e> =>
-  ReducerInterface_GenericDistribution.dispatch(call) |> E.O.default(chain(call))
+let dispatch = (call: ExpressionValue.functionCall, environment, chain): result<
+  expressionValue,
+  'e,
+> =>
+  ReducerInterface_GenericDistribution.dispatch(call, environment) |> E.O.default(
+    chain(call, environment),
+  )
 /*
 If your dispatch is too big you can divide it into smaller dispatches and pass the call so that it gets called finally.

--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res
@ -1,12 +1,12 @@
 module ExpressionValue = ReducerInterface_ExpressionValue
 type expressionValue = ReducerInterface_ExpressionValue.expressionValue

-let runGenericOperation = DistributionOperation.run(
-  ~env={
+let defaultEnv: DistributionOperation.env = {
  sampleCount: MagicNumbers.Environment.defaultSampleCount,
  xyPointLength: MagicNumbers.Environment.defaultXYPointLength,
-  },
-)
+}
+
+let runGenericOperation = DistributionOperation.run(~env=defaultEnv)

 module Helpers = {
  let arithmeticMap = r =>
@ -28,14 +28,13 @@ module Helpers = {
  let catchAndConvertTwoArgsToDists = (args: array<expressionValue>): option<(
    DistributionTypes.genericDist,
    DistributionTypes.genericDist,
-  )> => {
+  )> =>
    switch args {
    | [EvDistribution(a), EvDistribution(b)] => Some((a, b))
    | [EvNumber(a), EvDistribution(b)] => Some((GenericDist.fromFloat(a), b))
    | [EvDistribution(a), EvNumber(b)] => Some((a, GenericDist.fromFloat(b)))
    | _ => None
    }
-  }

  let toFloatFn = (
    fnCall: DistributionTypes.DistributionOperation.toFloat,
@ -119,7 +118,7 @@ module Helpers = {
    mixtureWithGivenWeights(distributions, weights)
  }

-  let mixture = (args: array<expressionValue>): DistributionOperation.outputType => {
+  let mixture = (args: array<expressionValue>): DistributionOperation.outputType =>
    switch E.A.last(args) {
    | Some(EvArray(b)) => {
        let weights = parseNumberArray(b)
@ -140,7 +139,6 @@ module Helpers = {
    | _ => GenDistError(ArgumentError("Last argument of mx must be array or distribution"))
    }
 }
-}

 module SymbolicConstructors = {
  let oneFloat = name =>
@ -175,7 +173,7 @@ module SymbolicConstructors = {
    }
 }

-let dispatchToGenericOutput = (call: ExpressionValue.functionCall): option<
+let dispatchToGenericOutput = (call: ExpressionValue.functionCall, _environment): option<
  DistributionOperation.outputType,
 > => {
  let (fnName, args) = call
@ -296,6 +294,6 @@ let genericOutputToReducerValue = (o: DistributionOperation.outputType): result<
  | GenDistError(err) => Error(REDistributionError(err))
  }

-let dispatch = call => {
-  dispatchToGenericOutput(call)->E.O2.fmap(genericOutputToReducerValue)
+let dispatch = (call, environment) => {
+  dispatchToGenericOutput(call, environment)->E.O2.fmap(genericOutputToReducerValue)
 }
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.resi
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.resi
@ -1,3 +1,5 @@
-let dispatch: ReducerInterface_ExpressionValue.functionCall => option<
-  result<ReducerInterface_ExpressionValue.expressionValue, Reducer_ErrorValue.errorValue>,
->
+let defaultEnv: DistributionOperation.env
+let dispatch: (
+  ReducerInterface_ExpressionValue.functionCall,
+  ReducerInterface_ExpressionValue.environment,
+) => option<result<ReducerInterface_ExpressionValue.expressionValue, Reducer_ErrorValue.errorValue>>
--- a/packages/squiggle-lang/src/rescript/TypescriptInterface.res
+++ b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
@ -38,7 +38,7 @@ let makeSampleSetDist = SampleSetDist.make
 let evaluate = Reducer.evaluate

@genType
-let evaluateUsingExternalBindings = Reducer.evaluateUsingExternalBindings
+let evaluateUsingOptions = Reducer.evaluateUsingOptions

