diff --git a/packages/squiggle-lang/__tests__/Distributions/DistributionOperation_test.res b/packages/squiggle-lang/__tests__/Distributions/DistributionOperation_test.res
index 078cad05..60e74d74 100644
--- a/packages/squiggle-lang/__tests__/Distributions/DistributionOperation_test.res
+++ b/packages/squiggle-lang/__tests__/Distributions/DistributionOperation_test.res
@@ -30,7 +30,7 @@ let toExt: option<'a> => 'a = E.O.toExt(
 describe("sparkline", () => {
   let runTest = (
     name: string,
-    dist: GenericDist_Types.genericDist,
+    dist: DistributionTypes.genericDist,
     expected: DistributionOperation.outputType,
   ) => {
     test(name, () => {
diff --git a/packages/squiggle-lang/__tests__/Distributions/GenericDist_Fixtures.res b/packages/squiggle-lang/__tests__/Distributions/GenericDist_Fixtures.res
index a967b924..4d41930f 100644
--- a/packages/squiggle-lang/__tests__/Distributions/GenericDist_Fixtures.res
+++ b/packages/squiggle-lang/__tests__/Distributions/GenericDist_Fixtures.res
@@ -1,14 +1,14 @@
-let normalDist5: GenericDist_Types.genericDist = Symbolic(#Normal({mean: 5.0, stdev: 2.0}))
-let normalDist10: GenericDist_Types.genericDist = Symbolic(#Normal({mean: 10.0, stdev: 2.0}))
-let normalDist20: GenericDist_Types.genericDist = Symbolic(#Normal({mean: 20.0, stdev: 2.0}))
-let normalDist: GenericDist_Types.genericDist = normalDist5
+let normalDist5: DistributionTypes.genericDist = Symbolic(#Normal({mean: 5.0, stdev: 2.0}))
+let normalDist10: DistributionTypes.genericDist = Symbolic(#Normal({mean: 10.0, stdev: 2.0}))
+let normalDist20: DistributionTypes.genericDist = Symbolic(#Normal({mean: 20.0, stdev: 2.0}))
+let normalDist: DistributionTypes.genericDist = normalDist5
 
