refactor reducer

removed some extra array references

rename Builder to ExpressionBuilder

Expression Builder

Trash Warning

remove parsePartial/Outer, add context to lambda

format

module Bindings

simplify types

module Macro

reduceValueList

do macro call

result map

bindings stop replacing on macro calls

Macro Test

doBindStatement

bind a statement

bindings tested. TODO bind shadowing in lambda

block tests defined

block tests defined

blocks tested

macro lambda test defined

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

@@ -0,0 +1,121 @@
+open Jest
+// open Expect
+
+open Reducer_Expression_ExpressionBuilder
+open Reducer_TestMacroHelpers
+module ExpressionT = Reducer_Expression_T
+
+let exampleExpression = eNumber(1.)
+let exampleExpressionY = eSymbol("y")
+let exampleStatement = eLetStatement("y", eNumber(1.))
+let exampleStatementX = eLetStatement("y", eSymbol("x"))
+let exampleStatementZ = eLetStatement("z", eSymbol("y"))
+
+// If it is not a mactro then it is not expanded
+testMacro([], exampleExpression, "Ok(1)")
+
+describe("bindStatement", () => {
+  // A statement is bound by the bindings created by the previous statement
+  testMacro([], eBindStatement(eBindings([]), exampleStatement), "Ok((:$setBindings {} :y 1))")
+  // Then it answers the bindings for the next statement when reduced
+  testMacroEval([], eBindStatement(eBindings([]), exampleStatement), "Ok({y: 1})")
+  // Now let's feed a binding to see what happens
+  testMacro(
+    [],
+    eBindStatement(eBindings([("x", EvNumber(2.))]), exampleStatementX),
+    "Ok((:$setBindings {x: 2} :y 2))",
+  )
+  // An expression does not return a binding, thus error
+  testMacro([], eBindStatement(eBindings([]), exampleExpression), "Error(Assignment expected)")
+  // When bindings from previous statement are missing the context is injected. This must be the first statement of a block
+  testMacro(
+    [("z", EvNumber(99.))],
+    eBindStatementDefault(exampleStatement),
+    "Ok((:$setBindings {z: 99} :y 1))",
+  )
+})
+
+describe("bindExpression", () => {
+  // x is simply bound in the expression
+  testMacro([], eBindExpression(eBindings([("x", EvNumber(2.))]), eSymbol("x")), "Ok(2)")
+  // When an let statement is the end expression then bindings are returned
+  testMacro(
+    [],
+    eBindExpression(eBindings([("x", EvNumber(2.))]), exampleStatement),
+    "Ok((:$exportBindings (:$setBindings {x: 2} :y 1)))",
+  )
+  // Now let's reduce that expression
+  testMacroEval(
+    [],
+    eBindExpression(eBindings([("x", EvNumber(2.))]), exampleStatement),
+    "Ok({x: 2,y: 1})",
+  )
+  // When bindings are missing the context is injected. This must be the first and last statement of a block
+  testMacroEval(
+    [("z", EvNumber(99.))],
+    eBindExpressionDefault(exampleStatement),
+    "Ok({y: 1,z: 99})",
+  )
+})
+
+describe("block", () => {
+  // Block with a single expression
+  testMacro([], eBlock(list{exampleExpression}), "Ok((:$$bindExpression 1))")
+  testMacroEval([], eBlock(list{exampleExpression}), "Ok(1)")
+  // Block with a single statement
+  testMacro([], eBlock(list{exampleStatement}), "Ok((:$$bindExpression (:$let :y 1)))")
+  testMacroEval([], eBlock(list{exampleStatement}), "Ok({y: 1})")
+  // Block with a statement and an expression
+  testMacro(
+    [],
+    eBlock(list{exampleStatement, exampleExpressionY}),
+    "Ok((:$$bindExpression (:$$bindStatement (:$let :y 1)) :y))",
+  )
+  testMacroEval([], eBlock(list{exampleStatement, exampleExpressionY}), "Ok(1)")
+  // Block with a statement and another statement
+  testMacro(
+    [],
+    eBlock(list{exampleStatement, exampleStatementZ}),
+    "Ok((:$$bindExpression (:$$bindStatement (:$let :y 1)) (:$let :z :y)))",
+  )
+  testMacroEval([], eBlock(list{exampleStatement, exampleStatementZ}), "Ok({y: 1,z: 1})")
+  // Block inside a block
+  testMacro(
+    [],
+    eBlock(list{eBlock(list{exampleExpression})}),
+    "Ok((:$$bindExpression (:$$block 1)))",
+  )
+  testMacroEval([], eBlock(list{eBlock(list{exampleExpression})}), "Ok(1)")
+  // Block assigned to a variable
+  testMacro(
+    [],
+    eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
+    "Ok((:$$bindExpression (:$let :z (:$$block (:$$block :y)))))",
+  )
+  testMacroEval(
+    [],
+    eBlock(list{eLetStatement("z", eBlock(list{eBlock(list{exampleExpressionY})}))}),
+    "Ok({z: :y})",
+  )
+  // Empty block
+  testMacro([], eBlock(list{}), "Ok(:undefined block)") //TODO: should be an error
+})
+
+describe("lambda", () => {
+  // assign a lambda to a variable
+  let lambdaExpression = eFunction("$$lambda", list{eArrayString(["y"]), exampleExpressionY})
+  testMacro([], lambdaExpression, "Ok(lambda(y=>internal))")
+  // call a lambda
+  let callLambdaExpression = list{lambdaExpression, eNumber(1.)}->ExpressionT.EList
+  testMacro([], callLambdaExpression, "Ok(((:$$lambda [y] :y) 1))")
+  testMacroEval([], callLambdaExpression, "Ok(1)")
+  // Parameters shadow the outer scope
+  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(1)")
+  // When not shadowed by the parameters, the outer scope variables are available
+  let lambdaExpression = eFunction(
+    "$$lambda",
+    list{eArrayString(["z"]), eFunction("add", list{eSymbol("y"), eSymbol("z")})},
+  )
+  let callLambdaExpression = eList(list{lambdaExpression, eNumber(1.)})
+  testMacroEval([("y", EvNumber(666.))], callLambdaExpression, "Ok(667)")
+})

packages/squiggle-lang/__tests__/Reducer/Reducer_Expression/Reducer_Expression_test.res

@@ -0,0 +1,6 @@
+open Jest
+open Expect
+
+test("dummy", () => {
+  expect(true)->toBe(true)
+})

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

@@ -1,4 +1,4 @@
-module Expression = Reducer.Expression
+module ExpressionT = Reducer_Expression_T
 module ExpressionValue = ReducerInterface.ExpressionValue
 module ErrorValue = Reducer_ErrorValue
 
@@ -14,47 +14,18 @@ let unwrapRecord = rValue =>
   )
 
 let expectParseToBe = (expr: string, answer: string) =>
-  Reducer.parse(expr)->Expression.toStringResult->expect->toBe(answer)
-
-let expectParseOuterToBe = (expr: string, answer: string) =>
-  Reducer.parseOuter(expr)->Expression.toStringResult->expect->toBe(answer)
-
-let expectParsePartialToBe = (expr: string, answer: string) =>
-  Reducer.parsePartial(expr)->Expression.toStringResult->expect->toBe(answer)
+  Reducer.parse(expr)->ExpressionT.toStringResult->expect->toBe(answer)
 
 let expectEvalToBe = (expr: string, answer: string) =>
   Reducer.evaluate(expr)->ExpressionValue.toStringResult->expect->toBe(answer)
 
 let expectEvalBindingsToBe = (expr: string, bindings: Reducer.externalBindings, answer: string) =>
-  Reducer.evaluateUsingOptions(
-    expr,
-    ~externalBindings=Some(bindings),
-    ~isPartial=None,
-    ~environment=None,
-  )
+  Reducer.evaluateUsingOptions(expr, ~externalBindings=Some(bindings), ~environment=None)
   ->ExpressionValue.toStringResult
   ->expect
   ->toBe(answer)
 
-let expectEvalPartialBindingsToBe = (
-  expr: string,
-  bindings: Reducer.externalBindings,
-  answer: string,
-) =>
-  Reducer.evaluateUsingOptions(
-    expr,
-    ~externalBindings=Some(bindings),
-    ~isPartial=Some(true),
-    ~environment=None,
-  )
-  ->unwrapRecord
-  ->ExpressionValue.toStringResultRecord
-  ->expect
-  ->toBe(answer)
-
 let testParseToBe = (expr, answer) => test(expr, () => expectParseToBe(expr, answer))
-let testParseOuterToBe = (expr, answer) => test(expr, () => expectParseOuterToBe(expr, answer))
-let testParsePartialToBe = (expr, answer) => test(expr, () => expectParsePartialToBe(expr, answer))
 let testDescriptionParseToBe = (desc, expr, answer) =>
   test(desc, () => expectParseToBe(expr, answer))
 
