diff --git a/packages/squiggle-lang/package.json b/packages/squiggle-lang/package.json
index 40f7e7c7..67dfed03 100644
--- 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",
diff --git a/packages/squiggle-lang/src/js/index.ts b/packages/squiggle-lang/src/js/index.ts
index abb563ed..c4c9b0d3 100644
--- a/packages/squiggle-lang/src/js/index.ts
+++ b/packages/squiggle-lang/src/js/index.ts
@@ -8,15 +8,6 @@ import {
   externalBindings,
   expressionValue,
   errorValue,
-  distributionError,
-  toPointSet,
-  continuousShape,
-  discreteShape,
-  distributionErrorToString,
-  internalCode,
-  mixedShape,
-  sampleSetDist,
-  symbolicDist,
 } from "../rescript/TypescriptInterface.gen";
 export {
   makeSampleSetDist,
@@ -46,48 +37,6 @@ export let defaultSamplingInputs: samplingParams = {
   xyPointLength: 10000,
 };
 
-export type result<a, b> =
-  | {
-      tag: "Ok";
-      value: a;
-    }
-  | {
-      tag: "Error";
-      value: b;
-    };
-
-export function resultMap<a, b, c>(
-  r: result<a, c>,
-  mapFn: (x: a) => b
-): result<b, c> {
-  if (r.tag === "Ok") {
-    return { tag: "Ok", value: mapFn(r.value) };
-  } else {
-    return r;
-  }
-}
-
-function Ok<a, b>(x: a): result<a, b> {
-  return { tag: "Ok", value: x };
-}
-
-type tagged<a, b> = { tag: a; value: b };
-
-function tag<a, b>(x: a, y: b): tagged<a, b> {
-  return { tag: x, value: y };
-}
-
-export type squiggleExpression =
-  | tagged<"symbol", string>
-  | tagged<"string", string>
-  | tagged<"call", string>
-  | tagged<"lambda", [string[], internalCode]>
-  | tagged<"array", squiggleExpression[]>
-  | tagged<"boolean", boolean>
-  | tagged<"distribution", Distribution>
-  | tagged<"number", number>
-  | tagged<"record", { [key: string]: squiggleExpression }>;
-
 export function run(
   squiggleString: string,
   bindings?: externalBindings,
diff --git a/packages/squiggle-lang/src/js/rescript_interop.ts b/packages/squiggle-lang/src/js/rescript_interop.ts
index 75c6e733..45f4124b 100644
--- a/packages/squiggle-lang/src/js/rescript_interop.ts
+++ b/packages/squiggle-lang/src/js/rescript_interop.ts
@@ -5,10 +5,9 @@ import {
   genericDist,
   environment,
   symbolicDist,
-  recordEV,
-  internalCode,
   discreteShape,
   continuousShape,
+  lambdaValue,
 } from "../rescript/TypescriptInterface.gen";
 import { Distribution } from "./distribution";
 import { tagged, tag } from "./types";
@@ -38,7 +37,7 @@ export type rescriptExport =
     }
   | {
       TAG: 5; // EvLambda
-      _0: [string[], recordEV, internalCode];
+      _0: lambdaValue;
     }
   | {
       TAG: 6; // EvNumber
@@ -80,7 +79,7 @@ export type squiggleExpression =
   | tagged<"symbol", string>
   | tagged<"string", string>
   | tagged<"call", string>
-  | tagged<"lambda", [string[], recordEV, internalCode]>
+  | tagged<"lambda", lambdaValue>
   | tagged<"array", squiggleExpression[]>
   | tagged<"arraystring", string[]>
   | tagged<"boolean", boolean>
diff --git a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
index 0d413bf4..a9151a8f 100644
--- 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)})`
diff --git a/packages/squiggle-lang/src/rescript/TypescriptInterface.res b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
index 114dc4e6..6ebb8377 100644
--- a/packages/squiggle-lang/src/rescript/TypescriptInterface.res
+++ b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
@@ -74,7 +74,7 @@ let errorValueToString = Reducer_ErrorValue.errorToString
 let distributionErrorToString = DistributionTypes.Error.toString
 
 @genType
-type internalCode = ReducerInterface_ExpressionValue.internalCode
+type lambdaValue = ReducerInterface_ExpressionValue.lambdaValue
 
 @genType
 let defaultSamplingEnv = ReducerInterface_GenericDistribution.defaultEnv