-let betaDist: GenericDist_Types.genericDist = Symbolic(#Beta({alpha: 2.0, beta: 5.0}))
-let lognormalDist: GenericDist_Types.genericDist = Symbolic(#Lognormal({mu: 0.0, sigma: 1.0}))
-let cauchyDist: GenericDist_Types.genericDist = Symbolic(#Cauchy({local: 1.0, scale: 1.0}))
-let triangularDist: GenericDist_Types.genericDist = Symbolic(
+let betaDist: DistributionTypes.genericDist = Symbolic(#Beta({alpha: 2.0, beta: 5.0}))
+let lognormalDist: DistributionTypes.genericDist = Symbolic(#Lognormal({mu: 0.0, sigma: 1.0}))
+let cauchyDist: DistributionTypes.genericDist = Symbolic(#Cauchy({local: 1.0, scale: 1.0}))
+let triangularDist: DistributionTypes.genericDist = Symbolic(
   #Triangular({low: 1.0, medium: 2.0, high: 3.0}),
 )
-let exponentialDist: GenericDist_Types.genericDist = Symbolic(#Exponential({rate: 2.0}))
-let uniformDist: GenericDist_Types.genericDist = Symbolic(#Uniform({low: 9.0, high: 10.0}))
-let floatDist: GenericDist_Types.genericDist = Symbolic(#Float(1e1))
+let exponentialDist: DistributionTypes.genericDist = Symbolic(#Exponential({rate: 2.0}))
+let uniformDist: DistributionTypes.genericDist = Symbolic(#Uniform({low: 9.0, high: 10.0}))
+let floatDist: DistributionTypes.genericDist = Symbolic(#Float(1e1))
diff --git a/packages/squiggle-lang/__tests__/Distributions/Invariants/AlgebraicCombination_test.res b/packages/squiggle-lang/__tests__/Distributions/Invariants/AlgebraicCombination_test.res
index c7e0ac46..718a4e14 100644
--- a/packages/squiggle-lang/__tests__/Distributions/Invariants/AlgebraicCombination_test.res
+++ b/packages/squiggle-lang/__tests__/Distributions/Invariants/AlgebraicCombination_test.res
@@ -43,7 +43,7 @@ describe("(Algebraic) addition of distributions", () => {
     test("normal(mean=5) + normal(mean=20)", () => {
       normalDist5
       ->algebraicAdd(normalDist20)
-      ->E.R2.fmap(GenericDist_Types.Constructors.UsingDists.mean)
+      ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
       ->E.R2.fmap(run)
       ->E.R2.fmap(toFloat)
       ->E.R.toExn
@@ -57,7 +57,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         uniformDist
         ->algebraicAdd(betaDist)
-        ->E.R2.fmap(GenericDist_Types.Constructors.UsingDists.mean)
+        ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -74,7 +74,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         betaDist
         ->algebraicAdd(uniformDist)
-        ->E.R2.fmap(GenericDist_Types.Constructors.UsingDists.mean)
+        ->E.R2.fmap(DistributionTypes.Constructors.UsingDists.mean)
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -95,7 +95,7 @@ describe("(Algebraic) addition of distributions", () => {
         let received =
           normalDist10 // this should be normal(10, sqrt(8))
           ->Ok
-          ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, x))
+          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, x))
           ->E.R2.fmap(run)
           ->E.R2.fmap(toFloat)
           ->E.R.toOption
@@ -103,7 +103,7 @@ describe("(Algebraic) addition of distributions", () => {
         let calculated =
           normalDist5
           ->algebraicAdd(normalDist5)
-          ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, x))
+          ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, x))
           ->E.R2.fmap(run)
           ->E.R2.fmap(toFloat)
           ->E.R.toOption
@@ -126,7 +126,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         normalDist20
         ->Ok
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, 1.9e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -134,7 +134,7 @@ describe("(Algebraic) addition of distributions", () => {
       let calculated =
         normalDist10
         ->algebraicAdd(normalDist10)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, 1.9e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1.9e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -155,7 +155,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         uniformDist
         ->algebraicAdd(betaDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, 1e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -170,7 +170,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         betaDist
         ->algebraicAdd(uniformDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.pdf(d, 1e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.pdf(d, 1e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -187,7 +187,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         normalDist10
         ->Ok
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, x))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -195,7 +195,7 @@ describe("(Algebraic) addition of distributions", () => {
       let calculated =
         normalDist5
         ->algebraicAdd(normalDist5)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, x))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, x))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -217,7 +217,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         normalDist20
         ->Ok
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, 1.25e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -225,7 +225,7 @@ describe("(Algebraic) addition of distributions", () => {
       let calculated =
         normalDist10
         ->algebraicAdd(normalDist10)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, 1.25e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1.25e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -246,7 +246,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         uniformDist
         ->algebraicAdd(betaDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, 1e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -261,7 +261,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         betaDist
         ->algebraicAdd(uniformDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.cdf(d, 1e1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.cdf(d, 1e1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -279,7 +279,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         normalDist10
         ->Ok
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, x))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -287,7 +287,7 @@ describe("(Algebraic) addition of distributions", () => {
       let calculated =
         normalDist5
         ->algebraicAdd(normalDist5)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, x))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, x))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -309,7 +309,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         normalDist20
         ->Ok
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, 1e-1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -317,7 +317,7 @@ describe("(Algebraic) addition of distributions", () => {
       let calculated =
         normalDist10
         ->algebraicAdd(normalDist10)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, 1e-1))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 1e-1))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toOption
@@ -338,7 +338,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         uniformDist
         ->algebraicAdd(betaDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, 2e-2))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
@@ -353,7 +353,7 @@ describe("(Algebraic) addition of distributions", () => {
       let received =
         betaDist
         ->algebraicAdd(uniformDist)
-        ->E.R2.fmap(d => GenericDist_Types.Constructors.UsingDists.inv(d, 2e-2))
+        ->E.R2.fmap(d => DistributionTypes.Constructors.UsingDists.inv(d, 2e-2))
         ->E.R2.fmap(run)
         ->E.R2.fmap(toFloat)
         ->E.R.toExn
diff --git a/packages/squiggle-lang/__tests__/Distributions/Invariants/Means_test.res b/packages/squiggle-lang/__tests__/Distributions/Invariants/Means_test.res
index bcc461bc..3806c7f9 100644
--- a/packages/squiggle-lang/__tests__/Distributions/Invariants/Means_test.res
+++ b/packages/squiggle-lang/__tests__/Distributions/Invariants/Means_test.res
@@ -15,7 +15,7 @@ open TestHelpers
 module Internals = {
   let epsilon = 5e1
 