@@ -62,34 +33,16 @@ let testEvalToBe = (expr, answer) => test(expr, () => expectEvalToBe(expr, answe
 let testDescriptionEvalToBe = (desc, expr, answer) => test(desc, () => expectEvalToBe(expr, answer))
 let testEvalBindingsToBe = (expr, bindingsList, answer) =>
   test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-  test(expr, () => expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
 
 module MySkip = {
   let testParseToBe = (expr, answer) => Skip.test(expr, () => expectParseToBe(expr, answer))
-  let testParseOuterToBe = (expr, answer) =>
-    Skip.test(expr, () => expectParseOuterToBe(expr, answer))
-  let testParsePartialToBe = (expr, answer) =>
-    Skip.test(expr, () => expectParsePartialToBe(expr, answer))
   let testEvalToBe = (expr, answer) => Skip.test(expr, () => expectEvalToBe(expr, answer))
   let testEvalBindingsToBe = (expr, bindingsList, answer) =>
     Skip.test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-  let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-    Skip.test(expr, () =>
-      expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer)
-    )
 }
 module MyOnly = {
   let testParseToBe = (expr, answer) => Only.test(expr, () => expectParseToBe(expr, answer))
-  let testParseOuterToBe = (expr, answer) =>
-    Only.test(expr, () => expectParseOuterToBe(expr, answer))
-  let testParsePartialToBe = (expr, answer) =>
-    Only.test(expr, () => expectParsePartialToBe(expr, answer))
   let testEvalToBe = (expr, answer) => Only.test(expr, () => expectEvalToBe(expr, answer))
   let testEvalBindingsToBe = (expr, bindingsList, answer) =>
     Only.test(expr, () => expectEvalBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer))
-  let testEvalPartialBindingsToBe = (expr, bindingsList, answer) =>
-    Only.test(expr, () =>
-      expectEvalPartialBindingsToBe(expr, bindingsList->Js.Dict.fromList, answer)
-    )
 }

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

@@ -0,0 +1,81 @@
+open Jest
+open Expect
+
+module Macro = Reducer_Expression_Macro
+module Bindings = Reducer_Expression_Bindings
+module Expression = Reducer_Expression
+module ExpressionValue = ReducerInterface_ExpressionValue
+module T = Reducer_Expression_T
+
+let testMacro_ = (
+  tester,
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedCode: string,
+) => {
+  let bindings = Belt.Map.String.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.expandMacroCall(
+      bindings,
+      ExpressionValue.defaultEnvironment,
+      Expression.reduceExpression,
+    )
+    ->T.toStringResult
+    ->expect
+    ->toEqual(expectedCode)
+  )
+}
+
+let testMacroEval_ = (
+  tester,
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedValue: string,
+) => {
+  let bindings = Belt.Map.String.fromArray(bindArray)
+  tester(expr->T.toString, () =>
+    expr
+    ->Macro.doMacroCall(bindings, ExpressionValue.defaultEnvironment, Expression.reduceExpression)
+    ->ExpressionValue.toStringResult
+    ->expect
+    ->toEqual(expectedValue)
+  )
+}
+
+let testMacro = (
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedExpr: string,
+) => testMacro_(test, bindArray, expr, expectedExpr)
+let testMacroEval = (
+  bindArray: array<(string, ExpressionValue.expressionValue)>,
+  expr: T.expression,
+  expectedValue: string,
+) => testMacroEval_(test, bindArray, expr, expectedValue)
+
+module MySkip = {
+  let testMacro = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Skip.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Skip.test, bindArray, expr, expectedValue)
+}
+
+module MyOnly = {
+  let testMacro = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedExpr: string,
+  ) => testMacro_(Only.test, bindArray, expr, expectedExpr)
+  let testMacroEval = (
+    bindArray: array<(string, ExpressionValue.expressionValue)>,
+    expr: T.expression,
+    expectedValue: string,
+  ) => testMacroEval_(Only.test, bindArray, expr, expectedValue)
+}

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

@@ -1,33 +1,34 @@
+// TODO: Reimplement with usual parse
 open Jest
 open Reducer_TestHelpers
 
-describe("Parse for Bindings", () => {
-  testParseOuterToBe("x", "Ok((:$$bindExpression (:$$bindings) :x))")
-  testParseOuterToBe("x+1", "Ok((:$$bindExpression (:$$bindings) (:add :x 1)))")
-  testParseOuterToBe(
-    "y = x+1; y",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) :y))",
-  )
-})
+// describe("Parse for Bindings", () => {
+//   testParseOuterToBe("x", "Ok((:$$bindExpression (:$$bindings) :x))")
+//   testParseOuterToBe("x+1", "Ok((:$$bindExpression (:$$bindings) (:add :x 1)))")
+//   testParseOuterToBe(
+//     "y = x+1; y",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) :y))",
+//   )
+// })
 
-describe("Parse Partial", () => {
-  testParsePartialToBe(
-    "x",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) :x) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y=x",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y :x)) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y=x+1",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$exportVariablesExpression)))",
-  )
-  testParsePartialToBe(
-    "y = x+1; z = y",
-    "Ok((:$$bindExpression (:$$bindStatement (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$let :z :y)) (:$exportVariablesExpression)))",
-  )
-})
+// describe("Parse Partial", () => {
+//   testParsePartialToBe(
+//     "x",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) :x) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y=x",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y :x)) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y=x+1",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$exportVariablesExpression)))",
+//   )
+//   testParsePartialToBe(
+//     "y = x+1; z = y",
+//     "Ok((:$$bindExpression (:$$bindStatement (:$$bindStatement (:$$bindings) (:$let :y (:add :x 1))) (:$let :z :y)) (:$exportVariablesExpression)))",
+//   )
+// })
 
 describe("Eval with Bindings", () => {
   testEvalBindingsToBe("x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok(1)")
@@ -39,22 +40,22 @@ describe("Eval with Bindings", () => {
     Partial code is a partial code fragment that is cut out from a larger code.
     Therefore it does not end with an expression.
 */
-describe("Eval Partial", () => {
-  testEvalPartialBindingsToBe(
-    //   A partial cannot end with an expression
-    "x",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Error(Assignment expected)",
-  )
-  testEvalPartialBindingsToBe("y=x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1, y: 1})")
-  testEvalPartialBindingsToBe(
-    "y=x+1",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Ok({x: 1, y: 2})",
-  )
-  testEvalPartialBindingsToBe(
-    "y = x+1; z = y",
-    list{("x", ExpressionValue.EvNumber(1.))},
-    "Ok({x: 1, y: 2, z: 2})",
-  )
-})
+// describe("Eval Partial", () => {
+//   testEvalPartialBindingsToBe(
+//     //   A partial cannot end with an expression
+//     "x",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Error(Assignment expected)",
+//   )
+//   testEvalPartialBindingsToBe("y=x", list{("x", ExpressionValue.EvNumber(1.))}, "Ok({x: 1,y: 1})")
+//   testEvalPartialBindingsToBe(
+//     "y=x+1",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Ok({x: 1,y: 2})",
+//   )
+//   testEvalPartialBindingsToBe(
+//     "y = x+1; z = y",
+//     list{("x", ExpressionValue.EvNumber(1.))},
+//     "Ok({x: 1,y: 2,z: 2})",
+//   )
+// })

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

@@ -2,8 +2,8 @@ open Jest
 open Reducer_TestHelpers
 
 describe("Parse function assignment", () => {
-  testParseToBe("f(x)=x", "Ok((:$let :f (:$lambda (x) :x)))")
-  testParseToBe("f(x)=2*x", "Ok((:$let :f (:$lambda (x) (:multiply 2 :x))))")
+  testParseToBe("f(x)=x", "Ok((:$$block (:$let :f (:$$lambda [x] (:$$block :x)))))")
+  testParseToBe("f(x)=2*x", "Ok((:$$block (:$let :f (:$$lambda [x] (:$$block (:multiply 2 :x))))))")
   //MathJs does not allow blocks in function definitions
 })
 

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

@@ -10,46 +10,39 @@ describe("reducer using mathjs parse", () => {
   // Those tests toString that we are converting mathjs parse tree to what we need
 
   describe("expressions", () => {
-    testParseToBe("1", "Ok(1)")
-    testParseToBe("(1)", "Ok(1)")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2", "Ok((:add 1 2))")
-    testParseToBe("1+2*3", "Ok((:add 1 (:multiply 2 3)))")
+    testParseToBe("1", "Ok((:$$block 1))")
+    testParseToBe("(1)", "Ok((:$$block 1))")
+    testParseToBe("1+2", "Ok((:$$block (:add 1 2)))")
+    testParseToBe("1+2*3", "Ok((:$$block (:add 1 (:multiply 2 3))))")
   })
   describe("arrays", () => {
     //Note. () is a empty list in Lisp
     //  The only builtin structure in Lisp is list. There are no arrays
     //  [1,2,3] becomes (1 2 3)
-    testDescriptionParseToBe("empty", "[]", "Ok(())")
-    testParseToBe("[1, 2, 3]", "Ok((1 2 3))")
-    testParseToBe("['hello', 'world']", "Ok(('hello' 'world'))")
-    testDescriptionParseToBe("index", "([0,1,2])[1]", "Ok((:$atIndex (0 1 2) (1)))")
+    testDescriptionParseToBe("empty", "[]", "Ok((:$$block ()))")
+    testParseToBe("[1, 2, 3]", "Ok((:$$block (1 2 3)))")
+    testParseToBe("['hello', 'world']", "Ok((:$$block ('hello' 'world')))")
+    testDescriptionParseToBe("index", "([0,1,2])[1]", "Ok((:$$block (:$atIndex (0 1 2) (1))))")
   })
   describe("records", () => {
-    testDescriptionParseToBe("define", "{a: 1, b: 2}", "Ok((:$constructRecord (('a' 1) ('b' 2))))")
+    testDescriptionParseToBe(
+      "define",
+      "{a: 1, b: 2}",
+      "Ok((:$$block (:$constructRecord (('a' 1) ('b' 2)))))",
+    )
     testDescriptionParseToBe(
       "use",
       "{a: 1, b: 2}.a",
-      "Ok((:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a')))",
+      "Ok((:$$block (:$atIndex (:$constructRecord (('a' 1) ('b' 2))) ('a'))))",
     )
   })
   describe("multi-line", () => {
-    testParseToBe("1; 2", "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) 1) 2))")
-    testParseToBe(
-      "1+1; 2+1",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:add 1 1)) (:add 2 1)))",
-    )
+    testParseToBe("1; 2", "Ok((:$$block (:$$block 1 2)))")
+    testParseToBe("1+1; 2+1", "Ok((:$$block (:$$block (:add 1 1) (:add 2 1))))")
   })
   describe("assignment", () => {
-    testParseToBe(
-      "x=1; x",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :x 1)) :x))",
-    )
-    testParseToBe(
-      "x=1+1; x+1",
-      "Ok((:$$bindExpression (:$$bindStatement (:$$bindings) (:$let :x (:add 1 1))) (:add :x 1)))",
-    )
+    testParseToBe("x=1; x", "Ok((:$$block (:$$block (:$let :x 1) :x)))")
+    testParseToBe("x=1+1; x+1", "Ok((:$$block (:$$block (:$let :x (:add 1 1)) (:add :x 1))))")
   })
 })
 
