Merge branch 'develop' into observable-refactor

packages/components/src/components/SquiggleItem.tsx

@@ -244,7 +244,28 @@ export const SquiggleItem: React.FC<SquiggleItemProps> = ({
     case "module": {
       return (
         <VariableBox heading="Module" showTypes={showTypes}>
-          <span className="text-slate-600 font-semibold">Internal Module</span>
+          <div className="space-y-3">
+            {Object.entries(expression.value)
+              .filter(([key, r]) => key !== "Math")
+              .map(([key, r]) => (
+                <div key={key} className="flex space-x-2">
+                  <div className="flex-none">
+                    <header className="text-slate-500 font-mono">{key}:</header>
+                  </div>
+                  <div className="px-2 grow bg-gray-50 border border-gray-100 rounded-sm">
+                    <SquiggleItem
+                      expression={r}
+                      width={width !== undefined ? width - 20 : width}
+                      height={height / 3}
+                      showTypes={showTypes}
+                      distributionPlotSettings={distributionPlotSettings}
+                      chartSettings={chartSettings}
+                      environment={environment}
+                    />
+                  </div>
+                </div>
+              ))}
+          </div>
         </VariableBox>
       );
     }

packages/squiggle-lang/.gitignore

@@ -22,3 +22,4 @@ _coverage
 coverage
 .nyc_output/
 src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.js
+src/rescript/Reducer/Reducer_Peggy/helpers.js

packages/squiggle-lang/__tests__/Reducer/Reducer_Category/Reducer_Category_Module_TypeChecker_test.res

@@ -0,0 +1,4 @@
+open Jest
+open Expect
+
+test("todo", () => expect("1")->toBe("1"))

packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros_test.res

@@ -19,23 +19,23 @@ describe("bindStatement", () => {
   testMacro(
     [],
     eBindStatement(eBindings([]), exampleStatementY),
-    "Ok((:$_setBindings_$ {} :y 1) context: {})",
+    "Ok((:$_setBindings_$ @{} :y 1) context: @{})",
   )
   // Then it answers the bindings for the next statement when reduced
-  testMacroEval([], eBindStatement(eBindings([]), exampleStatementY), "Ok({y: 1})")
+  testMacroEval([], eBindStatement(eBindings([]), exampleStatementY), "Ok(@{y: 1})")
   // Now let's feed a binding to see what happens
   testMacro(
     [],
-    eBindStatement(eBindings([("x", EvNumber(2.))]), exampleStatementX),
+    eBindStatement(eBindings([("x", IEvNumber(2.))]), exampleStatementX),
-    "Ok((:$_setBindings_$ {x: 2} :y 2) context: {x: 2})",
+    "Ok((:$_setBindings_$ @{x: 2} :y 2) context: @{x: 2})",
   )
   // An expression does not return a binding, thus error
   testMacro([], eBindStatement(eBindings([]), exampleExpression), "Assignment expected")
   // When bindings from previous statement are missing the context is injected. This must be the first statement of a block
   testMacro(
-    [("z", EvNumber(99.))],
+    [("z", IEvNumber(99.))],
     eBindStatementDefault(exampleStatementY),
-    "Ok((:$_setBindings_$ {z: 99} :y 1) context: {z: 99})",
+    "Ok((:$_setBindings_$ @{z: 99} :y 1) context: @{z: 99})",
   )
 })
 
@@ -43,26 +43,26 @@ describe("bindExpression", () => {
   // x is simply bound in the expression
   testMacro(
     [],
-    eBindExpression(eBindings([("x", EvNumber(2.))]), eSymbol("x")),
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), eSymbol("x")),
-    "Ok(2 context: {x: 2})",
+    "Ok(2 context: @{x: 2})",
   )
   // When an let statement is the end expression then bindings are returned
   testMacro(
     [],
-    eBindExpression(eBindings([("x", EvNumber(2.))]), exampleStatementY),
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), exampleStatementY),
-    "Ok((:$_exportBindings_$ (:$_setBindings_$ {x: 2} :y 1)) context: {x: 2})",
+    "Ok((:$_exportBindings_$ (:$_setBindings_$ @{x: 2} :y 1)) context: @{x: 2})",
   )
   // Now let's reduce that expression
   testMacroEval(
     [],
-    eBindExpression(eBindings([("x", EvNumber(2.))]), exampleStatementY),
+    eBindExpression(eBindings([("x", IEvNumber(2.))]), exampleStatementY),
-    "Ok({x: 2,y: 1})",
+    "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.))],
+    [("z", IEvNumber(99.))],
     eBindExpressionDefault(exampleStatementY),
-    "Ok({y: 1,z: 99})",
+    "Ok(@{y: 1,z: 99})",
   )
 })
 
@@ -72,7 +72,7 @@ describe("block", () => {
   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})")
+  testMacroEval([], eBlock(list{exampleStatementY}), "Ok(@{y: 1})")
   // Block with a statement and an expression
   testMacro(
     [],
@@ -86,7 +86,7 @@ describe("block", () => {
     eBlock(list{exampleStatementY, exampleStatementZ}),
     "Ok((:$$_bindExpression_$$ (:$$_bindStatement_$$ (:$_let_$ :y 1)) (:$_let_$ :z :y)))",
   )
-  testMacroEval([], eBlock(list{exampleStatementY, exampleStatementZ}), "Ok({y: 1,z: 1})")
+  testMacroEval([], eBlock(list{exampleStatementY, exampleStatementZ}), "Ok(@{y: 1,z: 1})")
   // Block inside a block
   testMacro([], eBlock(list{eBlock(list{exampleExpression})}), "Ok((:$$_bindExpression_$$ {1}))")
   testMacroEval([], eBlock(list{eBlock(list{exampleExpression})}), "Ok(1)")
@@ -99,7 +99,7 @@ describe("block", () => {
   testMacroEval(
     [],
     eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
-    "Ok({z: :y})",
+    "Ok(@{z: :y})",
   )
   // Empty block
   testMacro([], eBlock(list{}), "Ok(:undefined block)") //TODO: should be an error
@@ -115,7 +115,7 @@ describe("block", () => {
     "Ok((:$$_bindExpression_$$ {(:$_let_$ :y (:add :x 1)); :y}))",
   )
   testMacroEval(
-    [("x", EvNumber(1.))],
+    [("x", IEvNumber(1.))],
     eBlock(list{
       eBlock(list{
         eLetStatement("y", eFunction("add", list{eSymbol("x"), eNumber(1.)})),
@@ -135,12 +135,12 @@ describe("lambda", () => {
   testMacro([], callLambdaExpression, "Ok(((:$$_lambda_$$ [y] :y) 1))")
   testMacroEval([], callLambdaExpression, "Ok(1)")
   // Parameters shadow the outer scope
-  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(1)")
+  testMacroEval([("y", IEvNumber(666.))], callLambdaExpression, "Ok(1)")
   // When not shadowed by the parameters, the outer scope variables are available
   let lambdaExpression = eFunction(
     "$$_lambda_$$",
     list{eArrayString(["z"]), eFunction("add", list{eSymbol("y"), eSymbol("z")})},
   )
   let callLambdaExpression = eList(list{lambdaExpression, eNumber(1.)})
-  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(667)")
+  testMacroEval([("y", IEvNumber(666.))], callLambdaExpression, "Ok(667)")
 })

packages/squiggle-lang/__tests__/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn_test.res

@@ -1,4 +1,4 @@
-module ExpressionValue = ReducerInterface.ExpressionValue
+module ExpressionValue = ReducerInterface.ExternalExpressionValue
 
 open Jest
 open Expect

packages/squiggle-lang/__tests__/Reducer/Reducer_Helpers.res

@@ -1,19 +1,22 @@
-module ExpressionT = Reducer_Expression_T
+// Reducer_Helpers
-module ExpressionValue = ReducerInterface.ExpressionValue
 module ErrorValue = Reducer_ErrorValue
-module Bindings = Reducer_Category_Bindings
+module ExternalExpressionValue = ReducerInterface.ExternalExpressionValue
+module InternalExpressionValue = ReducerInterface.InternalExpressionValue
+module Module = Reducer_Category_Module
 
-let removeDefaults = (ev: ExpressionT.expressionValue): ExpressionT.expressionValue =>
+let removeDefaultsInternal = (iev: InternalExpressionValue.t) => {
-  switch ev {
+  switch iev {
-  | EvRecord(extbindings) => {
+  | InternalExpressionValue.IEvModule(nameSpace) =>
-      let bindings: Bindings.t = Bindings.fromRecord(extbindings)
+    Module.removeOther(
-      let keys = Js.Dict.keys(Reducer.defaultExternalBindings)
+      nameSpace,
-      Belt.Map.String.keep(bindings, (key, _value) => {
+      ReducerInterface.StdLib.internalStdLib,
-        let removeThis = Js.Array2.includes(keys, key)
+    )->InternalExpressionValue.IEvModule
-        !removeThis
-      })->Bindings.toExpressionValue
-    }
   | value => value
   }
+}
 
-let rRemoveDefaults = r => Belt.Result.map(r, ev => removeDefaults(ev))
+let removeDefaultsExternal = (ev: ExternalExpressionValue.t): ExternalExpressionValue.t =>
+  ev->InternalExpressionValue.toInternal->removeDefaultsInternal->InternalExpressionValue.toExternal
+
+let rRemoveDefaultsInternal = r => Belt.Result.map(r, removeDefaultsInternal)
+let rRemoveDefaultsExternal = r => Belt.Result.map(r, removeDefaultsExternal)

packages/squiggle-lang/__tests__/Reducer/Reducer_MathJs/Reducer_MathJsEval_test.res

@@ -1,4 +1,3 @@
-open ReducerInterface.ExpressionValue
 module MathJs = Reducer_MathJs
 module ErrorValue = Reducer.ErrorValue
 
@@ -6,14 +5,14 @@ open Jest
 open ExpectJs
 
 describe("eval", () => {
-  test("Number", () => expect(MathJs.Eval.eval("1"))->toEqual(Ok(EvNumber(1.))))
+  test("Number", () => expect(MathJs.Eval.eval("1"))->toEqual(Ok(IEvNumber(1.))))
-  test("Number expr", () => expect(MathJs.Eval.eval("1-1"))->toEqual(Ok(EvNumber(0.))))
+  test("Number expr", () => expect(MathJs.Eval.eval("1-1"))->toEqual(Ok(IEvNumber(0.))))
-  test("String", () => expect(MathJs.Eval.eval("'hello'"))->toEqual(Ok(EvString("hello"))))
+  test("String", () => expect(MathJs.Eval.eval("'hello'"))->toEqual(Ok(IEvString("hello"))))
   test("String expr", () =>
-    expect(MathJs.Eval.eval("concat('hello ','world')"))->toEqual(Ok(EvString("hello world")))
+    expect(MathJs.Eval.eval("concat('hello ','world')"))->toEqual(Ok(IEvString("hello world")))
   )
-  test("Boolean", () => expect(MathJs.Eval.eval("true"))->toEqual(Ok(EvBool(true))))
+  test("Boolean", () => expect(MathJs.Eval.eval("true"))->toEqual(Ok(IEvBool(true))))
-  test("Boolean expr", () => expect(MathJs.Eval.eval("2>1"))->toEqual(Ok(EvBool(true))))
+  test("Boolean expr", () => expect(MathJs.Eval.eval("2>1"))->toEqual(Ok(IEvBool(true))))
 })
 
 describe("errors", () => {

packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_TestHelpers.res

@@ -1,6 +1,6 @@
 module Expression = Reducer_Expression
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface_ExpressionValue
+module ExpressionValue = ReducerInterface.InternalExpressionValue
 module Parse = Reducer_Peggy_Parse
 module Result = Belt.Result
 module ToExpression = Reducer_Peggy_ToExpression
@@ -29,7 +29,7 @@ let expectToExpressionToBe = (expr, answer, ~v="_", ()) => {
           ExpressionValue.defaultEnvironment,
         )
       )
-      ->Reducer_Helpers.rRemoveDefaults
+      ->Reducer_Helpers.rRemoveDefaultsInternal
       ->ExpressionValue.toStringResultOkless
     (a1, a2)->expect->toEqual((answer, v))
   }

packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_test.res

@@ -22,11 +22,11 @@ describe("Peggy to Expression", () => {
 
   describe("multi-line", () => {
     testToExpression("x=1; 2", "{(:$_let_$ :x {1}); 2}", ~v="2", ())
-    testToExpression("x=1; y=2", "{(:$_let_$ :x {1}); (:$_let_$ :y {2})}", ~v="{x: 1,y: 2}", ())
+    testToExpression("x=1; y=2", "{(:$_let_$ :x {1}); (:$_let_$ :y {2})}", ~v="@{x: 1,y: 2}", ())
   })
 
   describe("variables", () => {
-    testToExpression("x = 1", "{(:$_let_$ :x {1})}", ~v="{x: 1}", ())
+    testToExpression("x = 1", "{(:$_let_$ :x {1})}", ~v="@{x: 1}", ())
     testToExpression("x", "{:x}", ~v=":x", ()) //TODO: value should return error
     testToExpression("x = 1; x", "{(:$_let_$ :x {1}); :x}", ~v="1", ())
   })
@@ -35,7 +35,7 @@ describe("Peggy to Expression", () => {
     testToExpression(
       "identity(x) = x",
       "{(:$_let_$ :identity (:$$_lambda_$$ [x] {:x}))}",
-      ~v="{identity: lambda(x=>internal code)}",
+      ~v="@{identity: lambda(x=>internal code)}",
       (),
     ) // Function definitions become lambda assignments
     testToExpression("identity(x)", "{(:identity :x)}", ()) // Note value returns error properly
@@ -155,7 +155,7 @@ describe("Peggy to Expression", () => {
     testToExpression(
       "y=99; x={y=1; y}",
       "{(:$_let_$ :y {99}); (:$_let_$ :x {(:$_let_$ :y {1}); :y})}",
-      ~v="{x: 1,y: 99}",
+      ~v="@{x: 1,y: 99}",
       (),
     )
   })
@@ -165,19 +165,19 @@ describe("Peggy to Expression", () => {
     testToExpression(
       "f={|x| x}",
       "{(:$_let_$ :f {(:$$_lambda_$$ [x] {:x})})}",
-      ~v="{f: lambda(x=>internal code)}",
+      ~v="@{f: lambda(x=>internal code)}",
       (),
     )
     testToExpression(
       "f(x)=x",
       "{(:$_let_$ :f (:$$_lambda_$$ [x] {:x}))}",
-      ~v="{f: lambda(x=>internal code)}",
+      ~v="@{f: lambda(x=>internal code)}",
       (),
     ) // Function definitions are lambda assignments
     testToExpression(
       "f(x)=x ? 1 : 0",
       "{(:$_let_$ :f (:$$_lambda_$$ [x] {(:$$_ternary_$$ :x 1 0)}))}",
-      ~v="{f: lambda(x=>internal code)}",
+      ~v="@{f: lambda(x=>internal code)}",
       (),
     )
   })

packages/squiggle-lang/__tests__/Reducer/Reducer_Peggy/Reducer_Peggy_ToExpression_type_test.res

@@ -6,7 +6,7 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "p: number",
       "{(:$_typeOf_$ :p #number)}",
-      ~v="{_typeReferences_: {p: #number}}",
+      ~v="@{_typeReferences_: {p: #number}}",
       (),
     )
   })
@@ -14,7 +14,7 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "type index=number",
       "{(:$_typeAlias_$ #index #number)}",
-      ~v="{_typeAliases_: {index: #number}}",
+      ~v="@{_typeAliases_: {index: #number}}",
       (),
     )
   })
@@ -22,7 +22,7 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "answer: number|string|distribution",
       "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ (#number #string #distribution))))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeOr',typeOr: [#number,#string,#distribution]}}}",
+      ~v="@{_typeReferences_: {answer: {typeOr: [#number,#string,#distribution],typeTag: 'typeOr'}}}",
       (),
     )
   })
@@ -30,13 +30,13 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "f: number=>number=>number",
       "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ (#number #number #number))))}",
-      ~v="{_typeReferences_: {f: {typeTag: 'typeFunction',inputs: [#number,#number],output: #number}}}",
+      ~v="@{_typeReferences_: {f: {inputs: [#number,#number],output: #number,typeTag: 'typeFunction'}}}",
       (),
     )
     testToExpression(
       "f: number=>number",
       "{(:$_typeOf_$ :f (:$_typeFunction_$ (:$_constructArray_$ (#number #number))))}",
-      ~v="{_typeReferences_: {f: {typeTag: 'typeFunction',inputs: [#number],output: #number}}}",
+      ~v="@{_typeReferences_: {f: {inputs: [#number],output: #number,typeTag: 'typeFunction'}}}",
       (),
     )
   })
@@ -44,37 +44,37 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "answer: number<-min(1)<-max(100)|string",
       "{(:$_typeOf_$ :answer (:$_typeOr_$ (:$_constructArray_$ ((:$_typeModifier_max_$ (:$_typeModifier_min_$ #number 1) 100) #string))))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeOr',typeOr: [{typeTag: 'typeIdentifier',typeIdentifier: #number,min: 1,max: 100},#string]}}}",
+      ~v="@{_typeReferences_: {answer: {typeOr: [{max: 100,min: 1,typeIdentifier: #number,typeTag: 'typeIdentifier'},#string],typeTag: 'typeOr'}}}",
       (),
     )
     testToExpression(
       "answer: number<-memberOf([1,3,5])",
       "{(:$_typeOf_$ :answer (:$_typeModifier_memberOf_$ #number (:$_constructArray_$ (1 3 5))))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeIdentifier',typeIdentifier: #number,memberOf: [1,3,5]}}}",
+      ~v="@{_typeReferences_: {answer: {memberOf: [1,3,5],typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
     testToExpression(
       "answer: number<-min(1)",
       "{(:$_typeOf_$ :answer (:$_typeModifier_min_$ #number 1))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeIdentifier',typeIdentifier: #number,min: 1}}}",
+      ~v="@{_typeReferences_: {answer: {min: 1,typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
     testToExpression(
       "answer: number<-max(10)",
       "{(:$_typeOf_$ :answer (:$_typeModifier_max_$ #number 10))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeIdentifier',typeIdentifier: #number,max: 10}}}",
+      ~v="@{_typeReferences_: {answer: {max: 10,typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
     testToExpression(
       "answer: number<-min(1)<-max(10)",
       "{(:$_typeOf_$ :answer (:$_typeModifier_max_$ (:$_typeModifier_min_$ #number 1) 10))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeIdentifier',typeIdentifier: #number,min: 1,max: 10}}}",
+      ~v="@{_typeReferences_: {answer: {max: 10,min: 1,typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
     testToExpression(
       "answer: number<-max(10)<-min(1)",
       "{(:$_typeOf_$ :answer (:$_typeModifier_min_$ (:$_typeModifier_max_$ #number 10) 1))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeIdentifier',typeIdentifier: #number,max: 10,min: 1}}}",
+      ~v="@{_typeReferences_: {answer: {max: 10,min: 1,typeIdentifier: #number,typeTag: 'typeIdentifier'}}}",
       (),
     )
   })
@@ -82,7 +82,7 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "answer: number | string $ opaque",
       "{(:$_typeOf_$ :answer (:$_typeModifier_opaque_$ (:$_typeOr_$ (:$_constructArray_$ (#number #string)))))}",
-      ~v="{_typeReferences_: {answer: {typeTag: 'typeOr',typeOr: [#number,#string],opaque: true}}}",
+      ~v="@{_typeReferences_: {answer: {opaque: true,typeOr: [#number,#string],typeTag: 'typeOr'}}}",
       (),
     )
   })
@@ -90,7 +90,7 @@ describe("Peggy Types to Expression", () => {
     testToExpression(
       "odds1 = [1,3,5]; odds2 = [7, 9]; type odds = number<-memberOf(concat(odds1, odds2))",
       "{(:$_let_$ :odds1 {(:$_constructArray_$ (1 3 5))}); (:$_let_$ :odds2 {(:$_constructArray_$ (7 9))}); (:$_typeAlias_$ #odds (:$_typeModifier_memberOf_$ #number (:concat :odds1 :odds2)))}",
-      ~v="{_typeAliases_: {odds: {typeTag: 'typeIdentifier',typeIdentifier: #number,memberOf: [1,3,5,7,9]}},odds1: [1,3,5],odds2: [7,9]}",
+      ~v="@{_typeAliases_: {odds: {memberOf: [1,3,5,7,9],typeIdentifier: #number,typeTag: 'typeIdentifier'}},odds1: [1,3,5],odds2: [7,9]}",
       (),
     )
   })

packages/squiggle-lang/__tests__/Reducer/Reducer_TestHelpers.res

@@ -1,7 +1,6 @@
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
+module ExternalExpressionValue = ReducerInterface.ExternalExpressionValue
 module ErrorValue = Reducer_ErrorValue
-module Bindings = Reducer_Category_Bindings
 
 open Jest
 open Expect
@@ -9,7 +8,7 @@ open Expect
 let unwrapRecord = rValue =>
   rValue->Belt.Result.flatMap(value =>
     switch value {
-    | ExpressionValue.EvRecord(aRecord) => Ok(aRecord)
+    | ExternalExpressionValue.EvRecord(aRecord) => Ok(aRecord)
     | _ => ErrorValue.RETodo("TODO: External bindings must be returned")->Error
     }
   )
@@ -19,18 +18,18 @@ let expectParseToBe = (expr: string, answer: string) =>
 
 let expectEvalToBe = (expr: string, answer: string) =>
   Reducer.evaluate(expr)
-  ->Reducer_Helpers.rRemoveDefaults
+  ->Reducer_Helpers.rRemoveDefaultsExternal
-  ->ExpressionValue.toStringResult
+  ->ExternalExpressionValue.toStringResult
   ->expect
   ->toBe(answer)
 
 let expectEvalError = (expr: string) =>
-  Reducer.evaluate(expr)->ExpressionValue.toStringResult->expect->toMatch("Error\(")
+  Reducer.evaluate(expr)->ExternalExpressionValue.toStringResult->expect->toMatch("Error\(")
 
 let expectEvalBindingsToBe = (expr: string, bindings: Reducer.externalBindings, answer: string) =>
   Reducer.evaluateUsingOptions(expr, ~externalBindings=Some(bindings), ~environment=None)
-  ->Reducer_Helpers.rRemoveDefaults
+  ->Reducer_Helpers.rRemoveDefaultsExternal
-  ->ExpressionValue.toStringResult
+  ->ExternalExpressionValue.toStringResult
   ->expect
   ->toBe(answer)
 

packages/squiggle-lang/__tests__/Reducer/Reducer_TestMacroHelpers.res

@@ -1,25 +1,27 @@
 open Jest
 open Expect
 
-module Bindings = Reducer_Expression_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
 module Expression = Reducer_Expression
-module ExpressionValue = ReducerInterface_ExpressionValue
+// module ExpressionValue = ReducerInterface.ExpressionValue
+module InternalExpressionValue = ReducerInterface.InternalExpressionValue
 module ExpressionWithContext = Reducer_ExpressionWithContext
 module Macro = Reducer_Expression_Macro
 module T = Reducer_Expression_T
+module Module = Reducer_Category_Module
 
 let testMacro_ = (
   tester,
-  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  bindArray: array<(string, InternalExpressionValue.t)>,
   expr: T.expression,
   expectedCode: string,
 ) => {
-  let bindings = Belt.Map.String.fromArray(bindArray)
+  let bindings = Module.fromArray(bindArray)
   tester(expr->T.toString, () =>
     expr
     ->Macro.expandMacroCall(
       bindings,
-      ExpressionValue.defaultEnvironment,
+      InternalExpressionValue.defaultEnvironment,
       Expression.reduceExpression,
     )
     ->ExpressionWithContext.toStringResult
@@ -30,39 +32,43 @@ let testMacro_ = (
 