-  let mean = GenericDist_Types.Constructors.UsingDists.mean
+  let mean = DistributionTypes.Constructors.UsingDists.mean
 
   let expectImpossiblePath: string => assertion = algebraicOp =>
     `${algebraicOp} has`->expect->toEqual("failed")
diff --git a/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res b/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
index d3defb40..65a76b88 100644
--- a/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
+++ b/packages/squiggle-lang/__tests__/ReducerInterface/ReducerInterface_Distribution_test.res
@@ -22,7 +22,7 @@ describe("eval on distribution functions", () => {
     testEval("mean(-normal(5,2))", "Ok(-5)")
   })
   describe("to", () => {
-    testEval("5 to 2", "Error(TODO: Low value must be less than high value.)")
+    testEval("5 to 2", "Error(Math Error: Low value must be less than high value.)")
     testEval("to(2,5)", "Ok(Lognormal(1.1512925464970227,0.27853260523016377))")
     testEval("to(-2,2)", "Ok(Normal(0,1.2159136638235384))")
   })
@@ -88,8 +88,14 @@ describe("eval on distribution functions", () => {
 
   describe("log", () => {
     testEval("log(2, uniform(5,8))", "Ok(Sample Set Distribution)")
-    testEval("log(normal(5,2), 3)", "Ok(Sample Set Distribution)")
-    testEval("log(normal(5,2), normal(10,1))", "Ok(Sample Set Distribution)")
+    testEval(
+      "log(normal(5,2), 3)",
+      "Error(Math Error: Operation Error: Operation returned complex result)",
+    )
+    testEval(
+      "log(normal(5,2), normal(10,1))",
+      "Error(Math Error: Operation Error: Operation returned complex result)",
+    )
     testEval("log(uniform(5,8))", "Ok(Sample Set Distribution)")
     testEval("log10(uniform(5,8))", "Ok(Sample Set Distribution)")
   })
diff --git a/packages/squiggle-lang/__tests__/TS/Symbolic_test.ts b/packages/squiggle-lang/__tests__/TS/Symbolic_test.ts
index 71d87642..1bcb1e2e 100644
--- a/packages/squiggle-lang/__tests__/TS/Symbolic_test.ts
+++ b/packages/squiggle-lang/__tests__/TS/Symbolic_test.ts
@@ -12,7 +12,7 @@ describe("Symbolic mean", () => {
             expect(squiggleResult.value).toBeCloseTo((x + y + z) / 3);
           } catch (err) {
             expect((err as Error).message).toEqual(
-              "Expected squiggle expression to evaluate but got error: TODO: Triangular values must be increasing order."
+              "Expected squiggle expression to evaluate but got error: Math Error: Triangular values must be increasing order."
             );
           }
         }
diff --git a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res
index 44584791..77d6acc5 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res
@@ -1,4 +1,4 @@
-type functionCallInfo = GenericDist_Types.Operation.genericFunctionCallInfo
+type functionCallInfo = DistributionTypes.DistributionOperation.genericFunctionCallInfo
 type genericDist = DistributionTypes.genericDist
 type error = DistributionTypes.error
 
@@ -120,7 +120,10 @@ let rec run = (~env, functionCallInfo: functionCallInfo): outputType => {
       (),
     )->OutputLocal.toDistR
 