@@ -70,13 +63,13 @@ describe("eval", () => {
   })
   describe("arrays", () => {
     test("empty array", () => expectEvalToBe("[]", "Ok([])"))
-    testEvalToBe("[1, 2, 3]", "Ok([1, 2, 3])")
-    testEvalToBe("['hello', 'world']", "Ok(['hello', 'world'])")
+    testEvalToBe("[1, 2, 3]", "Ok([1,2,3])")
+    testEvalToBe("['hello', 'world']", "Ok(['hello','world'])")
     testEvalToBe("([0,1,2])[1]", "Ok(1)")
     testDescriptionEvalToBe("index not found", "([0,1,2])[10]", "Error(Array index not found: 10)")
   })
   describe("records", () => {
-    test("define", () => expectEvalToBe("{a: 1, b: 2}", "Ok({a: 1, b: 2})"))
+    test("define", () => expectEvalToBe("{a: 1, b: 2}", "Ok({a: 1,b: 2})"))
     test("index", () => expectEvalToBe("{a: 1}.a", "Ok(1)"))
     test("index not found", () => expectEvalToBe("{a: 1}.b", "Error(Record property not found: b)"))
   })
@@ -91,7 +84,7 @@ describe("eval", () => {
     testEvalToBe("x=1; y=x+1; y+1", "Ok(3)")
     testEvalToBe("1; x=1", "Error(Assignment expected)")
     testEvalToBe("1; 1", "Error(Assignment expected)")
-    testEvalToBe("x=1; x=1", "Error(Expression expected)")
+    testEvalToBe("x=1; x=1", "Ok({x: 1})")
   })
 })
 

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

@@ -119,27 +119,33 @@ describe("eval on distribution functions", () => {
 
 describe("parse on distribution functions", () => {
   describe("power", () => {
-    testParse("normal(5,2) ^ normal(5,1)", "Ok((:pow (:normal 5 2) (:normal 5 1)))")
-    testParse("3 ^ normal(5,1)", "Ok((:pow 3 (:normal 5 1)))")
-    testParse("normal(5,2) ^ 3", "Ok((:pow (:normal 5 2) 3))")
+    testParse("normal(5,2) ^ normal(5,1)", "Ok((:$$block (:pow (:normal 5 2) (:normal 5 1))))")
+    testParse("3 ^ normal(5,1)", "Ok((:$$block (:pow 3 (:normal 5 1))))")
+    testParse("normal(5,2) ^ 3", "Ok((:$$block (:pow (:normal 5 2) 3)))")
   })
   describe("subtraction", () => {
-    testParse("10 - normal(5,1)", "Ok((:subtract 10 (:normal 5 1)))")
-    testParse("normal(5,1) - 10", "Ok((:subtract (:normal 5 1) 10))")
+    testParse("10 - normal(5,1)", "Ok((:$$block (:subtract 10 (:normal 5 1))))")
+    testParse("normal(5,1) - 10", "Ok((:$$block (:subtract (:normal 5 1) 10)))")
   })
   describe("pointwise arithmetic expressions", () => {
     testParse(~skip=true, "normal(5,2) .+ normal(5,1)", "Ok((:dotAdd (:normal 5 2) (:normal 5 1)))")
     testParse(
       ~skip=true,
       "normal(5,2) .- normal(5,1)",
-      "Ok((:dotSubtract (:normal 5 2) (:normal 5 1)))",
+      "Ok((:$$block (:dotPow (:normal 5 2) (:normal 5 1))))",
     )
-    testParse("normal(5,2) .* normal(5,1)", "Ok((:dotMultiply (:normal 5 2) (:normal 5 1)))")
-    testParse("normal(5,2) ./ normal(5,1)", "Ok((:dotDivide (:normal 5 2) (:normal 5 1)))")
-    testParse("normal(5,2) .^ normal(5,1)", "Ok((:dotPow (:normal 5 2) (:normal 5 1)))")
+    testParse(
+      "normal(5,2) .* normal(5,1)",
+      "Ok((:$$block (:dotMultiply (:normal 5 2) (:normal 5 1))))",
+    )
+    testParse(
+      "normal(5,2) ./ normal(5,1)",
+      "Ok((:$$block (:dotDivide (:normal 5 2) (:normal 5 1))))",
+    )
+    testParse("normal(5,2) .^ normal(5,1)", "Ok((:$$block (:dotPow (:normal 5 2) (:normal 5 1))))")
   })
   describe("equality", () => {
-    testParse("5 == normal(5,2)", "Ok((:equal 5 (:normal 5 2)))")
+    testParse("5 == normal(5,2)", "Ok((:$$block (:equal 5 (:normal 5 2))))")
   })
   describe("pointwise adding two normals", () => {
     testParse(~skip=true, "normal(5,2) .+ normal(5,1)", "Ok((:dotAdd (:normal 5 2) (:normal 5 1)))")

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

@@ -3,9 +3,9 @@ open Jest
 open Expect
 
 describe("ExpressionValue", () => {
-  test("argsToString", () => expect([EvNumber(1.), EvString("a")]->argsToString)->toBe("1, 'a'"))
+  test("argsToString", () => expect([EvNumber(1.), EvString("a")]->argsToString)->toBe("1,'a'"))
 
   test("toStringFunctionCall", () =>
-    expect(("fn", [EvNumber(1.), EvString("a")])->toStringFunctionCall)->toBe("fn(1, 'a')")
+    expect(("fn", [EvNumber(1.), EvString("a")])->toStringFunctionCall)->toBe("fn(1,'a')")
   )
 })

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

@@ -12,5 +12,3 @@ type externalBindings = ReducerInterface_ExpressionValue.externalBindings
 let evaluate = Expression.evaluate
 let evaluateUsingOptions = Expression.evaluateUsingOptions
 let parse = Expression.parse
-let parseOuter = Expression.parseOuter
-let parsePartial = Expression.parsePartial

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

@@ -18,12 +18,9 @@ type externalBindings = ReducerInterface_ExpressionValue.externalBindings
 let evaluateUsingOptions: (
   ~environment: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.environment>,
   ~externalBindings: option<QuriSquiggleLang.ReducerInterface_ExpressionValue.externalBindings>,
-  ~isPartial: option<bool>,
   string,
 ) => result<expressionValue, errorValue>
 @genType
 let evaluate: string => result<expressionValue, errorValue>
 
 let parse: string => result<Expression.expression, errorValue>
-let parseOuter: string => result<Expression.expression, errorValue>
-let parsePartial: string => result<Expression.expression, errorValue>

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

@@ -1,5 +1,6 @@
 module ExternalLibrary = ReducerInterface.ExternalLibrary
 module MathJs = Reducer_MathJs
+module Bindings = Reducer_Expression_Bindings
 open ReducerInterface.ExpressionValue
 open Reducer_ErrorValue
 
@@ -68,6 +69,20 @@ let callInternal = (call: functionCall, _environment): result<'b, errorValue> =>
     value->Ok
   }
 
+  let doSetBindings = (
+    externalBindings: externalBindings,
+    symbol: string,
+    value: expressionValue,
+  ) => {
+    Bindings.fromExternalBindings(externalBindings)
+    ->Belt.Map.String.set(symbol, value)
+    ->Bindings.toExternalBindings
+    ->EvRecord
+    ->Ok
+  }
+
+  let doExportBindings = (externalBindings: externalBindings) => EvRecord(externalBindings)->Ok
+
   switch call {
   | ("$atIndex", [EvArray(aValueArray), EvArray([EvNumber(fIndex)])]) =>
     arrayAtIndex(aValueArray, fIndex)
@@ -78,6 +93,9 @@ let callInternal = (call: functionCall, _environment): result<'b, errorValue> =>
   | ("inspect", [value, EvString(label)]) => inspectLabel(value, label)
   | ("inspect", [value]) => inspect(value)
   | ("inspectPerformance", [value, EvString(label)]) => inspectPerformance(value, label)
+  | ("$setBindings", [EvRecord(externalBindings), EvSymbol(symbol), value]) =>
+    doSetBindings(externalBindings, symbol, value)
+  | ("$exportBindings", [EvRecord(externalBindings)]) => doExportBindings(externalBindings)
   | call => callMathJs(call)
   }
 }

