format, rename, simplify

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

@@ -1,12 +1,10 @@
-module CT = Reducer.CodeTree
+module ExpressionValue = ReducerInterface.ExpressionValue
-module CTV = Reducer.Extension.CodeTreeValue
-module JsG = Reducer.Js.Gate
 
 open Jest
 open Expect
 
 let expectEvalToBe = (expr: string, answer: string) =>
-  Reducer.eval(expr) -> CTV.showResult -> expect -> toBe(answer)
+  Reducer.eval(expr)->ExpressionValue.showResult->expect->toBe(answer)
 
 describe("builtin", () => {
   // All MathJs operators and functions are available for string, number and boolean
@@ -21,5 +19,7 @@ describe("builtin", () => {
 
 describe("builtin exception", () => {
   //It's a pity that MathJs does not return error position
-  test("MathJs Exception", () => expectEvalToBe( "testZadanga()", "Error(JS Exception: Error: Undefined function testZadanga)"))
+  test("MathJs Exception", () =>
+    expectEvalToBe("testZadanga()", "Error(JS Exception: Error: Undefined function testZadanga)")
+  )
 })

packages/squiggle-lang/__tests__/Reducer/Reducer_Extension/ReducerExtension_CodeTreeValue_test.res

@@ -1,15 +1,11 @@
-module CTV = Reducer.Extension.CodeTreeValue
+open ReducerInterface.ExpressionValue
 open Jest
 open Expect
 
-describe("CodeTreeValue", () => {
+describe("ExpressionValue", () => {
-  test("showArgs", () =>
+  test("showArgs", () => expect([EvNumber(1.), EvString("a")]->showArgs)->toBe("1, 'a'"))
-    expect([CTV.CtvNumber(1.), CTV.CtvString("a")]->CTV.showArgs)
-    ->toBe("1, 'a'")
-  )
 
   test("showFunctionCall", () =>
-    expect( ("fn", [CTV.CtvNumber(1.), CTV.CtvString("a")])->CTV.showFunctionCall )
+    expect(("fn", [EvNumber(1.), EvString("a")])->showFunctionCall)->toBe("fn(1, 'a')")
-    ->toBe("fn(1, 'a')")
   )
 })

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

@@ -1,30 +1,32 @@
-module CTV = Reducer.Extension.CodeTreeValue
+open ReducerInterface.ExpressionValue
 module ME = Reducer.MathJs.Eval
-module Rerr = Reducer.Error
+module ErrorValue = Reducer.Error
 
 open Jest
 open ExpectJs
 
 describe("eval", () => {
-    test("Number", () => expect(ME.eval("1"))
+  test("Number", () => expect(ME.eval("1"))->toEqual(Ok(EvNumber(1.))))
-    -> toEqual(Ok(CTV.CtvNumber(1.))))
+  test("Number expr", () => expect(ME.eval("1-1"))->toEqual(Ok(EvNumber(0.))))
-    test("Number expr", () => expect(ME.eval("1-1"))
+  test("String", () => expect(ME.eval("'hello'"))->toEqual(Ok(EvString("hello"))))
-    -> toEqual(Ok(CTV.CtvNumber(0.))))
+  test("String expr", () =>
-    test("String", () => expect(ME.eval("'hello'"))
+    expect(ME.eval("concat('hello ','world')"))->toEqual(Ok(EvString("hello world")))
-    -> toEqual(Ok(CTV.CtvString("hello"))))
+  )
-    test("String expr", () => expect(ME.eval("concat('hello ','world')"))
+  test("Boolean", () => expect(ME.eval("true"))->toEqual(Ok(EvBool(true))))
-    -> toEqual(Ok(CTV.CtvString("hello world"))))
+  test("Boolean expr", () => expect(ME.eval("2>1"))->toEqual(Ok(EvBool(true))))
-    test("Boolean", () => expect(ME.eval("true"))
-    -> toEqual(Ok(CTV.CtvBool(true))))
-    test("Boolean expr", () => expect(ME.eval("2>1"))
-    -> toEqual(Ok(CTV.CtvBool(true))))
 })
 
 describe("errors", () => {
   // All those errors propagete up and are returned by the resolver
-  test("unknown function", () => expect(ME.eval("testZadanga()"))
+  test("unknown function", () =>
-  -> toEqual(Error(Rerr.RerrJs(Some("Undefined function testZadanga"), Some("Error")))))
+    expect(ME.eval("testZadanga()"))->toEqual(
+      Error(ErrorValue.REJs(Some("Undefined function testZadanga"), Some("Error"))),
+    )
+  )
 
-  test("unknown answer type", () => expect(ME.eval("1+1i"))
+  test("unknown answer type", () =>
-  -> toEqual(Error(Rerr.RerrTodo("Unhandled MathJs literal type: object"))))
+    expect(ME.eval("1+1i"))->toEqual(
+      Error(ErrorValue.RETodo("Unhandled MathJs literal type: object")),
+    )
+  )
 })

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

@@ -1,15 +1,13 @@
-module MJ=Reducer.MathJs.Parse
+module Parse = Reducer.MathJs.Parse
 module Result = Belt.Result
 
 open Jest
 open Expect
 
 let expectParseToBe = (expr, answer) =>
-  MJ.parse(expr) -> Result.flatMap(MJ.castNodeType) -> MJ.showResult
+  Parse.parse(expr)->Result.flatMap(Parse.castNodeType)->Parse.showResult->expect->toBe(answer)
-  -> expect -> toBe(answer)
 
 describe("MathJs parse", () => {
-
   describe("literals operators paranthesis", () => {
     test("1", () => expectParseToBe("1", "1"))
     test("'hello'", () => expectParseToBe("'hello'", "'hello'"))
@@ -33,8 +31,7 @@ describe("MathJs parse", () => {
   describe("arrays", () => {
     test("empty", () => expectParseToBe("[]", "[]"))
     test("define", () => expectParseToBe("[0, 1, 2]", "[0, 1, 2]"))
-    test("define with strings", () =>
+    test("define with strings", () => expectParseToBe("['hello', 'world']", "['hello', 'world']"))
-      expectParseToBe("['hello', 'world']", "['hello', 'world']"))
     Skip.test("range", () => expectParseToBe("range(0, 4)", "range(0, 4)"))
     test("index", () => expectParseToBe("([0,1,2])[1]", "([0, 1, 2])[1]"))
   })
@@ -51,5 +48,4 @@ describe("MathJs parse", () => {
   describe("if statement", () => {
     Skip.test("define", () => expectParseToBe("if (true) { 1 } else { 0 }", "???"))
   })
-
 })