-  let fromDistFn = (subFnName: GenericDist_Types.Operation.fromDist, dist: genericDist) => {
+  let fromDistFn = (
+    subFnName: DistributionTypes.DistributionOperation.fromDist,
+    dist: genericDist,
+  ) => {
     let response = switch subFnName {
     | ToFloat(distToFloatOperation) =>
       GenericDist.toFloatOperation(dist, ~toPointSetFn, ~distToFloatOperation)
@@ -162,9 +165,9 @@ let rec run = (~env, functionCallInfo: functionCallInfo): outputType => {
       ->GenericDist.pointwiseCombination(~toPointSetFn, ~arithmeticOperation, ~t2)
       ->E.R2.fmap(r => Dist(r))
       ->OutputLocal.fromResult
-    | ToDistCombination(Pointwise, arithmeticOperation, #Float(float)) =>
+    | ToDistCombination(Pointwise, arithmeticOperation, #Float(f)) =>
       dist
-      ->GenericDist.pointwiseCombinationFloat(~toPointSetFn, ~arithmeticOperation, ~float)
+      ->GenericDist.pointwiseCombinationFloat(~toPointSetFn, ~arithmeticOperation, ~f)
       ->E.R2.fmap(r => Dist(r))
       ->OutputLocal.fromResult
     }
@@ -192,7 +195,7 @@ module Output = {
   let fmap = (
     ~env,
     input: outputType,
-    functionCallInfo: GenericDist_Types.Operation.singleParamaterFunction,
+    functionCallInfo: DistributionTypes.DistributionOperation.singleParamaterFunction,
   ): outputType => {
     let newFnCall: result<functionCallInfo, error> = switch (functionCallInfo, input) {
     | (FromDist(fromDist), Dist(o)) => Ok(FromDist(fromDist, o))
@@ -205,11 +208,11 @@ module Output = {
   }
 }
 
-// See comment above GenericDist_Types.Constructors to explain the purpose of this module.
+// See comment above DistributionTypes.Constructors to explain the purpose of this module.
 // I tried having another internal module called UsingDists, similar to how its done in
-// GenericDist_Types.Constructors. However, this broke GenType for me, so beware.
+// DistributionTypes.Constructors. However, this broke GenType for me, so beware.
 module Constructors = {
-  module C = GenericDist_Types.Constructors.UsingDists
+  module C = DistributionTypes.Constructors.UsingDists
   open OutputLocal
   let mean = (~env, dist) => C.mean(dist)->run(~env)->toFloatR
   let sample = (~env, dist) => C.sample(dist)->run(~env)->toFloatR
diff --git a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi
index 9b21a04e..5ad34354 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.resi
@@ -4,7 +4,7 @@ type env = {
   xyPointLength: int,
 }
 
-open GenericDist_Types
+open DistributionTypes
 
 @genType
 type outputType =
@@ -15,15 +15,15 @@ type outputType =
   | GenDistError(error)
 
 @genType
-let run: (~env: env, GenericDist_Types.Operation.genericFunctionCallInfo) => outputType
+let run: (~env: env, DistributionTypes.DistributionOperation.genericFunctionCallInfo) => outputType
 let runFromDist: (
   ~env: env,
-  ~functionCallInfo: GenericDist_Types.Operation.fromDist,
+  ~functionCallInfo: DistributionTypes.DistributionOperation.fromDist,
   genericDist,
 ) => outputType
 let runFromFloat: (
   ~env: env,
-  ~functionCallInfo: GenericDist_Types.Operation.fromDist,
+  ~functionCallInfo: DistributionTypes.DistributionOperation.fromDist,
   float,
 ) => outputType
 
@@ -38,7 +38,7 @@ module Output: {
   let toBool: t => option<bool>
   let toBoolR: t => result<bool, error>
   let toError: t => option<error>
-  let fmap: (~env: env, t, GenericDist_Types.Operation.singleParamaterFunction) => t
+  let fmap: (~env: env, t, DistributionTypes.DistributionOperation.singleParamaterFunction) => t
 }
 
 module Constructors: {
diff --git a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
index 4082cb6e..b171fa95 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
@@ -9,9 +9,43 @@ type error =
   | NotYetImplemented
   | Unreachable
   | DistributionVerticalShiftIsInvalid
+  | TooFewSamples
   | ArgumentError(string)
+  | OperationError(Operation.invalidOperationError)
+  | PointSetConversionError(SampleSetDist.pointsetConversionError)
+  | SparklineError(PointSetDist.sparklineError) // This type of error is for when we find a sparkline of a discrete distribution. This should probably at some point be actually implemented
   | Other(string)
 