@genType
 let evaluatePartialUsingExternalBindings = Reducer.evaluatePartialUsingExternalBindings
@ -49,6 +49,9 @@ type externalBindings = Reducer.externalBindings
@genType
 type expressionValue = ReducerInterface_ExpressionValue.expressionValue

+@genType
+type recordEV = ReducerInterface_ExpressionValue.record
+
@genType
 type errorValue = Reducer_ErrorValue.errorValue

@ -69,3 +72,15 @@ let errorValueToString = Reducer_ErrorValue.errorToString

@genType
 let distributionErrorToString = DistributionTypes.Error.toString
+
+@genType
+type lambdaValue = ReducerInterface_ExpressionValue.lambdaValue
+
+@genType
+let defaultSamplingEnv = ReducerInterface_GenericDistribution.defaultEnv
+
+@genType
+type environment = ReducerInterface_ExpressionValue.environment
+
+@genType
+let defaultEnvironment = ReducerInterface_ExpressionValue.defaultEnvironment
--- a/yarn.lock
+++ b/yarn.lock
@ -4025,6 +4025,11 @@
    jest-matcher-utils "^27.0.0"
    pretty-format "^27.0.0"

+"@types/js-cookie@^2.2.6":
+  version "2.2.7"
+  resolved "https://registry.yarnpkg.com/@types/js-cookie/-/js-cookie-2.2.7.tgz#226a9e31680835a6188e887f3988e60c04d3f6a3"
+  integrity sha512-aLkWa0C0vO5b4Sr798E26QgOkss68Un0bLjs7u9qxzPT5CG+8DuNTffWES58YzJs3hrVAOs1wonycqEBqNJubA==
+
 "@types/json-schema@*", "@types/json-schema@^7.0.4", "@types/json-schema@^7.0.5", "@types/json-schema@^7.0.8", "@types/json-schema@^7.0.9":
  version "7.0.11"
  resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.11.tgz#d421b6c527a3037f7c84433fd2c4229e016863d3"
@ -4070,10 +4075,10 @@
    "@types/node" "*"
    form-data "^3.0.0"

-"@types/node@*", "@types/node@^17.0.29", "@types/node@^17.0.5":
-  version "17.0.30"
-  resolved "https://registry.yarnpkg.com/@types/node/-/node-17.0.30.tgz#2c6e8512acac70815e8176aa30c38025067880ef"
-  integrity sha512-oNBIZjIqyHYP8VCNAV9uEytXVeXG2oR0w9lgAXro20eugRQfY002qr3CUl6BAe+Yf/z3CRjPdz27Pu6WWtuSRw==
+"@types/node@*", "@types/node@^17.0.31", "@types/node@^17.0.5":
+  version "17.0.31"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-17.0.31.tgz#a5bb84ecfa27eec5e1c802c6bbf8139bdb163a5d"
+  integrity sha512-AR0x5HbXGqkEx9CadRH3EBYx/VkiUgZIhP4wvPn/+5KIsgpNoyFaRlVe0Zlx9gRtg8fA06a9tskE2MSN7TcG4Q==

 "@types/node@^14.0.10":
  version "14.18.16"
@ -4721,6 +4726,11 @@
  resolved "https://registry.yarnpkg.com/@webpack-cli/serve/-/serve-1.6.1.tgz#0de2875ac31b46b6c5bb1ae0a7d7f0ba5678dffe"
  integrity sha512-gNGTiTrjEVQ0OcVnzsRSqTxaBSr+dmTfm+qJsCDluky8uhdLWep7Gcr62QsAKHTMxjCS/8nEITsmFAhfIx+QSw==

+"@xobotyi/scrollbar-width@^1.9.5":
+  version "1.9.5"
+  resolved "https://registry.yarnpkg.com/@xobotyi/scrollbar-width/-/scrollbar-width-1.9.5.tgz#80224a6919272f405b87913ca13b92929bdf3c4d"
+  integrity sha512-N8tkAACJx2ww8vFMneJmaAgmjAG1tnVBZJRLRcx061tmsLRZHSEZSLuGWnwPtunsSLvSqXQ2wfp7Mgqg1I+2dQ==
+
 "@xtuc/ieee754@^1.2.0":
  version "1.2.0"
  resolved "https://registry.yarnpkg.com/@xtuc/ieee754/-/ieee754-1.2.0.tgz#eef014a3145ae477a1cbc00cd1e552336dceb790"
@ -6991,6 +7001,14 @@ css-has-pseudo@^3.0.4:
  dependencies:
    postcss-selector-parser "^6.0.9"