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

@@ -3,179 +3,143 @@
   they take expressions as parameters and return a new expression.
   Macros are used to define language building blocks. They are like Lisp macros.
 */
+module Bindings = Reducer_Expression_Bindings
 module ExpressionT = Reducer_Expression_T
 module ExpressionValue = ReducerInterface.ExpressionValue
 module Result = Belt.Result
-
-open Reducer_ErrorValue
+open Reducer_Expression_ExpressionBuilder
 
 type expression = ExpressionT.expression
 type environment = ExpressionValue.environment
-
-type reducerFn = (
-  expression,
-  ExpressionT.bindings,
-  environment,
-) => result<ExpressionValue.expressionValue, errorValue>
-
-let rec replaceSymbols = (expression: expression, bindings: ExpressionT.bindings): result<
-  expression,
-  errorValue,
-> => {
-  let getParameters = (bindings: ExpressionT.bindings): array<string> => {
-    let eParameters = Belt.Map.String.getWithDefault(bindings, "$parameters", EParameters([]))
-    switch eParameters {
-    | EParameters(parameters) => parameters
-    | _ => []
-    }
-  }
-
-  let putParameters = (
-    bindings: ExpressionT.bindings,
-    parameters: array<string>,
-  ): ExpressionT.bindings =>
-    Belt.Map.String.set(bindings, "$parameters", ExpressionT.EParameters(parameters))
-
-  let answerBindingIfNotParameter = (aSymbol, defaultExpression, parameters, bindings) =>
-    switch Js.Array2.some(parameters, a => a == aSymbol) {
-    | true => defaultExpression->Ok // We cannot bind the parameters with global values
-    | false =>
-      switch bindings->Belt.Map.String.get(aSymbol) {
-      | Some(boundExpression) => boundExpression->Ok
-      | None => RESymbolNotFound(aSymbol)->Error
-      }
-    }
-
-  let answerCallBindingIfNotParameter = (aSymbol, defaultExpression, parameters, bindings) =>
-    switch Js.Array2.some(parameters, a => a == aSymbol) {
-    | true => defaultExpression->Ok // We cannot bind the parameters with global values
-    | false =>
-      switch bindings->Belt.Map.String.get(aSymbol) {
-      | Some(boundExpression) => boundExpression->Ok
-      | None => defaultExpression->Ok
-      }
-    }
-
-  switch expression {
-  | ExpressionT.EValue(EvSymbol(aSymbol)) => {
-      let parameters = getParameters(bindings)
-      answerBindingIfNotParameter(aSymbol, expression, parameters, bindings)
-    }
-  | ExpressionT.EValue(EvCall(aSymbol)) => {
-      let parameters = getParameters(bindings)
-      answerCallBindingIfNotParameter(aSymbol, expression, parameters, bindings)
-    }
-  | ExpressionT.EValue(_) => expression->Ok
-  | ExpressionT.EBindings(_) => expression->Ok
-  | ExpressionT.EParameters(_) => expression->Ok
-  | ExpressionT.EList(list{
-      ExpressionT.EValue(EvCall("$lambda")),
-      ExpressionT.EParameters(parameters),
-      expr,
-    }) => {
-      let oldParameters = getParameters(bindings)
-      let newParameters = oldParameters->Js.Array2.concat(parameters)
-      let newBindings = putParameters(bindings, newParameters)
-      let rNewExpr = replaceSymbols(expr, newBindings)
-      rNewExpr->Result.flatMap(newExpr =>
-        ExpressionT.EList(list{
-          ExpressionT.EValue(EvCall("$lambda")),
-          ExpressionT.EParameters(parameters),
-          newExpr,
-        })->Ok
-      )
-    }
-  | ExpressionT.EList(list) => {
-      let racc = list->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
-        racc->Result.flatMap(acc => {
-          each
-          ->replaceSymbols(bindings)
-          ->Result.flatMap(newNode => {
-            acc->Belt.List.add(newNode)->Ok
-          })
-        })
-      )
-      racc->Result.map(acc => acc->ExpressionT.EList)
-    }
-  }
-}
+type errorValue = Reducer_ErrorValue.errorValue
 
 let dispatchMacroCall = (
-  list: list<expression>,
+  macroExpression: expression,
   bindings: ExpressionT.bindings,
   environment,
-  reduceExpression: reducerFn,
-): result<expression, 'e> => {
-  let doBindStatement = (statement: expression, bindings: ExpressionT.bindings) => {
+  reduceExpression: ExpressionT.reducerFn,
+): result<expression, errorValue> => {
+  let doBindStatement = (bindingExpr: expression, statement: expression, environment) =>
     switch statement {
-    | ExpressionT.EList(list{
-        ExpressionT.EValue(EvCall("$let")),
-        ExpressionT.EValue(EvSymbol(aSymbol)),
-        expressionToReduce,
-      }) => {
-        let rNewExpressionToReduce = replaceSymbols(expressionToReduce, bindings)
-
-        let rNewValue =
-          rNewExpressionToReduce->Result.flatMap(newExpressionToReduce =>
-            reduceExpression(newExpressionToReduce, bindings, environment)
-          )
-
-        let rNewExpression = rNewValue->Result.map(newValue => ExpressionT.EValue(newValue))
-        rNewExpression->Result.map(newExpression =>
-          Belt.Map.String.set(bindings, aSymbol, newExpression)->ExpressionT.EBindings
+    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), symbolExpr, statement}) => {
+        let rExternalBindingsValue = reduceExpression(
+          bindingExpr,
+          Bindings.defaultBindings,
+          environment,
         )
+
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement->Result.map(newStatement =>
+            eFunction(
+              "$setBindings",
+              list{newBindings->Bindings.toExternalBindings->eRecord, symbolExpr, newStatement},
+            )
+          )
+        })
       }
     | _ => REAssignmentExpected->Error
     }
-  }
 
-  let doExportVariableExpression = (bindings: ExpressionT.bindings) => {
-    let emptyDictionary: Js.Dict.t<ExpressionValue.expressionValue> = Js.Dict.empty()
-    let reducedBindings = bindings->Belt.Map.String.keep((_key, value) =>
-      switch value {
-      | ExpressionT.EValue(_) => true
-      | _ => false
-      }
-    )
-    let externalBindings = reducedBindings->Belt.Map.String.reduce(emptyDictionary, (
-      acc,
-      key,
-      expressionValue,
-    ) => {
-      let value = switch expressionValue {
-      | ExpressionT.EValue(aValue) => aValue
-      | _ => EvSymbol("internal")
-      }
-      Js.Dict.set(acc, key, value)
-      acc
-    })
-    externalBindings->ExpressionValue.EvRecord->ExpressionT.EValue->Ok
-  }
+  let doBindExpression = (bindingExpr: expression, statement: expression, environment) =>
+    switch statement {
+    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), symbolExpr, statement}) => {
+        let rExternalBindingsValue = reduceExpression(
+          bindingExpr,
+          Bindings.defaultBindings,
+          environment,
+        )
 
-  let doBindExpression = (expression: expression, bindings: ExpressionT.bindings) =>
-    switch expression {
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$let")), ..._}) =>
-      REExpressionExpected->Error
-    | ExpressionT.EList(list{ExpressionT.EValue(EvCall("$exportVariablesExpression"))}) =>
-      doExportVariableExpression(bindings)
-    | _ => replaceSymbols(expression, bindings)
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement->Result.map(newStatement =>
+            eFunction(
+              "$exportBindings",
+              list{
+                eFunction(
+                  "$setBindings",
+                  list{newBindings->Bindings.toExternalBindings->eRecord, symbolExpr, newStatement},
+                ),
+              },
+            )
+          )
+        })
+      }
+    | _ => {
+        let rExternalBindingsValue = reduceExpression(
+          bindingExpr,
+          Bindings.defaultBindings,
+          environment,
+        )
+        rExternalBindingsValue->Result.flatMap(externalBindingsValue => {
+          let newBindings = Bindings.fromValue(externalBindingsValue)
+          let rNewStatement = Bindings.replaceSymbols(newBindings, statement)
+          rNewStatement
+        })
+      }
     }
 
-  switch list {
-  | list{ExpressionT.EValue(EvCall("$$bindings"))} => bindings->ExpressionT.EBindings->Ok
+  let doBlock = (exprs: list<expression>, _bindings: ExpressionT.bindings, _environment): result<
+    expression,
+    errorValue,
+  > => {
+    let exprsArray = Belt.List.toArray(exprs)
+    let maxIndex = Js.Array2.length(exprsArray) - 1
+    exprsArray->Js.Array2.reducei((acc, statement, index) =>
+      if index == 0 {
+        if index == maxIndex {
+          eBindExpressionDefault(statement)
+        } else {
+          eBindStatementDefault(statement)
+        }
+      } else if index == maxIndex {
+        eBindExpression(acc, statement)
+      } else {
+        eBindStatement(acc, statement)
+      }
+    , eSymbol("undefined block"))->Ok
+  }
 