 let testMacroEval_ = (
   tester,
-  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  bindArray: array<(string, InternalExpressionValue.t)>,
   expr: T.expression,
   expectedValue: string,
 ) => {
-  let bindings = Belt.Map.String.fromArray(bindArray)
+  let bindings = Module.fromArray(bindArray)
   tester(expr->T.toString, () =>
     expr
-    ->Macro.doMacroCall(bindings, ExpressionValue.defaultEnvironment, Expression.reduceExpression)
+    ->Macro.doMacroCall(
-    ->ExpressionValue.toStringResult
+      bindings,
+      InternalExpressionValue.defaultEnvironment,
+      Expression.reduceExpression,
+    )
+    ->InternalExpressionValue.toStringResult
     ->expect
     ->toEqual(expectedValue)
   )
 }
 
 let testMacro = (
-  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  bindArray: array<(string, InternalExpressionValue.t)>,
   expr: T.expression,
   expectedExpr: string,
 ) => testMacro_(test, bindArray, expr, expectedExpr)
 let testMacroEval = (
-  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  bindArray: array<(string, InternalExpressionValue.t)>,
   expr: T.expression,
   expectedValue: string,
 ) => testMacroEval_(test, bindArray, expr, expectedValue)
 
 module MySkip = {
   let testMacro = (
-    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    bindArray: array<(string, InternalExpressionValue.t)>,
     expr: T.expression,
     expectedExpr: string,
   ) => testMacro_(Skip.test, bindArray, expr, expectedExpr)
   let testMacroEval = (
-    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    bindArray: array<(string, InternalExpressionValue.t)>,
     expr: T.expression,
     expectedValue: string,
   ) => testMacroEval_(Skip.test, bindArray, expr, expectedValue)
@@ -70,12 +76,12 @@ module MySkip = {
 
 module MyOnly = {
   let testMacro = (
-    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    bindArray: array<(string, InternalExpressionValue.t)>,
     expr: T.expression,
     expectedExpr: string,
   ) => testMacro_(Only.test, bindArray, expr, expectedExpr)
   let testMacroEval = (
-    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    bindArray: array<(string, InternalExpressionValue.t)>,
     expr: T.expression,
     expectedValue: string,
   ) => testMacroEval_(Only.test, bindArray, expr, expectedValue)

packages/squiggle-lang/__tests__/Reducer/Reducer_externalBindings_test.res

@@ -1,11 +1,14 @@
-// TODO: Reimplement with usual parse
 open Jest
 open Reducer_TestHelpers
 
 describe("Eval with Bindings", () => {
-  testEvalBindingsToBe("x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(1)")
+  testEvalBindingsToBe("x", list{("x", ExternalExpressionValue.EvNumber(1.))}, "Ok(1)")
-  testEvalBindingsToBe("x+1", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(2)")
+  testEvalBindingsToBe("x+1", list{("x", ExternalExpressionValue.EvNumber(1.))}, "Ok(2)")
   testParseToBe("y = x+1; y", "Ok({(:$_let_$ :y {(:add :x 1)}); :y})")
-  testEvalBindingsToBe("y = x+1; y", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(2)")
+  testEvalBindingsToBe("y = x+1; y", list{("x", ExternalExpressionValue.EvNumber(1.))}, "Ok(2)")
-  testEvalBindingsToBe("y = x+1", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1,y: 2})")
+  testEvalBindingsToBe(
+    "y = x+1",
+    list{("x", ExternalExpressionValue.EvNumber(1.))},
+    "Ok(@{x: 1,y: 2})",
+  )
 })

packages/squiggle-lang/__tests__/Reducer/Reducer_functionTricks_test.res

@@ -39,15 +39,15 @@ describe("symbol not defined", () => {
 })
 
 describe("call and bindings", () => {
-  testEvalToBe("f(x)=x+1", "Ok({f: lambda(x=>internal code)})")
+  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=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)", "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; 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)})",
+    "Ok(@{f: lambda(x=>internal code),g: lambda(x=>internal code)})",
   )
   testParseToBe(
     "f=99; g(x)=f; g(2)",
@@ -57,7 +57,7 @@ describe("call and bindings", () => {
   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})",
+    "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)")
 })
@@ -65,7 +65,7 @@ describe("call and bindings", () => {
 describe("function tricks", () => {
   testEvalError("f(x)=f(y)=2; f(2)") //Error because chain assignment is not allowed
   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})")
+  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
   testEvalToBe("myadd(x,y)=x+y; z=myadd; z", "Ok(lambda(x,y=>internal code))")
@@ -75,7 +75,7 @@ describe("function tricks", () => {
 describe("lambda in structures", () => {
   testEvalToBe(
     "myadd(x,y)=x+y; z=[myadd]",
-    "Ok({myadd: lambda(x,y=>internal code),z: [lambda(x,y=>internal code)]})",
+    "Ok(@{myadd: lambda(x,y=>internal code),z: [lambda(x,y=>internal code)]})",
   )
   testEvalToBe("myadd(x,y)=x+y; z=[myadd]; z[0]", "Ok(lambda(x,y=>internal code))")
   testEvalToBe("myadd(x,y)=x+y; z=[myadd]; z[0](3,2)", "Ok(5)")

packages/squiggle-lang/__tests__/Reducer/Reducer_test.res

@@ -39,7 +39,7 @@ describe("eval", () => {
     testEvalToBe("x=1; y=x+1; y+1", "Ok(3)")
     testEvalError("1; x=1")
     testEvalError("1; 1")
-    testEvalToBe("x=1; x=1", "Ok({x: 1})")
+    testEvalToBe("x=1; x=1", "Ok(@{x: 1})")
   })
 })
 

packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_ExpressionValue_test.res

@@ -1,4 +1,4 @@
-open ReducerInterface.ExpressionValue
+open ReducerInterface.ExternalExpressionValue
 open Jest
 open Expect
 

packages/squiggle-lang/package.json

@@ -5,8 +5,10 @@
   "license": "MIT",
   "scripts": {
     "peggy": "peggy --cache",
+    "rescript": "rescript",
     "build": "yarn build:peggy && yarn build:rescript && yarn build:typescript",
-    "build:peggy": "find . -type f -name *.peggy -exec yarn peggy {} \\;",
+    "build:peggy:helpers": "tsc --module commonjs --outDir src/rescript/Reducer/Reducer_Peggy/ src/rescript/Reducer/Reducer_Peggy/helpers.ts",
+    "build:peggy": "yarn build:peggy:helpers && find . -type f -name *.peggy -exec yarn peggy {} \\;",
     "build:rescript": "rescript build -with-deps",
     "build:typescript": "tsc",
     "bundle": "webpack",

packages/squiggle-lang/src/js/index.ts

@@ -10,7 +10,6 @@ import {
   evaluatePartialUsingExternalBindings,
   evaluateUsingOptions,
   foreignFunctionInterface,
-  parse as parseRescript,
 } from "../rescript/TypescriptInterface.gen";
 export {
   makeSampleSetDist,
@@ -32,12 +31,14 @@ import {
   convertRawToTypescript,
   lambdaValue,
 } from "./rescript_interop";
-import { Ok, result, resultMap, tag, tagged } from "./types";
+import { result, resultMap, tag, tagged } from "./types";
 import { Distribution, shape } from "./distribution";
 
 export { Distribution, resultMap, defaultEnvironment };
 export type { result, shape, environment, lambdaValue, squiggleExpression };
 
+export { parse } from "./parse";
+
 export let defaultSamplingInputs: environment = {
   sampleCount: 10000,
   xyPointLength: 10000,
@@ -59,23 +60,6 @@ export function run(
   return resultMap(res, (x) => createTsExport(x, e));
 }
 
-export function parse(
-  squiggleString: string
-): result<null, Extract<errorValue, { tag: "RESyntaxError" }>> {
-  const maybeExpression = parseRescript(squiggleString);
-  if (maybeExpression.tag === "Ok") {
-    return Ok(null); // TODO - return AST
-  } else {
-    if (
-      typeof maybeExpression.value !== "object" ||
-      maybeExpression.value.tag !== "RESyntaxError"
-    ) {
-      throw new Error("Expected syntax error");
-    }
-    return { tag: "Error", value: maybeExpression.value };
-  }
-}
-
 // Run Partial. A partial is a block of code that doesn't return a value
 export function runPartial(
   squiggleString: string,
@@ -147,30 +131,13 @@ function createTsExport(
       // case
       return tag(
         "array",
-        x.value.map((arrayItem): squiggleExpression => {
+        x.value.map(
-          switch (arrayItem.tag) {
+          (arrayItem): squiggleExpression =>
-            case "EvRecord":
+            convertRawToTypescript(
-              return tag(
+              arrayItem as unknown as rescriptExport,
-                "record",
+              environment
-                _.mapValues(arrayItem.value, (recordValue: unknown) =>
+            )
-                  convertRawToTypescript(
+        )
-                    recordValue as rescriptExport,
-                    environment
-                  )
-                )
-              );
-            case "EvArray":
-              let y = arrayItem.value as unknown as rescriptExport[];
-              return tag(
-                "array",
-                y.map((childArrayItem) =>
-                  convertRawToTypescript(childArrayItem, environment)
-                )
-              );
-            default:
-              return createTsExport(arrayItem, environment);
-          }
-        })
       );
     case "EvArrayString":
       return tag("arraystring", x.value);

packages/squiggle-lang/src/js/parse.ts

@@ -0,0 +1,23 @@
+import {
+  errorValue,
+  parse as parseRescript,
+} from "../rescript/TypescriptInterface.gen";
+import { result } from "./types";
+import { AnyPeggyNode } from "../rescript/Reducer/Reducer_Peggy/helpers";
+
+export function parse(
+  squiggleString: string
+): result<AnyPeggyNode, Extract<errorValue, { tag: "RESyntaxError" }>> {
+  const maybeExpression = parseRescript(squiggleString);
+  if (maybeExpression.tag === "Ok") {
+    return { tag: "Ok", value: maybeExpression.value as AnyPeggyNode };
+  } else {
+    if (
+      typeof maybeExpression.value !== "object" ||
+      maybeExpression.value.tag !== "RESyntaxError"
+    ) {
+      throw new Error("Expected syntax error");
+    }
+    return { tag: "Error", value: maybeExpression.value };
+  }
+}

packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res

@@ -1,3 +1,4 @@
+@@warning("-27") //TODO: Remove and fix the warning
 open Distributions
 
 type t = PointSetTypes.discreteShape

packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Mixed.res

@@ -1,3 +1,5 @@
+@@warning("-27") //TODO: Remove and fix the warning
+@@warning("-32") //TODO: Remove and fix the warning
 open Distributions
 
 type t = PointSetTypes.mixedShape

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Core.res

@@ -1,4 +1,4 @@
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type internalExpressionValue = ReducerInterface_InternalExpressionValue.t
 
 /*
   Function Registry "Type". A type, without any other information.
@@ -28,7 +28,7 @@ type rec frValue =
   | FRValueArray(array<frValue>)
   | FRValueDistOrNumber(frValueDistOrNumber)
   | FRValueRecord(frValueRecord)
-  | FRValueLambda(ReducerInterface_ExpressionValue.lambdaValue)
+  | FRValueLambda(ReducerInterface_InternalExpressionValue.lambdaValue)
   | FRValueString(string)
   | FRValueVariant(string)
   | FRValueAny(frValue)
@@ -41,7 +41,7 @@ and frValueDistOrNumber = FRValueNumber(float) | FRValueDist(DistributionTypes.g
 type fnDefinition = {
   name: string,
   inputs: array<frType>,
-  run: (array<frValue>, DistributionOperation.env) => result<expressionValue, string>,
+  run: (array<frValue>, DistributionOperation.env) => result<internalExpressionValue, string>,
 }
 
 type function = {
@@ -73,47 +73,47 @@ module FRType = {
     | FRTypeAny => `any`
     }
 
-  let rec toFrValue = (r: expressionValue): option<frValue> =>
+  let rec toFrValue = (r: internalExpressionValue): option<frValue> =>
     switch r {
-    | EvNumber(f) => Some(FRValueNumber(f))
+    | IEvNumber(f) => Some(FRValueNumber(f))
-    | EvString(f) => Some(FRValueString(f))
+    | IEvString(f) => Some(FRValueString(f))
-    | EvDistribution(f) => Some(FRValueDistOrNumber(FRValueDist(f)))
+    | IEvDistribution(f) => Some(FRValueDistOrNumber(FRValueDist(f)))
-    | EvLambda(f) => Some(FRValueLambda(f))
+    | IEvLambda(f) => Some(FRValueLambda(f))
-    | EvArray(elements) =>
+    | IEvArray(elements) =>
       elements->E.A2.fmap(toFrValue)->E.A.O.openIfAllSome->E.O2.fmap(r => FRValueArray(r))
-    | EvRecord(record) =>
+    | IEvRecord(map) =>
-      Js.Dict.entries(record)
+      Belt.Map.String.toArray(map)
       ->E.A2.fmap(((key, item)) => item->toFrValue->E.O2.fmap(o => (key, o)))
       ->E.A.O.openIfAllSome
       ->E.O2.fmap(r => FRValueRecord(r))
     | _ => None
     }
 
-  let rec matchWithExpressionValue = (t: t, r: expressionValue): option<frValue> =>
+  let rec matchWithExpressionValue = (t: t, r: internalExpressionValue): option<frValue> =>
     switch (t, r) {
     | (FRTypeAny, f) => toFrValue(f)
-    | (FRTypeString, EvString(f)) => Some(FRValueString(f))
+    | (FRTypeString, IEvString(f)) => Some(FRValueString(f))
-    | (FRTypeNumber, EvNumber(f)) => Some(FRValueNumber(f))
+    | (FRTypeNumber, IEvNumber(f)) => Some(FRValueNumber(f))
-    | (FRTypeDistOrNumber, EvNumber(f)) => Some(FRValueDistOrNumber(FRValueNumber(f)))
+    | (FRTypeDistOrNumber, IEvNumber(f)) => Some(FRValueDistOrNumber(FRValueNumber(f)))
-    | (FRTypeDistOrNumber, EvDistribution(Symbolic(#Float(f)))) =>
+    | (FRTypeDistOrNumber, IEvDistribution(Symbolic(#Float(f)))) =>
       Some(FRValueDistOrNumber(FRValueNumber(f)))
-    | (FRTypeDistOrNumber, EvDistribution(f)) => Some(FRValueDistOrNumber(FRValueDist(f)))
+    | (FRTypeDistOrNumber, IEvDistribution(f)) => Some(FRValueDistOrNumber(FRValueDist(f)))
-    | (FRTypeNumeric, EvNumber(f)) => Some(FRValueNumber(f))
+    | (FRTypeNumeric, IEvNumber(f)) => Some(FRValueNumber(f))
-    | (FRTypeNumeric, EvDistribution(Symbolic(#Float(f)))) => Some(FRValueNumber(f))
+    | (FRTypeNumeric, IEvDistribution(Symbolic(#Float(f)))) => Some(FRValueNumber(f))
-    | (FRTypeLambda, EvLambda(f)) => Some(FRValueLambda(f))
+    | (FRTypeLambda, IEvLambda(f)) => Some(FRValueLambda(f))
-    | (FRTypeArray(intendedType), EvArray(elements)) => {
+    | (FRTypeArray(intendedType), IEvArray(elements)) => {
         let el = elements->E.A2.fmap(matchWithExpressionValue(intendedType))
         E.A.O.openIfAllSome(el)->E.O2.fmap(r => FRValueArray(r))
       }
-    | (FRTypeDict(r), EvRecord(record)) =>
+    | (FRTypeDict(r), IEvRecord(map)) =>
-      record
+      map
-      ->Js.Dict.entries
+      ->Belt.Map.String.toArray
       ->E.A2.fmap(((key, item)) => matchWithExpressionValue(r, item)->E.O2.fmap(o => (key, o)))
       ->E.A.O.openIfAllSome
       ->E.O2.fmap(r => FRValueDict(Js.Dict.fromArray(r)))
-    | (FRTypeRecord(recordParams), EvRecord(record)) => {
+    | (FRTypeRecord(recordParams), IEvRecord(map)) => {
         let getAndMatch = (name, input) =>
-          E.Dict.get(record, name)->E.O.bind(matchWithExpressionValue(input))
+          Belt.Map.String.get(map, name)->E.O.bind(matchWithExpressionValue(input))
         //All names in the type must be present. If any are missing, the corresponding
         //value will be None, and this function would return None.
         let namesAndValues: array<option<(Js.Dict.key, frValue)>> =
@@ -125,35 +125,38 @@ module FRType = {
     | _ => None
     }
 
-  let rec matchReverse = (e: frValue): expressionValue =>
+  let rec matchReverse = (e: frValue): internalExpressionValue =>
     switch e {
-    | FRValueNumber(f) => EvNumber(f)
+    | FRValueNumber(f) => IEvNumber(f)
-    | FRValueDistOrNumber(FRValueNumber(n)) => EvNumber(n)
+    | FRValueDistOrNumber(FRValueNumber(n)) => IEvNumber(n)
-    | FRValueDistOrNumber(FRValueDist(n)) => EvDistribution(n)
+    | FRValueDistOrNumber(FRValueDist(n)) => IEvDistribution(n)
-    | FRValueDist(dist) => EvDistribution(dist)
+    | FRValueDist(dist) => IEvDistribution(dist)
-    | FRValueArray(elements) => EvArray(elements->E.A2.fmap(matchReverse))
+    | FRValueArray(elements) => IEvArray(elements->E.A2.fmap(matchReverse))
     | FRValueRecord(frValueRecord) => {
-        let record =
+        let map =
-          frValueRecord->E.A2.fmap(((name, value)) => (name, matchReverse(value)))->E.Dict.fromArray
+          frValueRecord
-        EvRecord(record)
+          ->E.A2.fmap(((name, value)) => (name, matchReverse(value)))
+          ->Belt.Map.String.fromArray
+        IEvRecord(map)
       }
     | FRValueDict(frValueRecord) => {
-        let record =
+        let map =
           frValueRecord
           ->Js.Dict.entries
           ->E.A2.fmap(((name, value)) => (name, matchReverse(value)))
-          ->E.Dict.fromArray
+          ->Belt.Map.String.fromArray
-        EvRecord(record)
+        IEvRecord(map)
       }
-    | FRValueLambda(l) => EvLambda(l)
+    | FRValueLambda(l) => IEvLambda(l)
-    | FRValueString(string) => EvString(string)
+    | FRValueString(string) => IEvString(string)
-    | FRValueVariant(string) => EvString(string)
+    | FRValueVariant(string) => IEvString(string)
     | FRValueAny(f) => matchReverse(f)
     }
 
-  let matchWithExpressionValueArray = (inputs: array<t>, args: array<expressionValue>): option<
+  let matchWithExpressionValueArray = (
-    array<frValue>,
+    inputs: array<t>,
-  > => {
+    args: array<internalExpressionValue>,
+  ): option<array<frValue>> => {
     let isSameLength = E.A.length(inputs) == E.A.length(args)
     if !isSameLength {
       None
@@ -204,14 +207,14 @@ module Matcher = {
   }
 
   module FnDefinition = {
-    let matchAssumingSameName = (f: fnDefinition, args: array<expressionValue>) => {
+    let matchAssumingSameName = (f: fnDefinition, args: array<internalExpressionValue>) => {
       switch FRType.matchWithExpressionValueArray(f.inputs, args) {
       | Some(_) => MatchSimple.FullMatch
       | None => MatchSimple.SameNameDifferentArguments
       }
     }
 
-    let match = (f: fnDefinition, fnName: string, args: array<expressionValue>) => {
+    let match = (f: fnDefinition, fnName: string, args: array<internalExpressionValue>) => {
       if f.name !== fnName {
         MatchSimple.DifferentName
       } else {
@@ -224,7 +227,7 @@ module Matcher = {
     type definitionId = int
     type match = Match.t<array<definitionId>, definitionId>
 
-    let match = (f: function, fnName: string, args: array<expressionValue>): match => {
+    let match = (f: function, fnName: string, args: array<internalExpressionValue>): match => {
       let matchedDefinition = () =>
         E.A.getIndexBy(f.definitions, r =>
           MatchSimple.isFullMatch(FnDefinition.match(r, fnName, args))
@@ -258,7 +261,7 @@ module Matcher = {
   }
 
   module Registry = {
-    let _findExactMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+    let _findExactMatches = (r: registry, fnName: string, args: array<internalExpressionValue>) => {
       let functionMatchPairs = r->E.A2.fmap(l => (l, Function.match(l, fnName, args)))
       let fullMatch = functionMatchPairs->E.A.getBy(((_, match)) => Match.isFullMatch(match))
       fullMatch->E.O.bind(((fn, match)) =>
@@ -269,7 +272,7 @@ module Matcher = {
       )
     }
 
-    let _findNameMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+    let _findNameMatches = (r: registry, fnName: string, args: array<internalExpressionValue>) => {
       let functionMatchPairs = r->E.A2.fmap(l => (l, Function.match(l, fnName, args)))
       let getNameMatches =
         functionMatchPairs
@@ -288,7 +291,7 @@ module Matcher = {
       E.A.toNoneIfEmpty(matches)
     }
 
-    let findMatches = (r: registry, fnName: string, args: array<expressionValue>) => {
+    let findMatches = (r: registry, fnName: string, args: array<internalExpressionValue>) => {
       switch _findExactMatches(r, fnName, args) {
       | Some(r) => Match.FullMatch(r)
       | None =>
@@ -316,7 +319,7 @@ module FnDefinition = {
     t.name ++ `(${inputs})`
   }
 
-  let run = (t: t, args: array<expressionValue>, env: DistributionOperation.env) => {
+  let run = (t: t, args: array<internalExpressionValue>, env: DistributionOperation.env) => {
     let argValues = FRType.matchWithExpressionValueArray(t.inputs, args)
     switch argValues {
     | Some(values) => t.run(values, env)
@@ -370,7 +373,7 @@ module Registry = {
   let matchAndRun = (
     ~registry: registry,
     ~fnName: string,
-    ~args: array<expressionValue>,
+    ~args: array<internalExpressionValue>,
     ~env: DistributionOperation.env,
   ) => {
     let matchToDef = m => Matcher.Registry.matchToDef(registry, m)

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Helpers.res

@@ -4,11 +4,11 @@ let impossibleError = "Wrong inputs / Logically impossible"
 
 module Wrappers = {
   let symbolic = r => DistributionTypes.Symbolic(r)
-  let evDistribution = r => ReducerInterface_ExpressionValue.EvDistribution(r)
+  let evDistribution = r => ReducerInterface_InternalExpressionValue.IEvDistribution(r)
-  let evNumber = r => ReducerInterface_ExpressionValue.EvNumber(r)
+  let evNumber = r => ReducerInterface_InternalExpressionValue.IEvNumber(r)
-  let evArray = r => ReducerInterface_ExpressionValue.EvArray(r)
+  let evArray = r => ReducerInterface_InternalExpressionValue.IEvArray(r)
-  let evRecord = r => ReducerInterface_ExpressionValue.EvRecord(r)
+  let evRecord = r => ReducerInterface_InternalExpressionValue.IEvRecord(r)
-  let evString = r => ReducerInterface_ExpressionValue.EvString(r)
+  let evString = r => ReducerInterface_InternalExpressionValue.IEvString(r)
   let symbolicEvDistribution = r => r->DistributionTypes.Symbolic->evDistribution
 }
 

packages/squiggle-lang/src/rescript/FunctionRegistry/FunctionRegistry_Library.res

@@ -9,7 +9,7 @@ module Declaration = {
     ("inputs", FRTypeArray(FRTypeRecord([("min", FRTypeNumber), ("max", FRTypeNumber)]))),
   ])
 
-  let fromExpressionValue = (e: frValue): result<expressionValue, string> => {
+  let fromExpressionValue = (e: frValue): result<internalExpressionValue, string> => {
     switch FunctionRegistry_Helpers.Prepare.ToValueArray.Record.twoArgs([e]) {
     | Ok([FRValueLambda(lambda), FRValueArray(inputs)]) => {
         open FunctionRegistry_Helpers.Prepare
@@ -20,7 +20,7 @@ module Declaration = {
         inputs
         ->E.A2.fmap(getMinMax)
         ->E.A.R.firstErrorOrOpen
-        ->E.R2.fmap(args => ReducerInterface_ExpressionValue.EvDeclaration(
+        ->E.R2.fmap(args => ReducerInterface_InternalExpressionValue.IEvDeclaration(
           Declaration.make(lambda, args),
         ))
       }
@@ -43,7 +43,9 @@ let inputsTodist = (inputs: array<FunctionRegistry_Core.frValue>, makeDist) => {
   let expressionValue =
     xyCoords
     ->E.R.bind(r => r->XYShape.T.makeFromZipped->E.R2.errMap(XYShape.Error.toString))
-    ->E.R2.fmap(r => ReducerInterface_ExpressionValue.EvDistribution(PointSet(makeDist(r))))
+    ->E.R2.fmap(r => ReducerInterface_InternalExpressionValue.IEvDistribution(
+      PointSet(makeDist(r)),
+    ))
   expressionValue
 }
 