+css-in-js-utils@^2.0.0:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/css-in-js-utils/-/css-in-js-utils-2.0.1.tgz#3b472b398787291b47cfe3e44fecfdd9e914ba99"
+  integrity sha512-PJF0SpJT+WdbVVt0AOYp9C8GnuruRlL/UFW7932nLWmFLQTaWEzTBQEx7/hn4BuV+WON75iAViSUJLiU3PKbpA==
+  dependencies:
+    hyphenate-style-name "^1.0.2"
+    isobject "^3.0.1"
+
 css-loader@^3.6.0:
  version "3.6.0"
  resolved "https://registry.yarnpkg.com/css-loader/-/css-loader-3.6.0.tgz#2e4b2c7e6e2d27f8c8f28f61bffcd2e6c91ef645"
@ -7247,7 +7265,7 @@ csstype@^2.5.7:
  resolved "https://registry.yarnpkg.com/csstype/-/csstype-2.6.20.tgz#9229c65ea0b260cf4d3d997cb06288e36a8d6dda"
  integrity sha512-/WwNkdXfckNgw6S5R125rrW8ez139lBHWouiBvX8dfMFtcn6V81REDqnH7+CRpRipfYlyU1CmOnOxrmGcFOjeA==

-csstype@^3.0.2:
+csstype@^3.0.2, csstype@^3.0.6:
  version "3.0.11"
  resolved "https://registry.yarnpkg.com/csstype/-/csstype-3.0.11.tgz#d66700c5eacfac1940deb4e3ee5642792d85cd33"
  integrity sha512-sa6P2wJ+CAbgyy4KFssIb/JNMLxFvKF1pCYCSXS8ZMuqZnMsrxqI2E5sPyoTpxoPU/gVZMzr2zjOfg8GIZOMsw==
@ -8662,6 +8680,11 @@ fast-levenshtein@^2.0.6, fast-levenshtein@~2.0.6:
  resolved "https://registry.yarnpkg.com/fast-levenshtein/-/fast-levenshtein-2.0.6.tgz#3d8a5c66883a16a30ca8643e851f19baa7797917"
  integrity sha1-PYpcZog6FqMMqGQ+hR8Zuqd5eRc=

+fast-shallow-equal@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/fast-shallow-equal/-/fast-shallow-equal-1.0.0.tgz#d4dcaf6472440dcefa6f88b98e3251e27f25628b"
+  integrity sha512-HPtaa38cPgWvaCFmRNhlc6NG7pv6NUHqjPgVAkWGoB9mQMwYB27/K0CvOM5Czy+qpT3e8XJ6Q4aPAnzpNpzNaw==
+
 fast-url-parser@1.1.3, fast-url-parser@^1.1.3:
  version "1.1.3"
  resolved "https://registry.yarnpkg.com/fast-url-parser/-/fast-url-parser-1.1.3.tgz#f4af3ea9f34d8a271cf58ad2b3759f431f0b318d"
@ -8674,6 +8697,11 @@ fastest-levenshtein@^1.0.12:
  resolved "https://registry.yarnpkg.com/fastest-levenshtein/-/fastest-levenshtein-1.0.12.tgz#9990f7d3a88cc5a9ffd1f1745745251700d497e2"
  integrity sha512-On2N+BpYJ15xIC974QNVuYGMOlEVt4s0EOI3wwMqOmK1fdDY+FN/zltPV8vosq4ad4c/gJ1KHScUn/6AWIgiow==

+fastest-stable-stringify@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/fastest-stable-stringify/-/fastest-stable-stringify-2.0.2.tgz#3757a6774f6ec8de40c4e86ec28ea02417214c76"
+  integrity sha512-bijHueCGd0LqqNK9b5oCMHc0MluJAx0cwqASgbWMvkO01lCYgIhacVRLcaDz3QnyYIRNJRDwMb41VuT6pHJ91Q==
+
 fastq@^1.6.0:
  version "1.13.0"
  resolved "https://registry.yarnpkg.com/fastq/-/fastq-1.13.0.tgz#616760f88a7526bdfc596b7cab8c18938c36b98c"
@ -9881,6 +9909,11 @@ human-signals@^2.1.0:
  resolved "https://registry.yarnpkg.com/human-signals/-/human-signals-2.1.0.tgz#dc91fcba42e4d06e4abaed33b3e7a3c02f514ea0"
  integrity sha512-B4FFZ6q/T2jhhksgkbEW3HBvWIfDW85snkQgawt07S7J5QXTk6BkNV+0yAeZrM5QpMAdYlocGoljn0sJ/WQkFw==