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

@@ -1,14 +1,14 @@
-module CT = Reducer.CodeTree
+module Expression = Reducer.Expression
-module CTV = Reducer.Extension.CodeTreeValue
+module ExpressionValue = ReducerInterface.ExpressionValue
 
 open Jest
 open Expect
 
 let expectParseToBe = (expr: string, answer: string) =>
-  Reducer.parse(expr) -> CT.showResult -> expect -> toBe(answer)
+  Reducer.parse(expr)->Expression.showResult->expect->toBe(answer)
 
 let expectEvalToBe = (expr: string, answer: string) =>
-  Reducer.eval(expr) -> CTV.showResult -> expect -> toBe(answer)
+  Reducer.eval(expr)->ExpressionValue.showResult->expect->toBe(answer)
 
 // Current configuration does not ignore this file so we have to have a test
 test("test helpers", () => expect(1)->toBe(1))

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

@@ -3,7 +3,7 @@ open Reducer_TestHelpers
 
 describe("reducer using mathjs parse", () => {
   // Test the MathJs parser compatibility
-  // Those tests show that there is a semantic mapping from MathJs to CodeTree
+  // Those tests show that there is a semantic mapping from MathJs to Expression
   // Reducer.parse is called by Reducer.eval
   // See https://mathjs.org/docs/expressions/syntax.html
   // See https://mathjs.org/docs/reference/functions.html
@@ -23,14 +23,19 @@ describe("reducer using mathjs parse", () => {
     //  [1,2,3] becomes (1 2 3)
     test("empty", () => expectParseToBe("[]", "Ok(())"))
     test("[1, 2, 3]", () => expectParseToBe("[1, 2, 3]", "Ok((1 2 3))"))
-    test("['hello', 'world']", () =>
+    test("['hello', 'world']", () => expectParseToBe("['hello', 'world']", "Ok(('hello' 'world'))"))
-      expectParseToBe( "['hello', 'world']", "Ok(('hello' 'world'))"))
     test("index", () => expectParseToBe("([0,1,2])[1]", "Ok((:$atIndex (0 1 2) (1)))"))
   })
   describe("records", () => {
-    test("define", () => expectParseToBe("{a: 1, b: 2}", "Ok((:$constructRecord (('a' 1) ('b' 2))))"))
+    test("define", () =>
+      expectParseToBe("{a: 1, b: 2}", "Ok((:$constructRecord (('a' 1) ('b' 2))))")
+    )
     test("use", () =>
-      expectParseToBe("{a: 1, b: 2}.a", "Ok((:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a')))"))
+      expectParseToBe(
+        "{a: 1, b: 2}.a",
+        "Ok((:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a')))",
+      )
+    )
   })
 })
 
@@ -54,23 +59,23 @@ describe("eval", () => {
     test("[1, 2, 3]", () => expectEvalToBe("[1, 2, 3]", "Ok([1, 2, 3])"))
     test("['hello', 'world']", () => expectEvalToBe("['hello', 'world']", "Ok(['hello', 'world'])"))
     test("index", () => expectEvalToBe("([0,1,2])[1]", "Ok(1)"))
-    test("index not found", ()
+    test("index not found", () =>
-      => expectEvalToBe("([0,1,2])[10]", "Error(Array index not found: 10)"))
+      expectEvalToBe("([0,1,2])[10]", "Error(Array index not found: 10)")
+    )
   })
   describe("records", () => {
-    test("define", () =>
+    test("define", () => expectEvalToBe("{a: 1, b: 2}", "Ok({a: 1, b: 2})"))
-      expectEvalToBe("{a: 1, b: 2}", "Ok({a: 1, b: 2})"))
+    test("index", () => expectEvalToBe("{a: 1}.a", "Ok(1)"))
-    test("index", () =>
+    test("index not found", () => expectEvalToBe("{a: 1}.b", "Error(Record property not found: b)"))
-      expectEvalToBe("{a: 1}.a", "Ok(1)"))
-    test("index not found", () =>
-      expectEvalToBe("{a: 1}.b", "Error(Record property not found: b)"))
   })
 })
 
 describe("test exceptions", () => {
   test("javascript exception", () =>
-    expectEvalToBe( "jsraise('div by 0')", "Error(JS Exception: Error: 'div by 0')"))
+    expectEvalToBe("jsraise('div by 0')", "Error(JS Exception: Error: 'div by 0')")
+  )
 
   test("rescript exception", () =>
-    expectEvalToBe( "resraise()", "Error(TODO: unhandled rescript exception)"))
+    expectEvalToBe("resraise()", "Error(TODO: unhandled rescript exception)")
+  )
 })

packages/squiggle-lang/src/rescript/Reducer/README.md

@@ -1,15 +1,17 @@
 To interface your library there only 2 files to be modified:
-- Reducer/Reducer_Extension/Reducer_Extension_CodeTreeValue.res
+
+- Reducer/ReducerInterface/ReducerInterface_ExpressionValue.res
 
   This is where your additional types are referred for the dispatcher.
 
-- Reducer/Reducer_Extension/Reducer_ReducerLibrary.res
+- Reducer/ReducerInterface/ReducerInterface_ExternalLibrary.res
 
   This is where dispatching to your library is done. If the dispatcher becomes beastly then feel free to divide it into submodules.
 
 The Reducer is built to use different external libraries as well as different external parsers. Both external parsers and external libraries are plugins.
 
 And finally try using Reducer.eval to how your extentions look:
+
 ```rescript
   test("1+2", () => expectEvalToBe( "1+2", "Ok(3)"))
 ```

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

@@ -1,10 +1,10 @@
-module CodeTree = Reducer_CodeTree
 module Dispatch = Reducer_Dispatch
-module Error = Reducer_Error
+module Error = Reducer_ErrorValue
-module Extension = Reducer_Extension
+module ErrorValue = Reducer_ErrorValue
+module Expression = Reducer_Expression
+module Extra = Reducer_Extra
 module Js = Reducer_Js
-module Etra = Reducer_Extra
 module MathJs = Reducer_MathJs
 
-let eval = CodeTree.eval
+let eval = Expression.eval
-let parse = CodeTree.parse
+let parse = Expression.parse

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

@@ -0,0 +1,9 @@
+module Dispatch = Reducer_Dispatch
+module Error = Reducer_ErrorValue
+module ErrorValue = Reducer_ErrorValue
+module Expression = Reducer_Expression
+module Extra = Reducer_Extra
+module Js = Reducer_Js
+module MathJs = Reducer_MathJs
+let eval: string => result<Expression.expressionValue, ErrorValue.errorValue>
+let parse: string => result<Expression.expression, ErrorValue.errorValue>

