experimental: replace result with exceptions in reducer

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

@@ -17,17 +17,22 @@ let testMacro_ = (
   expectedCode: string,
 ) => {
   let bindings = Bindings.fromArray(bindArray)
-  tester(expr->T.toString, () =>
+  tester(expr->T.toString, () => {
-    expr
+    let result = switch expr
-    ->Macro.expandMacroCall(
+    ->Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(
       bindings,
       ProjectAccessorsT.identityAccessors,
       Expression.reduceExpressionInProject,
-    )
+    ) {
+      | v => Ok(v)
+      | exception Reducer_ErrorValue.ErrorException(e) => Error(e)
+    }
+
+    result
     ->ExpressionWithContext.toStringResult
     ->expect
     ->toEqual(expectedCode)
-  )
+  })
 }
 
 let testMacroEval_ = (
@@ -44,6 +49,7 @@ let testMacroEval_ = (
       ProjectAccessorsT.identityAccessors,
       Expression.reduceExpressionInProject,
     )
+    ->Ok
     ->InternalExpressionValue.toStringResult
     ->expect
     ->toEqual(expectedValue)

packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_arguments_test.res

@@ -16,7 +16,7 @@ let checkArgumentsSourceCode = (aTypeSourceCode: string, sourceCode: string): re
 > => {
   let reducerFn = Expression.reduceExpressionInProject
   let rResult =
-    Expression.BackCompatible.parse(sourceCode)->Belt.Result.flatMap(expr =>
+    Expression.BackCompatible.parse(sourceCode)->Belt.Result.map(expr =>
       reducerFn(expr, Bindings.emptyBindings, ProjectAccessorsT.identityAccessors)
     )
   rResult->Belt.Result.flatMap(result =>

packages/squiggle-lang/__tests__/Reducer/Reducer_Type/Reducer_Type_TypeChecker_test.res

@@ -19,7 +19,7 @@ let isTypeOfSourceCode = (aTypeSourceCode: string, sourceCode: string): result<
 > => {
   let reducerFn = Expression.reduceExpressionInProject
   let rResult =
-    Expression.BackCompatible.parse(sourceCode)->Belt.Result.flatMap(expr =>
+    Expression.BackCompatible.parse(sourceCode)->Belt.Result.map(expr =>
       reducerFn(expr, Bindings.emptyBindings, ProjectAccessorsT.identityAccessors)
     )
   rResult->Belt.Result.flatMap(result => TypeChecker.isTypeOf(aTypeSourceCode, result, reducerFn))

packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Danger.res

@@ -74,12 +74,11 @@ module Integration = {
           reducer,
         )
         let result = switch resultAsInternalExpression {
-        | Ok(IEvNumber(x)) => Ok(x)
+        | IEvNumber(x) => Ok(x)
-        | Error(_) =>
+        | _ =>
           Error(
             "Error 1 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead",
           )
-        | _ => Error("Error 2 in Danger.integrate")
         }
         result
       }
@@ -143,7 +142,7 @@ module Integration = {
         }
       | Error(b) =>
         Error(
-          "Integration error 3 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead." ++
+          "Integration error 2 in Danger.integrate. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead." ++
           "Original error: " ++
           b,
         )
@@ -310,15 +309,10 @@ module DiminishingReturns = {
               reducer,
             )
             switch resultAsInternalExpression {
-            | Ok(IEvNumber(x)) => Ok(x)
+            | IEvNumber(x) => Ok(x)
-            | Error(_) =>
+            | _ => Error(
-              Error(
                 "Error 1 in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions. It's possible that your function doesn't return a number, try definining auxiliaryFunction(x) = mean(yourFunction(x)) and integrate auxiliaryFunction instead",
               )
-            | _ =>
-              Error(
-                "Error 2 in Danger.optimalAllocationGivenDiminishingMarginalReturnsForManyFunctions",
-              )
             }
           }
 

packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_List.res

@@ -32,19 +32,17 @@ module Internals = {
     accessors: ProjectAccessorsT.t,
     eLambdaValue,
     reducer: ProjectReducerFnT.t,
-  ): result<ReducerInterface_InternalExpressionValue.t, Reducer_ErrorValue.errorValue> => {
+  ): ReducerInterface_InternalExpressionValue.t => {
-    let rMappedList = array->E.A.reduceReverse(Ok(list{}), (rAcc, elem) =>
+    let mappedList = array->E.A.reduceReverse(list{}, (acc, elem) => {
-      rAcc->E.R.bind(_, acc => {
+      let newElem = Reducer_Expression_Lambda.doLambdaCall(
-        let rNewElem = Reducer_Expression_Lambda.doLambdaCall(
+        eLambdaValue,
-          eLambdaValue,
+        list{elem},
-          list{elem},
+        (accessors: ProjectAccessorsT.t),
-          (accessors: ProjectAccessorsT.t),
+        (reducer: ProjectReducerFnT.t),
-          (reducer: ProjectReducerFnT.t),
+      )
-        )
+      list{newElem, ...acc}
-        rNewElem->E.R2.fmap(newElem => list{newElem, ...acc})
+  })
-      })
+    mappedList->Belt.List.toArray->Wrappers.evArray
-    )
-    rMappedList->E.R2.fmap(mappedList => mappedList->Belt.List.toArray->Wrappers.evArray)
   }
 