@@ -369,7 +371,7 @@ to(5,10)
                 E.Dict.concat(d1, d2) |> Js.Dict.map((. r) =>
                   FunctionRegistry_Core.FRType.matchReverse(r)
                 )
-              newDict->Wrappers.evRecord->Ok
+              newDict->Js.Dict.entries->Belt.Map.String.fromArray->Wrappers.evRecord->Ok
             }
           | _ => Error(impossibleError)
           }
@@ -390,6 +392,7 @@ to(5,10)
         ->Prepare.ToTypedArray.dicts
         ->E.R2.fmap(E.Dict.concatMany)
         ->E.R2.fmap(Js.Dict.map((. r) => FunctionRegistry_Core.FRType.matchReverse(r)))
+        ->E.R2.fmap(r => r->Js.Dict.entries->Belt.Map.String.fromArray)
         ->E.R2.fmap(Wrappers.evRecord)
       ),
     ],
@@ -462,7 +465,7 @@ to(5,10)
             }
           })
           ->E.A.R.firstErrorOrOpen
-          ->E.R2.fmap(Js.Dict.fromArray)
+          ->E.R2.fmap(Belt.Map.String.fromArray)
           ->E.R2.fmap(Wrappers.evRecord)
         inputs->getOrError(0)->E.R.bind(Prepare.ToValueArray.Array.arrayOfArrays)
           |> E.R2.bind(convertInternalItems)

packages/squiggle-lang/src/rescript/Reducer/Reducer.res

@@ -1,13 +1,14 @@
 module ErrorValue = Reducer_ErrorValue
 module Expression = Reducer_Expression
-module ExpressionValue = ReducerInterface_ExpressionValue
+module ExternalExpressionValue = ReducerInterface_ExternalExpressionValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Lambda = Reducer_Expression_Lambda
 
-type environment = ReducerInterface_ExpressionValue.environment
+type environment = ReducerInterface_InternalExpressionValue.environment
 type errorValue = Reducer_ErrorValue.errorValue
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type expressionValue = ExternalExpressionValue.t
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type externalBindings = ReducerInterface_ExternalExpressionValue.externalBindings
-type lambdaValue = ExpressionValue.lambdaValue
+type lambdaValue = ExternalExpressionValue.lambdaValue
 
 let evaluate = Expression.evaluate
 let evaluateUsingOptions = Expression.evaluateUsingOptions
@@ -15,13 +16,20 @@ let evaluatePartialUsingExternalBindings = Expression.evaluatePartialUsingExtern
 let parse = Expression.parse
 
 let foreignFunctionInterface = (
-  lambdaValue: lambdaValue,
+  lambdaValue: ExternalExpressionValue.lambdaValue,
   argArray: array<expressionValue>,
-  environment: ExpressionValue.environment,
+  environment: ExternalExpressionValue.environment,
 ) => {
-  Lambda.foreignFunctionInterface(lambdaValue, argArray, environment, Expression.reduceExpression)
+  let internallambdaValue = InternalExpressionValue.lambdaValueToInternal(lambdaValue)
+  let internalArgArray = argArray->Js.Array2.map(InternalExpressionValue.toInternal)
+  Lambda.foreignFunctionInterface(
+    internallambdaValue,
+    internalArgArray,
+    environment,
+    Expression.reduceExpression,
+  )->Belt.Result.map(InternalExpressionValue.toExternal)
 }
 
-let defaultEnvironment = ExpressionValue.defaultEnvironment
+let defaultEnvironment = ExternalExpressionValue.defaultEnvironment
 
 let defaultExternalBindings = ReducerInterface_StdLib.externalStdLib

packages/squiggle-lang/src/rescript/Reducer/Reducer.resi

@@ -2,27 +2,29 @@ module ErrorValue = Reducer_ErrorValue
 module Expression = Reducer_Expression
 
 @genType
-type environment = ReducerInterface_ExpressionValue.environment
+type environment = ReducerInterface_ExternalExpressionValue.environment
 @genType
 type errorValue = Reducer_ErrorValue.errorValue
 @genType
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type expressionValue = ReducerInterface_ExternalExpressionValue.t
 @genType
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type externalBindings = ReducerInterface_ExternalExpressionValue.externalBindings
 @genType
-type lambdaValue = ReducerInterface_ExpressionValue.lambdaValue
+type lambdaValue = ReducerInterface_ExternalExpressionValue.lambdaValue
 
 @genType
 let evaluateUsingOptions: (
-  ~environment: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.environment>,
+  ~environment: option<QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.environment>,
-  ~externalBindings: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.externalBindings>,
+  ~externalBindings: option<
+    QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.externalBindings,
+  >,
   string,
 ) => result<expressionValue, errorValue>
 @genType
 let evaluatePartialUsingExternalBindings: (
   string,
-  QuriSquiggleLang.ReducerInterface_ExpressionValue.externalBindings,
+  QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.externalBindings,
-  QuriSquiggleLang.ReducerInterface_ExpressionValue.environment,
+  QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.environment,
 ) => result<externalBindings, errorValue>
 @genType
 let evaluate: string => result<expressionValue, errorValue>
@@ -31,9 +33,9 @@ let parse: string => result<Expression.expression, errorValue>
 
 @genType
 let foreignFunctionInterface: (
-  QuriSquiggleLang.ReducerInterface_ExpressionValue.lambdaValue,
+  QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.lambdaValue,
-  array<QuriSquiggleLang.ReducerInterface_ExpressionValue.expressionValue>,
+  array<QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.t>,
-  QuriSquiggleLang.ReducerInterface_ExpressionValue.environment,
+  QuriSquiggleLang.ReducerInterface_ExternalExpressionValue.environment,
 ) => result<expressionValue, errorValue>
 
 @genType

packages/squiggle-lang/src/rescript/Reducer/Reducer_Category/Reducer_Category_Bindings.res

@@ -1,12 +0,0 @@
-include Reducer_Category_Module // Bindings inherit from Module
-
-open ReducerInterface_ExpressionValue
-
-let emptyBindings = emptyModule
-
-let toExpressionValue = (container: t): expressionValue => EvRecord(toRecord(container))
-let fromExpressionValue = (aValue: expressionValue): t =>
-  switch aValue {
-  | EvRecord(r) => fromRecord(r)
-  | _ => emptyBindings
-  }

packages/squiggle-lang/src/rescript/Reducer/Reducer_Category/Reducer_Category_Module.res

@@ -1,33 +1,112 @@
 module ExpressionT = Reducer_Expression_T
-open ReducerInterface_ExpressionValue
+open ReducerInterface_InternalExpressionValue
 let expressionValueToString = toString
 
-type t = ExpressionT.bindings
+type t = ReducerInterface_InternalExpressionValue.nameSpace
 
 let typeAliasesKey = "_typeAliases_"
 let typeReferencesKey = "_typeReferences_"
 
-let emptyModule: t = Belt.Map.String.empty
+let getType = (nameSpace: t, id: string) => {
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.get(container, typeAliasesKey)->Belt.Option.flatMap(aliases =>
+    switch aliases {
+    | IEvRecord(r) => Belt.Map.String.get(r, id)
+    | _ => None
+    }
+  )
+}
 
-let cloneRecord = (r: record): record => r->Js.Dict.entries->Js.Dict.fromArray
+let getTypeOf = (nameSpace: t, id: string) => {
-let fromRecord = (r: record): t => Js.Dict.entries(r)->Belt.Map.String.fromArray
+  let NameSpace(container) = nameSpace
-let toRecord = (container: t): record => Belt.Map.String.toArray(container)->Js.Dict.fromArray
+  Belt.Map.String.get(container, typeReferencesKey)->Belt.Option.flatMap(defs =>
+    switch defs {
+    | IEvRecord(r) => Belt.Map.String.get(r, id)
+    | _ => None
+    }
+  )
+}
 
-let toExpressionValue = (container: t): expressionValue => EvModule(toRecord(container))
+let getWithDefault = (nameSpace: t, id: string, default) => {
-let fromExpressionValue = (aValue: expressionValue): t =>
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.getWithDefault(container, id, default)
+}
+
+let get = (nameSpace: t, id: string) => {
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.get(container, id)
+}
+
+let emptyMap: map = Belt.Map.String.empty
+
+let setTypeAlias = (nameSpace: t, id: string, value): t => {
+  let NameSpace(container) = nameSpace
+  let rValue = Belt.Map.String.getWithDefault(container, typeAliasesKey, IEvRecord(emptyMap))
+  let r = switch rValue {
+  | IEvRecord(r) => r
+  | _ => emptyMap
+  }
+  let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
+  Belt.Map.String.set(container, typeAliasesKey, r2)->NameSpace
+}
+
+let setTypeOf = (nameSpace: t, id: string, value): t => {
+  let NameSpace(container) = nameSpace
+  let rValue = Belt.Map.String.getWithDefault(container, typeReferencesKey, IEvRecord(emptyMap))
+  let r = switch rValue {
+  | IEvRecord(r) => r
+  | _ => emptyMap
+  }
+  let r2 = Belt.Map.String.set(r, id, value)->IEvRecord
+  Belt.Map.String.set(container, typeReferencesKey, r2)->NameSpace
+}
+
+let set = (nameSpace: t, id: string, value): t => {
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.set(container, id, value)->NameSpace
+}
+
+let emptyModule: t = NameSpace(Belt.Map.String.empty)
+
+let fromTypeScriptBindings = ReducerInterface_InternalExpressionValue.nameSpaceFromTypeScriptBindings
+let toTypeScriptBindings = ReducerInterface_InternalExpressionValue.nameSpaceToTypeScriptBindings
+
+let toExpressionValue = (nameSpace: t): internalExpressionValue => IEvModule(nameSpace)
+let fromExpressionValue = (aValue: internalExpressionValue): t =>
   switch aValue {
-  | EvModule(r) => fromRecord(r)
+  | IEvModule(nameSpace) => nameSpace
   | _ => emptyModule
   }
 
-let toString = (container: t): string => container->toRecord->EvRecord->expressionValueToString
+let fromArray = a => Belt.Map.String.fromArray(a)->NameSpace
+
+let merge = (nameSpace: t, other: t): t => {
+  let NameSpace(container) = nameSpace
+  let NameSpace(otherContainer) = other
+  otherContainer
+  ->Belt.Map.String.reduce(container, (container, key, value) =>
+    Belt.Map.String.set(container, key, value)
+  )
+  ->NameSpace
+}
+
+let removeOther = (nameSpace: t, other: t): t => {
+  let NameSpace(container) = nameSpace
+  let NameSpace(otherContainer) = other
+  let keys = Belt.Map.String.keysToArray(otherContainer)
+  Belt.Map.String.keep(container, (key, _value) => {
+    let removeThis = Js.Array2.includes(keys, key)
+    !removeThis
+  })->NameSpace
+}
 
 // -- Module definition
-let define = (container: t, identifier: string, ev: expressionValue): t =>
+let define = (nameSpace: t, identifier: string, ev: internalExpressionValue): t => {
-  Belt.Map.String.set(container, identifier, ev) // TODO build lambda for polymorphic functions here
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.set(container, identifier, ev)->NameSpace // TODO build lambda for polymorphic functions here
+}
+let defineNumber = (nameSpace: t, identifier: string, value: float): t =>
+  nameSpace->define(identifier, IEvNumber(value))
 
-let defineNumber = (container: t, identifier: string, value: float): t =>
+let defineModule = (nameSpace: t, identifier: string, value: t): t =>
-  container->define(identifier, EvNumber(value))
+  nameSpace->define(identifier, toExpressionValue(value))
-
-let defineModule = (container: t, identifier: string, value: t): t =>
-  container->define(identifier, toExpressionValue(value))

packages/squiggle-lang/src/rescript/Reducer/Reducer_Category/Reducer_Category_Module_TypeChecker.res

@@ -0,0 +1,16 @@
+module ExpressionValue = ReducerInterface_InternalExpressionValue
+module ExpressionT = Reducer_Expression_T
+open ExpressionValue
+
+let isOfResolvedType = (aType, aValue) => {
+  let caseTypeIdentifier = (aTypeIdentifier0, aValue) => {
+    let valueType = aValue->valueToValueType->valueTypeToString->Js.String2.toLowerCase
+    let aTypeIdentifier = aTypeIdentifier0->Js.String2.toLowerCase
+    aTypeIdentifier === valueType
+  }
+
+  switch aType {
+  | IEvTypeIdentifier(aTypeIdentifier) => caseTypeIdentifier(aTypeIdentifier, aValue)
+  | _ => false
+  }
+}

packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res

@@ -1,10 +1,11 @@
-module Bindings = Reducer_Expression_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
 module ExpressionT = Reducer_Expression_T
 module ExternalLibrary = ReducerInterface.ExternalLibrary
 module Lambda = Reducer_Expression_Lambda
 module MathJs = Reducer_MathJs
+module Module = Reducer_Category_Module
 module Result = Belt.Result
-open ReducerInterface.ExpressionValue
+open ReducerInterface_InternalExpressionValue
 open Reducer_ErrorValue
 
 /*
@@ -31,23 +32,29 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
   let constructRecord = arrayOfPairs => {
     Belt.Array.map(arrayOfPairs, pairValue =>
       switch pairValue {
-      | EvArray([EvString(key), valueValue]) => (key, valueValue)
+      | IEvArray([IEvString(key), valueValue]) => (key, valueValue)
-      | _ => ("wrong key type", pairValue->toStringWithType->EvString)
+      | _ => ("wrong key type", pairValue->toStringWithType->IEvString)
       }
     )
-    ->Js.Dict.fromArray
+    ->Belt.Map.String.fromArray
-    ->EvRecord
+    ->IEvRecord
     ->Ok
   }
 
-  let arrayAtIndex = (aValueArray: array<expressionValue>, fIndex: float) =>
+  let arrayAtIndex = (aValueArray: array<internalExpressionValue>, fIndex: float) =>
     switch Belt.Array.get(aValueArray, Belt.Int.fromFloat(fIndex)) {
     | Some(value) => value->Ok
     | None => REArrayIndexNotFound("Array index not found", Belt.Int.fromFloat(fIndex))->Error
     }
 
-  let recordAtIndex = (dict: Js.Dict.t<expressionValue>, sIndex) =>
+  let moduleAtIndex = (nameSpace: nameSpace, sIndex) =>
-    switch Js.Dict.get(dict, sIndex) {
+    switch Module.get(nameSpace, sIndex) {
+    | Some(value) => value->Ok
+    | None => RERecordPropertyNotFound("Module property not found", sIndex)->Error
+    }
+
+  let recordAtIndex = (dict: Belt.Map.String.t<internalExpressionValue>, sIndex) =>
+    switch Belt.Map.String.get(dict, sIndex) {
     | Some(value) => value->Ok
     | None => RERecordPropertyNotFound("Record property not found", sIndex)->Error
     }
@@ -55,70 +62,37 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
   let doAddArray = (originalA, b) => {
     let a = originalA->Js.Array2.copy
     let _ = Js.Array2.pushMany(a, b)
-    a->EvArray->Ok
+    a->IEvArray->Ok
   }
   let doAddString = (a, b) => {
     let answer = Js.String2.concat(a, b)
-    answer->EvString->Ok
+    answer->IEvString->Ok
   }
 
-  let inspect = (value: expressionValue) => {
+  let inspect = (value: internalExpressionValue) => {
     Js.log(value->toString)
     value->Ok
   }
 
-  let inspectLabel = (value: expressionValue, label: string) => {
+  let inspectLabel = (value: internalExpressionValue, label: string) => {
     Js.log(`${label}: ${value->toString}`)
     value->Ok
   }
 
-  let doSetBindings = (
+  let doSetBindings = (bindings: nameSpace, symbol: string, value: internalExpressionValue) => {
-    externalBindings: externalBindings,
+    Module.set(bindings, symbol, value)->IEvModule->Ok
-    symbol: string,
-    value: expressionValue,
-  ) => {
-    Bindings.fromExternalBindings(externalBindings)
-    ->Belt.Map.String.set(symbol, value)
-    ->Bindings.toExternalBindings
-    ->EvRecord
-    ->Ok
-  }
-
-  let doSetBindingsInNamespace = (
-    externalBindings: externalBindings,
-    symbol: string,
-    value: expressionValue,
-    namespace: string,
-  ) => {
-    let bindings = Bindings.fromExternalBindings(externalBindings)
-    let evAliases = bindings->Belt.Map.String.getWithDefault(namespace, EvRecord(Js.Dict.empty()))
-    let newEvAliases = switch evAliases {
-    | EvRecord(dict) => {
-        Js.Dict.set(dict, symbol, value)
-        dict->EvRecord
-      }
-    | _ => Js.Dict.empty()->EvRecord
-    }
-    bindings
-    ->Belt.Map.String.set(namespace, newEvAliases)
-    ->Bindings.toExternalBindings
-    ->EvRecord
-    ->Ok
   }
 
   let doSetTypeAliasBindings = (
-    externalBindings: externalBindings,
+    bindings: nameSpace,
     symbol: string,
-    value: expressionValue,
+    value: internalExpressionValue,
-  ) => doSetBindingsInNamespace(externalBindings, symbol, value, Bindings.typeAliasesKey)
+  ) => Module.setTypeAlias(bindings, symbol, value)->IEvModule->Ok
 
-  let doSetTypeOfBindings = (
+  let doSetTypeOfBindings = (bindings: nameSpace, symbol: string, value: internalExpressionValue) =>
-    externalBindings: externalBindings,
+    Module.setTypeOf(bindings, symbol, value)->IEvModule->Ok
-    symbol: string,
-    value: expressionValue,
-  ) => doSetBindingsInNamespace(externalBindings, symbol, value, Bindings.typeReferencesKey)
 
-  let doExportBindings = (externalBindings: externalBindings) => EvRecord(externalBindings)->Ok
+  let doExportBindings = (bindings: nameSpace) => bindings->Module.toExpressionValue->Ok
 
   let doKeepArray = (aValueArray, aLambdaValue) => {
     let rMappedList = aValueArray->Belt.Array.reduceReverse(Ok(list{}), (rAcc, elem) =>
@@ -126,13 +100,13 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
         let rNewElem = Lambda.doLambdaCall(aLambdaValue, list{elem}, environment, reducer)
         rNewElem->Result.map(newElem =>
           switch newElem {
-          | EvBool(true) => list{elem, ...acc}
+          | IEvBool(true) => list{elem, ...acc}
           | _ => acc
           }
         )
       })
     )
-    rMappedList->Result.map(mappedList => mappedList->Belt.List.toArray->EvArray)
+    rMappedList->Result.map(mappedList => mappedList->Belt.List.toArray->IEvArray)
   }
 
   let doMapArray = (aValueArray, aLambdaValue) => {
@@ -142,35 +116,36 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
         rNewElem->Result.map(newElem => list{newElem, ...acc})
       })
     )
-    rMappedList->Result.map(mappedList => mappedList->Belt.List.toArray->EvArray)
+    rMappedList->Result.map(mappedList => mappedList->Belt.List.toArray->IEvArray)
   }
 
   module SampleMap = {
     type t = SampleSetDist.t
     let doLambdaCall = (aLambdaValue, list) =>
       switch Lambda.doLambdaCall(aLambdaValue, list, environment, reducer) {
-      | Ok(EvNumber(f)) => Ok(f)
+      | Ok(IEvNumber(f)) => Ok(f)
       | _ => Error(Operation.SampleMapNeedsNtoNFunction)
       }
 
     let toType = r =>
       switch r {
-      | Ok(r) => Ok(EvDistribution(SampleSet(r)))
+      | Ok(r) => Ok(IEvDistribution(SampleSet(r)))
       | Error(r) => Error(REDistributionError(SampleSetError(r)))
       }
 
     let map1 = (sampleSetDist: t, aLambdaValue) => {
-      let fn = r => doLambdaCall(aLambdaValue, list{EvNumber(r)})
+      let fn = r => doLambdaCall(aLambdaValue, list{IEvNumber(r)})
       toType(SampleSetDist.samplesMap(~fn, sampleSetDist))
     }
 
     let map2 = (t1: t, t2: t, aLambdaValue) => {
-      let fn = (a, b) => doLambdaCall(aLambdaValue, list{EvNumber(a), EvNumber(b)})
+      let fn = (a, b) => doLambdaCall(aLambdaValue, list{IEvNumber(a), IEvNumber(b)})
       SampleSetDist.map2(~fn, ~t1, ~t2)->toType
     }
 
     let map3 = (t1: t, t2: t, t3: t, aLambdaValue) => {
-      let fn = (a, b, c) => doLambdaCall(aLambdaValue, list{EvNumber(a), EvNumber(b), EvNumber(c)})
+      let fn = (a, b, c) =>
+        doLambdaCall(aLambdaValue, list{IEvNumber(a), IEvNumber(b), IEvNumber(c)})
       SampleSetDist.map3(~fn, ~t1, ~t2, ~t3)->toType
     }
   }
@@ -192,132 +167,128 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
   }
 
   let typeModifier_memberOf = (aType, anArray) => {
-    let newRecord = Js.Dict.fromArray([
+    let newRecord = Belt.Map.String.fromArray([
-      ("typeTag", EvString("typeIdentifier")),
+      ("typeTag", IEvString("typeIdentifier")),
       ("typeIdentifier", aType),
     ])
-    newRecord->Js.Dict.set("memberOf", anArray)
+    newRecord->Belt.Map.String.set("memberOf", anArray)->IEvRecord->Ok
-    newRecord->EvRecord->Ok
   }
   let typeModifier_memberOf_update = (aRecord, anArray) => {
-    let newRecord = aRecord->Js.Dict.entries->Js.Dict.fromArray
+    aRecord->Belt.Map.String.set("memberOf", anArray)->IEvRecord->Ok
-    newRecord->Js.Dict.set("memberOf", anArray)
-    newRecord->EvRecord->Ok
   }
 
   let typeModifier_min = (aType, value) => {
-    let newRecord = Js.Dict.fromArray([
+    let newRecord = Belt.Map.String.fromArray([
-      ("typeTag", EvString("typeIdentifier")),
+      ("typeTag", IEvString("typeIdentifier")),
       ("typeIdentifier", aType),
     ])
-    newRecord->Js.Dict.set("min", value)
+    newRecord->Belt.Map.String.set("min", value)->IEvRecord->Ok
-    newRecord->EvRecord->Ok
   }
   let typeModifier_min_update = (aRecord, value) => {
-    let newRecord = aRecord->Js.Dict.entries->Js.Dict.fromArray
+    aRecord->Belt.Map.String.set("min", value)->IEvRecord->Ok
-    newRecord->Js.Dict.set("min", value)
-    newRecord->EvRecord->Ok
   }
 
   let typeModifier_max = (aType, value) => {
-    let newRecord = Js.Dict.fromArray([
+    let newRecord = Belt.Map.String.fromArray([
-      ("typeTag", EvString("typeIdentifier")),
+      ("typeTag", IEvString("typeIdentifier")),
       ("typeIdentifier", aType),
     ])
-    newRecord->Js.Dict.set("max", value)
+    newRecord->Belt.Map.String.set("max", value)->IEvRecord->Ok
-    newRecord->EvRecord->Ok
-  }
-  let typeModifier_max_update = (aRecord, value) => {
-    let newRecord = aRecord->Js.Dict.entries->Js.Dict.fromArray
-    newRecord->Js.Dict.set("max", value)
-    newRecord->EvRecord->Ok
   }
+  let typeModifier_max_update = (aRecord, value) =>
+    aRecord->Belt.Map.String.set("max", value)->IEvRecord->Ok
 