-  | list{
-      ExpressionT.EValue(EvCall("$$bindStatement")),
-      ExpressionT.EBindings(bindings),
-      statement,
-    } =>
-    doBindStatement(statement, bindings)
-  | list{
-      ExpressionT.EValue(EvCall("$$bindExpression")),
-      ExpressionT.EBindings(bindings),
-      expression,
-    } =>
-    doBindExpression(expression, bindings)
-  | _ => list->ExpressionT.EList->Ok
+  let doLambdaDefinition = (
+    bindings: ExpressionT.bindings,
+    parameters: array<string>,
+    lambdaDefinition: ExpressionT.expression,
+  ) => eLambda(parameters, bindings->Bindings.toExternalBindings, lambdaDefinition)->Ok
+
+  let expandExpressionList = (aList, bindings: ExpressionT.bindings, environment) =>
+    switch aList {
+    | list{
+        ExpressionT.EValue(EvCall("$$bindStatement")),
+        bindingExpr: ExpressionT.expression,
+        statement,
+      } =>
+      doBindStatement(bindingExpr, statement, environment)
+    | list{ExpressionT.EValue(EvCall("$$bindStatement")), statement} =>
+      // bindings of the context are used when there is no binding expression
+      doBindStatement(eRecord(Bindings.toExternalBindings(bindings)), statement, environment)
+    | list{
+        ExpressionT.EValue(EvCall("$$bindExpression")),
+        bindingExpr: ExpressionT.expression,
+        expression,
+      } =>
+      doBindExpression(bindingExpr, expression, environment)
+    | list{ExpressionT.EValue(EvCall("$$bindExpression")), expression} =>
+      // bindings of the context are used when there is no binding expression
+      doBindExpression(eRecord(Bindings.toExternalBindings(bindings)), expression, environment)
+    | list{ExpressionT.EValue(EvCall("$$block")), ...exprs} => doBlock(exprs, bindings, environment)
+    | list{
+        ExpressionT.EValue(EvCall("$$lambda")),
+        ExpressionT.EValue(EvArrayString(parameters)),
+        lambdaDefinition,
+      } =>
+      doLambdaDefinition(bindings, parameters, lambdaDefinition)
+    | _ => ExpressionT.EList(aList)->Ok
+    }
+
+  switch macroExpression {
+  | EList(aList) => expandExpressionList(aList, bindings, environment)
+  | _ => macroExpression->Ok
   }
 }

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

@@ -1,13 +1,14 @@
-module Builder = Reducer_Expression_Builder
+module Bindings = Reducer_Expression_Bindings
 module BuiltIn = Reducer_Dispatch_BuiltIn
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionValue = ReducerInterface.ExpressionValue
 module Extra = Reducer_Extra
+module Lambda = Reducer_Expression_Lambda
+module Macro = Reducer_Expression_Macro
 module MathJs = Reducer_MathJs
 module Result = Belt.Result
 module T = Reducer_Expression_T
 
-open Reducer_ErrorValue
-
 type environment = ReducerInterface_ExpressionValue.environment
 type errorValue = Reducer_ErrorValue.errorValue
 type expression = T.expression
@@ -16,30 +17,6 @@ type externalBindings = ReducerInterface_ExpressionValue.externalBindings
 type internalCode = ReducerInterface_ExpressionValue.internalCode
 type t = expression
 
-external castExpressionToInternalCode: expression => internalCode = "%identity"
-external castInternalCodeToExpression: internalCode => expression = "%identity"
-
-/*
-  Shows the expression as text of expression
-*/
-let rec toString = expression =>
-  switch expression {
-  | T.EBindings(_) => "$$bound"
-  | T.EParameters(params) => `(${Js.Array2.toString(params)})`
-  | T.EList(aList) =>
-    `(${Belt.List.map(aList, aValue => toString(aValue))
-      ->Extra.List.interperse(" ")
-      ->Belt.List.toArray
-      ->Js.String.concatMany("")})`
-  | EValue(aValue) => ExpressionValue.toString(aValue)
-  }
-
-let toStringResult = codeResult =>
-  switch codeResult {
-  | Ok(a) => `Ok(${toString(a)})`
-  | Error(m) => `Error(${Js.String.make(m)})`
-  }
-
 /*
   Converts a MathJs code to expression
 */
@@ -49,14 +26,6 @@ let parse_ = (expr: string, parser, converter): result<t, errorValue> =>
 let parse = (mathJsCode: string): result<t, errorValue> =>
   mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromNode)
 
-let parsePartial = (mathJsCode: string): result<t, errorValue> =>
-  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromPartialNode)
-
-let parseOuter = (mathJsCode: string): result<t, errorValue> =>
-  mathJsCode->parse_(MathJs.Parse.parse, MathJs.ToExpression.fromOuterNode)
-
-let defaultBindings: T.bindings = Belt.Map.String.empty
-
 /*
   Recursively evaluate/reduce the expression (Lisp AST)
 */
@@ -64,144 +33,63 @@ let rec reduceExpression = (expression: t, bindings: T.bindings, environment: en
   expressionValue,
   'e,
 > => {
-  /*
-    Macros are like functions but instead of taking values as parameters,
-    they take expressions as parameters and return a new expression.
-    Macros are used to define language building blocks. They are like Lisp macros.
- */
-  let doMacroCall = (list: list<t>, bindings: T.bindings, environment: environment): result<
-    t,
-    'e,
-  > =>
-    Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(list, bindings, environment, reduceExpression)
-
-  let applyParametersToLambda = (
-    internal: internalCode,
-    parameters: array<string>,
-    args: list<expressionValue>,
-    environment,
-  ): result<expressionValue, 'e> => {
-    let expr = castInternalCodeToExpression(internal)
-    let parameterList = parameters->Belt.List.fromArray
-    let zippedParameterList = parameterList->Belt.List.zip(args)
-    let bindings = Belt.List.reduce(zippedParameterList, defaultBindings, (a, (p, e)) =>
-      a->Belt.Map.String.set(p, e->T.EValue)
-    )
-    let newExpression = Builder.passToFunction(
-      "$$bindExpression",
-      list{Builder.passToFunction("$$bindings", list{}), expr},
-    )
-    reduceExpression(newExpression, bindings, environment)
+  switch expression {
+  | T.EValue(value) => value->Ok
+  | T.EList(list) =>
+    switch list {
+    | list{EValue(EvCall(fName)), ..._args} =>
+      switch Macro.isMacroName(fName) {
+      // A macro expands then reduces itself
+      | true => Macro.doMacroCall(expression, bindings, environment, reduceExpression)
+      | false => reduceExpressionList(list, bindings, environment)
+      }
+    | _ => reduceExpressionList(list, bindings, environment)
+    }
   }
-
-  /*
-    After reducing each level of expression(Lisp AST), we have a value list to evaluate
- */
-  let reduceValueList = (valueList: list<expressionValue>, environment): result<
-    expressionValue,
-    'e,
-  > =>
-    switch valueList {
-    | list{EvCall(fName), ...args} =>
-      (fName, args->Belt.List.toArray)->BuiltIn.dispatch(environment)
-    // "(lambda(x=>internal) param)"
-    | list{EvLambda((parameters, internal)), ...args} =>
-      applyParametersToLambda(internal, parameters, args, environment)
-    | _ => valueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
-    }
-
-  let rec seekMacros = (expression: t, bindings: T.bindings, environment): result<t, 'e> =>
-    switch expression {
-    | T.EValue(_value) => expression->Ok
-    | T.EBindings(_value) => expression->Ok
-    | T.EParameters(_value) => expression->Ok
-    | T.EList(list) => {
-        let racc: result<list<t>, 'e> = list->Belt.List.reduceReverse(Ok(list{}), (
-          racc,
-          each: expression,
-        ) =>
-          racc->Result.flatMap(acc => {
-            each
-            ->seekMacros(bindings, environment)
-            ->Result.flatMap(newNode => {
-              acc->Belt.List.add(newNode)->Ok
-            })
-          })
-        )
-        racc->Result.flatMap(acc => acc->doMacroCall(bindings, environment))
-      }
-    }
-
-  let rec reduceExpandedExpression = (expression: t, environment): result<expressionValue, 'e> =>
-    switch expression {
-    | T.EList(list{T.EValue(EvCall("$lambda")), T.EParameters(parameters), functionDefinition}) =>
-      EvLambda((parameters, functionDefinition->castExpressionToInternalCode))->Ok
-    | T.EValue(value) => value->Ok
-    | T.EList(list) => {
-        let racc: result<list<expressionValue>, 'e> = list->Belt.List.reduceReverse(Ok(list{}), (
-          racc,
-          each: expression,
-        ) =>
-          racc->Result.flatMap(acc => {
-            each
-            ->reduceExpandedExpression(environment)
-            ->Result.flatMap(newNode => {
-              acc->Belt.List.add(newNode)->Ok
-            })
-          })
-        )
-        racc->Result.flatMap(acc => acc->reduceValueList(environment))
-      }
-    | EBindings(_bindings) => RETodo("Error: Bindings cannot be reduced to values")->Error
-    | EParameters(_parameters) =>
-      RETodo("Error: Lambda Parameters cannot be reduced to values")->Error
-    }
-
-  let rExpandedExpression: result<t, 'e> = expression->seekMacros(bindings, environment)
-  rExpandedExpression->Result.flatMap(expandedExpression =>
-    expandedExpression->reduceExpandedExpression(environment)
+}
+and reduceExpressionList = (
+  expressions: list<t>,
+  bindings: T.bindings,
+  environment: environment,
+): result<expressionValue, 'e> => {
+  let racc: result<list<expressionValue>, 'e> = expressions->Belt.List.reduceReverse(Ok(list{}), (
+    racc,
+    each: expression,
+  ) =>
+    racc->Result.flatMap(acc => {
+      each
+      ->reduceExpression(bindings, environment)
+      ->Result.map(newNode => {
+        acc->Belt.List.add(newNode)
+      })
+    })
   )
+  racc->Result.flatMap(acc => acc->reduceValueList(environment))
 }
 
-let evalUsingExternalBindingsExpression_ = (aExpression, bindings, environment): result<
+/*
+    After reducing each level of expression(Lisp AST), we have a value list to evaluate
+ */
+and reduceValueList = (valueList: list<expressionValue>, environment): result<
+  expressionValue,
+  'e,
+> =>
+  switch valueList {
+  | list{EvCall(fName), ...args} => (fName, args->Belt.List.toArray)->BuiltIn.dispatch(environment)
+
+  | list{EvLambda(lamdaCall), ...args} =>
+    Lambda.doLambdaCall(lamdaCall, args, environment, reduceExpression)
+  | _ => valueList->Belt.List.toArray->ExpressionValue.EvArray->Ok
+  }
+
+let evalUsingBindingsExpression_ = (aExpression, bindings, environment): result<
   expressionValue,
   'e,
 > => reduceExpression(aExpression, bindings, environment)
 