+hyphenate-style-name@^1.0.2:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/hyphenate-style-name/-/hyphenate-style-name-1.0.4.tgz#691879af8e220aea5750e8827db4ef62a54e361d"
+  integrity sha512-ygGZLjmXfPHj+ZWh6LwbC37l43MhfztxetbFCoYTM2VjkIUpeHgSNn7QIyVFj7YQ1Wl9Cbw5sholVJPzWvC2MQ==
+
 iconv-lite@0.4.24:
  version "0.4.24"
  resolved "https://registry.yarnpkg.com/iconv-lite/-/iconv-lite-0.4.24.tgz#2022b4b25fbddc21d2f524974a474aafe733908b"
@ -10037,6 +10070,13 @@ inline-style-parser@0.1.1:
  resolved "https://registry.yarnpkg.com/inline-style-parser/-/inline-style-parser-0.1.1.tgz#ec8a3b429274e9c0a1f1c4ffa9453a7fef72cea1"
  integrity sha512-7NXolsK4CAS5+xvdj5OMMbI962hU/wvwoxk+LWR9Ek9bVtyuuYScDN6eS0rUm6TxApFpw7CX1o4uJzcd4AyD3Q==

+inline-style-prefixer@^6.0.0:
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/inline-style-prefixer/-/inline-style-prefixer-6.0.1.tgz#c5c0e43ba8831707afc5f5bbfd97edf45c1fa7ae"
+  integrity sha512-AsqazZ8KcRzJ9YPN1wMH2aNM7lkWQ8tSPrW5uDk1ziYwiAPWSZnUsC7lfZq+BDqLqz0B4Pho5wscWcJzVvRzDQ==
+  dependencies:
+    css-in-js-utils "^2.0.0"
+
 internal-slot@^1.0.3:
  version "1.0.3"
  resolved "https://registry.yarnpkg.com/internal-slot/-/internal-slot-1.0.3.tgz#7347e307deeea2faac2ac6205d4bc7d34967f59c"
@ -11163,6 +11203,11 @@ joi@^17.6.0:
    "@sideway/formula" "^3.0.0"
    "@sideway/pinpoint" "^2.0.0"

+js-cookie@^2.2.1:
+  version "2.2.1"
+  resolved "https://registry.yarnpkg.com/js-cookie/-/js-cookie-2.2.1.tgz#69e106dc5d5806894562902aa5baec3744e9b2b8"
+  integrity sha512-HvdH2LzI/EAZcUwA8+0nKNtWHqS+ZmijLA30RwZA0bo7ToCckjK5MkGhjED9KoRcXO6BaGI3I9UIzSA1FKFPOQ==
+
 js-string-escape@^1.0.1:
  version "1.0.1"
  resolved "https://registry.yarnpkg.com/js-string-escape/-/js-string-escape-1.0.1.tgz#e2625badbc0d67c7533e9edc1068c587ae4137ef"
@ -12183,6 +12228,20 @@ nan@^2.12.1:
  resolved "https://registry.yarnpkg.com/nan/-/nan-2.15.0.tgz#3f34a473ff18e15c1b5626b62903b5ad6e665fee"
  integrity sha512-8ZtvEnA2c5aYCZYd1cvgdnU6cqwixRoYg70xPLWUws5ORTa/lnw+u4amixRS/Ac5U5mQVgp9pnlSUnbNWFaWZQ==