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

@@ -1,91 +0,0 @@
-module BuiltIn = Reducer_Dispatch_BuiltIn
-module T = Reducer_CodeTree_T
-module CTV = Reducer_Extension.CodeTreeValue
-module MJ = Reducer_MathJs_Parse
-module MJT = Reducer_MathJs_ToCodeTree
-module RLE = Reducer_Extra_List
-module Rerr = Reducer_Error
-module Result = Belt.Result
-
-type codeTree = T.codeTree
-type codeTreeValue = CTV.codeTreeValue
-type reducerError = Rerr.reducerError
-
-/*
-  Shows the Lisp Code as text lisp code
-*/
-let rec show = codeTree => switch codeTree {
-| T.CtList(aList) => `(${(Belt.List.map(aList, aValue => show(aValue))
-    -> RLE.interperse(" ")
-    -> Belt.List.toArray -> Js.String.concatMany(""))})`
-| CtValue(aValue) => CTV.show(aValue)
-}
-
-let showResult = (codeResult) => switch codeResult {
-| Ok(a) => `Ok(${show(a)})`
-| Error(m) => `Error(${Js.String.make(m)})`
-}
-
-/*
-  Converts a MathJs code to Lisp Code
-*/
-let parse_ = (expr: string, parser, converter): result<codeTree, reducerError> =>
-  expr -> parser -> Result.flatMap(node => converter(node))
-
-let parse = (mathJsCode: string): result<codeTree, reducerError> =>
-  mathJsCode -> parse_( MJ.parse, MJT.fromNode )
-
-module MapString = Belt.Map.String
-type bindings = MapString.t<unit>
-let defaultBindings: bindings = MapString.fromArray([])
-// TODO Define bindings for function execution context
-
-/*
-  After reducing each level of code tree, we have a value list to evaluate
-*/
-let reduceValueList = (valueList: list<codeTreeValue>): result<codeTreeValue, 'e> =>
-      switch valueList {
-        | list{CtvSymbol(fName), ...args} =>
-            (fName, args->Belt.List.toArray) -> BuiltIn.dispatch
-        | _ =>
-            valueList -> Belt.List.toArray -> CTV.CtvArray -> Ok
-      }
-
-/*
-  Recursively evaluate/reduce the code tree
-*/
-let rec reduceCodeTree = (codeTree: codeTree, bindings): result<codeTreeValue, 'e> =>
-  switch codeTree {
-  | T.CtValue( value ) => value -> Ok
-  | T.CtList( list ) => {
-    let racc: result<list<codeTreeValue>, 'e> = list -> Belt.List.reduceReverse(
-
-      Ok(list{}),
-      (racc, each: codeTree) => racc->Result.flatMap( acc => {
-
-                  each
-                  ->  reduceCodeTree(bindings)
-                  ->  Result.flatMap( newNode => {
-                          acc->Belt.List.add(newNode)->Ok
-                      })
-
-      })
-
-    )
-    racc -> Result.flatMap( acc => acc->reduceValueList )}
-  }
-
-let evalWBindingsCodeTree = (aCodeTree, bindings): result<codeTreeValue, 'e> =>
-  reduceCodeTree(aCodeTree, bindings)
-
-/*
-  Evaluates MathJs code via Lisp using bindings and answers the result
-*/
-let evalWBindings = (codeText:string, bindings: bindings) => {
-  parse(codeText) -> Result.flatMap(code => code -> evalWBindingsCodeTree(bindings))
-}
-
-/*
-  Evaluates MathJs code via Lisp and answers the result
-*/
-let eval = (code: string) => evalWBindings(code, defaultBindings)

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

@@ -1,7 +0,0 @@
-module CTV = Reducer_Extension.CodeTreeValue
-
-type codeTreeValue = CTV.codeTreeValue
-
-type rec codeTree =
-| CtList(list<codeTree>)  // A list to map-reduce
-| CtValue(codeTreeValue)  // Irreducible built-in value. Reducer should not know the internals. External libraries are responsible

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

@@ -1,72 +1,72 @@
-module CTV = Reducer_Extension.CodeTreeValue
+module ExternalLibrary = ReducerInterface.ExternalLibrary
-module Lib = Reducer_Extension.ReducerLibrary
+module MathJs = Reducer_MathJs
-module ME = Reducer_MathJs.Eval
+open ReducerInterface.ExpressionValue
-module Rerr = Reducer_Error
+open Reducer_ErrorValue
+
 /*
   MathJs provides default implementations for builtins
   This is where all the expected builtins like + = * / sin cos log ln etc are handled
   DO NOT try to add external function mapping here!
 */
-type codeTreeValue = CTV.codeTreeValue
-type reducerError = Rerr.reducerError
 
 exception TestRescriptException
 
-let callInternal = (call: CTV.functionCall): result<'b, reducerError> =>{
+let callInternal = (call: functionCall): result<'b, errorValue> => {
-
+  let callMathJs = (call: functionCall): result<'b, errorValue> =>
-  let callMathJs = (call: CTV.functionCall): result<'b, reducerError> =>
     switch call {
-      | ("jsraise", [msg]) => Js.Exn.raiseError(CTV.show(msg)) // For Tests
+    | ("jsraise", [msg]) => Js.Exn.raiseError(show(msg)) // For Tests
     | ("resraise", _) => raise(TestRescriptException) // For Tests
-      | call => call->CTV.showFunctionCall-> ME.eval
+    | call => call->showFunctionCall->MathJs.Eval.eval
     }
 
   let constructRecord = arrayOfPairs => {
     Belt.Array.map(arrayOfPairs, pairValue => {
       switch pairValue {
-      | CTV.CtvArray([CTV.CtvString(key), valueValue]) =>
+      | EvArray([EvString(key), valueValue]) => (key, valueValue)
-        (key, valueValue)
+      | _ => ("wrong key type", pairValue->showWithType->EvString)
-      | _ => ("wrong key type", pairValue->CTV.showWithType->CTV.CtvString)}
+      }
-      }) -> Js.Dict.fromArray -> CTV.CtvRecord -> Ok
+    })
+    ->Js.Dict.fromArray
+    ->EvRecord
+    ->Ok
   }
 
-  let arrayAtIndex = (aValueArray: array<codeTreeValue>, fIndex: float) =>
+  let arrayAtIndex = (aValueArray: array<expressionValue>, fIndex: float) =>
     switch Belt.Array.get(aValueArray, Belt.Int.fromFloat(fIndex)) {
     | Some(value) => value->Ok
-    | None => Rerr.RerrArrayIndexNotFound("Array index not found", Belt.Int.fromFloat(fIndex)) -> Error
+    | None => REArrayIndexNotFound("Array index not found", Belt.Int.fromFloat(fIndex))->Error
     }
 