-  let typeModifier_opaque_update = aRecord => {
+  let typeModifier_opaque_update = aRecord =>
-    let newRecord = aRecord->Js.Dict.entries->Js.Dict.fromArray
+    aRecord->Belt.Map.String.set("opaque", IEvBool(true))->IEvRecord->Ok
-    newRecord->Js.Dict.set("opaque", EvBool(true))
-    newRecord->EvRecord->Ok
-  }
 
   let typeOr = evArray => {
-    let newRecord = Js.Dict.fromArray([("typeTag", EvString("typeOr")), ("typeOr", evArray)])
+    let newRecord = Belt.Map.String.fromArray([
-    newRecord->EvRecord->Ok
+      ("typeTag", IEvString("typeOr")),
+      ("typeOr", evArray),
+    ])
+    newRecord->IEvRecord->Ok
   }
   let typeFunction = anArray => {
     let output = Belt.Array.getUnsafe(anArray, Js.Array2.length(anArray) - 1)
     let inputs = Js.Array2.slice(anArray, ~start=0, ~end_=-1)
-    let newRecord = Js.Dict.fromArray([
+    let newRecord = Belt.Map.String.fromArray([
-      ("typeTag", EvString("typeFunction")),
+      ("typeTag", IEvString("typeFunction")),
-      ("inputs", EvArray(inputs)),
+      ("inputs", IEvArray(inputs)),
       ("output", output),
     ])
-    newRecord->EvRecord->Ok
+    newRecord->IEvRecord->Ok
   }
 
   switch call {
-  | ("$_atIndex_$", [EvArray(aValueArray), EvNumber(fIndex)]) => arrayAtIndex(aValueArray, fIndex)
+  | ("$_atIndex_$", [IEvArray(aValueArray), IEvNumber(fIndex)]) => arrayAtIndex(aValueArray, fIndex)
-  | ("$_atIndex_$", [EvModule(dict), EvString(sIndex)]) => recordAtIndex(dict, sIndex)
+  | ("$_atIndex_$", [IEvModule(dict), IEvString(sIndex)]) => moduleAtIndex(dict, sIndex)
-  | ("$_atIndex_$", [EvRecord(dict), EvString(sIndex)]) => recordAtIndex(dict, sIndex)
+  | ("$_atIndex_$", [IEvRecord(dict), IEvString(sIndex)]) => recordAtIndex(dict, sIndex)
-  | ("$_constructArray_$", [EvArray(aValueArray)]) => EvArray(aValueArray)->Ok
+  | ("$_constructArray_$", [IEvArray(aValueArray)]) => IEvArray(aValueArray)->Ok
-  | ("$_constructRecord_$", [EvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
+  | ("$_constructRecord_$", [IEvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
-  | ("$_exportBindings_$", [EvRecord(externalBindings)]) => doExportBindings(externalBindings)
+  | ("$_exportBindings_$", [IEvModule(nameSpace)]) => doExportBindings(nameSpace)
-  | ("$_setBindings_$", [EvRecord(externalBindings), EvSymbol(symbol), value]) =>
+  | ("$_setBindings_$", [IEvModule(nameSpace), IEvSymbol(symbol), value]) =>
-    doSetBindings(externalBindings, symbol, value)
+    doSetBindings(nameSpace, symbol, value)
-  | ("$_setTypeAliasBindings_$", [EvRecord(externalBindings), EvTypeIdentifier(symbol), value]) =>
+  | ("$_setTypeAliasBindings_$", [IEvModule(nameSpace), IEvTypeIdentifier(symbol), value]) =>
-    doSetTypeAliasBindings(externalBindings, symbol, value)
+    doSetTypeAliasBindings(nameSpace, symbol, value)
-  | ("$_setTypeOfBindings_$", [EvRecord(externalBindings), EvSymbol(symbol), value]) =>
+  | ("$_setTypeOfBindings_$", [IEvModule(nameSpace), IEvSymbol(symbol), value]) =>
-    doSetTypeOfBindings(externalBindings, symbol, value)
+    doSetTypeOfBindings(nameSpace, symbol, value)
-  | ("$_typeModifier_memberOf_$", [EvTypeIdentifier(typeIdentifier), EvArray(arr)]) =>
+  | ("$_typeModifier_memberOf_$", [IEvTypeIdentifier(typeIdentifier), IEvArray(arr)]) =>
-    typeModifier_memberOf(EvTypeIdentifier(typeIdentifier), EvArray(arr))
+    typeModifier_memberOf(IEvTypeIdentifier(typeIdentifier), IEvArray(arr))
-  | ("$_typeModifier_memberOf_$", [EvRecord(typeRecord), EvArray(arr)]) =>
+  | ("$_typeModifier_memberOf_$", [IEvRecord(typeRecord), IEvArray(arr)]) =>
-    typeModifier_memberOf_update(typeRecord, EvArray(arr))
+    typeModifier_memberOf_update(typeRecord, IEvArray(arr))
-  | ("$_typeModifier_min_$", [EvTypeIdentifier(typeIdentifier), value]) =>
+  | ("$_typeModifier_min_$", [IEvTypeIdentifier(typeIdentifier), value]) =>
-    typeModifier_min(EvTypeIdentifier(typeIdentifier), value)
+    typeModifier_min(IEvTypeIdentifier(typeIdentifier), value)
-  | ("$_typeModifier_min_$", [EvRecord(typeRecord), value]) =>
+  | ("$_typeModifier_min_$", [IEvRecord(typeRecord), value]) =>
     typeModifier_min_update(typeRecord, value)
-  | ("$_typeModifier_max_$", [EvTypeIdentifier(typeIdentifier), value]) =>
+  | ("$_typeModifier_max_$", [IEvTypeIdentifier(typeIdentifier), value]) =>
-    typeModifier_max(EvTypeIdentifier(typeIdentifier), value)
+    typeModifier_max(IEvTypeIdentifier(typeIdentifier), value)
-  | ("$_typeModifier_max_$", [EvRecord(typeRecord), value]) =>
+  | ("$_typeModifier_max_$", [IEvRecord(typeRecord), value]) =>
     typeModifier_max_update(typeRecord, value)
-  | ("$_typeModifier_opaque_$", [EvRecord(typeRecord)]) => typeModifier_opaque_update(typeRecord)
+  | ("$_typeModifier_opaque_$", [IEvRecord(typeRecord)]) => typeModifier_opaque_update(typeRecord)
-  | ("$_typeOr_$", [EvArray(arr)]) => typeOr(EvArray(arr))
+  | ("$_typeOr_$", [IEvArray(arr)]) => typeOr(IEvArray(arr))
-  | ("$_typeFunction_$", [EvArray(arr)]) => typeFunction(arr)
+  | ("$_typeFunction_$", [IEvArray(arr)]) => typeFunction(arr)
-  | ("concat", [EvArray(aValueArray), EvArray(bValueArray)]) => doAddArray(aValueArray, bValueArray)
+  | ("concat", [IEvArray(aValueArray), IEvArray(bValueArray)]) =>
-  | ("concat", [EvString(aValueString), EvString(bValueString)]) =>
+    doAddArray(aValueArray, bValueArray)
+  | ("concat", [IEvString(aValueString), IEvString(bValueString)]) =>
     doAddString(aValueString, bValueString)
-  | ("inspect", [value, EvString(label)]) => inspectLabel(value, label)
+  | ("inspect", [value, IEvString(label)]) => inspectLabel(value, label)
   | ("inspect", [value]) => inspect(value)
-  | ("filter", [EvArray(aValueArray), EvLambda(aLambdaValue)]) =>
+  | ("filter", [IEvArray(aValueArray), IEvLambda(aLambdaValue)]) =>
     doKeepArray(aValueArray, aLambdaValue)
-  | ("map", [EvArray(aValueArray), EvLambda(aLambdaValue)]) => doMapArray(aValueArray, aLambdaValue)
+  | ("map", [IEvArray(aValueArray), IEvLambda(aLambdaValue)]) =>
-  | ("mapSamples", [EvDistribution(SampleSet(dist)), EvLambda(aLambdaValue)]) =>
+    doMapArray(aValueArray, aLambdaValue)
+  | ("mapSamples", [IEvDistribution(SampleSet(dist)), IEvLambda(aLambdaValue)]) =>
     SampleMap.map1(dist, aLambdaValue)
   | (
       "mapSamples2",
-      [EvDistribution(SampleSet(dist1)), EvDistribution(SampleSet(dist2)), EvLambda(aLambdaValue)],
+      [
+        IEvDistribution(SampleSet(dist1)),
+        IEvDistribution(SampleSet(dist2)),
+        IEvLambda(aLambdaValue),
+      ],
     ) =>
     SampleMap.map2(dist1, dist2, aLambdaValue)
   | (
       "mapSamples3",
       [
-        EvDistribution(SampleSet(dist1)),
+        IEvDistribution(SampleSet(dist1)),
-        EvDistribution(SampleSet(dist2)),
+        IEvDistribution(SampleSet(dist2)),
-        EvDistribution(SampleSet(dist3)),
+        IEvDistribution(SampleSet(dist3)),
-        EvLambda(aLambdaValue),
+        IEvLambda(aLambdaValue),
       ],
     ) =>
     SampleMap.map3(dist1, dist2, dist3, aLambdaValue)
-  | ("reduce", [EvArray(aValueArray), initialValue, EvLambda(aLambdaValue)]) =>
+  | ("reduce", [IEvArray(aValueArray), initialValue, IEvLambda(aLambdaValue)]) =>
     doReduceArray(aValueArray, initialValue, aLambdaValue)
-  | ("reduceReverse", [EvArray(aValueArray), initialValue, EvLambda(aLambdaValue)]) =>
+  | ("reduceReverse", [IEvArray(aValueArray), initialValue, IEvLambda(aLambdaValue)]) =>
     doReduceReverseArray(aValueArray, initialValue, aLambdaValue)
-  | ("reverse", [EvArray(aValueArray)]) => aValueArray->Belt.Array.reverse->EvArray->Ok
+  | ("reverse", [IEvArray(aValueArray)]) => aValueArray->Belt.Array.reverse->IEvArray->Ok
-  | (_, [EvBool(_)])
+  | (_, [IEvBool(_)])
-  | (_, [EvNumber(_)])
+  | (_, [IEvNumber(_)])
-  | (_, [EvString(_)])
+  | (_, [IEvString(_)])
-  | (_, [EvBool(_), EvBool(_)])
+  | (_, [IEvBool(_), IEvBool(_)])
-  | (_, [EvNumber(_), EvNumber(_)])
+  | (_, [IEvNumber(_), IEvNumber(_)])
-  | (_, [EvString(_), EvString(_)]) =>
+  | (_, [IEvString(_), IEvString(_)]) =>
     callMathJs(call)
   | call =>
     Error(REFunctionNotFound(call->functionCallToCallSignature->functionCallSignatureToString)) // Report full type signature as error
@@ -328,7 +299,7 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
   Reducer uses Result monad while reducing expressions
 */
 let dispatch = (call: functionCall, environment, reducer: ExpressionT.reducerFn): result<
-  expressionValue,
+  internalExpressionValue,
   errorValue,
 > =>
   try {

packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltInMacros.res

@@ -3,19 +3,19 @@
   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 BindingsReplacer = Reducer_Expression_BindingsReplacer
 module ErrorValue = Reducer_ErrorValue
 module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module ExpressionWithContext = Reducer_ExpressionWithContext
+module Module = Reducer_Category_Module
 module Result = Belt.Result
 open Reducer_Expression_ExpressionBuilder
 
-type environment = ExpressionValue.environment
+type environment = InternalExpressionValue.environment
 type errorValue = ErrorValue.errorValue
 type expression = ExpressionT.expression
-type expressionValue = ExpressionValue.expressionValue
 type expressionWithContext = ExpressionWithContext.expressionWithContext
 
 let dispatchMacroCall = (
@@ -27,13 +27,13 @@ let dispatchMacroCall = (
   let useExpressionToSetBindings = (bindingExpr: expression, environment, statement, newCode) => {
     let rExternalBindingsValue = reduceExpression(bindingExpr, bindings, environment)
 
-    rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+    rExternalBindingsValue->Result.flatMap(nameSpaceValue => {
-      let newBindings = Bindings.fromValue(externalBindingsValue)
+      let newBindings = Module.fromExpressionValue(nameSpaceValue)
 
-      let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+      let rNewStatement = BindingsReplacer.replaceSymbols(newBindings, statement)
       rNewStatement->Result.map(boundStatement =>
         ExpressionWithContext.withContext(
-          newCode(newBindings->Bindings.toExternalBindings->eRecord, boundStatement),
+          newCode(newBindings->eModule, boundStatement),
           newBindings,
         )
       )
@@ -51,7 +51,7 @@ let dispatchMacroCall = (
   let doBindStatement = (bindingExpr: expression, statement: expression, environment) => {
     let defaultStatement = ErrorValue.REAssignmentExpected->Error
     switch statement {
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall(callName)), symbolExpr, statement}) => {
+    | ExpressionT.EList(list{ExpressionT.EValue(IEvCall(callName)), symbolExpr, statement}) => {
         let setBindingsFn = correspondingSetBindingsFn(callName)
         if setBindingsFn !== "" {
           useExpressionToSetBindings(bindingExpr, environment, statement, (
@@ -77,7 +77,7 @@ let dispatchMacroCall = (
       ) => boundStatement)
 
     switch statement {
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall(callName)), symbolExpr, statement}) => {
+    | ExpressionT.EList(list{ExpressionT.EValue(IEvCall(callName)), symbolExpr, statement}) => {
         let setBindingsFn = correspondingSetBindingsFn(callName)
         if setBindingsFn !== "" {
           useExpressionToSetBindings(bindingExpr, environment, statement, (
@@ -123,10 +123,7 @@ let dispatchMacroCall = (
     bindings: ExpressionT.bindings,
     parameters: array<string>,
     lambdaDefinition: ExpressionT.expression,
-  ) =>
+  ) => ExpressionWithContext.noContext(eLambda(parameters, bindings, lambdaDefinition))->Ok
-    ExpressionWithContext.noContext(
-      eLambda(parameters, bindings->Bindings.toExternalBindings, lambdaDefinition),
-    )->Ok
 
   let doTernary = (
     condition: expression,
@@ -139,11 +136,11 @@ let dispatchMacroCall = (
     let rCondition = reduceExpression(blockCondition, bindings, environment)
     rCondition->Result.flatMap(conditionValue =>
       switch conditionValue {
-      | ExpressionValue.EvBool(false) => {
+      | InternalExpressionValue.IEvBool(false) => {
           let ifFalseBlock = eBlock(list{ifFalse})
           ExpressionWithContext.withContext(ifFalseBlock, bindings)->Ok
         }
-      | ExpressionValue.EvBool(true) => {
+      | InternalExpressionValue.IEvBool(true) => {
           let ifTrueBlock = eBlock(list{ifTrue})
           ExpressionWithContext.withContext(ifTrueBlock, bindings)->Ok
         }
@@ -158,32 +155,32 @@ let dispatchMacroCall = (
   > =>
     switch aList {
     | list{
-        ExpressionT.EValue(EvCall("$$_bindStatement_$$")),
+        ExpressionT.EValue(IEvCall("$$_bindStatement_$$")),
         bindingExpr: ExpressionT.expression,
         statement,
       } =>
       doBindStatement(bindingExpr, statement, environment)
-    | list{ExpressionT.EValue(EvCall("$$_bindStatement_$$")), statement} =>
+    | list{ExpressionT.EValue(IEvCall("$$_bindStatement_$$")), statement} =>
       // bindings of the context are used when there is no binding expression
-      doBindStatement(eRecord(Bindings.toExternalBindings(bindings)), statement, environment)
+      doBindStatement(eModule(bindings), statement, environment)
     | list{
-        ExpressionT.EValue(EvCall("$$_bindExpression_$$")),
+        ExpressionT.EValue(IEvCall("$$_bindExpression_$$")),
         bindingExpr: ExpressionT.expression,
         expression,
       } =>
       doBindExpression(bindingExpr, expression, environment)
-    | list{ExpressionT.EValue(EvCall("$$_bindExpression_$$")), expression} =>
+    | list{ExpressionT.EValue(IEvCall("$$_bindExpression_$$")), expression} =>
       // bindings of the context are used when there is no binding expression
-      doBindExpression(eRecord(Bindings.toExternalBindings(bindings)), expression, environment)
+      doBindExpression(eModule(bindings), expression, environment)
-    | list{ExpressionT.EValue(EvCall("$$_block_$$")), ...exprs} =>
+    | list{ExpressionT.EValue(IEvCall("$$_block_$$")), ...exprs} =>
       doBlock(exprs, bindings, environment)
     | list{
-        ExpressionT.EValue(EvCall("$$_lambda_$$")),
+        ExpressionT.EValue(IEvCall("$$_lambda_$$")),
-        ExpressionT.EValue(EvArrayString(parameters)),
+        ExpressionT.EValue(IEvArrayString(parameters)),
         lambdaDefinition,
       } =>
       doLambdaDefinition(bindings, parameters, lambdaDefinition)
-    | list{ExpressionT.EValue(EvCall("$$_ternary_$$")), condition, ifTrue, ifFalse} =>
+    | list{ExpressionT.EValue(IEvCall("$$_ternary_$$")), condition, ifTrue, ifFalse} =>
       doTernary(condition, ifTrue, ifFalse, bindings, environment)
     | _ => ExpressionWithContext.noContext(ExpressionT.EList(aList))->Ok
     }

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression.res

@@ -1,20 +1,20 @@
-module Bindings = Reducer_Expression_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
 module BuiltIn = Reducer_Dispatch_BuiltIn
 module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
-module ExpressionValue = ReducerInterface.ExpressionValue
 module Extra = Reducer_Extra
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Lambda = Reducer_Expression_Lambda
 module Macro = Reducer_Expression_Macro
 module MathJs = Reducer_MathJs
+module Module = Reducer_Category_Module
 module Result = Belt.Result
 module T = Reducer_Expression_T
 
-type environment = ReducerInterface_ExpressionValue.environment
+type environment = InternalExpressionValue.environment
 type errorValue = Reducer_ErrorValue.errorValue
 type expression = T.expression
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type internalExpressionValue = InternalExpressionValue.t
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type externalExpressionValue = ReducerInterface_ExternalExpressionValue.t
-type internalCode = ReducerInterface_ExpressionValue.internalCode
 type t = expression
 
 /*
@@ -27,7 +27,7 @@ let parse = (peggyCode: string): result<t, errorValue> =>
   Recursively evaluate/reduce the expression (Lisp AST)
 */
 let rec reduceExpression = (expression: t, bindings: T.bindings, environment: environment): result<
-  expressionValue,
+  internalExpressionValue,
   'e,
 > => {
   // Js.log(`reduce: ${T.toString(expression)} bindings: ${bindings->Bindings.toString}`)
@@ -35,7 +35,7 @@ let rec reduceExpression = (expression: t, bindings: T.bindings, environment: en
   | T.EValue(value) => value->Ok
   | T.EList(list) =>
     switch list {
-    | list{EValue(EvCall(fName)), ..._args} =>
+    | list{EValue(IEvCall(fName)), ..._args} =>
       switch Macro.isMacroName(fName) {
       // A macro expands then reduces itself
       | true => Macro.doMacroCall(expression, bindings, environment, reduceExpression)
@@ -50,11 +50,11 @@ and reduceExpressionList = (
   expressions: list<t>,
   bindings: T.bindings,
   environment: environment,
-): result<expressionValue, 'e> => {
+): result<internalExpressionValue, 'e> => {
-  let racc: result<list<expressionValue>, 'e> = expressions->Belt.List.reduceReverse(Ok(list{}), (
+  let racc: result<
-    racc,
+    list<internalExpressionValue>,
-    each: expression,
+    'e,
-  ) =>
+  > = expressions->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
     racc->Result.flatMap(acc => {
       each
       ->reduceExpression(bindings, environment)
@@ -69,12 +69,12 @@ and reduceExpressionList = (
 /*
     After reducing each level of expression(Lisp AST), we have a value list to evaluate
  */
-and reduceValueList = (valueList: list<expressionValue>, environment): result<
+and reduceValueList = (valueList: list<internalExpressionValue>, environment): result<
-  expressionValue,
+  internalExpressionValue,
   'e,
 > =>
   switch valueList {
-  | list{EvCall(fName), ...args} => {
+  | list{IEvCall(fName), ...args} => {
       let rCheckedArgs = switch fName {
       | "$_setBindings_$" | "$_setTypeOfBindings_$" | "$_setTypeAliasBindings_$" => args->Ok
       | _ => args->Lambda.checkIfReduced
@@ -84,14 +84,14 @@ and reduceValueList = (valueList: list<expressionValue>, environment): result<
         (fName, checkedArgs->Belt.List.toArray)->BuiltIn.dispatch(environment, reduceExpression)
       )
     }
-  | list{EvLambda(_)} =>
+  | list{IEvLambda(_)} =>
     // TODO: remove on solving issue#558
     valueList
     ->Lambda.checkIfReduced
     ->Result.flatMap(reducedValueList =>
-      reducedValueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
+      reducedValueList->Belt.List.toArray->InternalExpressionValue.IEvArray->Ok
     )
-  | list{EvLambda(lamdaCall), ...args} =>
+  | list{IEvLambda(lamdaCall), ...args} =>
     args
     ->Lambda.checkIfReduced
     ->Result.flatMap(checkedArgs =>
@@ -102,60 +102,55 @@ and reduceValueList = (valueList: list<expressionValue>, environment): result<
     valueList
     ->Lambda.checkIfReduced
     ->Result.flatMap(reducedValueList =>
-      reducedValueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
+      reducedValueList->Belt.List.toArray->InternalExpressionValue.IEvArray->Ok
     )
   }
 
 let evalUsingBindingsExpression_ = (aExpression, bindings, environment): result<
-  expressionValue,
+  internalExpressionValue,
   'e,
 > => reduceExpression(aExpression, bindings, environment)
 
 let evaluateUsingOptions = (
-  ~environment: option<ReducerInterface_ExpressionValue.environment>,
+  ~environment: option<ReducerInterface_ExternalExpressionValue.environment>,
-  ~externalBindings: option<ReducerInterface_ExpressionValue.externalBindings>,
+  ~externalBindings: option<ReducerInterface_ExternalExpressionValue.externalBindings>,
   code: string,
-): result<expressionValue, errorValue> => {
+): result<externalExpressionValue, errorValue> => {
   let anEnvironment = Belt.Option.getWithDefault(
     environment,
-    ReducerInterface_ExpressionValue.defaultEnvironment,
+    ReducerInterface_ExternalExpressionValue.defaultEnvironment,
   )
 
-  let anExternalBindings = switch externalBindings {
+  let mergedBindings: InternalExpressionValue.nameSpace = Module.merge(
-  | Some(bindings) => {
+    ReducerInterface_StdLib.internalStdLib,
-      let cloneLib = ReducerInterface_StdLib.externalStdLib->Reducer_Category_Bindings.cloneRecord
+    Belt.Option.map(externalBindings, Module.fromTypeScriptBindings)->Belt.Option.getWithDefault(
-      Js.Dict.entries(bindings)->Js.Array2.reduce((acc, (key, value)) => {
+      Module.emptyModule,
-        acc->Js.Dict.set(key, value)
+    ),
-        acc
+  )
-      }, cloneLib)
-    }
-  | None => ReducerInterface_StdLib.externalStdLib
-  }
 
-  let bindings = anExternalBindings->Bindings.fromExternalBindings
+  parse(code)
-
+  ->Result.flatMap(expr => evalUsingBindingsExpression_(expr, mergedBindings, anEnvironment))
-  parse(code)->Result.flatMap(expr => evalUsingBindingsExpression_(expr, bindings, anEnvironment))
+  ->Result.map(ReducerInterface_InternalExpressionValue.toExternal)
 }
 