   let reduce = (
@@ -54,10 +52,8 @@ module Internals = {
     accessors: ProjectAccessorsT.t,
     reducer: ProjectReducerFnT.t,
   ) => {
-    aValueArray->E.A.reduce(Ok(initialValue), (rAcc, elem) =>
+    aValueArray->E.A.reduce(initialValue, (acc, elem) =>
-      rAcc->E.R.bind(_, acc =>
+      Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list{acc, elem}, accessors, reducer)
-        Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list{acc, elem}, accessors, reducer)
-      )
     )
   }
 
@@ -68,10 +64,8 @@ module Internals = {
     accessors: ProjectAccessorsT.t,
     reducer: ProjectReducerFnT.t,
   ) => {
-    aValueArray->Belt.Array.reduceReverse(Ok(initialValue), (rAcc, elem) =>
+    aValueArray->Belt.Array.reduceReverse(initialValue, (acc, elem) =>
-      rAcc->Belt.Result.flatMap(acc =>
+      Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list{acc, elem}, accessors, reducer)
-        Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list{acc, elem}, accessors, reducer)
-      )
     )
   }
 
@@ -81,25 +75,19 @@ module Internals = {
     accessors: ProjectAccessorsT.t,
     reducer: ProjectReducerFnT.t,
   ) => {
-    let rMappedList = aValueArray->Belt.Array.reduceReverse(Ok(list{}), (rAcc, elem) =>
+    let mappedList = aValueArray->Belt.Array.reduceReverse(list{}, (acc, elem) => {
-      rAcc->E.R.bind(_, acc => {
+      let newElem = Reducer_Expression_Lambda.doLambdaCall(
-        let rNewElem = Reducer_Expression_Lambda.doLambdaCall(
+        aLambdaValue,
-          aLambdaValue,
+        list{elem},
-          list{elem},
+        accessors,
-          accessors,
+        reducer,
-          reducer,
+      )
-        )
+      switch newElem {
-        rNewElem->E.R2.fmap(newElem => {
+        | IEvBool(true) => list{elem, ...acc}
-          switch newElem {
+        | _ => acc
-          | IEvBool(true) => list{elem, ...acc}
+      }
-          | _ => acc
+    })
-          }
+    mappedList->Belt.List.toArray->Wrappers.evArray
-        })
-      })
-    )
-    let result =
-      rMappedList->E.R2.fmap(mappedList => mappedList->Belt.List.toArray->Wrappers.evArray)
-    result
   }
 }
 
@@ -216,7 +204,7 @@ let library = [
         ~run=(inputs, _, accessors: ProjectAccessorsT.t, reducer) =>
           switch inputs {
           | [IEvArray(array), IEvLambda(lambda)] =>
-            Internals.map(array, accessors, lambda, reducer)->E.R2.errMap(_ => "Error!")
+            Ok(Internals.map(array, accessors, lambda, reducer))
           | _ => Error(impossibleError)
           },
         (),
@@ -236,9 +224,7 @@ let library = [
         ~run=(inputs, _, accessors: ProjectAccessorsT.t, reducer) =>
           switch inputs {
           | [IEvArray(array), initialValue, IEvLambda(lambda)] =>
-            Internals.reduce(array, initialValue, lambda, accessors, reducer)->E.R2.errMap(_ =>
+            Ok(Internals.reduce(array, initialValue, lambda, accessors, reducer))
-              "Error!"
-            )
           | _ => Error(impossibleError)
           },
         (),
@@ -258,13 +244,13 @@ let library = [
         ~run=(inputs, _, accessors: ProjectAccessorsT.t, reducer: ProjectReducerFnT.t) =>
           switch inputs {
           | [IEvArray(array), initialValue, IEvLambda(lambda)] =>
-            Internals.reduceReverse(
+            Ok(Internals.reduceReverse(
               array,
               initialValue,
               lambda,
               accessors,
               reducer,
-            )->E.R2.errMap(_ => "Error!")
+            ))
           | _ => Error(impossibleError)
           },
         (),
@@ -284,7 +270,7 @@ let library = [
         ~run=(inputs, _, accessors: ProjectAccessorsT.t, reducer: ProjectReducerFnT.t) =>
           switch inputs {
           | [IEvArray(array), IEvLambda(lambda)] =>
-            Internals.filter(array, lambda, accessors, reducer)->E.R2.errMap(_ => "Error!")
+            Ok(Internals.filter(array, lambda, accessors, reducer))
           | _ => Error(impossibleError)
           },
         (),

packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Pointset.res

@@ -37,7 +37,7 @@ module Internal = {
 
   let doLambdaCall = (aLambdaValue, list, environment, reducer) =>
     switch Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list, environment, reducer) {
-    | Ok(IEvNumber(f)) => Ok(f)
+    | IEvNumber(f) => Ok(f)
     | _ => Error(Operation.SampleMapNeedsNtoNFunction)
     }
 

packages/squiggle-lang/src/rescript/FunctionRegistry/Library/FR_Sampleset.res

@@ -16,7 +16,7 @@ module Internal = {
     reducer: ProjectReducerFnT.t,
   ) =>
     switch Reducer_Expression_Lambda.doLambdaCall(aLambdaValue, list, accessors, reducer) {
-    | Ok(IEvNumber(f)) => Ok(f)
+    | IEvNumber(f) => Ok(f)
     | _ => Error(Operation.SampleMapNeedsNtoNFunction)
     }
 

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

@@ -13,6 +13,7 @@ module TypeBuilder = Reducer_Type_TypeBuilder
 open ReducerInterface_InternalExpressionValue
 open Reducer_ErrorValue
 
+
 /*
   MathJs provides default implementations for built-ins
   This is where all the expected built-ins like + = * / sin cos log ln etc are handled
@@ -111,7 +112,7 @@ let callInternal = (
   module SampleMap = {
     let doLambdaCall = (aLambdaValue, list) =>
       switch Lambda.doLambdaCall(aLambdaValue, list, accessors, reducer) {
-      | Ok(IEvNumber(f)) => Ok(f)
+      | IEvNumber(f) => Ok(f)
       | _ => Error(Operation.SampleMapNeedsNtoNFunction)
       }
 
@@ -201,13 +202,17 @@ let dispatch = (
   call: functionCall,
   accessors: ProjectAccessorsT.t,
   reducer: ProjectReducerFnT.t,
-): result<internalExpressionValue, errorValue> =>
+): internalExpressionValue =>
   try {
     let (fn, args) = call
     // There is a bug that prevents string match in patterns
     // So we have to recreate a copy of the string
-    ExternalLibrary.dispatch((Js.String.make(fn), args), accessors, reducer, callInternal)
+    switch ExternalLibrary.dispatch((Js.String.make(fn), args), accessors, reducer, callInternal) {
+    | Ok(v) => v
+    | Error(e) => raise(ErrorException(e))
+    }
   } catch {
-  | Js.Exn.Error(obj) => REJavaScriptExn(Js.Exn.message(obj), Js.Exn.name(obj))->Error
+  | ErrorException(e) => raise(ErrorException(e))
-  | _ => RETodo("unhandled rescript exception")->Error
+  | Js.Exn.Error(obj) => raise(ErrorException(REJavaScriptExn(Js.Exn.message(obj), Js.Exn.name(obj))))
+  | _ => raise(ErrorException(RETodo("unhandled rescript exception")))
   }

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

@@ -12,11 +12,10 @@ module ExpressionWithContext = Reducer_ExpressionWithContext
 module InternalExpressionValue = ReducerInterface_InternalExpressionValue
 module ProjectAccessorsT = ReducerProject_ProjectAccessors_T
 module ProjectReducerFnT = ReducerProject_ReducerFn_T
-module Result = Belt.Result
 
 open Reducer_Expression_ExpressionBuilder
 
-type errorValue = ErrorValue.errorValue
+exception ErrorException = ErrorValue.ErrorException
 type expression = ExpressionT.expression
 type expressionWithContext = ExpressionWithContext.expressionWithContext
 
@@ -25,21 +24,18 @@ let dispatchMacroCall = (
   bindings: ExpressionT.bindings,
   accessors: ProjectAccessorsT.t,
   reduceExpression: ProjectReducerFnT.t,
-): result<expressionWithContext, errorValue> => {
+): expressionWithContext => {
   let useExpressionToSetBindings = (bindingExpr: expression, accessors, statement, newCode) => {
-    let rExternalBindingsValue = reduceExpression(bindingExpr, bindings, accessors)
+    let nameSpaceValue = reduceExpression(bindingExpr, bindings, accessors)
 