-  let recordAtIndex = (dict: Js.Dict.t<codeTreeValue>, sIndex) =>
+  let recordAtIndex = (dict: Js.Dict.t<expressionValue>, sIndex) =>
-    switch (Js.Dict.get(dict, sIndex)) {
+    switch Js.Dict.get(dict, sIndex) {
     | Some(value) => value->Ok
-      | None => Rerr.RerrRecordPropertyNotFound("Record property not found", sIndex) -> Error
+    | None => RERecordPropertyNotFound("Record property not found", sIndex)->Error
     }
 
   switch call {
   // | ("$constructRecord", pairArray)
-  // | ("$atIndex", [CTV.CtvArray(anArray), CTV.CtvNumber(fIndex)]) => arrayAtIndex(anArray, fIndex)
+  // | ("$atIndex", [EvArray(anArray), EvNumber(fIndex)]) => arrayAtIndex(anArray, fIndex)
-  // | ("$atIndex", [CTV.CtvRecord(aRecord), CTV.CtvString(sIndex)]) => recordAtIndex(aRecord, sIndex)
+  // | ("$atIndex", [EvRecord(aRecord), EvString(sIndex)]) => recordAtIndex(aRecord, sIndex)
-  | ("$constructRecord", [CTV.CtvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
+  | ("$constructRecord", [EvArray(arrayOfPairs)]) => constructRecord(arrayOfPairs)
-  | ("$atIndex", [CTV.CtvArray(aValueArray), CTV.CtvArray([CTV.CtvNumber(fIndex)])])  =>
+  | ("$atIndex", [EvArray(aValueArray), EvArray([EvNumber(fIndex)])]) =>
     arrayAtIndex(aValueArray, fIndex)
-  | ("$atIndex", [CTV.CtvRecord(dict), CTV.CtvArray([CTV.CtvString(sIndex)])]) => recordAtIndex(dict, sIndex)
+  | ("$atIndex", [EvRecord(dict), EvArray([EvString(sIndex)])]) => recordAtIndex(dict, sIndex)
-  | ("$atIndex", [obj, index]) => (CTV.showWithType(obj) ++ "??~~~~" ++ CTV.showWithType(index))->CTV.CtvString->Ok
+  | ("$atIndex", [obj, index]) =>
+    (showWithType(obj) ++ "??~~~~" ++ showWithType(index))->EvString->Ok
   | call => callMathJs(call)
   }
-
 }
 
 /*
   Lisp engine uses Result monad while reducing expressions
 */
-let dispatch = (call: CTV.functionCall): result<codeTreeValue, reducerError> =>
+let dispatch = (call: functionCall): result<expressionValue, errorValue> =>
   try {
     let (fn, args) = call
     // There is a bug that prevents string match in patterns
     // So we have to recreate a copy of the string
-    Lib.dispatch((Js.String.make(fn), args), callInternal)
+    ExternalLibrary.dispatch((Js.String.make(fn), args), callInternal)
   } catch {
-  | Js.Exn.Error(obj) =>
+  | Js.Exn.Error(obj) => REJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
-    RerrJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
+  | _ => RETodo("unhandled rescript exception")->Error
-  | _ => RerrTodo("unhandled rescript exception")->Error
   }

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

@@ -1,27 +0,0 @@
-type reducerError =
-| RerrFunctionExpected( string )
-| RerrJs(option<string>, option<string>)   // Javascript Exception
-| RerrTodo(string) // To do
-| RerrUnexecutedCode( string )
-| RerrArrayIndexNotFound(string, int)
-| RerrRecordPropertyNotFound(string, string)
-
-let showError = (err) => switch err {
-  | RerrTodo( msg ) => `TODO: ${msg}`
-  | RerrJs( omsg, oname ) => {
-      let answer = "JS Exception:"
-      let answer = switch oname {
-        | Some(name) => `${answer} ${name}`
-        | _ => answer
-      }
-      let answer = switch omsg {
-        | Some(msg) => `${answer}: ${msg}`
-        | _ => answer
-      }
-      answer
-    }
-  | RerrArrayIndexNotFound(msg, index) => `${msg}: ${Js.String.make(index)}`
-  | RerrRecordPropertyNotFound(msg, index) => `${msg}: ${index}`
-  | RerrUnexecutedCode( codeString ) => `Unexecuted code remaining: ${codeString}`
-  | RerrFunctionExpected( msg ) => `Function expected: ${msg}`
-  }

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

@@ -0,0 +1,26 @@
+type errorValue =
+  | REArrayIndexNotFound(string, int)
+  | REFunctionExpected(string)
+  | REJs(option<string>, option<string>) // Javascript Exception
+  | RERecordPropertyNotFound(string, string)
+  | RETodo(string) // To do
+
+let showError = err =>
+  switch err {
+  | REArrayIndexNotFound(msg, index) => `${msg}: ${Js.String.make(index)}`
+  | REFunctionExpected(msg) => `Function expected: ${msg}`
+  | REJs(omsg, oname) => {
+      let answer = "JS Exception:"
+      let answer = switch oname {
+      | Some(name) => `${answer} ${name}`
+      | _ => answer
+      }
+      let answer = switch omsg {
+      | Some(msg) => `${answer}: ${msg}`
+      | _ => answer
+      }
+      answer
+    }
+  | RERecordPropertyNotFound(msg, index) => `${msg}: ${index}`
+  | RETodo(msg) => `TODO: ${msg}`
+  }