+nano-css@^5.3.1:
+  version "5.3.4"
+  resolved "https://registry.yarnpkg.com/nano-css/-/nano-css-5.3.4.tgz#40af6a83a76f84204f346e8ccaa9169cdae9167b"
+  integrity sha512-wfcviJB6NOxDIDfr7RFn/GlaN7I/Bhe4d39ZRCJ3xvZX60LVe2qZ+rDqM49nm4YT81gAjzS+ZklhKP/Gnfnubg==
+  dependencies:
+    css-tree "^1.1.2"
+    csstype "^3.0.6"
+    fastest-stable-stringify "^2.0.2"
+    inline-style-prefixer "^6.0.0"
+    rtl-css-js "^1.14.0"
+    sourcemap-codec "^1.4.8"
+    stacktrace-js "^2.0.2"
+    stylis "^4.0.6"
+
 nanoid@^3.1.23, nanoid@^3.3.1:
  version "3.3.3"
  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.3.tgz#fd8e8b7aa761fe807dba2d1b98fb7241bb724a25"
@ -14778,6 +14837,31 @@ react-textarea-autosize@^8.3.0, react-textarea-autosize@^8.3.2:
    use-composed-ref "^1.0.0"
    use-latest "^1.0.0"

+react-universal-interface@^0.6.2:
+  version "0.6.2"
+  resolved "https://registry.yarnpkg.com/react-universal-interface/-/react-universal-interface-0.6.2.tgz#5e8d438a01729a4dbbcbeeceb0b86be146fe2b3b"
+  integrity sha512-dg8yXdcQmvgR13RIlZbTRQOoUrDciFVoSBZILwjE2LFISxZZ8loVJKAkuzswl5js8BHda79bIb2b84ehU8IjXw==
+
+react-use@^17.3.2:
+  version "17.3.2"
+  resolved "https://registry.yarnpkg.com/react-use/-/react-use-17.3.2.tgz#448abf515f47c41c32455024db28167cb6e53be8"
+  integrity sha512-bj7OD0/1wL03KyWmzFXAFe425zziuTf7q8olwCYBfOeFHY1qfO1FAMjROQLsLZYwG4Rx63xAfb7XAbBrJsZmEw==
+  dependencies:
+    "@types/js-cookie" "^2.2.6"
+    "@xobotyi/scrollbar-width" "^1.9.5"
+    copy-to-clipboard "^3.3.1"
+    fast-deep-equal "^3.1.3"
+    fast-shallow-equal "^1.0.0"
+    js-cookie "^2.2.1"
+    nano-css "^5.3.1"
+    react-universal-interface "^0.6.2"
+    resize-observer-polyfill "^1.5.1"
+    screenfull "^5.1.0"
+    set-harmonic-interval "^1.0.1"
+    throttle-debounce "^3.0.1"
+    ts-easing "^0.2.0"
+    tslib "^2.1.0"
+
 react-vega@^7.5.0:
  version "7.5.0"
  resolved "https://registry.yarnpkg.com/react-vega/-/react-vega-7.5.0.tgz#b9726d4fd7f35299d417d340935e093bf4bed558"
@ -15335,6 +15419,13 @@ rsvp@^4.8.4:
  resolved "https://registry.yarnpkg.com/rsvp/-/rsvp-4.8.5.tgz#c8f155311d167f68f21e168df71ec5b083113734"
  integrity sha512-nfMOlASu9OnRJo1mbEk2cz0D56a1MBNrJ7orjRZQG10XDyuvwksKbuXNp6qa+kbn839HwjwhBzhFmdsaEAfauA==

+rtl-css-js@^1.14.0:
+  version "1.15.0"
+  resolved "https://registry.yarnpkg.com/rtl-css-js/-/rtl-css-js-1.15.0.tgz#680ed816e570a9ebccba9e1cd0f202c6a8bb2dc0"
+  integrity sha512-99Cu4wNNIhrI10xxUaABHsdDqzalrSRTie4GeCmbGVuehm4oj+fIy8fTzB+16pmKe8Bv9rl+hxIBez6KxExTew==
+  dependencies:
+    "@babel/runtime" "^7.1.2"
+
 rtl-detect@^1.0.4:
  version "1.0.4"
  resolved "https://registry.yarnpkg.com/rtl-detect/-/rtl-detect-1.0.4.tgz#40ae0ea7302a150b96bc75af7d749607392ecac6"
@ -15496,6 +15587,11 @@ schema-utils@^4.0.0:
    ajv-formats "^2.1.1"
    ajv-keywords "^5.0.0"