 /*
-  Evaluates Squiggle code and bindings via Reducer and answers the result
+  IEvaluates Squiggle code and bindings via Reducer and answers the result
 */
-let evaluate = (code: string): result<expressionValue, errorValue> => {
+let evaluate = (code: string): result<externalExpressionValue, errorValue> => {
   evaluateUsingOptions(~environment=None, ~externalBindings=None, code)
 }
-let eval = evaluate
 let evaluatePartialUsingExternalBindings = (
   code: string,
-  externalBindings: ReducerInterface_ExpressionValue.externalBindings,
+  externalBindings: ReducerInterface_ExternalExpressionValue.externalBindings,
-  environment: ReducerInterface_ExpressionValue.environment,
+  environment: ReducerInterface_ExternalExpressionValue.environment,
-): result<externalBindings, errorValue> => {
+): result<ReducerInterface_ExternalExpressionValue.externalBindings, errorValue> => {
   let rAnswer = evaluateUsingOptions(
     ~environment=Some(environment),
     ~externalBindings=Some(externalBindings),
     code,
   )
   switch rAnswer {
-  | Ok(EvRecord(externalBindings)) => Ok(externalBindings)
+  | Ok(EvModule(externalBindings)) => Ok(externalBindings)
   | Ok(_) =>
     Error(Reducer_ErrorValue.RESyntaxError(`Partials must end with an assignment or record`, None))
   | Error(err) => err->Error

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_ExpressionWithContext.res

@@ -1,16 +1,16 @@
-module Bindings = Reducer_Expression_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
 module ErrorValue = Reducer_ErrorValue
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module Result = Belt.Result
+module Module = Reducer_Category_Module
 
 type bindings = ExpressionT.bindings
 type context = bindings
-type environment = ExpressionValue.environment
+type environment = InternalExpressionValue.environment
 type errorValue = Reducer_ErrorValue.errorValue
 type expression = ExpressionT.expression
-type expressionValue = ExpressionValue.expressionValue
+type internalExpressionValue = InternalExpressionValue.t
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
 type reducerFn = ExpressionT.reducerFn
 
 type expressionWithContext =
@@ -22,7 +22,7 @@ let callReducer = (
   bindings: bindings,
   environment: environment,
   reducer: reducerFn,
-): result<expressionValue, errorValue> => {
+): result<internalExpressionValue, errorValue> => {
   switch expressionWithContext {
   | ExpressionNoContext(expr) =>
     // Js.log(`callReducer: bindings ${Bindings.toString(bindings)} expr ${ExpressionT.toString(expr)}`)
@@ -40,7 +40,9 @@ let toString = expressionWithContext =>
   switch expressionWithContext {
   | ExpressionNoContext(expr) => ExpressionT.toString(expr)
   | ExpressionWithContext(expr, context) =>
-    `${ExpressionT.toString(expr)} context: ${Bindings.toString(context)}`
+    `${ExpressionT.toString(expr)} context: ${context
+      ->Module.toExpressionValue
+      ->InternalExpressionValue.toString}`
   }
 
 let toStringResult = rExpressionWithContext =>

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Bindings.res

@@ -1,72 +0,0 @@
-module ErrorValue = Reducer_ErrorValue
-module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
-module Result = Belt.Result
-module Bindings = Reducer_Category_Bindings
-
-type errorValue = Reducer_ErrorValue.errorValue
-type expression = ExpressionT.expression
-type expressionValue = ExpressionValue.expressionValue
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
-
-let emptyBindings = Reducer_Category_Bindings.emptyBindings
-
-let typeAliasesKey = Bindings.typeAliasesKey
-let typeReferencesKey = Bindings.typeReferencesKey
-
-let toExternalBindings = (bindings: ExpressionT.bindings): externalBindings =>
-  Bindings.toRecord(bindings)
-
-let fromExternalBindings = (externalBindings: externalBindings): ExpressionT.bindings =>
-  Bindings.fromRecord(externalBindings)
-
-let fromValue = (aValue: expressionValue) => Bindings.fromExpressionValue(aValue)
-
-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

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_BindingsReplacer.res

@@ -0,0 +1,53 @@
+module ErrorValue = Reducer_ErrorValue
+module ExpressionT = Reducer_Expression_T
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+module Result = Belt.Result
+module Module = Reducer_Category_Module
+
+type errorValue = Reducer_ErrorValue.errorValue
+type expression = ExpressionT.expression
+type internalExpressionValue = InternalExpressionValue.t
+type externalBindings = ReducerInterface_ExternalExpressionValue.externalBindings
+
+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(IEvCall(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: internalExpressionValue) =>
+  switch evValue {
+  | IEvSymbol(symbol) => Module.getWithDefault(bindings, symbol, evValue)->Ok
+  | IEvCall(symbol) => Module.getWithDefault(bindings, symbol, evValue)->checkIfCallable
+  | _ => evValue->Ok
+  }
+and checkIfCallable = (evValue: internalExpressionValue) =>
+  switch evValue {
+  | IEvCall(_) | IEvLambda(_) => evValue->Ok
+  | _ => ErrorValue.RENotAFunction(InternalExpressionValue.toString(evValue))->Error
+  }

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_ExpressionBuilder.res

@@ -1,24 +1,28 @@
-module BBindings = Reducer_Expression_Bindings
+module BBindingsReplacer = Reducer_Expression_BindingsReplacer
 module BErrorValue = Reducer_ErrorValue
 module BExpressionT = Reducer_Expression_T
-module BExpressionValue = ReducerInterface.ExpressionValue
+module BInternalExpressionValue = ReducerInterface_InternalExpressionValue
+module BModule = Reducer_Category_Module
 
 type errorValue = BErrorValue.errorValue
 type expression = BExpressionT.expression
-type internalCode = ReducerInterface_ExpressionValue.internalCode
+type expressionOrFFI = BExpressionT.expressionOrFFI
+type ffiFn = BExpressionT.ffiFn
+type internalCode = ReducerInterface_InternalExpressionValue.internalCode
 
-external castExpressionToInternalCode: expression => internalCode = "%identity"
+external castExpressionToInternalCode: expressionOrFFI => internalCode = "%identity"
 
-let eArray = anArray => anArray->BExpressionValue.EvArray->BExpressionT.EValue
+let eArray = anArray => anArray->BInternalExpressionValue.IEvArray->BExpressionT.EValue
 
-let eArrayString = anArray => anArray->BExpressionValue.EvArrayString->BExpressionT.EValue
+let eArrayString = anArray => anArray->BInternalExpressionValue.IEvArrayString->BExpressionT.EValue
 
-let eBindings = (anArray: array<(string, BExpressionValue.expressionValue)>) =>
+let eBindings = (anArray: array<(string, BInternalExpressionValue.t)>) =>
-  anArray->Js.Dict.fromArray->BExpressionValue.EvRecord->BExpressionT.EValue
+  anArray->BModule.fromArray->BModule.toExpressionValue->BExpressionT.EValue
 
-let eBool = aBool => aBool->BExpressionValue.EvBool->BExpressionT.EValue
+let eBool = aBool => aBool->BInternalExpressionValue.IEvBool->BExpressionT.EValue
 
-let eCall = (name: string): expression => name->BExpressionValue.EvCall->BExpressionT.EValue
+let eCall = (name: string): expression =>
+  name->BInternalExpressionValue.IEvCall->BExpressionT.EValue
 
 let eFunction = (fName: string, lispArgs: list<expression>): expression => {
   let fn = fName->eCall
@@ -27,29 +31,41 @@ let eFunction = (fName: string, lispArgs: list<expression>): expression => {
 
 let eLambda = (
   parameters: array<string>,
-  context: BExpressionValue.externalBindings,
+  context: BInternalExpressionValue.nameSpace,
   expr: expression,
 ) => {
-  // Js.log(`eLambda context ${BBindings.externalBindingsToString(context)}`)
+  BInternalExpressionValue.IEvLambda({
-  BExpressionValue.EvLambda({
     parameters: parameters,
     context: context,
-    body: expr->castExpressionToInternalCode,
+    body: NotFFI(expr)->castExpressionToInternalCode,
   })->BExpressionT.EValue
 }
 
-let eNumber = aNumber => aNumber->BExpressionValue.EvNumber->BExpressionT.EValue
+let eLambdaFFI = (parameters: array<string>, ffiFn: ffiFn) => {
+  let context = BModule.emptyModule
+  BInternalExpressionValue.IEvLambda({
+    parameters: parameters,
+    context: context,
+    body: FFI(ffiFn)->castExpressionToInternalCode,
+  })->BExpressionT.EValue
+}
 
-let eRecord = aRecord => aRecord->BExpressionValue.EvRecord->BExpressionT.EValue
+let eNumber = aNumber => aNumber->BInternalExpressionValue.IEvNumber->BExpressionT.EValue
 
-let eString = aString => aString->BExpressionValue.EvString->BExpressionT.EValue
+let eRecord = aMap => aMap->BInternalExpressionValue.IEvRecord->BExpressionT.EValue
 
-let eSymbol = (name: string): expression => name->BExpressionValue.EvSymbol->BExpressionT.EValue
+let eString = aString => aString->BInternalExpressionValue.IEvString->BExpressionT.EValue
+
+let eSymbol = (name: string): expression =>
+  name->BInternalExpressionValue.IEvSymbol->BExpressionT.EValue
 
 let eList = (list: list<expression>): expression => list->BExpressionT.EList
 
 let eBlock = (exprs: list<expression>): expression => eFunction("$$_block_$$", exprs)
 
+let eModule = (nameSpace: BInternalExpressionValue.nameSpace): expression =>
+  nameSpace->BInternalExpressionValue.IEvModule->BExpressionT.EValue
+
 let eLetStatement = (symbol: string, valueExpression: expression): expression =>
   eFunction("$_let_$", list{eSymbol(symbol), valueExpression})
 
@@ -65,7 +81,8 @@ let eBindExpression = (bindingExpr: expression, expression: expression): express
 let eBindExpressionDefault = (expression: expression): expression =>
   eFunction("$$_bindExpression_$$", list{expression})
 
-let eIdentifier = (name: string): expression => name->BExpressionValue.EvSymbol->BExpressionT.EValue
+let eIdentifier = (name: string): expression =>
+  name->BInternalExpressionValue.IEvSymbol->BExpressionT.EValue
 
 let eTypeIdentifier = (name: string): expression =>
-  name->BExpressionValue.EvTypeIdentifier->BExpressionT.EValue
+  name->BInternalExpressionValue.IEvTypeIdentifier->BExpressionT.EValue

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Lambda.res

@@ -1,19 +1,24 @@
-module Bindings = Reducer_Expression_Bindings
+module BindingsReplacer = Reducer_Expression_BindingsReplacer
 module ErrorValue = Reducer_ErrorValue
 module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
+module ExpressionValue = ReducerInterface_InternalExpressionValue
+module Module = Reducer_Category_Module
 module Result = Belt.Result
 
-type environment = ReducerInterface_ExpressionValue.environment
+type environment = ReducerInterface_InternalExpressionValue.environment
 type expression = ExpressionT.expression
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type expressionOrFFI = ExpressionT.expressionOrFFI
-type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type internalExpressionValue = ReducerInterface_InternalExpressionValue.t
-type internalCode = ReducerInterface_ExpressionValue.internalCode
+// type tmpExternalBindings = ReducerInterface_InternalExpressionValue.tmpExternalBindings
+type internalCode = ReducerInterface_InternalExpressionValue.internalCode
 
-external castInternalCodeToExpression: internalCode => expression = "%identity"
+external castInternalCodeToExpression: internalCode => expressionOrFFI = "%identity"
 
-let checkArity = (lambdaValue: ExpressionValue.lambdaValue, args: list<expressionValue>) => {
+let checkArity = (
+  lambdaValue: ExpressionValue.lambdaValue,
+  args: list<internalExpressionValue>,
+) => {
   let argsLength = Belt.List.length(args)
   let parametersLength = Js.Array2.length(lambdaValue.parameters)
   if argsLength !== parametersLength {
@@ -23,34 +28,44 @@ let checkArity = (lambdaValue: ExpressionValue.lambdaValue, args: list<expressio
   }
 }
 
-let checkIfReduced = (args: list<expressionValue>) =>
+let checkIfReduced = (args: list<internalExpressionValue>) =>
   args->Belt.List.reduceReverse(Ok(list{}), (rAcc, arg) =>
     rAcc->Result.flatMap(acc =>
       switch arg {
-      | EvSymbol(symbol) => ErrorValue.RESymbolNotFound(symbol)->Error
+      | IEvSymbol(symbol) => ErrorValue.RESymbolNotFound(symbol)->Error
       | _ => list{arg, ...acc}->Ok
       }
     )
   )
 
+let caseNotFFI = (lambdaValue: ExpressionValue.lambdaValue, expr, args, environment, reducer) => {
+  let parameterList = lambdaValue.parameters->Belt.List.fromArray
+  let zippedParameterList = parameterList->Belt.List.zip(args)
+  let bindings = Belt.List.reduce(zippedParameterList, lambdaValue.context, (
+    acc,
+    (variable, variableValue),
+  ) => acc->Module.set(variable, variableValue))
+  let newExpression = ExpressionBuilder.eBlock(list{expr})
+  reducer(newExpression, bindings, environment)
+}
+
+let caseFFI = (ffiFn: ExpressionT.ffiFn, args, environment) => {
+  ffiFn(args->Belt.List.toArray, environment)
+}
+
 let applyParametersToLambda = (
   lambdaValue: ExpressionValue.lambdaValue,
   args,
   environment,
   reducer: ExpressionT.reducerFn,
-): result<expressionValue, 'e> => {
+): result<internalExpressionValue, 'e> => {
   checkArity(lambdaValue, args)->Result.flatMap(args =>
     checkIfReduced(args)->Result.flatMap(args => {
-      let expr = castInternalCodeToExpression(lambdaValue.body)
+      let exprOrFFI = castInternalCodeToExpression(lambdaValue.body)
-      let parameterList = lambdaValue.parameters->Belt.List.fromArray
+      switch exprOrFFI {
-      let zippedParameterList = parameterList->Belt.List.zip(args)
+      | NotFFI(expr) => caseNotFFI(lambdaValue, expr, args, environment, reducer)
-      let bindings = Belt.List.reduce(
+      | FFI(ffiFn) => caseFFI(ffiFn, args, environment)
-        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)
     })
   )
 }
@@ -60,10 +75,10 @@ let doLambdaCall = (lambdaValue: ExpressionValue.lambdaValue, args, environment,
 
 let foreignFunctionInterface = (
   lambdaValue: ExpressionValue.lambdaValue,
-  argArray: array<expressionValue>,
+  argArray: array<internalExpressionValue>,
   environment: ExpressionValue.environment,
   reducer: ExpressionT.reducerFn,
-): result<expressionValue, 'e> => {
+): result<internalExpressionValue, 'e> => {
   let args = argArray->Belt.List.fromArray
   applyParametersToLambda(lambdaValue, args, environment, reducer)
 }

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_Macro.res

@@ -1,11 +1,11 @@
 module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module ExpressionWithContext = Reducer_ExpressionWithContext
 module Result = Belt.Result
 
-type environment = ExpressionValue.environment
+type environment = InternalExpressionValue.environment
 type expression = ExpressionT.expression
-type expressionValue = ExpressionValue.expressionValue
+type internalExpressionValue = InternalExpressionValue.t
 type expressionWithContext = ExpressionWithContext.expressionWithContext
 
 let expandMacroCall = (
@@ -26,7 +26,7 @@ let doMacroCall = (
   bindings: ExpressionT.bindings,
   environment: environment,
   reduceExpression: ExpressionT.reducerFn,
-): result<expressionValue, 'e> =>
+): result<internalExpressionValue, 'e> =>
   expandMacroCall(
     macroExpression,
     bindings,

packages/squiggle-lang/src/rescript/Reducer/Reducer_Expression/Reducer_Expression_T.res

@@ -7,28 +7,28 @@
   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
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 
-type expressionValue = ExpressionValue.expressionValue
+type internalExpressionValue = InternalExpressionValue.t
-type environment = ExpressionValue.environment
+type environment = ReducerInterface_InternalExpressionValue.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
+  | EValue(internalExpressionValue) // Irreducible built-in value. Reducer should not know the internals. External libraries are responsible
-and bindings = Belt.Map.String.t<expressionValue>
+and bindings = InternalExpressionValue.nameSpace
 
 type reducerFn = (
   expression,
   bindings,
   environment,
-) => result<expressionValue, Reducer_ErrorValue.errorValue>
+) => result<internalExpressionValue, Reducer_ErrorValue.errorValue>
 
 /*
   Converts the expression to String
 */
 let rec toString = expression =>
   switch expression {
-  | EList(list{EValue(EvCall("$$_block_$$")), ...statements}) =>
+  | EList(list{EValue(IEvCall("$$_block_$$")), ...statements}) =>
     `{${Belt.List.map(statements, aValue => toString(aValue))
       ->Extra.List.interperse("; ")
       ->Belt.List.toArray
@@ -38,7 +38,7 @@ let rec toString = expression =>
       ->Extra.List.interperse(" ")
       ->Belt.List.toArray
       ->Js.String.concatMany("")})`
-  | EValue(aValue) => ExpressionValue.toString(aValue)
+  | EValue(aValue) => InternalExpressionValue.toString(aValue)
   }
 
 let toStringResult = codeResult =>
@@ -65,3 +65,12 @@ let inspectResult = (r: result<expression, Reducer_ErrorValue.errorValue>): resu
   Js.log(toStringResult(r))
   r
 }
+
+type ffiFn = (
+  array<internalExpressionValue>,
+  environment,
+) => result<internalExpressionValue, Reducer_ErrorValue.errorValue>
+
+type expressionOrFFI =
+  | NotFFI(expression)
+  | FFI(ffiFn)

packages/squiggle-lang/src/rescript/Reducer/Reducer_Js/Reducer_Js_Gate.res

@@ -1,4 +1,4 @@
-open ReducerInterface.ExpressionValue
+open ReducerInterface_InternalExpressionValue
 open Reducer_ErrorValue
 
 external castBool: unit => bool = "%identity"
@@ -8,10 +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 jsToIEv = (jsValue): result<internalExpressionValue, errorValue> =>
   switch Js.typeof(jsValue) {
-  | "boolean" => jsValue->castBool->EvBool->Ok
+  | "boolean" => jsValue->castBool->IEvBool->Ok
-  | "number" => jsValue->castNumber->EvNumber->Ok
+  | "number" => jsValue->castNumber->IEvNumber->Ok
-  | "string" => jsValue->castString->EvString->Ok
+  | "string" => jsValue->castString->IEvString->Ok
   | other => RETodo(`Unhandled MathJs literal type: ${Js.String.make(other)}`)->Error
   }

packages/squiggle-lang/src/rescript/Reducer/Reducer_MathJs/Reducer_MathJs_Eval.res

@@ -1,5 +1,5 @@
 module JavaScript = Reducer_Js
-open ReducerInterface.ExpressionValue
+open ReducerInterface_InternalExpressionValue
 open Reducer_ErrorValue
 
 @module("mathjs") external dummy_: string => unit = "evaluate"
@@ -17,10 +17,10 @@ let eval__: string => 'a = %raw(`function (expr) { return {value: Mathjs.evaluat
 /*
   Call MathJs evaluate and return as a variant
 */
-let eval = (expr: string): result<expressionValue, errorValue> => {
+let eval = (expr: string): result<internalExpressionValue, errorValue> => {
   try {
     let answer = eval__(expr)
-    answer["value"]->JavaScript.Gate.jsToEv
+    answer["value"]->JavaScript.Gate.jsToIEv
   } catch {
   | Js.Exn.Error(obj) => REJavaScriptExn(Js.Exn.message(obj), Js.Exn.name(obj))->Error
   }

packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/Reducer_Peggy_GeneratedParser.peggy

@@ -1,74 +1,7 @@
 // Try in https://peggyjs.org/online
 
 {{
-  var toFunction = {
+  const h = require('./helpers');
-    '-': 'subtract',
-    '->': 'pipe',
-    '!=': 'unequal',
-    '.-': 'dotSubtract',
-    '.*': 'dotMultiply',
-    './': 'dotDivide',
-    '.^': 'dotPow',
-    '.+': 'dotAdd',
-    '*': 'multiply',
-    '/': 'divide',
-    '&&': 'and',
-    '^': 'pow', // or xor
-    '+': 'add',
-    '<': 'smaller',
-    '<=': 'smallerEq',
-    '==': 'equal',
-    '>': 'larger',
-    '>=': 'largerEq',
-    '||': 'or',
-    'to': 'credibleIntervalToDistribution',
-  } 
-
-  var unaryToFunction = {
-    '-': 'unaryMinus', 
-    '!': 'not',
-    '.-': 'unaryDotMinus',
-  }
-
-  var postOperatorToFunction = {
-    '.': '$_atIndex_$',
-    '()': '$$_applyAll_$$',
-    '[]': '$_atIndex_$',
-  }
-
-  function makeFunctionCall(fn, args) {
-    if (fn === '$$_applyAll_$$') {
-      // Any list of values is applied from left to right anyway. 
-      // Like in Haskell and Lisp.
-      // So we remove the redundant $$_applyAll_$$.
-      if (args[0].type === "Identifier") {args[0].type = "CallIdentifier"}
-      return nodeExpression(args) 
-    } else {
-      return nodeExpression([nodeCallIndentifier(fn), ...args]) 
-    }
-  }
-
-  function apply(fn, arg) { return makeFunctionCall(fn, [arg]); }
-  function constructArray(elems)  { return apply('$_constructArray_$', nodeExpression(elems)); }
-  function constructRecord(elems) { return apply('$_constructRecord_$', nodeExpression(elems)); }
-
-  function nodeBlock(statements) {return{type: 'Block', statements: statements}}
-  function nodeBoolean(value) {return {type: 'Boolean', value: value}}
-  function nodeCallIndentifier(value) {return {type: 'CallIdentifier', value: value}}
-  function nodeExpression(args) {return {type: 'Expression', nodes: args}}
-  function nodeFloat(value) {return {type: 'Float', value: value}}
-  function nodeIdentifier(value) {return {type: 'Identifier', value: value}}
-  function nodeInteger(value) {return {type: 'Integer', value: value}}
-  function nodeKeyValue(key, value) { 
-    if (key.type === 'Identifier') {key.type = 'String'}
-    return {type: 'KeyValue', key: key, value: value}}  
-  function nodeLambda(args, body) {return {type: 'Lambda', args: args, body: body}}
-  function nodeLetStatment(variable, value) {return {type: 'LetStatement', variable: variable, value: value}}
-  function nodeModuleIdentifier(value) {return {type: 'ModuleIdentifier', value: value}}
-  function nodeString(value) {return {type: 'String', value: value}}
-  function nodeTernary(condition, trueExpression, falseExpression) {return {type: 'Ternary', condition: condition, trueExpression: trueExpression, falseExpression: falseExpression}}
-  
-  function nodeTypeIdentifier(typeValue) {return {type: 'TypeIdentifier', value: typeValue}}
 }}
 
 start
@@ -80,21 +13,21 @@ zeroOMoreArgumentsBlockOrExpression = innerBlockOrExpression / lambda
 outerBlock 
 	= statements:array_statements  finalExpression: (statementSeparator @expression)?
     { if (finalExpression != null) { statements.push(finalExpression) }
-        return nodeBlock(statements) }
+        return h.nodeBlock(statements) }
   / finalExpression: expression
-    { return nodeBlock([finalExpression])}
+    { return h.nodeBlock([finalExpression])}
     
 innerBlockOrExpression  
   = quotedInnerBlock
   / finalExpression: expression
-    { return nodeBlock([finalExpression])}
+    { return h.nodeBlock([finalExpression])}
 
 quotedInnerBlock  
   = '{' _nl statements:array_statements  finalExpression: (statementSeparator @expression)  _nl '}'
 	  { statements.push(finalExpression) 
-    	return nodeBlock(statements) }
+    	return h.nodeBlock(statements) }
   / '{' _nl finalExpression: expression  _nl '}'
-	  { return nodeBlock([finalExpression]) }
+	  { return h.nodeBlock([finalExpression]) }
 
 array_statements
   = head:statement tail:(statementSeparator @array_statements )
@@ -109,12 +42,12 @@ statement
 
 letStatement 
   = variable:identifier _ assignmentOp _nl value:zeroOMoreArgumentsBlockOrExpression
-  { return nodeLetStatment(variable, value) }
+  { return h.nodeLetStatement(variable, value) }
 
 defunStatement
   = variable:identifier '(' _nl args:array_parameters _nl ')' _ assignmentOp _nl body:innerBlockOrExpression
-    { var value = nodeLambda(args, body)
+    { var value = h.nodeLambda(args, body)
-      return nodeLetStatment(variable, value) }
+      return h.nodeLetStatement(variable, value) }
 
   assignmentOp "assignment" = '='
 