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

@@ -0,0 +1,90 @@
+module BuiltIn = Reducer_Dispatch_BuiltIn
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Extra = Reducer_Extra
+module MathJs = Reducer_MathJs
+module Result = Belt.Result
+module T = Reducer_Expression_T
+open Reducer_ErrorValue
+
+type expression = T.expression
+type expressionValue = ExpressionValue.expressionValue
+
+/*
+  Shows the Lisp Code as text lisp code
+*/
+let rec show = expression =>
+  switch expression {
+  | T.EList(aList) =>
+    `(${Belt.List.map(aList, aValue => show(aValue))
+      ->Extra.List.interperse(" ")
+      ->Belt.List.toArray
+      ->Js.String.concatMany("")})`
+  | EValue(aValue) => ExpressionValue.show(aValue)
+  }
+
+let showResult = codeResult =>
+  switch codeResult {
+  | Ok(a) => `Ok(${show(a)})`
+  | Error(m) => `Error(${Js.String.make(m)})`
+  }
+
+/*
+  Converts a MathJs code to Lisp Code
+*/
+let parse_ = (expr: string, parser, converter): result<expression, errorValue> =>
+  expr->parser->Result.flatMap(node => converter(node))
+
+let parse = (mathJsCode: string): result<expression, errorValue> =>
+  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromNode)
+
+module MapString = Belt.Map.String
+type bindings = MapString.t<unit>
+let defaultBindings: bindings = MapString.fromArray([])
+// TODO Define bindings for function execution context
+
+/*
+  After reducing each level of code tree, we have a value list to evaluate
+*/
+let reduceValueList = (valueList: list<expressionValue>): result<expressionValue, 'e> =>
+  switch valueList {
+  | list{EvSymbol(fName), ...args} => (fName, args->Belt.List.toArray)->BuiltIn.dispatch
+  | _ => valueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
+  }
+
+/*
+  Recursively evaluate/reduce the code tree
+*/
+let rec reduceExpression = (expression: expression, bindings): result<expressionValue, 'e> =>
+  switch expression {
+  | T.EValue(value) => value->Ok
+  | T.EList(list) => {
+      let racc: result<list<expressionValue>, 'e> = list->Belt.List.reduceReverse(Ok(list{}), (
+        racc,
+        each: expression,
+      ) =>
+        racc->Result.flatMap(acc => {
+          each
+          ->reduceExpression(bindings)
+          ->Result.flatMap(newNode => {
+            acc->Belt.List.add(newNode)->Ok
+          })
+        })
+      )
+      racc->Result.flatMap(acc => acc->reduceValueList)
+    }
+  }
+
+let evalWBindingsExpression = (aExpression, bindings): result<expressionValue, 'e> =>
+  reduceExpression(aExpression, bindings)
+
+/*
+  Evaluates MathJs code via Lisp using bindings and answers the result
+*/
+let evalWBindings = (codeText: string, bindings: bindings) => {
+  parse(codeText)->Result.flatMap(code => code->evalWBindingsExpression(bindings))
+}
+
+/*
+  Evaluates MathJs code via Lisp and answers the result
+*/
+let eval = (code: string) => evalWBindings(code, defaultBindings)

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

@@ -0,0 +1,5 @@
+open ReducerInterface.ExpressionValue
+
+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

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

@@ -1,2 +0,0 @@
-module CodeTreeValue = Reducer_Extension_CodeTreeValue
-module ReducerLibrary = Reducer_Extension_ReducerLibrary

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

@@ -1,59 +0,0 @@
-/*
-  Irreducible values. Reducer does not know about those. Only used for external calls
-  This is a configuration to to make external calls of those types
-*/
-module AE = Reducer_Extra_Array
-module Rerr = Reducer_Error
-
-type rec codeTreeValue =
-| CtvBool(bool)
-| CtvNumber(float)
-| CtvString(string)
-| CtvSymbol(string)
-| CtvArray(array<codeTreeValue>)
-| CtvRecord(Js.Dict.t<codeTreeValue>)
-
-type functionCall  = (string, array<codeTreeValue>)
-
-let rec show = aValue => switch aValue {
-  | CtvBool( aBool ) => Js.String.make( aBool )
-  | CtvNumber( aNumber ) => Js.String.make( aNumber )
-  | CtvString( aString ) => `'${aString}'`
-  | CtvSymbol( aString ) => `:${aString}`
-  | CtvArray( anArray ) => {
-      let args = anArray
-        -> Belt.Array.map(each => show(each))
-        -> AE.interperse(", ")
-        -> Js.String.concatMany("")
-      `[${args}]`}
-  | CtvRecord( aRecord ) => {
-      let pairs = aRecord
-        -> Js.Dict.entries
-        -> Belt.Array.map( ((eachKey, eachValue)) => `${eachKey}: ${show(eachValue)}` )
-        -> AE.interperse(", ")
-        -> Js.String.concatMany("")
-        `{${pairs}}`
-  }
-}
-
-let showWithType = aValue => switch aValue {
-  | CtvBool( _ ) => `Bool::${show(aValue)}`
-  | CtvNumber( _ ) => `Number::${show(aValue)}`
-  | CtvString( _ ) => `String::${show(aValue)}`
-  | CtvSymbol( _ ) => `Symbol::${show(aValue)}`
-  | CtvArray( _ ) => `Array::${show(aValue)}`
-  | CtvRecord( _ ) => `Record::${show(aValue)}`
-}
-
-let showArgs = (args: array<codeTreeValue>): string => {
-  args
-  -> Belt.Array.map(arg => arg->show)
-  -> AE.interperse(", ")
-  -> Js.String.concatMany("") }
-
-let showFunctionCall = ((fn, args)): string => `${fn}(${ showArgs(args) })`
-
-let showResult = (x) => switch x {
-  | Ok(a) => `Ok(${ show(a) })`
-  | Error(m) => `Error(${Rerr.showError(m)})`
-}

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

@@ -1,7 +1,7 @@
 /*
   Insert seperator between the elements of an array
 */
-module LE = Reducer_Extra_List
+module ExtraList = Reducer_Extra_List
 
 let interperse = (anArray, seperator) =>
-  anArray -> Belt.List.fromArray -> LE.interperse(seperator) -> Belt.List.toArray
+  anArray->Belt.List.fromArray->ExtraList.interperse(seperator)->Belt.List.toArray

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

@@ -1,7 +1,8 @@
 /*
   Insert seperator between the elements of a list
 */
-let rec interperse = (aList, seperator) => switch aList {
+let rec interperse = (aList, seperator) =>
+  switch aList {
   | list{} => list{}
   | list{a} => list{a}
   | list{a, ...rest} => list{a, seperator, ...interperse(rest, seperator)}

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

@@ -1,8 +1,5 @@
-module CTV = Reducer_Extension.CodeTreeValue
+open ReducerInterface.ExpressionValue
-module Rerr = Reducer_Error
+open Reducer_ErrorValue
-
-type codeTreeValue = CTV.codeTreeValue
-type reducerError = Rerr.reducerError
 
 external castBool: unit => bool = "%identity"
 external castNumber: unit => float = "%identity"
@@ -11,11 +8,11 @@ external castString: unit => string = "%identity"
 /*
   As JavaScript returns us any type, we need to type check and cast type propertype before using it
 */
-let jsToCtv = (jsValue): result<codeTreeValue, reducerError> => {
+let jsToEv = (jsValue): result<expressionValue, errorValue> => {
   switch Js.typeof(jsValue) {
-  | "boolean" => jsValue -> castBool -> CTV.CtvBool -> Ok
+  | "boolean" => jsValue->castBool->EvBool->Ok
-  | "number" => jsValue -> castNumber -> CTV.CtvNumber -> Ok
+  | "number" => jsValue->castNumber->EvNumber->Ok
-  | "string" => jsValue -> castString -> CTV.CtvString -> Ok
+  | "string" => jsValue->castString->EvString->Ok
-  | other => Rerr.RerrTodo(`Unhandled MathJs literal type: ${Js.String.make(other)}`) -> Error
+  | other => RETodo(`Unhandled MathJs literal type: ${Js.String.make(other)}`)->Error
   }
 }