+let sampleErrorToDistErr = (err: SampleSetDist.sampleSetError): error =>
+  switch err {
+  | TooFewSamples => TooFewSamples
+  }
+
+@genType
+module Error = {
+  type t = error
+
+  let fromString = (s: string): t => Other(s)
+
+  @genType
+  let toString = (err: error): string =>
+    switch err {
+    | NotYetImplemented => "Function Not Yet Implemented"
+    | Unreachable => "Unreachable"
+    | DistributionVerticalShiftIsInvalid => "Distribution Vertical Shift is Invalid"
+    | ArgumentError(s) => `Argument Error ${s}`
+    | TooFewSamples => "Too Few Samples"
+    | OperationError(err) => `Operation Error: ${Operation.invalidOperationErrorToString(err)}`
+    | PointSetConversionError(err) => SampleSetDist.pointsetConversionErrorToString(err)
+    | SparklineError(err) => PointSetDist.sparklineErrorToString(err)
+    | Other(s) => s
+    }
+
+  let resultStringToResultError: result<'a, string> => result<'a, error> = n =>
+    n->E.R2.errMap(r => r->fromString)
+}
+
+@genType
 module Operation = {
   type direction =
     | Algebraic
@@ -43,6 +77,9 @@ module Operation = {
     | #Mean
     | #Sample
   ]
+
+  @genType
+  type pointsetXSelection = [#Linear | #ByWeight]
 }
 
 module DistributionOperation = {
@@ -55,6 +92,12 @@ module DistributionOperation = {
 
   type toFloatArray = Sample(int)
 
+  type toBool = IsNormalized
+
+  type toString =
+    | ToString
+    | ToSparkline(int)
+
   type fromDist =
     | ToFloat(Operation.toFloat)
     | ToDist(toDist)
@@ -63,7 +106,8 @@ module DistributionOperation = {
         Operation.arithmeticOperation,
         [#Dist(genericDist) | #Float(float)],
       )
-    | ToString
+    | ToString(toString)
+    | ToBool(toBool)
 
   type singleParamaterFunction =
     | FromDist(fromDist)
@@ -86,7 +130,9 @@ module DistributionOperation = {
     | ToDist(ToSampleSet(r)) => `toSampleSet(${E.I.toString(r)})`
     | ToDist(Truncate(_, _)) => `truncate`
     | ToDist(Inspect) => `inspect`
-    | ToString => `toString`
+    | ToString(ToString) => `toString`
+    | ToString(ToSparkline(n)) => `toSparkline(${E.I.toString(n)})`
+    | ToBool(IsNormalized) => `isNormalized`
     | ToDistCombination(Algebraic, _, _) => `algebraic`
     | ToDistCombination(Pointwise, _, _) => `pointwise`
     }
@@ -97,3 +143,71 @@ module DistributionOperation = {
     | Mixture(_) => `mixture`
     }
 }
+module Constructors = {
+  type t = DistributionOperation.genericFunctionCallInfo
+
+  module UsingDists = {
+    @genType
+    let mean = (dist): t => FromDist(ToFloat(#Mean), dist)
+    let sample = (dist): t => FromDist(ToFloat(#Sample), dist)
+    let cdf = (dist, x): t => FromDist(ToFloat(#Cdf(x)), dist)
+    let inv = (dist, x): t => FromDist(ToFloat(#Inv(x)), dist)
+    let pdf = (dist, x): t => FromDist(ToFloat(#Pdf(x)), dist)
+    let normalize = (dist): t => FromDist(ToDist(Normalize), dist)
+    let isNormalized = (dist): t => FromDist(ToBool(IsNormalized), dist)
+    let toPointSet = (dist): t => FromDist(ToDist(ToPointSet), dist)
+    let toSampleSet = (dist, r): t => FromDist(ToDist(ToSampleSet(r)), dist)
+    let truncate = (dist, left, right): t => FromDist(ToDist(Truncate(left, right)), dist)
+    let inspect = (dist): t => FromDist(ToDist(Inspect), dist)
+    let toString = (dist): t => FromDist(ToString(ToString), dist)
+    let toSparkline = (dist, n): t => FromDist(ToString(ToSparkline(n)), dist)
+    let algebraicAdd = (dist1, dist2: genericDist): t => FromDist(
+      ToDistCombination(Algebraic, #Add, #Dist(dist2)),
+      dist1,
+    )
+    let algebraicMultiply = (dist1, dist2): t => FromDist(
+      ToDistCombination(Algebraic, #Multiply, #Dist(dist2)),
+      dist1,
+    )
+    let algebraicDivide = (dist1, dist2): t => FromDist(
+      ToDistCombination(Algebraic, #Divide, #Dist(dist2)),
+      dist1,
+    )
+    let algebraicSubtract = (dist1, dist2): t => FromDist(
+      ToDistCombination(Algebraic, #Subtract, #Dist(dist2)),
+      dist1,
+    )
+    let algebraicLogarithm = (dist1, dist2): t => FromDist(
+      ToDistCombination(Algebraic, #Logarithm, #Dist(dist2)),
+      dist1,
+    )
+    let algebraicPower = (dist1, dist2): t => FromDist(
+      ToDistCombination(Algebraic, #Power, #Dist(dist2)),
+      dist1,
+    )
+    let pointwiseAdd = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Add, #Dist(dist2)),
+      dist1,
+    )
+    let pointwiseMultiply = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Multiply, #Dist(dist2)),
+      dist1,
+    )
+    let pointwiseDivide = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Divide, #Dist(dist2)),
+      dist1,
+    )
+    let pointwiseSubtract = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Subtract, #Dist(dist2)),
+      dist1,
+    )
+    let pointwiseLogarithm = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Logarithm, #Dist(dist2)),
+      dist1,
+    )
+    let pointwisePower = (dist1, dist2): t => FromDist(
+      ToDistCombination(Pointwise, #Power, #Dist(dist2)),
+      dist1,
+    )
+  }
+}
diff --git a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.res b/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.res
index 5e62de53..5a195f4b 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.res
@@ -14,7 +14,7 @@ let sampleN = (t: t, n) =>
   }
 