-/*
-  Evaluates MathJs code via Reducer using bindings and answers the result.
-  When bindings are used, the code is a partial code as if it is cut from a larger code.
-  Therefore all statements are assignments.
-*/
-let evalPartial_ = (codeText: string, bindings: T.bindings, environment: environment) => {
-  parsePartial(codeText)->Result.flatMap(expression =>
-    expression->evalUsingExternalBindingsExpression_(bindings, environment)
-  )
-}
-
-/*
-  Evaluates MathJs code via Reducer using bindings and answers the result.
-  When bindings are used, the code is a partial code as if it is cut from a larger code.
-  Therefore all statments are assignments.
-*/
-let evalOuter_ = (codeText: string, bindings: T.bindings, environment: environment) => {
-  parseOuter(codeText)->Result.flatMap(expression =>
-    expression->evalUsingExternalBindingsExpression_(bindings, environment)
-  )
-}
-
-let externalBindingsToBindings = (externalBindings: externalBindings): T.bindings => {
-  let keys = Js.Dict.keys(externalBindings)
-  keys->Belt.Array.reduce(defaultBindings, (acc, key) => {
-    let value = Js.Dict.unsafeGet(externalBindings, key)
-    acc->Belt.Map.String.set(key, T.EValue(value))
-  })
-}
-
 let evaluateUsingOptions = (
   ~environment: option<ReducerInterface_ExpressionValue.environment>,
   ~externalBindings: option<ReducerInterface_ExpressionValue.externalBindings>,
-  ~isPartial: option<bool>,
   code: string,
 ): result<expressionValue, errorValue> => {
   let anEnvironment = switch environment {
@@ -214,24 +102,15 @@ let evaluateUsingOptions = (
   | None => ReducerInterface_ExpressionValue.defaultExternalBindings
   }
 
-  let anIsPartial = switch isPartial {
-  | Some(isPartial) => isPartial
-  | None => false
-  }
+  let bindings = anExternalBindings->Bindings.fromExternalBindings
 
-  let bindings = anExternalBindings->externalBindingsToBindings
-
-  if anIsPartial {
-    evalPartial_(code, bindings, anEnvironment)
-  } else {
-    evalOuter_(code, bindings, anEnvironment)
-  }
+  parse(code)->Result.flatMap(expr => evalUsingBindingsExpression_(expr, bindings, anEnvironment))
 }
 
 /*
   Evaluates MathJs code and bindings via Reducer and answers the result
 */
 let evaluate = (code: string): result<expressionValue, errorValue> => {
-  evaluateUsingOptions(~environment=None, ~externalBindings=None, ~isPartial=None, code)
+  evaluateUsingOptions(~environment=None, ~externalBindings=None, code)
 }
 let eval = evaluate

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

@@ -0,0 +1,73 @@
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Result = Belt.Result
+
+type errorValue = Reducer_ErrorValue.errorValue
+type expression = ExpressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+
+let defaultBindings: ExpressionT.bindings = Belt.Map.String.empty
+
+let fromExternalBindings = (externalBindings: externalBindings): ExpressionT.bindings => {
+  let keys = Js.Dict.keys(externalBindings)
+  keys->Belt.Array.reduce(defaultBindings, (acc, key) => {
+    let value = Js.Dict.unsafeGet(externalBindings, key)
+    acc->Belt.Map.String.set(key, value)
+  })
+}
+
+let toExternalBindings = (bindings: ExpressionT.bindings): externalBindings => {
+  let keys = Belt.Map.String.keysToArray(bindings)
+  keys->Belt.Array.reduce(Js.Dict.empty(), (acc, key) => {
+    let value = bindings->Belt.Map.String.getExn(key)
+    Js.Dict.set(acc, key, value)
+    acc
+  })
+}
+
+let fromValue = (aValue: expressionValue) =>
+  switch aValue {
+  | EvRecord(externalBindings) => fromExternalBindings(externalBindings)
+  | _ => defaultBindings
+  }
+
+let externalFromArray = anArray => Js.Dict.fromArray(anArray)
+
+let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")
+
+let rec replaceSymbols = (bindings: ExpressionT.bindings, expression: expression): result<
+  expression,
+  errorValue,
+> =>
+  switch expression {
+  | ExpressionT.EValue(value) =>
+    replaceSymbolOnValue(bindings, value)->Result.map(evValue => evValue->ExpressionT.EValue)
+  | ExpressionT.EList(list) =>
+    switch list {
+    | list{EValue(EvCall(fName)), ..._args} =>
+      switch isMacroName(fName) {
+      // A macro reduces itself so we dont dive in it
+      | true => expression->Ok
+      | false => replaceSymbolsOnExpressionList(bindings, list)
+      }
+    | _ => replaceSymbolsOnExpressionList(bindings, list)
+    }
+  }
+
+and replaceSymbolsOnExpressionList = (bindings, list) => {
+  let racc = list->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
+    racc->Result.flatMap(acc => {
+      replaceSymbols(bindings, each)->Result.flatMap(newNode => {
+        acc->Belt.List.add(newNode)->Ok
+      })
+    })
+  )
+  racc->Result.map(acc => acc->ExpressionT.EList)
+}
+and replaceSymbolOnValue = (bindings, evValue: expressionValue) =>
+  switch evValue {
+  | EvSymbol(symbol) | EvCall(symbol) =>
+    Belt.Map.String.getWithDefault(bindings, symbol, evValue)->Ok
+  | _ => evValue->Ok
+  }

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

@@ -1,16 +0,0 @@
-module ErrorValue = Reducer_ErrorValue
-module ExpressionT = Reducer_Expression_T
-module ExpressionValue = ReducerInterface.ExpressionValue
-module Result = Belt.Result
-
-type errorValue = ErrorValue.errorValue
-type expression = ExpressionT.expression
-
-let passToFunction = (fName: string, lispArgs: list<expression>): expression => {
-  let toEvCallValue = (name: string): expression => name->ExpressionValue.EvCall->ExpressionT.EValue
-  let fn = fName->toEvCallValue
-  list{fn, ...lispArgs}->ExpressionT.EList
-}
-
-let toEvSymbolValue = (name: string): expression =>
-  name->ExpressionValue.EvSymbol->ExpressionT.EValue

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

@@ -0,0 +1,60 @@
+module BBindings = Reducer_Expression_Bindings
+module BErrorValue = Reducer_ErrorValue
+module BExpressionT = Reducer_Expression_T
+module BExpressionValue = ReducerInterface.ExpressionValue
+
+type errorValue = BErrorValue.errorValue
+type expression = BExpressionT.expression
+type internalCode = ReducerInterface_ExpressionValue.internalCode
+
+external castExpressionToInternalCode: expression => internalCode = "%identity"
+
+let eArray = anArray => anArray->BExpressionValue.EvArray->BExpressionT.EValue
+
+let eArrayString = anArray => anArray->BExpressionValue.EvArrayString->BExpressionT.EValue
+
+let eBindings = (anArray: array<(string, BExpressionValue.expressionValue)>) =>
+  anArray->Js.Dict.fromArray->EvRecord->BExpressionT.EValue
+
+let eBool = aBool => aBool->BExpressionValue.EvBool->BExpressionT.EValue
+
+let eCall = (name: string): expression => name->BExpressionValue.EvCall->BExpressionT.EValue
+
+let eFunction = (fName: string, lispArgs: list<expression>): expression => {
+  let fn = fName->eCall
+  list{fn, ...lispArgs}->BExpressionT.EList
+}
+
+let eLambda = (parameters: array<string>, context, expr) =>
+  BExpressionValue.EvLambda(
+    parameters,
+    context,
+    expr->castExpressionToInternalCode,
+  )->BExpressionT.EValue
+
+let eNumber = aNumber => aNumber->BExpressionValue.EvNumber->BExpressionT.EValue
+
+let eRecord = aRecord => aRecord->BExpressionValue.EvRecord->BExpressionT.EValue
+
+let eString = aString => aString->BExpressionValue.EvString->BExpressionT.EValue
+
+let eSymbol = (name: string): expression => name->BExpressionValue.EvSymbol->BExpressionT.EValue
+
+let eList = (list: list<expression>): expression => list->BExpressionT.EList
+
+let eBlock = (exprs: list<expression>): expression => eFunction("$$block", exprs)
+
+let eLetStatement = (symbol: string, valueExpression: expression): expression =>
+  eFunction("$let", list{eSymbol(symbol), valueExpression})
+
+let eBindStatement = (bindingExpr: expression, letStatement: expression): expression =>
+  eFunction("$$bindStatement", list{bindingExpr, letStatement})
+
+let eBindStatementDefault = (letStatement: expression): expression =>
+  eFunction("$$bindStatement", list{letStatement})
+
+let eBindExpression = (bindingExpr: expression, expression: expression): expression =>
+  eFunction("$$bindExpression", list{bindingExpr, expression})
+
+let eBindExpressionDefault = (expression: expression): expression =>
+  eFunction("$$bindExpression", list{expression})