-    rExternalBindingsValue->Result.flatMap(nameSpaceValue => {
+    let newBindings = Bindings.fromExpressionValue(nameSpaceValue)
-      let newBindings = Bindings.fromExpressionValue(nameSpaceValue)
 
-      let rNewStatement = BindingsReplacer.replaceSymbols(newBindings, statement)
+    let boundStatement = BindingsReplacer.replaceSymbols(newBindings, statement)
-      rNewStatement->Result.map(boundStatement =>
+
-        ExpressionWithContext.withContext(
+    ExpressionWithContext.withContext(
-          newCode(newBindings->eModule, boundStatement),
+      newCode(newBindings->eModule, boundStatement),
-          newBindings,
+      newBindings,
-        )
+    )
-      )
-    })
   }
 
   let correspondingSetBindingsFn = (fnName: string): string =>
@@ -52,7 +48,7 @@ let dispatchMacroCall = (
     }
 
   let doBindStatement = (bindingExpr: expression, statement: expression, accessors) => {
-    let defaultStatement = ErrorValue.REAssignmentExpected->Error
+    let defaultStatement = ErrorValue.REAssignmentExpected->ErrorException
     switch statement {
     | ExpressionT.EList(list{ExpressionT.EValue(IEvCall(callName)), symbolExpr, statement}) => {
         let setBindingsFn = correspondingSetBindingsFn(callName)
@@ -62,17 +58,14 @@ let dispatchMacroCall = (
             boundStatement,
           ) => eFunction(setBindingsFn, list{newBindingsExpr, symbolExpr, boundStatement}))
         } else {
-          defaultStatement
+          raise(defaultStatement)
         }
       }
-    | _ => defaultStatement
+    | _ => raise(defaultStatement)
     }
   }
 
-  let doBindExpression = (bindingExpr: expression, statement: expression, accessors): result<
+  let doBindExpression = (bindingExpr: expression, statement: expression, accessors): expressionWithContext => {
-    expressionWithContext,
-    errorValue,
-  > => {
     let defaultStatement = () =>
       useExpressionToSetBindings(bindingExpr, accessors, statement, (
         _newBindingsExpr,
@@ -100,10 +93,7 @@ let dispatchMacroCall = (
     }
   }
 
-  let doBlock = (exprs: list<expression>, _bindings: ExpressionT.bindings, _accessors): result<
+  let doBlock = (exprs: list<expression>, _bindings: ExpressionT.bindings, _accessors): expressionWithContext => {
-    expressionWithContext,
-    errorValue,
-  > => {
     let exprsArray = Belt.List.toArray(exprs)
     let maxIndex = Js.Array2.length(exprsArray) - 1
     let newStatement = exprsArray->Js.Array2.reducei((acc, statement, index) =>
@@ -119,14 +109,14 @@ let dispatchMacroCall = (
         eBindStatement(acc, statement)
       }
     , eSymbol("undefined block"))
-    ExpressionWithContext.noContext(newStatement)->Ok
+    ExpressionWithContext.noContext(newStatement)
   }
 
   let doLambdaDefinition = (
     bindings: ExpressionT.bindings,
     parameters: array<string>,
     lambdaDefinition: ExpressionT.expression,
-  ) => ExpressionWithContext.noContext(eLambda(parameters, bindings, lambdaDefinition))->Ok
+  ) => ExpressionWithContext.noContext(eLambda(parameters, bindings, lambdaDefinition))
 
   let doTernary = (
     condition: expression,
@@ -134,28 +124,25 @@ let dispatchMacroCall = (
     ifFalse: expression,
     bindings: ExpressionT.bindings,
     accessors,
-  ): result<expressionWithContext, errorValue> => {
+  ): expressionWithContext => {
     let blockCondition = ExpressionBuilder.eBlock(list{condition})
-    let rCondition = reduceExpression(blockCondition, bindings, accessors)
+    let conditionValue = reduceExpression(blockCondition, bindings, accessors)
-    rCondition->Result.flatMap(conditionValue =>
+
-      switch conditionValue {
+    switch conditionValue {
-      | InternalExpressionValue.IEvBool(false) => {
+    | InternalExpressionValue.IEvBool(false) => {
-          let ifFalseBlock = eBlock(list{ifFalse})
+        let ifFalseBlock = eBlock(list{ifFalse})
-          ExpressionWithContext.withContext(ifFalseBlock, bindings)->Ok
+        ExpressionWithContext.withContext(ifFalseBlock, bindings)
-        }
-      | InternalExpressionValue.IEvBool(true) => {
-          let ifTrueBlock = eBlock(list{ifTrue})
-          ExpressionWithContext.withContext(ifTrueBlock, bindings)->Ok
-        }
-      | _ => REExpectedType("Boolean", "")->Error
       }
-    )
+    | InternalExpressionValue.IEvBool(true) => {
+        let ifTrueBlock = eBlock(list{ifTrue})
+        ExpressionWithContext.withContext(ifTrueBlock, bindings)
+      }
+    | _ => raise(ErrorException(REExpectedType("Boolean", "")))
+    }
   }
 