 let toSampleSetDist = (t: t, n) =>
-  SampleSetDist.make(sampleN(t, n))->GenericDist_Types.Error.resultStringToResultError
+  SampleSetDist.make(sampleN(t, n))->E.R2.errMap(DistributionTypes.sampleErrorToDistErr)
 
 let fromFloat = (f: float): t => Symbolic(SymbolicDist.Float.make(f))
 
@@ -68,7 +68,7 @@ let toPointSet = (
   t,
   ~xyPointLength,
   ~sampleCount,
-  ~xSelection: GenericDist_Types.Operation.pointsetXSelection=#ByWeight,
+  ~xSelection: DistributionTypes.Operation.pointsetXSelection=#ByWeight,
   (),
 ): result<PointSetTypes.pointSetDist, error> => {
   switch (t: t) {
@@ -83,7 +83,7 @@ let toPointSet = (
         pointSetDistLength: xyPointLength,
         kernelWidth: None,
       },
-    )->GenericDist_Types.Error.resultStringToResultError
+    )->E.R2.errMap(x => DistributionTypes.PointSetConversionError(x))
   }
 }
 
@@ -97,7 +97,7 @@ let toSparkline = (t: t, ~sampleCount: int, ~bucketCount: int=20, ()): result<st
   t
   ->toPointSet(~xSelection=#Linear, ~xyPointLength=bucketCount * 3, ~sampleCount, ())
   ->E.R.bind(r =>
-    r->PointSetDist.toSparkline(bucketCount)->GenericDist_Types.Error.resultStringToResultError
+    r->PointSetDist.toSparkline(bucketCount)->E.R2.errMap(x => DistributionTypes.SparklineError(x))
   )
 
 module Truncate = {
@@ -148,10 +148,10 @@ let truncate = Truncate.run
 */
 module AlgebraicCombination = {
   let tryAnalyticalSimplification = (
-    arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
+    arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
     t1: t,
     t2: t,
-  ): option<result<SymbolicDistTypes.symbolicDist, string>> =>
+  ): option<result<SymbolicDistTypes.symbolicDist, Operation.invalidOperationError>> =>
     switch (arithmeticOperation, t1, t2) {
     | (arithmeticOperation, Symbolic(d1), Symbolic(d2)) =>
       switch SymbolicDist.T.tryAnalyticalSimplification(d1, d2, arithmeticOperation) {
@@ -174,14 +174,14 @@ module AlgebraicCombination = {
 