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

@@ -0,0 +1,35 @@
+module Bindings = Reducer_Expression_Bindings
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+
+type environment = ReducerInterface_ExpressionValue.environment
+type expression = ExpressionT.expression
+type expressionValue = ReducerInterface_ExpressionValue.expressionValue
+type externalBindings = ReducerInterface_ExpressionValue.externalBindings
+type internalCode = ReducerInterface_ExpressionValue.internalCode
+
+external castInternalCodeToExpression: internalCode => expression = "%identity"
+
+let applyParametersToLambda = (
+  internal: internalCode,
+  parameters: array<string>,
+  args: list<expressionValue>,
+  context: externalBindings,
+  environment,
+  reducer: ExpressionT.reducerFn,
+): result<expressionValue, 'e> => {
+  let expr = castInternalCodeToExpression(internal)
+  let parameterList = parameters->Belt.List.fromArray
+  let zippedParameterList = parameterList->Belt.List.zip(args)
+  let bindings = Belt.List.reduce(zippedParameterList, context->Bindings.fromExternalBindings, (
+    acc,
+    (variable, variableValue),
+  ) => acc->Belt.Map.String.set(variable, variableValue))
+  let newExpression = ExpressionBuilder.eBlock(list{expr})
+  reducer(newExpression, bindings, environment)
+}
+
+let doLambdaCall = ((parameters, context, internal), args, environment, reducer) => {
+  applyParametersToLambda(internal, parameters, args, context, environment, reducer)
+}

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

@@ -0,0 +1,35 @@
+module ExpressionT = Reducer_Expression_T
+module ExpressionValue = ReducerInterface.ExpressionValue
+module Result = Belt.Result
+
+type environment = ExpressionValue.environment
+type expression = ExpressionT.expression
+type expressionValue = ExpressionValue.expressionValue
+
+let expandMacroCall = (
+  macroExpression: expression,
+  bindings: ExpressionT.bindings,
+  environment: environment,
+  reduceExpression: ExpressionT.reducerFn,
+): result<expression, 'e> =>
+  Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(
+    macroExpression,
+    bindings,
+    environment,
+    reduceExpression,
+  )
+
+let doMacroCall = (
+  macroExpression: expression,
+  bindings: ExpressionT.bindings,
+  environment: environment,
+  reduceExpression: ExpressionT.reducerFn,
+): result<expressionValue, 'e> =>
+  expandMacroCall(
+    macroExpression,
+    bindings,
+    environment,
+    reduceExpression,
+  )->Result.flatMap(expression => reduceExpression(expression, bindings, environment))
+
+let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")

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

@@ -1,5 +1,3 @@
-open ReducerInterface.ExpressionValue
-
 /*
   An expression is a Lisp AST. An expression is either a primitive value or a list of expressions.
   In the case of a list of expressions (e1, e2, e3, ...eN), the semantic is
@@ -8,9 +6,51 @@ open ReducerInterface.ExpressionValue
   A Lisp AST contains only expressions/primitive values to apply to their left.
   The act of defining the semantics of a functional language is to write it in terms of Lisp AST.
 */
+module Extra = Reducer_Extra
+module ExpressionValue = ReducerInterface.ExpressionValue
+
+type expressionValue = ExpressionValue.expressionValue
+type environment = ExpressionValue.environment
+
 type rec expression =
   | EList(list<expression>) // A list to map-reduce
   | EValue(expressionValue) // Irreducible built-in value. Reducer should not know the internals. External libraries are responsible
-  | EBindings(bindings) // $let kind of statements return bindings; for internal use only
-  | EParameters(array<string>) // for $defun; for internal use only
-and bindings = Belt.Map.String.t<expression>
+and bindings = Belt.Map.String.t<expressionValue>
+
+type reducerFn = (
+  expression,
+  bindings,
+  environment,
+) => result<expressionValue, Reducer_ErrorValue.errorValue>
+
+/*
+  Converts the expression to String
+*/
+let rec toString = expression =>
+  switch expression {
+  | EList(aList) =>
+    `(${Belt.List.map(aList, aValue => toString(aValue))
+      ->Extra.List.interperse(" ")
+      ->Belt.List.toArray
+      ->Js.String.concatMany("")})`
+  | EValue(aValue) => ExpressionValue.toString(aValue)
+  }
+
+let toStringResult = codeResult =>
+  switch codeResult {
+  | Ok(a) => `Ok(${toString(a)})`
+  | Error(m) => `Error(${Reducer_ErrorValue.errorToString(m)})`
+  }
+
+let inspect = (expr: expression): expression => {
+  Js.log(toString(expr))
+  expr
+}
+
+let inspectResult = (r: result<expression, Reducer_ErrorValue.errorValue>): result<
+  expression,
+  Reducer_ErrorValue.errorValue,
+> => {
+  Js.log(toStringResult(r))
+  r
+}

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

@@ -1,37 +1,34 @@
-module Builder = Reducer_Expression_Builder
+/* * WARNING. DO NOT EDIT, BEAUTIFY, COMMENT ON OR REFACTOR THIS CODE. 
+We will stop using MathJs parser and
+this whole file will go to trash
+**/
 module ErrorValue = Reducer_ErrorValue
+module ExpressionBuilder = Reducer_Expression_ExpressionBuilder
 module ExpressionT = Reducer_Expression_T
 module ExpressionValue = ReducerInterface.ExpressionValue
 module JavaScript = Reducer_Js
 module Parse = Reducer_MathJs_Parse
 module Result = Belt.Result
 
+type errorValue = ErrorValue.errorValue
 type expression = ExpressionT.expression
 type expressionValue = ExpressionValue.expressionValue
-type errorValue = ErrorValue.errorValue
 
-type blockTag =
-  | ImportVariablesStatement
-  | ExportVariablesExpression
-type tagOrNode =
-  | BlockTag(blockTag)
-  | BlockNode(Parse.node)
+let blockToNode = block => block["node"]
 
-let toTagOrNode = block => BlockNode(block["node"])
-
-let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
+let rec fromInnerNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
   Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
     let fromNodeList = (nodeList: list<Parse.node>): result<list<expression>, 'e> =>
       Belt.List.reduceReverse(nodeList, Ok(list{}), (racc, currNode) =>
         racc->Result.flatMap(acc =>
-          fromNode(currNode)->Result.map(currCode => list{currCode, ...acc})
+          fromInnerNode(currNode)->Result.map(currCode => list{currCode, ...acc})
         )
       )
 
     let caseFunctionNode = fNode => {
       let rLispArgs = fNode["args"]->Belt.List.fromArray->fromNodeList
-      rLispArgs->Result.flatMap(lispArgs =>
-        Builder.passToFunction(fNode->Parse.nameOfFunctionNode, lispArgs)->Ok
+      rLispArgs->Result.map(lispArgs =>
+        ExpressionBuilder.eFunction(fNode->Parse.nameOfFunctionNode, lispArgs)
       )
     }
 
@@ -42,18 +39,15 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
           (key: string, value: Parse.node),
         ) =>
           racc->Result.flatMap(acc =>
-            fromNode(value)->Result.map(valueExpression => {
+            fromInnerNode(value)->Result.map(valueExpression => {
               let entryCode =
-                list{
-                  key->ExpressionValue.EvString->ExpressionT.EValue,
-                  valueExpression,
-                }->ExpressionT.EList
+                list{ExpressionBuilder.eString(key), valueExpression}->ExpressionT.EList
               list{entryCode, ...acc}
             })
           )
         )
         rargs->Result.flatMap(args =>
-          Builder.passToFunction("$constructRecord", list{ExpressionT.EList(args)})->Ok
+          ExpressionBuilder.eFunction("$constructRecord", list{ExpressionT.EList(args)})->Ok
         ) // $constructRecord gets a single argument: List of key-value paiers
       }
 
@@ -66,7 +60,7 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
         Ok(list{}),
         (racc, currentPropertyMathJsNode) =>
           racc->Result.flatMap(acc =>
-            fromNode(currentPropertyMathJsNode)->Result.map(propertyCode => list{
+            fromInnerNode(currentPropertyMathJsNode)->Result.map(propertyCode => list{
               propertyCode,
               ...acc,
             })
@@ -77,28 +71,41 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
 
     let caseAccessorNode = (objectNode, indexNode) => {
       caseIndexNode(indexNode)->Result.flatMap(indexCode => {
-        fromNode(objectNode)->Result.flatMap(objectCode =>
-          Builder.passToFunction("$atIndex", list{objectCode, indexCode})->Ok
+        fromInnerNode(objectNode)->Result.flatMap(objectCode =>
+          ExpressionBuilder.eFunction("$atIndex", list{objectCode, indexCode})->Ok
         )
       })
     }
 
+    let caseBlock = (nodesArray: array<Parse.node>): result<expression, errorValue> => {
+      let rStatements: result<list<expression>, 'a> =
+        nodesArray
+        ->Belt.List.fromArray
+        ->Belt.List.reduceReverse(Ok(list{}), (racc, currNode) =>
+          racc->Result.flatMap(acc =>
+            fromInnerNode(currNode)->Result.map(currCode => list{currCode, ...acc})
+          )
+        )
+      rStatements->Result.map(statements => ExpressionBuilder.eBlock(statements))
+    }
+
     let caseAssignmentNode = aNode => {
-      let symbol = aNode["object"]["name"]->Builder.toEvSymbolValue
-      let rValueExpression = fromNode(aNode["value"])
-      rValueExpression->Result.flatMap(valueExpression =>
-        Builder.passToFunction("$let", list{symbol, valueExpression})->Ok
+      let symbolName = aNode["object"]["name"]
+      let rValueExpression = fromInnerNode(aNode["value"])
+      rValueExpression->Result.map(valueExpression =>
+        ExpressionBuilder.eLetStatement(symbolName, valueExpression)
       )
     }
 
     let caseFunctionAssignmentNode = faNode => {
-      let symbol = faNode["name"]->Builder.toEvSymbolValue
-      let rValueExpression = fromNode(faNode["expr"])
+      let symbol = faNode["name"]->ExpressionBuilder.eSymbol
+      let rValueExpression = fromInnerNode(faNode["expr"])
 
       rValueExpression->Result.flatMap(valueExpression => {
-        let lispParams = faNode["params"]->ExpressionT.EParameters
-        let lambda = Builder.passToFunction("$lambda", list{lispParams, valueExpression})
-        Builder.passToFunction("$let", list{symbol, lambda})->Ok
+        let lispParams = ExpressionBuilder.eArrayString(faNode["params"])
+        let valueBlock = ExpressionBuilder.eBlock(list{valueExpression})
+        let lambda = ExpressionBuilder.eFunction("$$lambda", list{lispParams, valueBlock})
+        ExpressionBuilder.eFunction("$let", list{symbol, lambda})->Ok
       })
     }
 