-  let expandExpressionList = (aList, bindings: ExpressionT.bindings, accessors): result<
+  let expandExpressionList = (aList, bindings: ExpressionT.bindings, accessors): expressionWithContext
-    expressionWithContext,
+   =>
-    errorValue,
-  > =>
     switch aList {
     | list{
         ExpressionT.EValue(IEvCall("$$_bindStatement_$$")),
@@ -185,11 +172,11 @@ let dispatchMacroCall = (
       doLambdaDefinition(bindings, parameters, lambdaDefinition)
     | list{ExpressionT.EValue(IEvCall("$$_ternary_$$")), condition, ifTrue, ifFalse} =>
       doTernary(condition, ifTrue, ifFalse, bindings, accessors)
-    | _ => ExpressionWithContext.noContext(ExpressionT.EList(aList))->Ok
+    | _ => ExpressionWithContext.noContext(ExpressionT.EList(aList))
     }
 
   switch macroExpression {
   | EList(aList) => expandExpressionList(aList, bindings, accessors)
-  | _ => ExpressionWithContext.noContext(macroExpression)->Ok
+  | _ => ExpressionWithContext.noContext(macroExpression)
   }
 }

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

@@ -26,6 +26,8 @@ type errorValue =
 
 type t = errorValue
 
+exception ErrorException(errorValue)
+
 let errorToString = err =>
   switch err {
   | REArityError(_oFnName, arity, usedArity) =>

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

@@ -14,6 +14,8 @@ module T = Reducer_Expression_T
 type errorValue = Reducer_ErrorValue.errorValue
 type t = T.t
 
+exception ErrorException = Reducer_ErrorValue.ErrorException
+
 /*
   Recursively evaluate/reduce the expression (Lisp AST/Lambda calculus)
 */
@@ -21,10 +23,10 @@ let rec reduceExpressionInProject = (
   expression: t,
   continuation: T.bindings,
   accessors: ProjectAccessorsT.t,
-): result<InternalExpressionValue.t, 'e> => {
+): InternalExpressionValue.t => {
   // Js.log(`reduce: ${T.toString(expression)} bindings: ${bindings->Bindings.toString}`)
   switch expression {
-  | T.EValue(value) => value->Ok
+  | T.EValue(value) => value
   | T.EList(list) =>
     switch list {
     | list{EValue(IEvCall(fName)), ..._args} =>
@@ -41,20 +43,13 @@ and reduceExpressionList = (
   expressions: list<t>,
   continuation: T.bindings,
   accessors: ProjectAccessorsT.t,
-): result<InternalExpressionValue.t, 'e> => {
+): InternalExpressionValue.t => {
-  let racc: result<
+  let acc: list<InternalExpressionValue.t> = expressions->Belt.List.reduceReverse(list{}, (acc, each: t) =>
-    list<InternalExpressionValue.t>,
+    acc->Belt.List.add(
-    'e,
+      each->reduceExpressionInProject(continuation, accessors)
-  > = expressions->Belt.List.reduceReverse(Ok(list{}), (racc, each: t) =>
+    )
-    racc->Result.flatMap(acc => {
-      each
-      ->reduceExpressionInProject(continuation, accessors)
-      ->Result.map(newNode => {
-        acc->Belt.List.add(newNode)
-      })
-    })
   )
-  racc->Result.flatMap(acc => acc->reduceValueList(accessors))
+  acc->reduceValueList(accessors)
 }
 
 /*
@@ -63,48 +58,39 @@ and reduceExpressionList = (
 and reduceValueList = (
   valueList: list<InternalExpressionValue.t>,
   accessors: ProjectAccessorsT.t,
-): result<InternalExpressionValue.t, 'e> =>
+): InternalExpressionValue.t =>
   switch valueList {
   | list{IEvCall(fName), ...args} => {
-      let rCheckedArgs = switch fName {
+      let checkedArgs = switch fName {
-      | "$_setBindings_$" | "$_setTypeOfBindings_$" | "$_setTypeAliasBindings_$" => args->Ok
+      | "$_setBindings_$" | "$_setTypeOfBindings_$" | "$_setTypeAliasBindings_$" => args
       | _ => args->Lambda.checkIfReduced
       }
 