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

@@ -1,2 +1,3 @@
 module Eval = Reducer_MathJs_Eval
 module Parse = Reducer_MathJs_Parse
+module ToExpression = Reducer_MathJs_ToExpression

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

@@ -1,16 +1,11 @@
-module CTV = Reducer_Extension.CodeTreeValue
+module JavaScript = Reducer_Js
-module JsG = Reducer_Js_Gate
+open ReducerInterface.ExpressionValue
-module Rerr = Reducer_Error
+open Reducer_ErrorValue
-
-type codeTreeValue = CTV.codeTreeValue
-type reducerError = Rerr.reducerError
 
 @module("mathjs") external dummy_: string => unit = "evaluate"
 let dummy1_ = dummy_ //Deceive the compiler to make the import although we wont make a call from rescript. Otherwise the optimizer deletes the import
 
-type answer = {
+type answer = {"value": unit}
-  "value": unit
-}
 
 /*
  The result has to be delivered in an object so that we can type cast.
@@ -22,12 +17,11 @@ let eval__ = %raw(`function (expr) { return {value: Mathjs.evaluate(expr)}; }`)
 /*
   Call MathJs evaluate and return as a variant
 */
-let eval = (expr: string): result<codeTreeValue, reducerError> => {
+let eval = (expr: string): result<expressionValue, errorValue> => {
   try {
     let answer = eval__(expr)
-  answer["value"]->JsG.jsToCtv
+    answer["value"]->JavaScript.Gate.jsToEv
   } catch {
-  | Js.Exn.Error(obj) =>
+  | Js.Exn.Error(obj) => REJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
-    RerrJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
   }
 }

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

@@ -2,63 +2,27 @@
   MathJs Nodes
   We make MathJs Nodes strong-typed
 */
-module AE = Reducer_Extra_Array
+module Extra = Reducer_Extra
-module JsG = Reducer_Js_Gate
+open Reducer_ErrorValue
-module Rerr = Reducer_Error
 
-type reducerError = Rerr.reducerError
+type node = {"type": string, "isNode": bool, "comment": string}
-
+type arrayNode = {...node, "items": array<node>}
-type node = {
-  "type": string,
-  "isNode": bool,
-  "comment": string
-}
-type arrayNode = {
-  ...node,
-  "items": array<node>
-}
 //assignmentNode
 //blockNode
 //conditionalNode
-type constantNode = {
+type constantNode = {...node, "value": unit}
-  ...node,
-  "value": unit
-}
 //functionAssignmentNode
-type functionNode = {
+type functionNode = {...node, "fn": string, "args": array<node>}
-  ...node,
+type indexNode = {...node, "dimensions": array<node>}
-  "fn": string,
+type objectNode = {...node, "properties": Js.Dict.t<node>}
-  "args": array<node>
+type accessorNode = {...node, "object": node, "index": indexNode}
-}
+type operatorNode = {...functionNode, "op": string}
-type indexNode = {
-  ...node,
-  "dimensions": array<node>
-}
-type objectNode = {
-  ...node,
-  "properties": Js.Dict.t<node>
-}
-type accessorNode = {
-  ...node,
-  "object": node,
-  "index": indexNode
-}
-type operatorNode = {
-  ...functionNode,
-  "op": string,
-}
 
 //parenthesisNode
-type parenthesisNode = {
+type parenthesisNode = {...node, "content": node}
-  ...node,
-  "content": node
-}
 //rangeNode
 //relationalNode
-type symbolNode = {
+type symbolNode = {...node, "name": string}
-  ...node,
-  "name": string
-}
 
 external castAccessorNode: node => accessorNode = "%identity"
 external castArrayNode: node => arrayNode = "%identity"
@@ -76,12 +40,11 @@ external castSymbolNode: node => symbolNode = "%identity"
 */
 @module("mathjs") external parse__: string => node = "parse"
 
-let parse = (expr: string): result<node, reducerError> =>
+let parse = (expr: string): result<node, errorValue> =>
   try {
     Ok(parse__(expr))
   } catch {
-  | Js.Exn.Error(obj) =>
+  | Js.Exn.Error(obj) => REJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
-    RerrJs(Js.Exn.message(obj), Js.Exn.name(obj))->Error
   }
 
 type mjNode =
@@ -95,7 +58,8 @@ type mjNode =
   | MjParenthesisNode(parenthesisNode)
   | MjSymbolNode(symbolNode)
 
-let castNodeType = (node: node) => switch node["type"] {
+let castNodeType = (node: node) =>
+  switch node["type"] {
   | "AccessorNode" => node->castAccessorNode->MjAccessorNode->Ok
   | "ArrayNode" => node->castArrayNode->MjArrayNode->Ok
   | "ConstantNode" => node->castConstantNode->MjConstantNode->Ok
@@ -105,11 +69,12 @@ let castNodeType = (node: node) => switch node["type"] {
   | "OperatorNode" => node->castOperatorNode->MjOperatorNode->Ok
   | "ParenthesisNode" => node->castParenthesisNode->MjParenthesisNode->Ok
   | "SymbolNode" => node->castSymbolNode->MjSymbolNode->Ok
-  | _ => Rerr.RerrTodo(`Argg, unhandled MathJsNode: ${node["type"]}`)-> Error
+  | _ => RETodo(`Argg, unhandled MathJsNode: ${node["type"]}`)->Error
   }
 
 let rec show = (mjNode: mjNode): string => {
-  let showValue = (a: 'a): string => if (Js.typeof(a) == "string") {
+  let showValue = (a: 'a): string =>
+    if Js.typeof(a) == "string" {
       `'${Js.String.make(a)}'`
     } else {
       Js.String.make(a)
@@ -118,25 +83,24 @@ let rec show = (mjNode: mjNode): string => {
   let showNodeArray = (nodeArray: array<node>): string =>
     nodeArray
     ->Belt.Array.map(a => showMathJsNode(a))
-    -> AE.interperse(", ")
+    ->Extra.Array.interperse(", ")
     ->Js.String.concatMany("")
 
   let showFunctionNode = (fnode: functionNode): string =>
     `${fnode["fn"]}(${fnode["args"]->showNodeArray})`
 