@@ -128,16 +61,16 @@ ifthenelse
   = 'if' __nl condition:logicalAdditive 
   	__nl 'then' __nl trueExpression:innerBlockOrExpression 
     __nl 'else' __nl falseExpression:(ifthenelse/innerBlockOrExpression)
-    { return nodeTernary(condition, trueExpression, falseExpression) }
+    { return h.nodeTernary(condition, trueExpression, falseExpression) }
   
 ternary 
   = condition:logicalAdditive _ '?' _nl trueExpression:logicalAdditive _ ':' _nl falseExpression:(ternary/logicalAdditive)
-    { return nodeTernary(condition, trueExpression, falseExpression) }
+    { return h.nodeTernary(condition, trueExpression, falseExpression) }
 
 logicalAdditive
   = head:logicalMultiplicative tail:(_ operator:logicalAdditiveOp _nl arg:logicalMultiplicative {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
   logicalAdditiveOp "operator" = '||'
@@ -146,21 +79,21 @@ logicalAdditive
 logicalMultiplicative
   = head:equality tail:(_ operator:logicalMultiplicativeOp _nl arg:equality {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
   logicalMultiplicativeOp "operator" = '&&'
 
 equality
   = left:relational _ operator:equalityOp _nl right:relational 
-  { return makeFunctionCall(toFunction[operator], [left, right])}
+  { return h.makeFunctionCall(h.toFunction[operator], [left, right])}
   / relational  
  
  equalityOp "operator" = '=='/'!='
 
 relational
   = left:additive _ operator:relationalOp _nl right:additive 
-  { return makeFunctionCall(toFunction[operator], [left, right])}
+  { return h.makeFunctionCall(h.toFunction[operator], [left, right])}
   / additive
 
   relationalOp "operator" = '<='/'<'/'>='/'>'
@@ -168,7 +101,7 @@ relational
 additive
   = head:multiplicative tail:(_ operator:additiveOp _nl arg:multiplicative {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
   additiveOp "operator" = '+' / '-' / '.+' / '.-'
@@ -176,7 +109,7 @@ additive
 multiplicative
   = head:power tail:(_ operator:multiplicativeOp _nl arg:power {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
   multiplicativeOp "operator" = '*' / '/' / '.*' / './'
@@ -184,7 +117,7 @@ multiplicative
 power
   = head:credibleInterval tail:(_ operator:powerOp _nl arg:credibleInterval {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
   powerOp "operator" = '^' / '.^'
@@ -192,7 +125,7 @@ power
 credibleInterval
   = head:chainFunctionCall tail:(__ operator:credibleIntervalOp __nl arg:chainFunctionCall {return {operator: operator, right: arg}})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(toFunction[element.operator], [result, element.right])
+      return h.makeFunctionCall(h.toFunction[element.operator], [result, element.right])
     }, head)}
 
     credibleIntervalOp "operator" = 'to'
@@ -200,7 +133,7 @@ credibleInterval
 chainFunctionCall
   = head:unary tail:(_ ('->'/'|>') _nl chained:chainedFunction {return chained})* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(element.fnName, [result, ...element.args])
+      return h.makeFunctionCall(element.fnName, [result, ...element.args])
     }, head)}
 
   chainedFunction
@@ -215,7 +148,7 @@ chainFunctionCall
 
 unary
   = unaryOperator:unaryOperator _nl right:(unary/postOperator)
-  { return apply(unaryToFunction[unaryOperator], right)}
+  { return h.apply(h.unaryToFunction[unaryOperator], right)}
   / postOperator
   
   unaryOperator "unary operator"
@@ -230,12 +163,12 @@ indexedValue
 collectionElement
   = head:atom &('['/'('/'.')
     tail:(
-      _ '[' _nl arg:expression  _nl ']' {return {fn: postOperatorToFunction['[]'], args: [arg]}}
+      _ '[' _nl arg:expression  _nl ']' {return {fn: h.postOperatorToFunction['[]'], args: [arg]}}
-    / _ '(' _nl args:array_functionArguments  _nl ')' {return {fn: postOperatorToFunction['()'], args: args}}
+    / _ '(' _nl args:array_functionArguments  _nl ')' {return {fn: h.postOperatorToFunction['()'], args: args}}
-    / '.' arg:$dollarIdentifier {return {fn: postOperatorToFunction['[]'], args: [nodeString(arg)]}}
+    / '.' arg:$dollarIdentifier {return {fn: h.postOperatorToFunction['[]'], args: [h.nodeString(arg)]}}
     )* 
   { return tail.reduce(function(result, element) {
-      return makeFunctionCall(element.fn, [result, ...element.args])
+      return h.makeFunctionCall(element.fn, [result, ...element.args])
     }, head)}
 
     array_functionArguments 
@@ -261,49 +194,49 @@ dollarIdentifierWithModule 'identifier'
     final:$dollarIdentifier
   { tail.push(final);
     return tail.reduce(function(result, element) {
-      return makeFunctionCall(postOperatorToFunction['[]'], [result, nodeString(element)])
+      return h.makeFunctionCall(h.postOperatorToFunction['[]'], [result, h.nodeString(element)])
     }, head)}
 
 identifier 'identifier'
-  = ([_a-z]+[_a-z0-9]i*) {return nodeIdentifier(text())} 
+  = ([_a-z]+[_a-z0-9]i*) {return h.nodeIdentifier(text(), location())} 
 
 unitIdentifier 'identifier'
-  = ([_a-zA-Z]+[_a-z0-9]i*) {return nodeIdentifier(text())} 
+  = ([_a-zA-Z]+[_a-z0-9]i*) {return h.nodeIdentifier(text(), location())} 
 
 dollarIdentifier '$identifier'
-  = ([\$_a-z]+[\$_a-z0-9]i*) {return nodeIdentifier(text())} 
+  = ([\$_a-z]+[\$_a-z0-9]i*) {return h.nodeIdentifier(text(), location())} 
 
 moduleIdentifier 'identifier'
-  = ([A-Z]+[_a-z0-9]i*) {return nodeModuleIdentifier(text())} 
+  = ([A-Z]+[_a-z0-9]i*) {return h.nodeModuleIdentifier(text())} 
 
 
 string 'string'
-  = characters:("'" @([^'])* "'") {return nodeString(characters.join(''))} 
+  = characters:("'" @([^'])* "'") {return h.nodeString(characters.join(''))} 
-  / characters:('"' @([^"])* '"') {return nodeString(characters.join(''))}
+  / characters:('"' @([^"])* '"') {return h.nodeString(characters.join(''))}
 
 number = number:(float / integer) unit:unitIdentifier?
   { 
     if (unit === null)
       { return number }
     else
-      { return apply('fromUnit_'+unit.value, number) 
+      { return h.apply('fromUnit_'+unit.value, number) 
       }
   }
 
 integer 'integer'
   = d+ !"\." ![e]i
-  { return nodeInteger(parseInt(text()))} 
+  { return h.nodeInteger(parseInt(text()))} 
   
 float 'float'
   = $(((d+ "\." d*) / ("\." d+)) floatExponent? / d+ floatExponent)
-  { return nodeFloat(parseFloat(text()))} 
+  { return h.nodeFloat(parseFloat(text()))} 
 
 	floatExponent = [e]i '-'? d+
 	d = [0-9]
     
 boolean 'boolean'
   = ('true'/'false') 
-  { return nodeBoolean(text() === 'true')}   
+  { return h.nodeBoolean(text() === 'true')}   
 
 valueConstructor
   = recordConstructor
@@ -314,15 +247,15 @@ valueConstructor
 lambda  
   = '{' _nl '|' _nl args:array_parameters _nl '|' _nl statements:array_statements  finalExpression: (statementSeparator @expression)  _nl '}'
 	  { statements.push(finalExpression) 
-    	return nodeLambda(args, nodeBlock(statements)) }
+    	return h.nodeLambda(args, h.nodeBlock(statements)) }
   / '{' _nl '|' _nl args:array_parameters _nl '|' _nl finalExpression: expression  _nl '}'
-	  { return nodeLambda(args, nodeBlock([finalExpression])) }
+	  { return h.nodeLambda(args, h.nodeBlock([finalExpression])) }
 
 arrayConstructor 'array'
   = '[' _nl ']'
-    { return constructArray([]); }
+    { return h.constructArray([]); }
   / '[' _nl args:array_elements _nl ']' 
-    { return constructArray(args); }
+    { return h.constructArray(args); }
 
   array_elements 
     = head:expression tail:(_ ',' _nl @expression)* 
@@ -330,7 +263,7 @@ arrayConstructor 'array'
 
 recordConstructor  'record'
   = '{' _nl args:array_recordArguments _nl '}' 
-  { return constructRecord(args); }
+  { return h.constructRecord(args); }
 
   array_recordArguments 
     = head:keyValuePair tail:(_ ',' _nl @keyValuePair)* 
@@ -338,7 +271,7 @@ recordConstructor  'record'
 
   keyValuePair 
     = key:expression _ ':' _nl value:expression 
-    { return nodeKeyValue(key, value)}
+    { return h.nodeKeyValue(key, value)}
 
 // Separators
 
@@ -377,30 +310,30 @@ statementSeparator 'statement separator'
 noArguments = ('(' _nl ')' )?
 
 typeIdentifier 'type identifier'
-  = ([a-z]+[_a-z0-9]i*) {return nodeTypeIdentifier(text())} 
+  = ([a-z]+[_a-z0-9]i*) {return h.nodeTypeIdentifier(text())} 
 
 typeConstructorIdentifier 'type constructor identifier'
-  = ([A-Z]+[_a-z0-9]i*) {return nodeTypeIdentifier(text())} 
+  = ([A-Z]+[_a-z0-9]i*) {return h.nodeTypeIdentifier(text())} 
 
 typeExpression = typePostModifierExpression
 
 typePostModifierExpression = head:typeOr tail:(_ '$' _nl @typeModifier)*
   { 
     return tail.reduce((result, element) => {
-      return makeFunctionCall('$_typeModifier_'+element.modifier.value+'_$', [result, ...element.args])
+      return h.makeFunctionCall('$_typeModifier_'+element.modifier.value+'_$', [result, ...element.args])
     }, head)
   }
 
 typeOr = head:typeFunction tail:(_ '|' _nl @typeFunction)*
-  { return tail.length === 0 ? head : apply('$_typeOr_$', constructArray([head, ...tail])); }
+  { return tail.length === 0 ? head : h.apply('$_typeOr_$', h.constructArray([head, ...tail])); }
 
 typeFunction = head:typeModifierExpression tail:(_ '=>' _nl @typeModifierExpression)*    
-  { return tail.length === 0 ? head : apply( '$_typeFunction_$', constructArray([head, ...tail])); }
+  { return tail.length === 0 ? head : h.apply( '$_typeFunction_$', h.constructArray([head, ...tail])); }
 
 typeModifierExpression = head:basicType tail:(_ '<-' _nl @typeModifier)* 
   { 
     return tail.reduce((result, element) => {
-      return makeFunctionCall('$_typeModifier_'+element.modifier.value+'_$', [result, ...element.args])
+      return h.makeFunctionCall('$_typeModifier_'+element.modifier.value+'_$', [result, ...element.args])
     }, head)
   }
 
@@ -413,10 +346,10 @@ typeModifierExpression = head:basicType tail:(_ '<-' _nl @typeModifier)*
 basicType = typeConstructor / typeArray / typeRecord / typeInParanthesis / typeIdentifier
 
 typeArray = '[' _nl elem:typeExpression _nl ']' 
-  {return apply('$_typeArray_$', elem)}
+  {return h.apply('$_typeArray_$', elem)}
 
 typeRecord = '{' _nl elems:array_typeRecordArguments _nl '}' 
-  { return apply('$_typeRecord_$', constructRecord(elems)); }  
+  { return h.apply('$_typeRecord_$', h.constructRecord(elems)); }  
 
   array_typeRecordArguments 
     = head:typeKeyValuePair tail:(_ ',' _nl @typeKeyValuePair)* 
@@ -424,22 +357,22 @@ typeRecord = '{' _nl elems:array_typeRecordArguments _nl '}'
 
   typeKeyValuePair 
     = key:identifier _ ':' _nl value:typeExpression 
-    { return nodeKeyValue(key, value)}
+    { return h.nodeKeyValue(key, value)}
 
 typeConstructor 
   = constructor:typeConstructorIdentifier _ '(' _nl args:array_types _nl ')' 
-    { return makeFunctionCall('$_typeConstructor_$', [constructor, constructArray(args)]); }
+    { return h.makeFunctionCall('$_typeConstructor_$', [constructor, h.constructArray(args)]); }
   / constructor:typeConstructorIdentifier _ noArguments
-    { return makeFunctionCall('$_typeConstructor_$', [constructor, constructArray([])]); }
+    { return h.makeFunctionCall('$_typeConstructor_$', [constructor, h.constructArray([])]); }
 
   array_types = head:typeExpression tail:(_ ',' _nl @typeExpression)* 
     { return [head, ...tail]; }
 
 typeStatement = typeAliasStatement / typeOfStatement
 typeAliasStatement = 'type' __nl typeIdentifier:typeIdentifier _nl '=' _nl typeExpression:typeExpression 
-  { return makeFunctionCall('$_typeAlias_$', [typeIdentifier, typeExpression])}
+  { return h.makeFunctionCall('$_typeAlias_$', [typeIdentifier, typeExpression])}
 typeOfStatement = identifier:identifier _ ':' _nl typeExpression:typeExpression
-  { return makeFunctionCall('$_typeOf_$', [identifier, typeExpression])}
+  { return h.makeFunctionCall('$_typeOf_$', [identifier, typeExpression])}
 
 typeInParanthesis = '(' _nl typeExpression:typeExpression _nl ')' {return typeExpression}
 
@@ -447,4 +380,4 @@ typeInParanthesis = '(' _nl typeExpression:typeExpression _nl ')' {return typeEx
 // TODO: Example of foo = {a: 2, b: 5}; type fooKeys = string $ memberOf(foo->keys)
 // TODO: Example of memberOf( [1,2,3] )
 // TODO: Example of $ 
-// TODO: Cons(a, list) | EmptyList
+// TODO: Cons(a, list) | EmptyList

packages/squiggle-lang/src/rescript/Reducer/Reducer_Peggy/helpers.ts

@@ -0,0 +1,215 @@
+import { LocationRange } from "peggy";
+
+export const toFunction = {
+  "-": "subtract",
+  "->": "pipe",
+  "!=": "unequal",
+  ".-": "dotSubtract",
+  ".*": "dotMultiply",
+  "./": "dotDivide",
+  ".^": "dotPow",
+  ".+": "dotAdd",
+  "*": "multiply",
+  "/": "divide",
+  "&&": "and",
+  "^": "pow", // or xor
+  "+": "add",
+  "<": "smaller",
+  "<=": "smallerEq",
+  "==": "equal",
+  ">": "larger",
+  ">=": "largerEq",
+  "||": "or",
+  to: "credibleIntervalToDistribution",
+};
+
+export const unaryToFunction = {
+  "-": "unaryMinus",
+  "!": "not",
+  ".-": "unaryDotMinus",
+};
+
+export const postOperatorToFunction = {
+  ".": "$_atIndex_$",
+  "()": "$$_applyAll_$$",
+  "[]": "$_atIndex_$",
+};
+
+type NodeBlock = {
+  type: "Block";
+  statements: AnyPeggyNode[];
+};
+
+type NodeExpression = {
+  type: "Expression";
+  nodes: AnyPeggyNode[];
+};
+
+type NodeFloat = {
+  type: "Float";
+  value: number;
+};
+
+type NodeInteger = {
+  type: "Integer";
+  value: number;
+};
+
+type NodeIdentifier = {
+  type: "Identifier";
+  value: string;
+  location: LocationRange;
+};
+
+type NodeCallIdentifier = {
+  type: "CallIdentifier";
+  value: string;
+};
+
+type NodeLetStatement = {
+  type: "LetStatement";
+  variable: NodeIdentifier;
+  value: AnyPeggyNode;
+};
+
+type NodeLambda = {
+  type: "Lambda";
+  args: AnyPeggyNode[];
+  body: AnyPeggyNode;
+};
+
+type NodeTernary = {
+  type: "Ternary";
+  condition: AnyPeggyNode;
+  trueExpression: AnyPeggyNode;
+  falseExpression: AnyPeggyNode;
+};
+
+type NodeKeyValue = {
+  type: "KeyValue";
+  key: AnyPeggyNode;
+  value: AnyPeggyNode;
+};
+
+type NodeString = {
+  type: "String";
+  value: string;
+  location?: LocationRange;
+};
+
+type NodeBoolean = {
+  type: "Boolean";
+  value: boolean;
+};
+
+export type AnyPeggyNode =
+  | NodeBlock
+  | NodeExpression
+  | NodeFloat
+  | NodeInteger
+  | NodeIdentifier
+  | NodeCallIdentifier
+  | NodeLetStatement
+  | NodeLambda
+  | NodeTernary
+  | NodeKeyValue
+  | NodeString
+  | NodeBoolean;
+
+export function makeFunctionCall(fn: string, args: AnyPeggyNode[]) {
+  if (fn === "$$_applyAll_$$") {
+    // Any list of values is applied from left to right anyway.
+    // Like in Haskell and Lisp.
+    // So we remove the redundant $$_applyAll_$$.
+    if (args[0].type === "Identifier") {
+      args[0] = {
+        ...args[0],
+        type: "CallIdentifier",
+      };
+    }
+    return nodeExpression(args);
+  } else {
+    return nodeExpression([nodeCallIndentifier(fn), ...args]);
+  }
+}
+
+export function apply(fn: string, arg: AnyPeggyNode) {
+  return makeFunctionCall(fn, [arg]);
+}
+export function constructArray(elems: AnyPeggyNode[]) {
+  return apply("$_constructArray_$", nodeExpression(elems));
+}
+export function constructRecord(elems: AnyPeggyNode[]) {
+  return apply("$_constructRecord_$", nodeExpression(elems));
+}
+
+export function nodeBlock(statements: AnyPeggyNode[]): NodeBlock {
+  return { type: "Block", statements };
+}
+export function nodeBoolean(value: boolean): NodeBoolean {
+  return { type: "Boolean", value };
+}
+export function nodeCallIndentifier(value: string): NodeCallIdentifier {
+  return { type: "CallIdentifier", value };
+}
+export function nodeExpression(args: AnyPeggyNode[]): NodeExpression {
+  return { type: "Expression", nodes: args };
+}
+export function nodeFloat(value: number): NodeFloat {
+  return { type: "Float", value };
+}
+export function nodeIdentifier(
+  value: string,
+  location: LocationRange
+): NodeIdentifier {
+  return { type: "Identifier", value, location };
+}
+export function nodeInteger(value: number): NodeInteger {
+  return { type: "Integer", value };
+}
+export function nodeKeyValue(
+  key: AnyPeggyNode,
+  value: AnyPeggyNode
+): NodeKeyValue {
+  if (key.type === "Identifier") {
+    key = {
+      ...key,
+      type: "String",
+    };
+  }
+  return { type: "KeyValue", key, value };
+}
+export function nodeLambda(
+  args: AnyPeggyNode[],
+  body: AnyPeggyNode
+): NodeLambda {
+  return { type: "Lambda", args, body };
+}
+export function nodeLetStatement(
+  variable: NodeIdentifier,
+  value: AnyPeggyNode
+): NodeLetStatement {
+  return { type: "LetStatement", variable, value };
+}
+export function nodeModuleIdentifier(value: string) {
+  return { type: "ModuleIdentifier", value };
+}
+export function nodeString(value: string): NodeString {
+  return { type: "String", value };
+}
+export function nodeTernary(
+  condition: AnyPeggyNode,
+  trueExpression: AnyPeggyNode,
+  falseExpression: AnyPeggyNode
+): NodeTernary {
+  return {
+    type: "Ternary",
+    condition,
+    trueExpression,
+    falseExpression,
+  };
+}
+
+export function nodeTypeIdentifier(typeValue: string) {
+  return { type: "TypeIdentifier", value: typeValue };
+}

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface.res

@@ -1,2 +1,4 @@
-module ExpressionValue = ReducerInterface_ExpressionValue
+module ExternalExpressionValue = ReducerInterface_ExternalExpressionValue
 module ExternalLibrary = ReducerInterface_ExternalLibrary
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
+module StdLib = ReducerInterface_StdLib

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Date.res

@@ -1,27 +1,27 @@
-module EV = ReducerInterface_ExpressionValue
+module IEV = ReducerInterface_InternalExpressionValue
-type expressionValue = EV.expressionValue
+type internalExpressionValue = IEV.t
 
-let dispatch = (call: EV.functionCall, _: DistributionOperation.env): option<
+let dispatch = (call: IEV.functionCall, _: DistributionOperation.env): option<
-  result<expressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
+  result<internalExpressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
 > => {
   switch call {
-  | ("toString", [EvDate(t)]) => EV.EvString(DateTime.Date.toString(t))->Ok->Some
+  | ("toString", [IEvDate(t)]) => IEV.IEvString(DateTime.Date.toString(t))->Ok->Some
-  | ("makeDateFromYear", [EvNumber(year)]) =>
+  | ("makeDateFromYear", [IEvNumber(year)]) =>
     switch DateTime.Date.makeFromYear(year) {
-    | Ok(t) => EV.EvDate(t)->Ok->Some
+    | Ok(t) => IEV.IEvDate(t)->Ok->Some
     | Error(e) => Reducer_ErrorValue.RETodo(e)->Error->Some
     }
-  | ("dateFromNumber", [EvNumber(f)]) => EV.EvDate(DateTime.Date.fromFloat(f))->Ok->Some
+  | ("dateFromNumber", [IEvNumber(f)]) => IEV.IEvDate(DateTime.Date.fromFloat(f))->Ok->Some
-  | ("toNumber", [EvDate(f)]) => EV.EvNumber(DateTime.Date.toFloat(f))->Ok->Some
+  | ("toNumber", [IEvDate(f)]) => IEV.IEvNumber(DateTime.Date.toFloat(f))->Ok->Some
-  | ("subtract", [EvDate(d1), EvDate(d2)]) =>
+  | ("subtract", [IEvDate(d1), IEvDate(d2)]) =>
     switch DateTime.Date.subtract(d1, d2) {
-    | Ok(d) => EV.EvTimeDuration(d)->Ok
+    | Ok(d) => IEV.IEvTimeDuration(d)->Ok
     | Error(e) => Error(RETodo(e))
     }->Some
-  | ("subtract", [EvDate(d1), EvTimeDuration(d2)]) =>
+  | ("subtract", [IEvDate(d1), IEvTimeDuration(d2)]) =>
-    EV.EvDate(DateTime.Date.subtractDuration(d1, d2))->Ok->Some
+    IEV.IEvDate(DateTime.Date.subtractDuration(d1, d2))->Ok->Some
-  | ("add", [EvDate(d1), EvTimeDuration(d2)]) =>
+  | ("add", [IEvDate(d1), IEvTimeDuration(d2)]) =>
-    EV.EvDate(DateTime.Date.addDuration(d1, d2))->Ok->Some
+    IEV.IEvDate(DateTime.Date.addDuration(d1, d2))->Ok->Some
   | _ => None
   }
 }

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Duration.res

@@ -1,33 +1,36 @@
-module EV = ReducerInterface_ExpressionValue
+module IEV = ReducerInterface_InternalExpressionValue
-type expressionValue = EV.expressionValue
+type internalExpressionValue = IEV.t
 