-      rCheckedArgs->Result.flatMap(checkedArgs =>
+      (fName, checkedArgs->Belt.List.toArray)->BuiltIn.dispatch(
-        (fName, checkedArgs->Belt.List.toArray)->BuiltIn.dispatch(
+        accessors,
-          accessors,
+        reduceExpressionInProject,
-          reduceExpressionInProject,
-        )
       )
     }
   | list{IEvLambda(_)} =>
     // TODO: remove on solving issue#558
     valueList
     ->Lambda.checkIfReduced
-    ->Result.flatMap(reducedValueList =>
+    ->Belt.List.toArray->InternalExpressionValue.IEvArray
-      reducedValueList->Belt.List.toArray->InternalExpressionValue.IEvArray->Ok
-    )
   | list{IEvLambda(lambdaCall), ...args} =>
     args
     ->Lambda.checkIfReduced
-    ->Result.flatMap(checkedArgs =>
+    ->Lambda.doLambdaCall(lambdaCall, _, accessors, reduceExpressionInProject)
-      Lambda.doLambdaCall(lambdaCall, checkedArgs, accessors, reduceExpressionInProject)
-    )
-
   | _ =>
     valueList
     ->Lambda.checkIfReduced
-    ->Result.flatMap(reducedValueList =>
+    ->Belt.List.toArray->InternalExpressionValue.IEvArray
-      reducedValueList->Belt.List.toArray->InternalExpressionValue.IEvArray->Ok
-    )
   }
 
 let reduceReturningBindings = (
   expression: t,
   continuation: T.bindings,
   accessors: ProjectAccessorsT.t,
-): (result<InternalExpressionValue.t, 'e>, T.bindings) => {
+): (InternalExpressionValue.t, T.bindings) => {
   let states = accessors.states
   let result = reduceExpressionInProject(expression, continuation, accessors)
   (result, states.continuation)
@@ -118,7 +104,12 @@ module BackCompatible = {
 
   let evaluate = (expression: t): result<InternalExpressionValue.t, errorValue> => {
     let accessors = ProjectAccessorsT.identityAccessors
-    expression->reduceExpressionInProject(accessors.stdLib, accessors)
+    try {
+      expression->reduceExpressionInProject(accessors.stdLib, accessors)->Ok
+    } catch {
+    | ErrorException(e) => Error(e)
+    | _ => raise(ErrorException(RETodo("internal exception")))
+    }
   }
 
   let evaluateString = (peggyCode: string): result<InternalExpressionValue.t, errorValue> =>

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

@@ -23,7 +23,7 @@ let callReducer = (
   bindings: bindings,
   accessors: ProjectAccessorsT.t,
   reducer: ProjectReducerFnT.t,
-): result<internalExpressionValue, errorValue> => {
+): internalExpressionValue => {
   switch expressionWithContext {
   | ExpressionNoContext(expr) =>
     // Js.log(`callReducer: bindings ${Bindings.toString(bindings)} expr ${ExpressionT.toString(expr)}`)

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

@@ -1,7 +1,6 @@
 module ErrorValue = Reducer_ErrorValue
 module ExpressionT = Reducer_Expression_T
 module InternalExpressionValue = ReducerInterface_InternalExpressionValue
-module Result = Belt.Result
 module Bindings = Reducer_Bindings
 
 type errorValue = Reducer_ErrorValue.errorValue
@@ -10,19 +9,16 @@ type internalExpressionValue = InternalExpressionValue.t
 
 let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")
 
-let rec replaceSymbols = (bindings: ExpressionT.bindings, expression: expression): result<
+let rec replaceSymbols = (bindings: ExpressionT.bindings, expression: expression): expression =>
-  expression,
-  errorValue,
-> =>
   switch expression {
   | ExpressionT.EValue(value) =>
-    replaceSymbolOnValue(bindings, value)->Result.map(evValue => evValue->ExpressionT.EValue)
+    replaceSymbolOnValue(bindings, value)->ExpressionT.EValue
   | ExpressionT.EList(list) =>
     switch list {
     | list{EValue(IEvCall(fName)), ..._args} =>
       switch isMacroName(fName) {
       // A macro reduces itself so we dont dive in it
-      | true => expression->Ok
+      | true => expression
       | false => replaceSymbolsOnExpressionList(bindings, list)
       }
     | _ => replaceSymbolsOnExpressionList(bindings, list)
@@ -30,23 +26,19 @@ let rec replaceSymbols = (bindings: ExpressionT.bindings, expression: expression
   }
 