-  let showObjectEntry = ( (key: string, value: node) ): string =>
+  let showObjectEntry = ((key: string, value: node)): string => `${key}: ${value->showMathJsNode}`
-    `${key}: ${value->showMathJsNode}`
 
   let showObjectNode = (oNode: objectNode): string =>
     `{${oNode["properties"]
       ->Js.Dict.entries
       ->Belt.Array.map(entry => entry->showObjectEntry)
-          ->AE.interperse(", ")->Js.String.concatMany("")
+      ->Extra.Array.interperse(", ")
-    }}`
+      ->Js.String.concatMany("")}}`
 
   let showIndexNode = (iNode: indexNode): string =>
     iNode["dimensions"]
-    -> Belt.Array.map( each => `${showResult(each->castNodeType)}`)
+    ->Belt.Array.map(each => showResult(each->castNodeType))
     ->Js.String.concatMany("")
 
   switch mjNode {
@@ -149,10 +113,11 @@ let rec show = (mjNode: mjNode): string => {
   | MjOperatorNode(opNode) => opNode->castOperatorNodeToFunctionNode->showFunctionNode
   | MjParenthesisNode(pNode) => `(${showMathJsNode(pNode["content"])})`
   | MjSymbolNode(sNode) => sNode["name"]
-}}
+  }
-and let showResult = (rmjnode: result<mjNode, reducerError>): string =>
+}
+and showResult = (rmjnode: result<mjNode, errorValue>): string =>
   switch rmjnode {
-    | Error(e) => Rerr.showError(e)
+  | Error(e) => showError(e)
   | Ok(mjNode) => show(mjNode)
   }
-and let showMathJsNode = (node) => node -> castNodeType -> showResult
+and showMathJsNode = node => node->castNodeType->showResult

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

@@ -1,99 +0,0 @@
-module CTT = Reducer_CodeTree_T
-module CTV = Reducer_Extension.CodeTreeValue
-module JsG = Reducer_Js_Gate
-module MJ = Reducer_MathJs_Parse
-module Rerr = Reducer_Error
-module Result = Belt.Result
-
-type codeTree = CTT.codeTree
-type codeTreeValue = CTV.codeTreeValue
-type reducerError = Rerr.reducerError
-
-let rec fromNode =
-  (mjnode: MJ.node): result<codeTree, reducerError> =>
-    MJ.castNodeType(mjnode) -> Result.flatMap(typedMjNode => {
-
-      let fromNodeList = (nodeList: list<MJ.node>): result<list<codeTree>, 'e> =>
-        Belt.List.reduceReverse(nodeList, Ok(list{}), (racc, currNode) =>
-          racc -> Result.flatMap(
-            acc => fromNode(currNode) -> Result.map(
-              currCode => list{currCode, ...acc})))
-
-      let caseFunctionNode = (fNode) => {
-        let fn = fNode["fn"] -> CTV.CtvSymbol -> CTT.CtValue
-        let lispArgs = fNode["args"] -> Belt.List.fromArray -> fromNodeList
-        lispArgs -> Result.map(
-          argsCode => list{fn, ...argsCode} -> CTT.CtList )
-      }
-
-      let caseObjectNode = oNode => {
-
-        let fromObjectEntries = ( entryList ) => {
-          let rargs = Belt.List.reduceReverse(
-                          entryList,
-                          Ok(list{}),
-                          (racc, (key: string, value: MJ.node))
-                          =>
-            racc
-              -> Result.flatMap( acc =>
-                    fromNode(value) -> Result.map(valueCodeTree => {
-                      let entryCode = list{key->CTV.CtvString->CTT.CtValue, valueCodeTree}
-                        -> CTT.CtList
-                      list{entryCode, ...acc}})))
-          let lispName = "$constructRecord" -> CTV.CtvSymbol -> CTT.CtValue
-          rargs -> Result.map(args => list{lispName, CTT.CtList(args)} -> CTT.CtList)
-        }
-
-        oNode["properties"]
-        -> Js.Dict.entries
-        -> Belt.List.fromArray
-        -> fromObjectEntries
-      }
-
-      let caseIndexNode = iNode => {
-          let rpropertyCodeList = Belt.List.reduceReverse(
-                                iNode["dimensions"]->Belt.List.fromArray,
-                                Ok(list{}),
-                                (racc, currentPropertyMjNode)
-                                =>
-            racc -> Result.flatMap( acc =>
-              fromNode(currentPropertyMjNode)
-              -> Result.map( propertyCode =>
-                  list{ propertyCode, ...acc} )
-            )
-          )
-          rpropertyCodeList -> Result.map(
-            propertyCodeList => CTT.CtList(propertyCodeList))
-      }
-
-      let caseAccessorNode = ( objectNode, indexNode ) => {
-        let fn = "$atIndex" -> CTV.CtvSymbol -> CTT.CtValue
-
-        caseIndexNode( indexNode ) -> Result.flatMap(
-          indexCode => {
-            fromNode( objectNode ) -> Result.map(
-              objectCode => list{fn, objectCode, indexCode} -> CTT.CtList )
-          }
-        )
-      }
-
-
-      switch typedMjNode {
-        | MjArrayNode(aNode) =>
-            aNode["items"]
-            -> Belt.List.fromArray
-            -> fromNodeList
-            -> Result.map(list => CTT.CtList(list))
-        | MjConstantNode(cNode) =>
-            cNode["value"]-> JsG.jsToCtv -> Result.map( v => v->CTT.CtValue)
-        | MjFunctionNode(fNode) => fNode
-            -> caseFunctionNode
-        | MjOperatorNode(opNode) => opNode
-            ->  MJ.castOperatorNodeToFunctionNode  -> caseFunctionNode
-        | MjParenthesisNode(pNode) => pNode["content"] -> fromNode
-        | MjAccessorNode(aNode) => caseAccessorNode(aNode["object"], aNode["index"])
-        | MjObjectNode(oNode) => caseObjectNode(oNode)
-        | MjSymbolNode(sNode) =>
-            sNode["name"]-> CTV.CtvSymbol -> CTT.CtValue -> Ok
-        | MjIndexNode(iNode) => caseIndexNode(iNode)
-      }})