-let dispatch = (call: EV.functionCall, _: DistributionOperation.env): option<
+let dispatch = (call: IEV.functionCall, _: DistributionOperation.env): option<
-  result<expressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
+  result<internalExpressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
 > => {
   switch call {
-  | ("toString", [EvTimeDuration(t)]) => EV.EvString(DateTime.Duration.toString(t))->Ok->Some
+  | ("toString", [IEvTimeDuration(t)]) => IEV.IEvString(DateTime.Duration.toString(t))->Ok->Some
-  | ("minutes", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
+  | ("minutes", [IEvNumber(f)]) => IEV.IEvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
-  | ("fromUnit_minutes", [EvNumber(f)]) =>
+  | ("fromUnit_minutes", [IEvNumber(f)]) =>
-    EV.EvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
+    IEV.IEvTimeDuration(DateTime.Duration.fromMinutes(f))->Ok->Some
-  | ("hours", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
+  | ("hours", [IEvNumber(f)]) => IEV.IEvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
-  | ("fromUnit_hours", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
+  | ("fromUnit_hours", [IEvNumber(f)]) =>
-  | ("days", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
+    IEV.IEvTimeDuration(DateTime.Duration.fromHours(f))->Ok->Some
-  | ("fromUnit_days", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
+  | ("days", [IEvNumber(f)]) => IEV.IEvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
-  | ("years", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
+  | ("fromUnit_days", [IEvNumber(f)]) =>
-  | ("fromUnit_years", [EvNumber(f)]) => EV.EvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
+    IEV.IEvTimeDuration(DateTime.Duration.fromDays(f))->Ok->Some
-  | ("toHours", [EvTimeDuration(f)]) => EV.EvNumber(DateTime.Duration.toHours(f))->Ok->Some
+  | ("years", [IEvNumber(f)]) => IEV.IEvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
-  | ("toMinutes", [EvTimeDuration(f)]) => EV.EvNumber(DateTime.Duration.toMinutes(f))->Ok->Some
+  | ("fromUnit_years", [IEvNumber(f)]) =>
-  | ("toDays", [EvTimeDuration(f)]) => EV.EvNumber(DateTime.Duration.toDays(f))->Ok->Some
+    IEV.IEvTimeDuration(DateTime.Duration.fromYears(f))->Ok->Some
-  | ("toYears", [EvTimeDuration(f)]) => EV.EvNumber(DateTime.Duration.toYears(f))->Ok->Some
+  | ("toHours", [IEvTimeDuration(f)]) => IEV.IEvNumber(DateTime.Duration.toHours(f))->Ok->Some
-  | ("add", [EvTimeDuration(d1), EvTimeDuration(d2)]) =>
+  | ("toMinutes", [IEvTimeDuration(f)]) => IEV.IEvNumber(DateTime.Duration.toMinutes(f))->Ok->Some
-    EV.EvTimeDuration(DateTime.Duration.add(d1, d2))->Ok->Some
+  | ("toDays", [IEvTimeDuration(f)]) => IEV.IEvNumber(DateTime.Duration.toDays(f))->Ok->Some
-  | ("subtract", [EvTimeDuration(d1), EvTimeDuration(d2)]) =>
+  | ("toYears", [IEvTimeDuration(f)]) => IEV.IEvNumber(DateTime.Duration.toYears(f))->Ok->Some
-    EV.EvTimeDuration(DateTime.Duration.subtract(d1, d2))->Ok->Some
+  | ("add", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) =>
-  | ("multiply", [EvTimeDuration(d1), EvNumber(d2)]) =>
+    IEV.IEvTimeDuration(DateTime.Duration.add(d1, d2))->Ok->Some
-    EV.EvTimeDuration(DateTime.Duration.multiply(d1, d2))->Ok->Some
+  | ("subtract", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) =>
-  | ("divide", [EvTimeDuration(d1), EvNumber(d2)]) =>
+    IEV.IEvTimeDuration(DateTime.Duration.subtract(d1, d2))->Ok->Some
-    EV.EvTimeDuration(DateTime.Duration.divide(d1, d2))->Ok->Some
+  | ("multiply", [IEvTimeDuration(d1), IEvNumber(d2)]) =>
-  | ("divide", [EvTimeDuration(d1), EvTimeDuration(d2)]) => EV.EvNumber(d1 /. d2)->Ok->Some
+    IEV.IEvTimeDuration(DateTime.Duration.multiply(d1, d2))->Ok->Some
+  | ("divide", [IEvTimeDuration(d1), IEvNumber(d2)]) =>
+    IEV.IEvTimeDuration(DateTime.Duration.divide(d1, d2))->Ok->Some
+  | ("divide", [IEvTimeDuration(d1), IEvTimeDuration(d2)]) => IEV.IEvNumber(d1 /. d2)->Ok->Some
   | _ => None
   }
 }

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalExpressionValue.res

@@ -8,8 +8,8 @@ module ErrorValue = Reducer_ErrorValue
 type internalCode = Object
 
 @genType
-type rec expressionValue =
+type rec externalExpressionValue =
-  | EvArray(array<expressionValue>)
+  | EvArray(array<externalExpressionValue>)
   | EvArrayString(array<string>)
   | EvBool(bool)
   | EvCall(string) // External function call
@@ -24,7 +24,7 @@ type rec expressionValue =
   | EvDeclaration(lambdaDeclaration)
   | EvTypeIdentifier(string)
   | EvModule(record)
-and record = Js.Dict.t<expressionValue>
+and record = Js.Dict.t<externalExpressionValue>
 and externalBindings = record
 and lambdaValue = {
   parameters: array<string>,
@@ -33,7 +33,10 @@ and lambdaValue = {
 }
 and lambdaDeclaration = Declaration.declaration<lambdaValue>
 
-type functionCall = (string, array<expressionValue>)
+@genType
+type t = externalExpressionValue
+
+type functionCall = (string, array<externalExpressionValue>)
 
 let rec toString = aValue =>
   switch aValue {
@@ -68,26 +71,7 @@ and toStringRecord = aRecord => {
   `{${pairs}}`
 }
 
-let toStringWithType = aValue =>
+let argsToString = (args: array<externalExpressionValue>): string => {
-  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)}`
-  | EvDate(_) => `Date::${toString(aValue)}`
-  | EvTimeDuration(_) => `Date::${toString(aValue)}`
-  | EvDeclaration(_) => `Declaration::${toString(aValue)}`
-  | EvTypeIdentifier(_) => `TypeIdentifier::${toString(aValue)}`
-  | EvModule(_) => `Module::${toString(aValue)}`
-  }
-
-let argsToString = (args: array<expressionValue>): string => {
   args->Js.Array2.map(arg => arg->toString)->Js.Array2.toString
 }
 
@@ -99,18 +83,6 @@ let toStringResult = x =>
   | Error(m) => `Error(${ErrorValue.errorToString(m)})`
   }
 
-let toStringResultOkless = (codeResult: result<expressionValue, ErrorValue.errorValue>): string =>
-  switch codeResult {
-  | Ok(a) => toString(a)
-  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
-  }
-
-let toStringResultRecord = x =>
-  switch x {
-  | Ok(a) => `Ok(${toStringRecord(a)})`
-  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
-  }
-
 @genType
 type environment = DistributionOperation.env
 
@@ -141,14 +113,14 @@ type functionDefinitionSignature =
 let valueToValueType = value =>
   switch value {
   | EvArray(_) => EvtArray
-  | EvArrayString(_) => EvtArray
+  | EvArrayString(_) => EvtArrayString
   | EvBool(_) => EvtBool
   | EvCall(_) => EvtCall
   | EvDistribution(_) => EvtDistribution
   | EvLambda(_) => EvtLambda
   | EvNumber(_) => EvtNumber
   | EvRecord(_) => EvtRecord
-  | EvString(_) => EvtArray
+  | EvString(_) => EvtString
   | EvSymbol(_) => EvtSymbol
   | EvDate(_) => EvtDate
   | EvTimeDuration(_) => EvtTimeDuration

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExternalLibrary.res

@@ -1,6 +1,6 @@
-module ExpressionValue = ReducerInterface_ExpressionValue
+module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 
-type expressionValue = ExpressionValue.expressionValue
+type internalExpressionValue = InternalExpressionValue.t
 
 // module Sample = {
 //   // In real life real libraries should be somewhere else
@@ -17,14 +17,14 @@ type expressionValue = ExpressionValue.expressionValue
 // I expect that it's important to build this first, so it doesn't get recalculated for each tryRegistry() call.
 let registry = FunctionRegistry_Library.registry
 
-let tryRegistry = ((fnName, args): ExpressionValue.functionCall, env) => {
+let tryRegistry = ((fnName, args): InternalExpressionValue.functionCall, env) => {
   FunctionRegistry_Core.Registry.matchAndRun(~registry, ~fnName, ~args, ~env)->E.O2.fmap(
     E.R2.errMap(_, s => Reducer_ErrorValue.RETodo(s)),
   )
 }
 
-let dispatch = (call: ExpressionValue.functionCall, environment, chain): result<
+let dispatch = (call: InternalExpressionValue.functionCall, environment, chain): result<
-  expressionValue,
+  internalExpressionValue,
   'e,
 > => {
   E.A.O.firstSomeFn([

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res

@@ -1,5 +1,5 @@
-module ExpressionValue = ReducerInterface_ExpressionValue
+module IEV = ReducerInterface_InternalExpressionValue
-type expressionValue = ExpressionValue.expressionValue
+type internalExpressionValue = IEV.t
 
 module Helpers = {
   let arithmeticMap = r =>
@@ -18,14 +18,14 @@ module Helpers = {
     | _ => #Multiply
     }
 
-  let catchAndConvertTwoArgsToDists = (args: array<expressionValue>): option<(
+  let catchAndConvertTwoArgsToDists = (args: array<internalExpressionValue>): option<(
     DistributionTypes.genericDist,
     DistributionTypes.genericDist,
   )> =>
     switch args {
-    | [EvDistribution(a), EvDistribution(b)] => Some((a, b))
+    | [IEvDistribution(a), IEvDistribution(b)] => Some((a, b))
-    | [EvNumber(a), EvDistribution(b)] => Some((GenericDist.fromFloat(a), b))
+    | [IEvNumber(a), IEvDistribution(b)] => Some((GenericDist.fromFloat(a), b))
-    | [EvDistribution(a), EvNumber(b)] => Some((a, GenericDist.fromFloat(b)))
+    | [IEvDistribution(a), IEvNumber(b)] => Some((a, GenericDist.fromFloat(b)))
     | _ => None
     }
 
@@ -80,23 +80,28 @@ module Helpers = {
     )->DistributionOperation.run(~env)
   }
 
-  let parseNumber = (args: expressionValue): Belt.Result.t<float, string> =>
+  let parseNumber = (args: internalExpressionValue): Belt.Result.t<float, string> =>
     switch args {
-    | EvNumber(x) => Ok(x)
+    | IEvNumber(x) => Ok(x)
     | _ => Error("Not a number")
     }
 
-  let parseNumberArray = (ags: array<expressionValue>): Belt.Result.t<array<float>, string> =>
+  let parseNumberArray = (ags: array<internalExpressionValue>): Belt.Result.t<
-    E.A.fmap(parseNumber, ags) |> E.A.R.firstErrorOrOpen
+    array<float>,
+    string,
+  > => E.A.fmap(parseNumber, ags) |> E.A.R.firstErrorOrOpen
 
-  let parseDist = (args: expressionValue): Belt.Result.t<DistributionTypes.genericDist, string> =>
+  let parseDist = (args: internalExpressionValue): Belt.Result.t<
+    DistributionTypes.genericDist,
+    string,
+  > =>
     switch args {
-    | EvDistribution(x) => Ok(x)
+    | IEvDistribution(x) => Ok(x)
-    | EvNumber(x) => Ok(GenericDist.fromFloat(x))
+    | IEvNumber(x) => Ok(GenericDist.fromFloat(x))
     | _ => Error("Not a distribution")
     }
 
-  let parseDistributionArray = (ags: array<expressionValue>): Belt.Result.t<
+  let parseDistributionArray = (ags: array<internalExpressionValue>): Belt.Result.t<
     array<DistributionTypes.genericDist>,
     string,
   > => E.A.fmap(parseDist, ags) |> E.A.R.firstErrorOrOpen
@@ -122,18 +127,18 @@ module Helpers = {
   }
 
   let mixture = (
-    args: array<expressionValue>,
+    args: array<internalExpressionValue>,
     ~env: DistributionOperation.env,
   ): DistributionOperation.outputType => {
     let error = (err: string): DistributionOperation.outputType =>
       err->DistributionTypes.ArgumentError->GenDistError
     switch args {
-    | [EvArray(distributions)] =>
+    | [IEvArray(distributions)] =>
       switch parseDistributionArray(distributions) {
       | Ok(distrs) => mixtureWithDefaultWeights(distrs, ~env)
       | Error(err) => error(err)
       }
-    | [EvArray(distributions), EvArray(weights)] =>
+    | [IEvArray(distributions), IEvArray(weights)] =>
       switch (parseDistributionArray(distributions), parseNumberArray(weights)) {
       | (Ok(distrs), Ok(wghts)) => mixtureWithGivenWeights(distrs, wghts, ~env)
       | (Error(err), Ok(_)) => error(err)
@@ -142,7 +147,7 @@ module Helpers = {
       }
     | _ =>
       switch E.A.last(args) {
-      | Some(EvArray(b)) => {
+      | Some(IEvArray(b)) => {
           let weights = parseNumberArray(b)
           let distributions = parseDistributionArray(
             Belt.Array.slice(args, ~offset=0, ~len=E.A.length(args) - 1),
@@ -152,8 +157,8 @@ module Helpers = {
           | Error(err) => error(err)
           }
         }
-      | Some(EvNumber(_))
+      | Some(IEvNumber(_))
-      | Some(EvDistribution(_)) =>
+      | Some(IEvDistribution(_)) =>
         switch parseDistributionArray(args) {
         | Ok(distributions) => mixtureWithDefaultWeights(distributions, ~env)
         | Error(err) => error(err)
@@ -194,20 +199,19 @@ module SymbolicConstructors = {
     }
 }
 
-let dispatchToGenericOutput = (
+let dispatchToGenericOutput = (call: IEV.functionCall, env: DistributionOperation.env): option<
-  call: ExpressionValue.functionCall,
+  DistributionOperation.outputType,
-  env: DistributionOperation.env,
+> => {
-): option<DistributionOperation.outputType> => {
   let (fnName, args) = call
   switch (fnName, args) {
-  | ("triangular" as fnName, [EvNumber(f1), EvNumber(f2), EvNumber(f3)]) =>
+  | ("triangular" as fnName, [IEvNumber(f1), IEvNumber(f2), IEvNumber(f3)]) =>
     SymbolicConstructors.threeFloat(fnName)
     ->E.R.bind(r => r(f1, f2, f3))
     ->SymbolicConstructors.symbolicResultToOutput
-  | ("sample", [EvDistribution(dist)]) => Helpers.toFloatFn(#Sample, dist, ~env)
+  | ("sample", [IEvDistribution(dist)]) => Helpers.toFloatFn(#Sample, dist, ~env)
-  | ("sampleN", [EvDistribution(dist), EvNumber(n)]) =>
+  | ("sampleN", [IEvDistribution(dist), IEvNumber(n)]) =>
     Some(FloatArray(GenericDist.sampleN(dist, Belt.Int.fromFloat(n))))
-  | (("mean" | "stdev" | "variance" | "min" | "max" | "mode") as op, [EvDistribution(dist)]) => {
+  | (("mean" | "stdev" | "variance" | "min" | "max" | "mode") as op, [IEvDistribution(dist)]) => {
       let fn = switch op {
       | "mean" => #Mean
       | "stdev" => #Stdev
@@ -219,13 +223,13 @@ let dispatchToGenericOutput = (
       }
       Helpers.toFloatFn(fn, dist, ~env)
     }
-  | ("integralSum", [EvDistribution(dist)]) => Helpers.toFloatFn(#IntegralSum, dist, ~env)
+  | ("integralSum", [IEvDistribution(dist)]) => Helpers.toFloatFn(#IntegralSum, dist, ~env)
-  | ("toString", [EvDistribution(dist)]) => Helpers.toStringFn(ToString, dist, ~env)
+  | ("toString", [IEvDistribution(dist)]) => Helpers.toStringFn(ToString, dist, ~env)
-  | ("sparkline", [EvDistribution(dist)]) =>
+  | ("sparkline", [IEvDistribution(dist)]) =>
     Helpers.toStringFn(ToSparkline(MagicNumbers.Environment.sparklineLength), dist, ~env)
-  | ("sparkline", [EvDistribution(dist), EvNumber(n)]) =>
+  | ("sparkline", [IEvDistribution(dist), IEvNumber(n)]) =>
     Helpers.toStringFn(ToSparkline(Belt.Float.toInt(n)), dist, ~env)
-  | ("exp", [EvDistribution(a)]) =>
+  | ("exp", [IEvDistribution(a)]) =>
     // https://mathjs.org/docs/reference/functions/exp.html
     Helpers.twoDiststoDistFn(
       Algebraic(AsDefault),
@@ -234,55 +238,62 @@ let dispatchToGenericOutput = (
       a,
       ~env,
     )->Some
-  | ("normalize", [EvDistribution(dist)]) => Helpers.toDistFn(Normalize, dist, ~env)
+  | ("normalize", [IEvDistribution(dist)]) => Helpers.toDistFn(Normalize, dist, ~env)
-  | ("klDivergence", [EvDistribution(prediction), EvDistribution(answer)]) =>
+  | ("klDivergence", [IEvDistribution(prediction), IEvDistribution(answer)]) =>
     Some(DistributionOperation.run(FromDist(ToScore(KLDivergence(answer)), prediction), ~env))
-  | ("klDivergence", [EvDistribution(prediction), EvDistribution(answer), EvDistribution(prior)]) =>
+  | (
+      "klDivergence",
+      [IEvDistribution(prediction), IEvDistribution(answer), IEvDistribution(prior)],
+    ) =>
     Helpers.klDivergenceWithPrior(prediction, answer, prior, env)
   | (
     "logScoreWithPointAnswer",
-    [EvDistribution(prediction), EvNumber(answer), EvDistribution(prior)],
+    [IEvDistribution(prediction), IEvNumber(answer), IEvDistribution(prior)],
   )
   | (
     "logScoreWithPointAnswer",
-    [EvDistribution(prediction), EvDistribution(Symbolic(#Float(answer))), EvDistribution(prior)],
+    [
+      IEvDistribution(prediction),
+      IEvDistribution(Symbolic(#Float(answer))),
+      IEvDistribution(prior),
+    ],
   ) =>
     DistributionOperation.run(
       FromDist(ToScore(LogScore(answer, prior->Some)), prediction),
       ~env,
     )->Some
-  | ("logScoreWithPointAnswer", [EvDistribution(prediction), EvNumber(answer)])
+  | ("logScoreWithPointAnswer", [IEvDistribution(prediction), IEvNumber(answer)])
   | (
     "logScoreWithPointAnswer",
-    [EvDistribution(prediction), EvDistribution(Symbolic(#Float(answer)))],
+    [IEvDistribution(prediction), IEvDistribution(Symbolic(#Float(answer)))],
   ) =>
     DistributionOperation.run(FromDist(ToScore(LogScore(answer, None)), prediction), ~env)->Some
-  | ("isNormalized", [EvDistribution(dist)]) => Helpers.toBoolFn(IsNormalized, dist, ~env)
+  | ("isNormalized", [IEvDistribution(dist)]) => Helpers.toBoolFn(IsNormalized, dist, ~env)
-  | ("toPointSet", [EvDistribution(dist)]) => Helpers.toDistFn(ToPointSet, dist, ~env)
+  | ("toPointSet", [IEvDistribution(dist)]) => Helpers.toDistFn(ToPointSet, dist, ~env)
-  | ("scaleLog", [EvDistribution(dist)]) =>
+  | ("scaleLog", [IEvDistribution(dist)]) =>
     Helpers.toDistFn(Scale(#Logarithm, MagicNumbers.Math.e), dist, ~env)
-  | ("scaleLog10", [EvDistribution(dist)]) => Helpers.toDistFn(Scale(#Logarithm, 10.0), dist, ~env)
+  | ("scaleLog10", [IEvDistribution(dist)]) => Helpers.toDistFn(Scale(#Logarithm, 10.0), dist, ~env)
-  | ("scaleLog", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("scaleLog", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(Scale(#Logarithm, float), dist, ~env)
-  | ("scaleLogWithThreshold", [EvDistribution(dist), EvNumber(base), EvNumber(eps)]) =>
+  | ("scaleLogWithThreshold", [IEvDistribution(dist), IEvNumber(base), IEvNumber(eps)]) =>
     Helpers.toDistFn(Scale(#LogarithmWithThreshold(eps), base), dist, ~env)
-  | ("scaleMultiply", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("scaleMultiply", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(Scale(#Multiply, float), dist, ~env)
-  | ("scalePow", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("scalePow", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(Scale(#Power, float), dist, ~env)
-  | ("scaleExp", [EvDistribution(dist)]) =>
+  | ("scaleExp", [IEvDistribution(dist)]) =>
     Helpers.toDistFn(Scale(#Power, MagicNumbers.Math.e), dist, ~env)
-  | ("cdf", [EvDistribution(dist), EvNumber(float)]) => Helpers.toFloatFn(#Cdf(float), dist, ~env)
+  | ("cdf", [IEvDistribution(dist), IEvNumber(float)]) => Helpers.toFloatFn(#Cdf(float), dist, ~env)
-  | ("pdf", [EvDistribution(dist), EvNumber(float)]) => Helpers.toFloatFn(#Pdf(float), dist, ~env)
+  | ("pdf", [IEvDistribution(dist), IEvNumber(float)]) => Helpers.toFloatFn(#Pdf(float), dist, ~env)
-  | ("inv", [EvDistribution(dist), EvNumber(float)]) => Helpers.toFloatFn(#Inv(float), dist, ~env)
+  | ("inv", [IEvDistribution(dist), IEvNumber(float)]) => Helpers.toFloatFn(#Inv(float), dist, ~env)
-  | ("quantile", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("quantile", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toFloatFn(#Inv(float), dist, ~env)
-  | ("toSampleSet", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("toSampleSet", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(ToSampleSet(Belt.Int.fromFloat(float)), dist, ~env)
-  | ("toSampleSet", [EvDistribution(dist)]) =>
+  | ("toSampleSet", [IEvDistribution(dist)]) =>
     Helpers.toDistFn(ToSampleSet(env.sampleCount), dist, ~env)
-  | ("toList", [EvDistribution(SampleSet(dist))]) => Some(FloatArray(SampleSetDist.T.get(dist)))
+  | ("toList", [IEvDistribution(SampleSet(dist))]) => Some(FloatArray(SampleSetDist.T.get(dist)))
-  | ("fromSamples", [EvArray(inputArray)]) => {
+  | ("fromSamples", [IEvArray(inputArray)]) => {
       let _wrapInputErrors = x => SampleSetDist.NonNumericInput(x)
       let parsedArray = Helpers.parseNumberArray(inputArray)->E.R2.errMap(_wrapInputErrors)
       switch parsedArray {
@@ -290,15 +301,15 @@ let dispatchToGenericOutput = (
       | Error(e) => GenDistError(SampleSetError(e))
       }->Some
     }
-  | ("inspect", [EvDistribution(dist)]) => Helpers.toDistFn(Inspect, dist, ~env)
+  | ("inspect", [IEvDistribution(dist)]) => Helpers.toDistFn(Inspect, dist, ~env)
-  | ("truncateLeft", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("truncateLeft", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(Truncate(Some(float), None), dist, ~env)
-  | ("truncateRight", [EvDistribution(dist), EvNumber(float)]) =>
+  | ("truncateRight", [IEvDistribution(dist), IEvNumber(float)]) =>
     Helpers.toDistFn(Truncate(None, Some(float)), dist, ~env)
-  | ("truncate", [EvDistribution(dist), EvNumber(float1), EvNumber(float2)]) =>
+  | ("truncate", [IEvDistribution(dist), IEvNumber(float1), IEvNumber(float2)]) =>
     Helpers.toDistFn(Truncate(Some(float1), Some(float2)), dist, ~env)
   | ("mx" | "mixture", args) => Helpers.mixture(args, ~env)->Some
-  | ("log", [EvDistribution(a)]) =>
+  | ("log", [IEvDistribution(a)]) =>
     Helpers.twoDiststoDistFn(
       Algebraic(AsDefault),
       "log",
@@ -306,7 +317,7 @@ let dispatchToGenericOutput = (
       GenericDist.fromFloat(MagicNumbers.Math.e),
       ~env,
     )->Some
-  | ("log10", [EvDistribution(a)]) =>
+  | ("log10", [IEvDistribution(a)]) =>
     Helpers.twoDiststoDistFn(
       Algebraic(AsDefault),
       "log",
@@ -314,7 +325,7 @@ let dispatchToGenericOutput = (
       GenericDist.fromFloat(10.0),
       ~env,
     )->Some
-  | ("unaryMinus", [EvDistribution(a)]) =>
+  | ("unaryMinus", [IEvDistribution(a)]) =>
     Helpers.twoDiststoDistFn(
       Algebraic(AsDefault),
       "multiply",
@@ -337,7 +348,7 @@ let dispatchToGenericOutput = (
     Helpers.catchAndConvertTwoArgsToDists(args)->E.O2.fmap(((fst, snd)) =>
       Helpers.twoDiststoDistFn(Pointwise, arithmetic, fst, snd, ~env)
     )
-  | ("dotExp", [EvDistribution(a)]) =>
+  | ("dotExp", [IEvDistribution(a)]) =>
     Helpers.twoDiststoDistFn(
       Pointwise,
       "dotPow",
@@ -350,17 +361,18 @@ let dispatchToGenericOutput = (
 }
 
 let genericOutputToReducerValue = (o: DistributionOperation.outputType): result<
-  expressionValue,
+  internalExpressionValue,
   Reducer_ErrorValue.errorValue,
 > =>
   switch o {
-  | Dist(d) => Ok(ReducerInterface_ExpressionValue.EvDistribution(d))
+  | Dist(d) => Ok(ReducerInterface_InternalExpressionValue.IEvDistribution(d))
-  | Float(d) => Ok(EvNumber(d))
+  | Float(d) => Ok(IEvNumber(d))
-  | String(d) => Ok(EvString(d))
+  | String(d) => Ok(IEvString(d))
-  | Bool(d) => Ok(EvBool(d))
+  | Bool(d) => Ok(IEvBool(d))
-  | FloatArray(d) => Ok(EvArray(d |> E.A.fmap(r => ReducerInterface_ExpressionValue.EvNumber(r))))
+  | FloatArray(d) =>
+    Ok(IEvArray(d |> E.A.fmap(r => ReducerInterface_InternalExpressionValue.IEvNumber(r))))
   | GenDistError(err) => Error(REDistributionError(err))
   }
 