 and replaceSymbolsOnExpressionList = (bindings, list) => {
-  let racc = list->Belt.List.reduceReverse(Ok(list{}), (racc, each: expression) =>
+  let racc = list->Belt.List.reduceReverse(list{}, (acc, each: expression) =>
-    racc->Result.flatMap(acc => {
+    replaceSymbols(bindings, each)->Belt.List.add(acc, _)
-      replaceSymbols(bindings, each)->Result.flatMap(newNode => {
-        acc->Belt.List.add(newNode)->Ok
-      })
-    })
   )
-  racc->Result.map(acc => acc->ExpressionT.EList)
+  ExpressionT.EList(racc)
 }
 and replaceSymbolOnValue = (bindings, evValue: internalExpressionValue) =>
   switch evValue {
-  | IEvSymbol(symbol) => Bindings.getWithDefault(bindings, symbol, evValue)->Ok
+  | IEvSymbol(symbol) => Bindings.getWithDefault(bindings, symbol, evValue)
   | IEvCall(symbol) => Bindings.getWithDefault(bindings, symbol, evValue)->checkIfCallable
-  | _ => evValue->Ok
+  | _ => evValue
   }
 and checkIfCallable = (evValue: internalExpressionValue) =>
   switch evValue {
-  | IEvCall(_) | IEvLambda(_) => evValue->Ok
+  | IEvCall(_) | IEvLambda(_) => evValue
-  | _ => ErrorValue.RENotAFunction(InternalExpressionValue.toString(evValue))->Error
+  | _ => raise(ErrorValue.ErrorException(ErrorValue.RENotAFunction(InternalExpressionValue.toString(evValue))))
   }

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

@@ -23,26 +23,24 @@ let checkArity = (
     let argsLength = Belt.List.length(args)
     let parametersLength = Js.Array2.length(lambdaValue.parameters)
     if argsLength !== parametersLength {
-      ErrorValue.REArityError(None, parametersLength, argsLength)->Error
+      raise(ErrorValue.ErrorException(ErrorValue.REArityError(None, parametersLength, argsLength)))
     } else {
-      args->Ok
+      args
     }
   }
   let exprOrFFI = castInternalCodeToExpression(lambdaValue.body)
   switch exprOrFFI {
   | NotFFI(_) => reallyCheck
-  | FFI(_) => args->Ok
+  | FFI(_) => args
   }
 }
 
 let checkIfReduced = (args: list<internalExpressionValue>) =>
-  args->Belt.List.reduceReverse(Ok(list{}), (rAcc, arg) =>
+  args->Belt.List.reduceReverse(list{}, (acc, arg) =>
-    rAcc->Result.flatMap(acc =>
       switch arg {
-      | IEvSymbol(symbol) => ErrorValue.RESymbolNotFound(symbol)->Error
+      | IEvSymbol(symbol) => raise(ErrorValue.ErrorException(ErrorValue.RESymbolNotFound(symbol)))
-      | _ => list{arg, ...acc}->Ok
+      | _ => list{arg, ...acc}
       }
-    )
   )
 
 let caseNotFFI = (
@@ -63,7 +61,10 @@ let caseNotFFI = (
 }
 
 let caseFFI = (ffiFn: ExpressionT.ffiFn, args, accessors: ProjectAccessorsT.t) => {
-  ffiFn(args->Belt.List.toArray, accessors.environment)
+  switch ffiFn(args->Belt.List.toArray, accessors.environment) {
+    | Ok(value) => value
+    | Error(value) => raise(ErrorValue.ErrorException(value))
+  }
 }
 
 let applyParametersToLambda = (
@@ -71,16 +72,13 @@ let applyParametersToLambda = (
   args,
   accessors: ProjectAccessorsT.t,
   reducer: ProjectReducerFnT.t,
-): result<internalExpressionValue, 'e> => {
+): internalExpressionValue => {
-  checkArity(lambdaValue, args)->Result.flatMap(args =>
+  let args = checkArity(lambdaValue, args)->checkIfReduced
-    checkIfReduced(args)->Result.flatMap(args => {
+  let exprOrFFI = castInternalCodeToExpression(lambdaValue.body)
-      let exprOrFFI = castInternalCodeToExpression(lambdaValue.body)
+  switch exprOrFFI {
-      switch exprOrFFI {
+  | NotFFI(expr) => caseNotFFI(lambdaValue, expr, args, accessors, reducer)
-      | NotFFI(expr) => caseNotFFI(lambdaValue, expr, args, accessors, reducer)
+  | FFI(ffiFn) => caseFFI(ffiFn, args, accessors)
-      | FFI(ffiFn) => caseFFI(ffiFn, args, accessors)
+  }
-      }
-    })
-  )
 }
 
 let doLambdaCall = (
@@ -95,7 +93,7 @@ let foreignFunctionInterface = (
   argArray: array<internalExpressionValue>,
   accessors: ProjectAccessorsT.t,
   reducer: ProjectReducerFnT.t,
-): result<internalExpressionValue, Reducer_ErrorValue.errorValue> => {
+): internalExpressionValue => {
   let args = argArray->Belt.List.fromArray
   applyParametersToLambda(lambdaValue, args, accessors, reducer)
 }