   let runMonteCarlo = (
     toSampleSet: toSampleSetFn,
-    arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
+    arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
     t1: t,
     t2: t,
-  ) => {
+  ): result<t, error> => {
     let fn = Operation.Algebraic.toFn(arithmeticOperation)
     E.R.merge(toSampleSet(t1), toSampleSet(t2))
     ->E.R.bind(((t1, t2)) => {
-      SampleSetDist.map2(~fn, ~t1, ~t2)->GenericDist_Types.Error.resultStringToResultError
+      SampleSetDist.map2(~fn, ~t1, ~t2)->E.R2.errMap(x => DistributionTypes.OperationError(x))
     })
     ->E.R2.fmap(r => DistributionTypes.SampleSet(r))
   }
@@ -224,7 +224,7 @@ module AlgebraicCombination = {
   ): result<t, error> => {
     switch tryAnalyticalSimplification(arithmeticOperation, t1, t2) {
     | Some(Ok(symbolicDist)) => Ok(Symbolic(symbolicDist))
-    | Some(Error(e)) => Error(Other(e))
+    | Some(Error(e)) => Error(OperationError(e))
     | None =>
       switch chooseConvolutionOrMonteCarlo(arithmeticOperation, t1, t2) {
       | MonteCarlo => runMonteCarlo(toSampleSetFn, arithmeticOperation, t1, t2)
@@ -247,7 +247,7 @@ let pointwiseCombination = (
   E.R.merge(toPointSetFn(t1), toPointSetFn(t2))
   ->E.R2.fmap(((t1, t2)) =>
     PointSetDist.combinePointwise(
-      GenericDist_Types.Operation.arithmeticToFn(arithmeticOperation),
+      DistributionTypes.Operation.arithmeticToFn(arithmeticOperation),
       t1,
       t2,
     )
@@ -258,23 +258,23 @@ let pointwiseCombination = (
 let pointwiseCombinationFloat = (
   t: t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
-  ~float: float,
+  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~f: float,
 ): result<t, error> => {
   let m = switch arithmeticOperation {
   | #Add | #Subtract => Error(DistributionTypes.DistributionVerticalShiftIsInvalid)
   | (#Multiply | #Divide | #Power | #Logarithm) as arithmeticOperation =>
-    toPointSetFn(t)->E.R2.fmap(t => {
+    toPointSetFn(t)->E.R.bind(t => {
       //TODO: Move to PointSet codebase
       let fn = (secondary, main) => Operation.Scale.toFn(arithmeticOperation, main, secondary)
       let integralSumCacheFn = Operation.Scale.toIntegralSumCacheFn(arithmeticOperation)
       let integralCacheFn = Operation.Scale.toIntegralCacheFn(arithmeticOperation)
-      PointSetDist.T.mapY(
-        ~integralSumCacheFn=integralSumCacheFn(float),
-        ~integralCacheFn=integralCacheFn(float),
-        ~fn=fn(float),
+      PointSetDist.T.mapYResult(
+        ~integralSumCacheFn=integralSumCacheFn(f),
+        ~integralCacheFn=integralCacheFn(f),
+        ~fn=fn(f),
         t,
-      )
+      )->E.R2.errMap(x => DistributionTypes.OperationError(x))
     })
   }
   m->E.R2.fmap(r => DistributionTypes.PointSet(r))
diff --git a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.resi b/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.resi
index c49d18b5..276ca4e3 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.resi
+++ b/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.resi
@@ -1,5 +1,5 @@
-type t = GenericDist_Types.genericDist
-type error = GenericDist_Types.error
+type t = DistributionTypes.genericDist
+type error = DistributionTypes.error
 type toPointSetFn = t => result<PointSetTypes.pointSetDist, error>
 type toSampleSetFn = t => result<SampleSetDist.t, error>
 type scaleMultiplyFn = (t, float) => result<t, error>
@@ -28,7 +28,7 @@ let toPointSet: (
   t,
   ~xyPointLength: int,
   ~sampleCount: int,
-  ~xSelection: GenericDist_Types.Operation.pointsetXSelection=?,
+  ~xSelection: DistributionTypes.Operation.pointsetXSelection=?,
   unit,
 ) => result<PointSetTypes.pointSetDist, error>
 let toSparkline: (t, ~sampleCount: int, ~bucketCount: int=?, unit) => result<string, error>
@@ -45,22 +45,22 @@ let algebraicCombination: (
   t,
   ~toPointSetFn: toPointSetFn,
   ~toSampleSetFn: toSampleSetFn,
-  ~arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
+  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
   ~t2: t,
 ) => result<t, error>
 