-let dispatch = (call: ExpressionValue.functionCall, environment) =>
+let dispatch = (call: IEV.functionCall, environment) =>
   dispatchToGenericOutput(call, environment)->E.O2.fmap(genericOutputToReducerValue)

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.resi

@@ -1,4 +1,4 @@
 let dispatch: (
-  ReducerInterface_ExpressionValue.functionCall,
+  ReducerInterface_InternalExpressionValue.functionCall,
-  ReducerInterface_ExpressionValue.environment,
+  ReducerInterface_ExternalExpressionValue.environment,
-) => option<result<ReducerInterface_ExpressionValue.expressionValue, Reducer_ErrorValue.errorValue>>
+) => option<result<ReducerInterface_InternalExpressionValue.t, Reducer_ErrorValue.errorValue>>

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_InternalExpressionValue.res

@@ -0,0 +1,259 @@
+module ErrorValue = Reducer_ErrorValue
+module ExternalExpressionValue = ReducerInterface_ExternalExpressionValue
+module Extra_Array = Reducer_Extra_Array
+type internalCode = ExternalExpressionValue.internalCode
+type environment = ExternalExpressionValue.environment
+
+let defaultEnvironment = ExternalExpressionValue.defaultEnvironment
+
+type rec t =
+  | IEvArray(array<t>) // FIXME: Convert
+  | IEvArrayString(array<string>) // FIXME: Convert
+  | IEvBool(bool)
+  | IEvCall(string) // External function call
+  | IEvDate(Js.Date.t)
+  | IEvDeclaration(lambdaDeclaration)
+  | IEvDistribution(DistributionTypes.genericDist)
+  | IEvLambda(lambdaValue)
+  | IEvModule(nameSpace)
+  | IEvNumber(float)
+  | IEvRecord(map)
+  | IEvString(string)
+  | IEvSymbol(string)
+  | IEvTimeDuration(float)
+  | IEvTypeIdentifier(string)
+and map = Belt.Map.String.t<t>
+and nameSpace = NameSpace(Belt.Map.String.t<t>)
+and lambdaValue = {
+  parameters: array<string>,
+  context: nameSpace,
+  body: internalCode,
+}
+and lambdaDeclaration = Declaration.declaration<lambdaValue>
+
+type internalExpressionValue = t
+
+type functionCall = (string, array<t>)
+
+let rec toString = aValue =>
+  switch aValue {
+  | IEvArray(anArray) => {
+      let args = anArray->Js.Array2.map(each => toString(each))->Js.Array2.toString
+      `[${args}]`
+    }
+  | IEvArrayString(anArray) => {
+      let args = anArray->Js.Array2.toString
+      `[${args}]`
+    }
+  | IEvBool(aBool) => Js.String.make(aBool)
+  | IEvCall(fName) => `:${fName}`
+  | IEvDate(date) => DateTime.Date.toString(date)
+  | IEvDeclaration(d) => Declaration.toString(d, r => toString(IEvLambda(r)))
+  | IEvDistribution(dist) => GenericDist.toString(dist)
+  | IEvLambda(lambdaValue) => `lambda(${Js.Array2.toString(lambdaValue.parameters)}=>internal code)`
+  | IEvModule(m) => `@${m->toStringNameSpace}`
+  | IEvNumber(aNumber) => Js.String.make(aNumber)
+  | IEvRecord(aMap) => aMap->toStringMap
+  | IEvString(aString) => `'${aString}'`
+  | IEvSymbol(aString) => `:${aString}`
+  | IEvTimeDuration(t) => DateTime.Duration.toString(t)
+  | IEvTypeIdentifier(id) => `#${id}`
+  }
+and toStringMap = aMap => {
+  let pairs =
+    aMap
+    ->Belt.Map.String.toArray
+    ->Js.Array2.map(((eachKey, eachValue)) => `${eachKey}: ${toString(eachValue)}`)
+    ->Js.Array2.toString
+  `{${pairs}}`
+}
+and toStringNameSpace = nameSpace => {
+  let NameSpace(container) = nameSpace
+  container->toStringMap
+}
+
+let toStringWithType = aValue =>
+  switch aValue {
+  | IEvArray(_) => `Array::${toString(aValue)}`
+  | IEvArrayString(_) => `ArrayString::${toString(aValue)}`
+  | IEvBool(_) => `Bool::${toString(aValue)}`
+  | IEvCall(_) => `Call::${toString(aValue)}`
+  | IEvDistribution(_) => `Distribution::${toString(aValue)}`
+  | IEvLambda(_) => `Lambda::${toString(aValue)}`
+  | IEvNumber(_) => `Number::${toString(aValue)}`
+  | IEvRecord(_) => `Record::${toString(aValue)}`
+  | IEvString(_) => `String::${toString(aValue)}`
+  | IEvSymbol(_) => `Symbol::${toString(aValue)}`
+  | IEvDate(_) => `Date::${toString(aValue)}`
+  | IEvTimeDuration(_) => `Date::${toString(aValue)}`
+  | IEvDeclaration(_) => `Declaration::${toString(aValue)}`
+  | IEvTypeIdentifier(_) => `TypeIdentifier::${toString(aValue)}`
+  | IEvModule(_) => `Module::${toString(aValue)}`
+  }
+
+let argsToString = (args: array<t>): string => {
+  args->Js.Array2.map(arg => arg->toString)->Js.Array2.toString
+}
+
+let toStringFunctionCall = ((fn, args)): string => `${fn}(${argsToString(args)})`
+
+let toStringResult = x =>
+  switch x {
+  | Ok(a) => `Ok(${toString(a)})`
+  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
+  }
+
+let toStringResultOkless = (codeResult: result<t, ErrorValue.errorValue>): string =>
+  switch codeResult {
+  | Ok(a) => toString(a)
+  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
+  }
+
+let toStringResultRecord = x =>
+  switch x {
+  | Ok(a) => `Ok(${ExternalExpressionValue.toStringRecord(a)})`
+  | Error(m) => `Error(${ErrorValue.errorToString(m)})`
+  }
+
+type internalExpressionValueType =
+  | EvtArray
+  | EvtArrayString
+  | EvtBool
+  | EvtCall
+  | EvtDistribution
+  | EvtLambda
+  | EvtNumber
+  | EvtRecord
+  | EvtString
+  | EvtSymbol
+  | EvtDate
+  | EvtTimeDuration
+  | EvtDeclaration
+  | EvtTypeIdentifier
+  | EvtModule
+
+type functionCallSignature = CallSignature(string, array<internalExpressionValueType>)
+type functionDefinitionSignature =
+  FunctionDefinitionSignature(functionCallSignature, internalExpressionValueType)
+
+let valueToValueType = value =>
+  switch value {
+  | IEvArray(_) => EvtArray
+  | IEvArrayString(_) => EvtArrayString
+  | IEvBool(_) => EvtBool
+  | IEvCall(_) => EvtCall
+  | IEvDistribution(_) => EvtDistribution
+  | IEvLambda(_) => EvtLambda
+  | IEvNumber(_) => EvtNumber
+  | IEvRecord(_) => EvtRecord
+  | IEvString(_) => EvtString
+  | IEvSymbol(_) => EvtSymbol
+  | IEvDate(_) => EvtDate
+  | IEvTimeDuration(_) => EvtTimeDuration
+  | IEvDeclaration(_) => EvtDeclaration
+  | IEvTypeIdentifier(_) => EvtTypeIdentifier
+  | IEvModule(_) => EvtModule
+  }
+
+let functionCallToCallSignature = (functionCall: functionCall): functionCallSignature => {
+  let (fn, args) = functionCall
+  CallSignature(fn, args->Js.Array2.map(valueToValueType))
+}
+
+let valueTypeToString = (valueType: internalExpressionValueType): string =>
+  switch valueType {
+  | EvtArray => `Array`
+  | EvtArrayString => `ArrayString`
+  | EvtBool => `Bool`
+  | EvtCall => `Call`
+  | EvtDistribution => `Distribution`
+  | EvtLambda => `Lambda`
+  | EvtNumber => `Number`
+  | EvtRecord => `Record`
+  | EvtString => `String`
+  | EvtSymbol => `Symbol`
+  | EvtDate => `Date`
+  | EvtTimeDuration => `Duration`
+  | EvtDeclaration => `Declaration`
+  | EvtTypeIdentifier => `TypeIdentifier`
+  | EvtModule => `Module`
+  }
+
+let functionCallSignatureToString = (functionCallSignature: functionCallSignature): string => {
+  let CallSignature(fn, args) = functionCallSignature
+  `${fn}(${args->Js.Array2.map(valueTypeToString)->Js.Array2.toString})`
+}
+
+let rec toExternal = (iev: t): ExternalExpressionValue.t => {
+  switch iev {
+  | IEvArray(v) => v->Belt.Array.map(e => toExternal(e))->EvArray
+  | IEvArrayString(v) => EvArrayString(v)
+  | IEvBool(v) => EvBool(v)
+  | IEvCall(v) => EvCall(v)
+  | IEvDistribution(v) => EvDistribution(v)
+  | IEvLambda(v) => EvLambda(lambdaValueToExternal(v))
+  | IEvNumber(v) => EvNumber(v)
+  | IEvRecord(v) => v->mapToExternal->EvRecord
+  | IEvString(v) => EvString(v)
+  | IEvSymbol(v) => EvSymbol(v)
+  | IEvDate(v) => EvDate(v)
+  | IEvTimeDuration(v) => EvTimeDuration(v)
+  | IEvDeclaration(v) => {
+      let fn = lambdaValueToExternal(v.fn)
+      let args = v.args
+      EvDeclaration({fn: fn, args: args})
+    }
+  | IEvTypeIdentifier(v) => EvTypeIdentifier(v)
+  | IEvModule(v) => v->nameSpaceToTypeScriptBindings->EvModule
+  }
+}
+and mapToExternal = v =>
+  v->Belt.Map.String.map(e => toExternal(e))->Belt.Map.String.toArray->Js.Dict.fromArray
+and lambdaValueToExternal = v => {
+  let p = v.parameters
+  let c = v.context->nameSpaceToTypeScriptBindings
+  let b = v.body
+  {parameters: p, context: c, body: b}
+}
+and nameSpaceToTypeScriptBindings = (
+  nameSpace: nameSpace,
+): ReducerInterface_ExternalExpressionValue.externalBindings => {
+  let NameSpace(container) = nameSpace
+  Belt.Map.String.map(container, e => toExternal(e))->Belt.Map.String.toArray->Js.Dict.fromArray
+}
+
+let rec toInternal = (ev: ExternalExpressionValue.t): t => {
+  switch ev {
+  | EvArray(v) => v->Belt.Array.map(e => toInternal(e))->IEvArray
+  | EvArrayString(v) => IEvArrayString(v)
+  | EvBool(v) => IEvBool(v)
+  | EvCall(v) => IEvCall(v)
+  | EvDistribution(v) => IEvDistribution(v)
+  | EvLambda(v) => IEvLambda(lambdaValueToInternal(v))
+  | EvNumber(v) => IEvNumber(v)
+  | EvRecord(v) => v->recordToInternal->IEvRecord
+  | EvString(v) => IEvString(v)
+  | EvSymbol(v) => IEvSymbol(v)
+  | EvDate(v) => IEvDate(v)
+  | EvTimeDuration(v) => IEvTimeDuration(v)
+  | EvDeclaration(v) => {
+      let fn = lambdaValueToInternal(v.fn)
+      let args = v.args
+      IEvDeclaration({fn: fn, args: args})
+    }
+  | EvTypeIdentifier(v) => IEvTypeIdentifier(v)
+  | EvModule(v) => v->nameSpaceFromTypeScriptBindings->IEvModule
+  }
+}
+and recordToInternal = v =>
+  v->Js.Dict.entries->Belt.Map.String.fromArray->Belt.Map.String.map(e => toInternal(e))
+and lambdaValueToInternal = v => {
+  let p = v.parameters
+  let c = v.context->nameSpaceFromTypeScriptBindings
+  let b = v.body
+  {parameters: p, context: c, body: b}
+}
+and nameSpaceFromTypeScriptBindings = (
+  r: ReducerInterface_ExternalExpressionValue.externalBindings,
+): nameSpace =>
+  r->Js.Dict.entries->Belt.Map.String.fromArray->Belt.Map.String.map(e => toInternal(e))->NameSpace

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_Number.res

@@ -1,5 +1,5 @@
-module EV = ReducerInterface_ExpressionValue
+module IEV = ReducerInterface_InternalExpressionValue
-type expressionValue = EV.expressionValue
+type internalExpressionValue = IEV.t
 
 module ScientificUnit = {
   let nameToMultiplier = str =>
@@ -24,8 +24,8 @@ module ScientificUnit = {
   }
 }
 
-let dispatch = (call: EV.functionCall, _: DistributionOperation.env): option<
+let dispatch = (call: IEV.functionCall, _: DistributionOperation.env): option<
-  result<expressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
+  result<internalExpressionValue, QuriSquiggleLang.Reducer_ErrorValue.errorValue>,
 > => {
   switch call {
   | (
@@ -37,9 +37,9 @@ let dispatch = (call: EV.functionCall, _: DistributionOperation.env): option<
       | "fromUnit_G"
       | "fromUnit_T"
       | "fromUnit_P") as op,
-      [EvNumber(f)],
+      [IEvNumber(f)],
     ) =>
-    op->ScientificUnit.getMultiplier->E.O2.fmap(multiplier => EV.EvNumber(f *. multiplier)->Ok)
+    op->ScientificUnit.getMultiplier->E.O2.fmap(multiplier => IEV.IEvNumber(f *. multiplier)->Ok)
   | _ => None
   }
 }

packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_StdLib.res

@@ -1,6 +1,6 @@
-module Bindings = Reducer_Category_Bindings
+module Module = Reducer_Category_Module
 
-let internalStdLib = Bindings.emptyBindings->SquiggleLibrary_Math.makeBindings
+let internalStdLib = Module.emptyModule->SquiggleLibrary_Math.makeBindings
 
 @genType
-let externalStdLib = internalStdLib->Bindings.toRecord
+let externalStdLib = internalStdLib->Module.toTypeScriptBindings

packages/squiggle-lang/src/rescript/SquiggleLibrary/SquiggleLibrary_Math.res

@@ -1,4 +1,4 @@
-module Bindings = Reducer_Category_Bindings
+module Bindings = Reducer_Category_Module
 module Module = Reducer_Category_Module
 
 let availableNumbers: array<(string, float)> = [
@@ -14,10 +14,10 @@ let availableNumbers: array<(string, float)> = [
   ("tau", 6.283185307179586),
 ]
 
-let mathBindings: Bindings.ExpressionT.bindings =
+let mathBindings: Bindings.t =
   availableNumbers
-  ->E.A2.fmap(((name, v)) => (name, ReducerInterface_ExpressionValue.EvNumber(v)))
+  ->E.A2.fmap(((name, v)) => (name, ReducerInterface_InternalExpressionValue.IEvNumber(v)))
-  ->Belt.Map.String.fromArray
+  ->Bindings.fromArray
 
 let makeBindings = (previousBindings: Bindings.t): Bindings.t =>
   previousBindings->Bindings.defineModule("Math", mathBindings)

packages/squiggle-lang/src/rescript/TypescriptInterface.res

@@ -50,10 +50,10 @@ let evaluatePartialUsingExternalBindings = Reducer.evaluatePartialUsingExternalB
 type externalBindings = Reducer.externalBindings
 
 @genType
-type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type expressionValue = ReducerInterface_ExternalExpressionValue.t
 
 @genType
-type recordEV = ReducerInterface_ExpressionValue.record
+type recordEV = ReducerInterface_ExternalExpressionValue.record
 
 @genType
 type errorValue = Reducer_ErrorValue.errorValue
@@ -77,19 +77,19 @@ let errorValueToString = Reducer_ErrorValue.errorToString
 let distributionErrorToString = DistributionTypes.Error.toString
 
 @genType
-type lambdaValue = ReducerInterface_ExpressionValue.lambdaValue
+type lambdaValue = ReducerInterface_ExternalExpressionValue.lambdaValue
 
 @genType
-type lambdaDeclaration = ReducerInterface_ExpressionValue.lambdaDeclaration
+type lambdaDeclaration = ReducerInterface_ExternalExpressionValue.lambdaDeclaration
 
 @genType
 let defaultSamplingEnv = DistributionOperation.defaultEnv
 
 @genType
-type environment = ReducerInterface_ExpressionValue.environment
+type environment = ReducerInterface_ExternalExpressionValue.environment
 
 @genType
-let defaultEnvironment = ReducerInterface_ExpressionValue.defaultEnvironment
+let defaultEnvironment = ReducerInterface_ExternalExpressionValue.defaultEnvironment
 
 @genType
 let foreignFunctionInterface = Reducer.foreignFunctionInterface

packages/vscode-ext/client/src/extension.ts

@@ -4,6 +4,7 @@ import * as vscode from "vscode";
 import { startClient, stopClient } from "./client";
 
 import { SquiggleEditorProvider } from "./editor";
+import { registerSemanticHighlight } from "./highlight";
 import { registerPreviewCommand } from "./preview";
 
 // this method is called when your extension is activated
@@ -13,6 +14,8 @@ export function activate(context: vscode.ExtensionContext) {
 
   registerPreviewCommand(context);
 
+  registerSemanticHighlight();
+
   startClient(context);
 }
 

packages/vscode-ext/client/src/highlight.ts

@@ -0,0 +1,96 @@
+import * as vscode from "vscode";
+
+import { parse } from "@quri/squiggle-lang";
+import { AnyPeggyNode } from "@quri/squiggle-lang/dist/src/rescript/Reducer/Reducer_Peggy/helpers";
+
+const tokenTypes = ["enum", "function", "variable", "property"];
+const tokenModifiers = ["declaration", "documentation"];
+const legend = new vscode.SemanticTokensLegend(tokenTypes, tokenModifiers);
+
+const convertRange = (
+  range: Extract<AnyPeggyNode, { type: "Identifier" }>["location"]
+) =>
+  new vscode.Range(
+    new vscode.Position(range.start.line - 1, range.start.column - 1),
+    new vscode.Position(range.end.line - 1, range.end.column - 1)
+  );
+
+const populateTokensBuilder = (
+  tokensBuilder: vscode.SemanticTokensBuilder,
+  node: AnyPeggyNode
+  // bindings: { [key: string]: boolean }
+) => {
+  switch (node.type) {
+    case "Expression":
+      for (const child of node.nodes) {
+        populateTokensBuilder(tokensBuilder, child);
+      }
+      break;
+    case "Block":
+      for (const child of node.statements) {
+        populateTokensBuilder(tokensBuilder, child);
+      }
+      break;
+    case "LetStatement":
+      tokensBuilder.push(
+        convertRange(node.variable.location),
+        node.value.type === "Lambda" ? "function" : "variable",
+        ["declaration"]
+      );
+      populateTokensBuilder(tokensBuilder, node.value);
+      break;
+    case "Lambda":
+      for (const arg of node.args) {
+        populateTokensBuilder(tokensBuilder, arg);
+      }
+      populateTokensBuilder(tokensBuilder, node.body);
+      break;
+    case "Ternary":
+      populateTokensBuilder(tokensBuilder, node.condition);
+      populateTokensBuilder(tokensBuilder, node.trueExpression);
+      populateTokensBuilder(tokensBuilder, node.falseExpression);
+      break;
+    case "KeyValue":
+      if (node.key.type === "String" && node.key.location) {
+        tokensBuilder.push(convertRange(node.key.location), "property", [
+          "declaration",
+        ]);
+      } else {
+        populateTokensBuilder(tokensBuilder, node.key);
+      }
+      populateTokensBuilder(tokensBuilder, node.value);
+      break;
+    case "Identifier":
+      tokensBuilder.push(convertRange(node.location), "variable");
+      break;
+  }
+};
+
+export const registerSemanticHighlight = () => {
+  const provider: vscode.DocumentSemanticTokensProvider = {
+    provideDocumentSemanticTokens(
+      document: vscode.TextDocument
+    ): vscode.ProviderResult<vscode.SemanticTokens> {
+      const parseResult = parse(document.getText());
+
+      const tokensBuilder = new vscode.SemanticTokensBuilder(legend);
+      if (parseResult.tag === "Ok") {
+        populateTokensBuilder(
+          tokensBuilder,
+          parseResult.value
+          // {}
+        );
+      }
+
+      return tokensBuilder.build();
+    },
+  };
+
+  const selector = { language: "squiggle", scheme: "file" };
+
+  vscode.languages.registerDocumentSemanticTokensProvider(
+    selector,
+    provider,
+    legend
+  );
+};

packages/vscode-ext/server/src/server.ts

@@ -13,6 +13,10 @@ import { parse } from "@quri/squiggle-lang";
 
 import { TextDocument } from "vscode-languageserver-textdocument";
 
+// Documentation:
+// - https://code.visualstudio.com/api/language-extensions/language-server-extension-guide
+// - https://microsoft.github.io/language-server-protocol/specifications/specification-current
+
 // Create a connection for the server, using Node's IPC as a transport.
 // Also include all preview / proposed LSP features.
 let connection = createConnection(ProposedFeatures.all);
@@ -23,17 +27,7 @@ documents.onDidChangeContent((change) => {
   validateSquiggleDocument(change.document);
 });
 
-let hasDiagnosticRelatedInformationCapability = false;
-
 connection.onInitialize((params: InitializeParams) => {
-  const capabilities = params.capabilities;
-
-  hasDiagnosticRelatedInformationCapability = !!(
-    capabilities.textDocument &&
-    capabilities.textDocument.publishDiagnostics &&
-    capabilities.textDocument.publishDiagnostics.relatedInformation
-  );
-
   const result: InitializeResult = {
     capabilities: {
       textDocumentSync: TextDocumentSyncKind.Incremental,