+screenfull@^5.1.0:
+  version "5.2.0"
+  resolved "https://registry.yarnpkg.com/screenfull/-/screenfull-5.2.0.tgz#6533d524d30621fc1283b9692146f3f13a93d1ba"
+  integrity sha512-9BakfsO2aUQN2K9Fdbj87RJIEZ82Q9IGim7FqM5OsebfoFC6ZHXgDq/KvniuLTPdeM8wY2o6Dj3WQ7KeQCj3cA==
+
 scroll-into-view-if-needed@^2.2.25:
  version "2.2.29"
  resolved "https://registry.yarnpkg.com/scroll-into-view-if-needed/-/scroll-into-view-if-needed-2.2.29.tgz#551791a84b7e2287706511f8c68161e4990ab885"
@ -15669,6 +15765,11 @@ set-blocking@^2.0.0:
  resolved "https://registry.yarnpkg.com/set-blocking/-/set-blocking-2.0.0.tgz#045f9782d011ae9a6803ddd382b24392b3d890f7"
  integrity sha1-BF+XgtARrppoA93TgrJDkrPYkPc=

+set-harmonic-interval@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/set-harmonic-interval/-/set-harmonic-interval-1.0.1.tgz#e1773705539cdfb80ce1c3d99e7f298bb3995249"
+  integrity sha512-AhICkFV84tBP1aWqPwLZqFvAwqEoVA9kxNMniGEUvzOlm4vLmOFLiTT3UZ6bziJTy4bOVpzWGTfSCbmaayGx8g==
+
 set-value@^2.0.0, set-value@^2.0.1:
  version "2.0.1"
  resolved "https://registry.yarnpkg.com/set-value/-/set-value-2.0.1.tgz#a18d40530e6f07de4228c7defe4227af8cad005b"
@ -15900,6 +16001,11 @@ source-map-url@^0.4.0:
  resolved "https://registry.yarnpkg.com/source-map-url/-/source-map-url-0.4.1.tgz#0af66605a745a5a2f91cf1bbf8a7afbc283dec56"
  integrity sha512-cPiFOTLUKvJFIg4SKVScy4ilPPW6rFgMgfuZJPNoDuMs3nC1HbMUycBoJw77xFIp6z1UJQJOfx6C9GMH80DiTw==

+source-map@0.5.6:
+  version "0.5.6"
+  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.6.tgz#75ce38f52bf0733c5a7f0c118d81334a2bb5f412"
+  integrity sha1-dc449SvwczxafwwRjYEzSiu19BI=
+
 source-map@0.6.1, source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.0, source-map@~0.6.1:
  version "0.6.1"
  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
@ -16024,6 +16130,13 @@ stable@^0.1.8:
  resolved "https://registry.yarnpkg.com/stable/-/stable-0.1.8.tgz#836eb3c8382fe2936feaf544631017ce7d47a3cf"
  integrity sha512-ji9qxRnOVfcuLDySj9qzhGSEFVobyt1kIOSkj1qZzYLzq7Tos/oUUWvotUPQLlrsidqsK6tBH89Bc9kL5zHA6w==

+stack-generator@^2.0.5:
+  version "2.0.5"
+  resolved "https://registry.yarnpkg.com/stack-generator/-/stack-generator-2.0.5.tgz#fb00e5b4ee97de603e0773ea78ce944d81596c36"
+  integrity sha512-/t1ebrbHkrLrDuNMdeAcsvynWgoH/i4o8EGGfX7dEYDoTXOYVAkEpFdtshlvabzc6JlJ8Kf9YdFEoz7JkzGN9Q==
+  dependencies:
+    stackframe "^1.1.1"
+
 stack-utils@^2.0.3:
  version "2.0.5"
  resolved "https://registry.yarnpkg.com/stack-utils/-/stack-utils-2.0.5.tgz#d25265fca995154659dbbfba3b49254778d2fdd5"
@ -16036,6 +16149,23 @@ stackframe@^1.1.1:
  resolved "https://registry.yarnpkg.com/stackframe/-/stackframe-1.2.1.tgz#1033a3473ee67f08e2f2fc8eba6aef4f845124e1"
  integrity sha512-h88QkzREN/hy8eRdyNhhsO7RSJ5oyTqxxmmn0dzBIMUclZsjpfmrsg81vp8mjjAs2vAZ72nyWxRUwSwmh0e4xg==