@@ -111,11 +118,11 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
     | MjArrayNode(aNode) => caseArrayNode(aNode)
     | MjAssignmentNode(aNode) => caseAssignmentNode(aNode)
     | MjSymbolNode(sNode) => {
-        let expr: expression = Builder.toEvSymbolValue(sNode["name"])
+        let expr: expression = ExpressionBuilder.eSymbol(sNode["name"])
         let rExpr: result<expression, errorValue> = expr->Ok
         rExpr
       }
-    | MjBlockNode(bNode) => bNode["blocks"]->Belt.Array.map(toTagOrNode)->caseTagOrNodes
+    | MjBlockNode(bNode) => bNode["blocks"]->Js.Array2.map(blockToNode)->caseBlock
     | MjConstantNode(cNode) =>
       cNode["value"]->JavaScript.Gate.jsToEv->Result.flatMap(v => v->ExpressionT.EValue->Ok)
     | MjFunctionAssignmentNode(faNode) => caseFunctionAssignmentNode(faNode)
@@ -123,78 +130,10 @@ let rec fromNode = (mathJsNode: Parse.node): result<expression, errorValue> =>
     | MjIndexNode(iNode) => caseIndexNode(iNode)
     | MjObjectNode(oNode) => caseObjectNode(oNode)
     | MjOperatorNode(opNode) => opNode->Parse.castOperatorNodeToFunctionNode->caseFunctionNode
-    | MjParenthesisNode(pNode) => pNode["content"]->fromNode
+    | MjParenthesisNode(pNode) => pNode["content"]->fromInnerNode
     }
     rFinalExpression
   })
-and caseTagOrNodes = (tagOrNodes): result<expression, errorValue> => {
-  let initialBindings = Builder.passToFunction("$$bindings", list{})->Ok
-  let lastIndex = Belt.Array.length(tagOrNodes) - 1
-  tagOrNodes->Belt.Array.reduceWithIndex(initialBindings, (rPreviousBindings, tagOrNode, i) => {
-    rPreviousBindings->Result.flatMap(previousBindings => {
-      let rStatement: result<expression, errorValue> = switch tagOrNode {
-      | BlockNode(node) => fromNode(node)
-      | BlockTag(tag) =>
-        switch tag {
-        | ImportVariablesStatement =>
-          Builder.passToFunction("$importVariablesStatement", list{})->Ok
-        | ExportVariablesExpression =>
-          Builder.passToFunction("$exportVariablesExpression", list{})->Ok
-        }
-      }
 
-      let bindName = if i == lastIndex {
-        "$$bindExpression"
-      } else {
-        "$$bindStatement"
-      }
-
-      rStatement->Result.flatMap((statement: expression) => {
-        Builder.passToFunction(bindName, list{previousBindings, statement})->Ok
-      })
-    })
-  })
-}
-
-let fromPartialNode = (mathJsNode: Parse.node): result<expression, errorValue> => {
-  Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
-    let casePartialBlockNode = (bNode: Parse.blockNode) => {
-      let blocksOrTags = bNode["blocks"]->Belt.Array.map(toTagOrNode)
-      let completed = Js.Array2.concat(blocksOrTags, [BlockTag(ExportVariablesExpression)])
-      completed->caseTagOrNodes
-    }
-
-    let casePartialExpression = (node: Parse.node) => {
-      let completed = [BlockNode(node), BlockTag(ExportVariablesExpression)]
-
-      completed->caseTagOrNodes
-    }
-
-    let rFinalExpression: result<expression, errorValue> = switch typedMathJsNode {
-    | MjBlockNode(bNode) => casePartialBlockNode(bNode)
-    | _ => casePartialExpression(mathJsNode)
-    }
-    rFinalExpression
-  })
-}
-
-let fromOuterNode = (mathJsNode: Parse.node): result<expression, errorValue> => {
-  Parse.castNodeType(mathJsNode)->Result.flatMap(typedMathJsNode => {
-    let casePartialBlockNode = (bNode: Parse.blockNode) => {
-      let blocksOrTags = bNode["blocks"]->Belt.Array.map(toTagOrNode)
-      let completed = blocksOrTags
-      completed->caseTagOrNodes
-    }
-
-    let casePartialExpression = (node: Parse.node) => {
-      let completed = [BlockNode(node)]
-      completed->caseTagOrNodes
-    }
-
-    let rFinalExpression: result<expression, errorValue> = switch typedMathJsNode {
-    | MjBlockNode(bNode) => casePartialBlockNode(bNode)
-    | _ => casePartialExpression(mathJsNode)
-    }
-    rFinalExpression
-  })
-}
+let fromNode = (node: Parse.node): result<expression, errorValue> =>
+  fromInnerNode(node)->Result.map(expr => ExpressionBuilder.eBlock(list{expr}))

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

@@ -11,17 +11,19 @@ type internalCode = Object
 @genType
 type rec expressionValue =
   | EvArray(array<expressionValue>)
+  | EvArrayString(array<string>)
   | EvBool(bool)
   | EvCall(string) // External function call
   | EvDistribution(DistributionTypes.genericDist)
-  | EvLambda((array<string>, internalCode))
+  | EvLambda((array<string>, record, internalCode))
   | EvNumber(float)
-  | EvRecord(Js.Dict.t<expressionValue>)
+  | EvRecord(record)
   | EvString(string)
   | EvSymbol(string)
+and record = Js.Dict.t<expressionValue>
 
 @genType
-type externalBindings = Js.Dict.t<expressionValue>
+type externalBindings = record
 @genType
 let defaultExternalBindings: externalBindings = Js.Dict.empty()
 
@@ -29,20 +31,21 @@ type functionCall = (string, array<expressionValue>)
 
 let rec toString = aValue =>
   switch aValue {
+  | EvArray(anArray) => {
+      let args = anArray->Js.Array2.map(each => toString(each))->Js.Array2.toString
+      `[${args}]`
+    }
+  | EvArrayString(anArray) => {
+      let args = anArray->Js.Array2.toString
+      `[${args}]`
+    }
   | EvBool(aBool) => Js.String.make(aBool)
   | EvCall(fName) => `:${fName}`
-  | EvLambda((parameters, _internalCode)) => `lambda(${Js.Array2.toString(parameters)}=>internal)`
+  | EvLambda((parameters, _context, _internalCode)) =>
+    `lambda(${Js.Array2.toString(parameters)}=>internal)`
   | EvNumber(aNumber) => Js.String.make(aNumber)
   | EvString(aString) => `'${aString}'`
   | EvSymbol(aString) => `:${aString}`
-  | EvArray(anArray) => {
-      let args =
-        anArray
-        ->Belt.Array.map(each => toString(each))
-        ->Extra_Array.interperse(", ")
-        ->Js.String.concatMany("")
-      `[${args}]`
-    }
   | EvRecord(aRecord) => aRecord->toStringRecord
   | EvDistribution(dist) => GenericDist.toString(dist)
   }
@@ -50,19 +53,19 @@ and toStringRecord = aRecord => {
   let pairs =
     aRecord
     ->Js.Dict.entries
-    ->Belt.Array.map(((eachKey, eachValue)) => `${eachKey}: ${toString(eachValue)}`)
-    ->Extra_Array.interperse(", ")
-    ->Js.String.concatMany("")
+    ->Js.Array2.map(((eachKey, eachValue)) => `${eachKey}: ${toString(eachValue)}`)
+    ->Js.Array2.toString
   `{${pairs}}`
 }
 
 let toStringWithType = aValue =>
   switch aValue {
   | EvArray(_) => `Array::${toString(aValue)}`
+  | EvArrayString(_) => `ArrayString::${toString(aValue)}`
   | EvBool(_) => `Bool::${toString(aValue)}`
   | EvCall(_) => `Call::${toString(aValue)}`
   | EvDistribution(_) => `Distribution::${toString(aValue)}`
-  | EvLambda((_parameters, _internalCode)) => `Lambda::${toString(aValue)}`
+  | EvLambda((_parameters, _context, _internalCode)) => `Lambda::${toString(aValue)}`
   | EvNumber(_) => `Number::${toString(aValue)}`
   | EvRecord(_) => `Record::${toString(aValue)}`
   | EvString(_) => `String::${toString(aValue)}`
@@ -70,7 +73,7 @@ let toStringWithType = aValue =>
   }
 
 let argsToString = (args: array<expressionValue>): string => {
-  args->Belt.Array.map(arg => arg->toString)->Extra_Array.interperse(", ")->Js.String.concatMany("")
+  args->Js.Array2.map(arg => arg->toString)->Js.Array2.toString
 }
 
 let toStringFunctionCall = ((fn, args)): string => `${fn}(${argsToString(args)})`