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

@@ -10,32 +10,17 @@ type expression = ExpressionT.expression
 type internalExpressionValue = InternalExpressionValue.t
 type expressionWithContext = ExpressionWithContext.expressionWithContext
 
-let expandMacroCall = (
-  macroExpression: expression,
-  bindings: ExpressionT.bindings,
-  accessors: ProjectAccessorsT.t,
-  reduceExpression: ProjectReducerFnT.t,
-): result<expressionWithContext, 'e> =>
-  Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(
-    macroExpression,
-    bindings,
-    accessors,
-    reduceExpression,
-  )
-
 let doMacroCall = (
   macroExpression: expression,
   bindings: ExpressionT.bindings,
   accessors: ProjectAccessorsT.t,
   reduceExpression: ProjectReducerFnT.t,
-): result<internalExpressionValue, 'e> =>
+): internalExpressionValue =>
-  expandMacroCall(
+  Reducer_Dispatch_BuiltInMacros.dispatchMacroCall(
     macroExpression,
     bindings,
     (accessors: ProjectAccessorsT.t),
     (reduceExpression: ProjectReducerFnT.t),
-  )->Result.flatMap(expressionWithContext =>
+  )->ExpressionWithContext.callReducer(bindings, accessors, reduceExpression)
-    ExpressionWithContext.callReducer(expressionWithContext, bindings, accessors, reduceExpression)
-  )
 
 let isMacroName = (fName: string): bool => fName->Js.String2.startsWith("$$")

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

@@ -18,13 +18,9 @@ let ievFromTypeExpression = (
     let result = reducerFn(expr, Bindings.emptyBindings, accessors)
     let nameSpace = accessors.states.continuation
 
-    switch result {
+    switch Bindings.getType(nameSpace, sIndex) {
-    | Ok(_) =>
+    | Some(value) => value->Ok
-      switch Bindings.getType(nameSpace, sIndex) {
+    | None => raise(Reducer_Exception.ImpossibleException("Reducer_Type_Compile-none"))
-      | Some(value) => value->Ok
-      | None => raise(Reducer_Exception.ImpossibleException("Reducer_Type_Compile-none"))
-      }
-    | err => err
     }
   })
 }

packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ProjectItem.res

@@ -183,16 +183,16 @@ let buildExpression = (this: t): t => {
   }
 }
 
-let wrappedReducer = (
+// let wrappedReducer = (
-  rExpression: T.expressionArgumentType,
+//   rExpression: T.expressionArgumentType,
-  aContinuation: T.continuation,
+//   aContinuation: T.continuation,
-  accessors: ProjectAccessorsT.t,
+//   accessors: ProjectAccessorsT.t,
-): T.resultArgumentType => {
+// ): T.resultArgumentType => {
-  Belt.Result.flatMap(
+//   Belt.Result.flatMap(
-    rExpression,
+//     rExpression,
-    Reducer_Expression.reduceExpressionInProject(_, aContinuation, accessors),
+//     Reducer_Expression.reduceExpressionInProject(_, aContinuation, accessors),
-  )
+//   )
-}
+// }
 
 let doBuildResult = (
   this: t,
@@ -204,7 +204,13 @@ let doBuildResult = (
   ->Belt.Option.map(
     Belt.Result.flatMap(
       _,
-      Reducer_Expression.reduceExpressionInProject(_, aContinuation, accessors),
+      expression =>
+      try {
+        Reducer_Expression.reduceExpressionInProject(expression, aContinuation, accessors)->Ok
+      } catch {
+      | Reducer_ErrorValue.ErrorException(e) => e->Error
+      | _ => RETodo("unhandled rescript exception")->Error
+      }
     ),
   )
 

packages/squiggle-lang/src/rescript/ReducerProject/ReducerProject_ReducerFn_T.res

@@ -6,4 +6,4 @@ type t = (
   ExpressionT.t,
   ExpressionT.bindings,
   ProjectAccessorsT.t,
-) => result<InternalExpressionValue.t, Reducer_ErrorValue.errorValue>
+) => InternalExpressionValue.t