+stacktrace-gps@^3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/stacktrace-gps/-/stacktrace-gps-3.0.4.tgz#7688dc2fc09ffb3a13165ebe0dbcaf41bcf0c69a"
+  integrity sha512-qIr8x41yZVSldqdqe6jciXEaSCKw1U8XTXpjDuy0ki/apyTn/r3w9hDAAQOhZdxvsC93H+WwwEu5cq5VemzYeg==
+  dependencies:
+    source-map "0.5.6"
+    stackframe "^1.1.1"
+
+stacktrace-js@^2.0.2:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/stacktrace-js/-/stacktrace-js-2.0.2.tgz#4ca93ea9f494752d55709a081d400fdaebee897b"
+  integrity sha512-Je5vBeY4S1r/RnLydLl0TBTi3F2qdfWmYsGvtfZgEI+SCprPppaIhQf5nGcal4gI4cGpCV/duLcAzT1np6sQqg==
+  dependencies:
+    error-stack-parser "^2.0.6"
+    stack-generator "^2.0.5"
+    stacktrace-gps "^3.0.4"
+
 state-toggle@^1.0.0:
  version "1.0.3"
  resolved "https://registry.yarnpkg.com/state-toggle/-/state-toggle-1.0.3.tgz#e123b16a88e143139b09c6852221bc9815917dfe"
@ -16348,6 +16478,11 @@ stylehacks@^5.1.0:
    browserslist "^4.16.6"
    postcss-selector-parser "^6.0.4"

+stylis@^4.0.6:
+  version "4.1.1"
+  resolved "https://registry.yarnpkg.com/stylis/-/stylis-4.1.1.tgz#e46c6a9bbf7c58db1e65bb730be157311ae1fe12"
+  integrity sha512-lVrM/bNdhVX2OgBFNa2YJ9Lxj7kPzylieHd3TNjuGE0Re9JB7joL5VUKOVH1kdNNJTgGPpT8hmwIAPLaSyEVFQ==
+
 supports-color@^2.0.0:
  version "2.0.0"
  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-2.0.0.tgz#535d045ce6b6363fa40117084629995e9df324c7"
@ -16792,6 +16927,11 @@ ts-dedent@^2.0.0:
  resolved "https://registry.yarnpkg.com/ts-dedent/-/ts-dedent-2.2.0.tgz#39e4bd297cd036292ae2394eb3412be63f563bb5"
  integrity sha512-q5W7tVM71e2xjHZTlgfTDoPF/SmqKG5hddq9SzR49CH2hayqRKJtQ4mtRlSxKaJlR/+9rEM+mnBHf7I2/BQcpQ==

+ts-easing@^0.2.0:
+  version "0.2.0"
+  resolved "https://registry.yarnpkg.com/ts-easing/-/ts-easing-0.2.0.tgz#c8a8a35025105566588d87dbda05dd7fbfa5a4ec"
+  integrity sha512-Z86EW+fFFh/IFB1fqQ3/+7Zpf9t2ebOAxNI/V6Wo7r5gqiqtxmgTlQ1qbqQcjLKYeSHPTsEmvlJUDg/EuL0uHQ==
+
 ts-jest@^27.1.4:
  version "27.1.4"
  resolved "https://registry.yarnpkg.com/ts-jest/-/ts-jest-27.1.4.tgz#84d42cf0f4e7157a52e7c64b1492c46330943e00"
@ -16806,10 +16946,10 @@ ts-jest@^27.1.4:
    semver "7.x"
    yargs-parser "20.x"

-ts-loader@^9.2.8, ts-loader@^9.2.9:
-  version "9.2.9"
-  resolved "https://registry.yarnpkg.com/ts-loader/-/ts-loader-9.2.9.tgz#0653e07fa1b4f225d0ca57a84fddbfd43d930f9e"
-  integrity sha512-b0+vUY2/enb0qYtDQuNlDnJ9900NTiPiJcDJ6sY7ax1CCCwXfYIqPOMm/BwW7jsF1km+Oz8W9s31HLuD+FLIMg==
+ts-loader@^9.3.0:
+  version "9.3.0"
+  resolved "https://registry.yarnpkg.com/ts-loader/-/ts-loader-9.3.0.tgz#980f4dbfb60e517179e15e10ed98e454b132159f"
+  integrity sha512-2kLLAdAD+FCKijvGKi9sS0OzoqxLCF3CxHpok7rVgCZ5UldRzH0TkbwG9XECKjBzHsAewntC5oDaI/FwKzEUog==
  dependencies:
    chalk "^4.1.0"
    enhanced-resolve "^5.0.0"