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

@@ -0,0 +1,86 @@
+module ErrorValue = Reducer_ErrorValue
+module ExpressionValue = ReducerInterface.ExpressionValue
+module ExtressionT = Reducer_Expression_T
+module JavaScript = Reducer_Js
+module Parse = Reducer_MathJs_Parse
+module Result = Belt.Result
+
+type expression = ExtressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+type errorValue = ErrorValue.errorValue
+
+let rec fromNode = (mjnode: Parse.node): result<expression, errorValue> =>
+  Parse.castNodeType(mjnode)->Result.flatMap(typedMjNode => {
+    let fromNodeList = (nodeList: list<Parse.node>): result<list<expression>, 'e> =>
+      Belt.List.reduceReverse(nodeList, Ok(list{}), (racc, currNode) =>
+        racc->Result.flatMap(acc =>
+          fromNode(currNode)->Result.map(currCode => list{currCode, ...acc})
+        )
+      )
+
+    let caseFunctionNode = fNode => {
+      let fn = fNode["fn"]->ExpressionValue.EvSymbol->ExtressionT.EValue
+      let lispArgs = fNode["args"]->Belt.List.fromArray->fromNodeList
+      lispArgs->Result.map(argsCode => list{fn, ...argsCode}->ExtressionT.EList)
+    }
+
+    let caseObjectNode = oNode => {
+      let fromObjectEntries = entryList => {
+        let rargs = Belt.List.reduceReverse(entryList, Ok(list{}), (
+          racc,
+          (key: string, value: Parse.node),
+        ) =>
+          racc->Result.flatMap(acc =>
+            fromNode(value)->Result.map(valueExpression => {
+              let entryCode =
+                list{
+                  key->ExpressionValue.EvString->ExtressionT.EValue,
+                  valueExpression,
+                }->ExtressionT.EList
+              list{entryCode, ...acc}
+            })
+          )
+        )
+        let lispName = "$constructRecord"->ExpressionValue.EvSymbol->ExtressionT.EValue
+        rargs->Result.map(args => list{lispName, ExtressionT.EList(args)}->ExtressionT.EList)
+      }
+
+      oNode["properties"]->Js.Dict.entries->Belt.List.fromArray->fromObjectEntries
+    }
+
+    let caseIndexNode = iNode => {
+      let rpropertyCodeList = Belt.List.reduceReverse(
+        iNode["dimensions"]->Belt.List.fromArray,
+        Ok(list{}),
+        (racc, currentPropertyMjNode) =>
+          racc->Result.flatMap(acc =>
+            fromNode(currentPropertyMjNode)->Result.map(propertyCode => list{propertyCode, ...acc})
+          ),
+      )
+      rpropertyCodeList->Result.map(propertyCodeList => ExtressionT.EList(propertyCodeList))
+    }
+
+    let caseAccessorNode = (objectNode, indexNode) => {
+      let fn = "$atIndex"->ExpressionValue.EvSymbol->ExtressionT.EValue
+
+      caseIndexNode(indexNode)->Result.flatMap(indexCode => {
+        fromNode(objectNode)->Result.map(objectCode =>
+          list{fn, objectCode, indexCode}->ExtressionT.EList
+        )
+      })
+    }
+
+    switch typedMjNode {
+    | MjArrayNode(aNode) =>
+      aNode["items"]->Belt.List.fromArray->fromNodeList->Result.map(list => ExtressionT.EList(list))
+    | MjConstantNode(cNode) =>
+      cNode["value"]->JavaScript.Gate.jsToEv->Result.map(v => v->ExtressionT.EValue)
+    | MjFunctionNode(fNode) => fNode->caseFunctionNode
+    | MjOperatorNode(opNode) => opNode->Parse.castOperatorNodeToFunctionNode->caseFunctionNode
+    | MjParenthesisNode(pNode) => pNode["content"]->fromNode
+    | MjAccessorNode(aNode) => caseAccessorNode(aNode["object"], aNode["index"])
+    | MjObjectNode(oNode) => caseObjectNode(oNode)
+    | MjSymbolNode(sNode) => sNode["name"]->ExpressionValue.EvSymbol->ExtressionT.EValue->Ok
+    | MjIndexNode(iNode) => caseIndexNode(iNode)
+    }
+  })

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

@@ -0,0 +1,2 @@
+module ExpressionValue = ReducerInterface_ExpressionValue
+module ExternalLibrary = ReducerInterface_ExternalLibrary

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

@@ -0,0 +1,60 @@
+/*
+  Irreducible values. Reducer does not know about those. Only used for external calls
+  This is a configuration to to make external calls of those types
+*/
+module AE = Reducer_Extra_Array
+module ErrorValue = Reducer_ErrorValue
+
+type rec expressionValue =
+  | EvBool(bool)
+  | EvNumber(float)
+  | EvString(string)
+  | EvSymbol(string)
+  | EvArray(array<expressionValue>)
+  | EvRecord(Js.Dict.t<expressionValue>)
+
+type functionCall = (string, array<expressionValue>)
+
+let rec show = aValue =>
+  switch aValue {
+  | EvBool(aBool) => Js.String.make(aBool)
+  | EvNumber(aNumber) => Js.String.make(aNumber)
+  | EvString(aString) => `'${aString}'`
+  | EvSymbol(aString) => `:${aString}`
+  | EvArray(anArray) => {
+      let args =
+        anArray->Belt.Array.map(each => show(each))->AE.interperse(", ")->Js.String.concatMany("")
+      `[${args}]`
+    }
+  | EvRecord(aRecord) => {
+      let pairs =
+        aRecord
+        ->Js.Dict.entries
+        ->Belt.Array.map(((eachKey, eachValue)) => `${eachKey}: ${show(eachValue)}`)
+        ->AE.interperse(", ")
+        ->Js.String.concatMany("")
+      `{${pairs}}`
+    }
+  }
+
+let showWithType = aValue =>
+  switch aValue {
+  | EvBool(_) => `Bool::${show(aValue)}`
+  | EvNumber(_) => `Number::${show(aValue)}`
+  | EvString(_) => `String::${show(aValue)}`
+  | EvSymbol(_) => `Symbol::${show(aValue)}`
+  | EvArray(_) => `Array::${show(aValue)}`
+  | EvRecord(_) => `Record::${show(aValue)}`
+  }
+
+let showArgs = (args: array<expressionValue>): string => {
+  args->Belt.Array.map(arg => arg->show)->AE.interperse(", ")->Js.String.concatMany("")
+}
+
+let showFunctionCall = ((fn, args)): string => `${fn}(${showArgs(args)})`
+
+let showResult = x =>
+  switch x {
+  | Ok(a) => `Ok(${show(a)})`
+  | Error(m) => `Error(${ErrorValue.showError(m)})`
+  }

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

@@ -1,8 +1,9 @@
-module CTV = Reducer_Extension_CodeTreeValue
+module ExpressionValue = ReducerInterface_ExpressionValue
 
-type codeTreeValue = CTV.codeTreeValue
+type expressionValue = ExpressionValue.expressionValue
 
-module Sample = { // In real life real libraries should be somewhere else
+module Sample = {
+  // In real life real libraries should be somewhere else
   /*
     For an example of mapping polymorphic custom functions. To be deleted after real integration
  */
@@ -12,9 +13,9 @@ module Sample = { // In real life real libraries should be somewhere else
 /*
   Map external calls of Reducer
 */
-let dispatch = (call: CTV.functionCall, chain): result<codeTreeValue, 'e> => switch call {
+let dispatch = (call: ExpressionValue.functionCall, chain): result<expressionValue, 'e> =>
-
+  switch call {
-|  ("add", [CtvNumber(a), CtvNumber(b)]) =>  Sample.customAdd(a, b)  -> CtvNumber -> Ok
+  | ("add", [EvNumber(a), EvNumber(b)]) => Sample.customAdd(a, b)->EvNumber->Ok
 
   | call => chain(call)