 let pointwiseCombination: (
   t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
+  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
   ~t2: t,
 ) => result<t, error>
 
 let pointwiseCombinationFloat: (
   t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: GenericDist_Types.Operation.arithmeticOperation,
-  ~float: float,
+  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~f: float,
 ) => result<t, error>
 
 let mixture: (
diff --git a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist_Types.res b/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist_Types.res
deleted file mode 100644
index b045a6d5..00000000
--- a/packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist_Types.res
+++ /dev/null
@@ -1,194 +0,0 @@
-type genericDist = DistributionTypes.genericDist
-@genType
-type error = DistributionTypes.error
-
-@genType
-module Error = {
-  type t = error
-
-  let fromString = (s: string): t => Other(s)
-
-  @genType
-  let toString = (x: t) => {
-    switch x {
-    | NotYetImplemented => "Not Yet Implemented"
-    | Unreachable => "Unreachable"
-    | DistributionVerticalShiftIsInvalid => "Distribution Vertical Shift Is Invalid"
-    | ArgumentError(x) => `Argument Error: ${x}`
-    | Other(s) => s
-    }
-  }
-
-  let resultStringToResultError: result<'a, string> => result<'a, error> = n =>
-    n->E.R2.errMap(r => r->fromString->Error)
-}
-
-module Operation = {
-  type direction =
-    | Algebraic
-    | Pointwise
-
-  type arithmeticOperation = [
-    | #Add
-    | #Multiply
-    | #Subtract
-    | #Divide
-    | #Power
-    | #Logarithm
-  ]
-
-  let arithmeticToFn = (arithmetic: arithmeticOperation) =>
-    switch arithmetic {
-    | #Add => \"+."
-    | #Multiply => \"*."
-    | #Subtract => \"-."
-    | #Power => \"**"
-    | #Divide => \"/."
-    | #Logarithm => (a, b) => log(a) /. log(b)
-    }
-
-  type toFloat = [
-    | #Cdf(float)
-    | #Inv(float)
-    | #Mean
-    | #Pdf(float)
-    | #Sample
-  ]
-
-  @genType
-  type pointsetXSelection = [#Linear | #ByWeight]
-
-  type toDist =
-    | Normalize
-    | ToPointSet
-    | ToSampleSet(int)
-    | Truncate(option<float>, option<float>)
-    | Inspect
-
-  type toFloatArray = Sample(int)
-
-  type toString =
-    | ToString
-    | ToSparkline(int)
-
-  type toBool = IsNormalized
-
-  type fromDist =
-    | ToFloat(toFloat)
-    | ToDist(toDist)
-    | ToDistCombination(direction, arithmeticOperation, [#Dist(genericDist) | #Float(float)])
-    | ToString(toString)
-    | ToBool(toBool)
-
-  type singleParamaterFunction =
-    | FromDist(fromDist)
-    | FromFloat(fromDist)
-
-  @genType
-  type genericFunctionCallInfo =
-    | FromDist(fromDist, genericDist)
-    | FromFloat(fromDist, float)
-    | Mixture(array<(genericDist, float)>)
-
-  let distCallToString = (distFunction: fromDist): string =>
-    switch distFunction {
-    | ToFloat(#Cdf(r)) => `cdf(${E.Float.toFixed(r)})`
-    | ToFloat(#Inv(r)) => `inv(${E.Float.toFixed(r)})`
-    | ToFloat(#Mean) => `mean`
-    | ToFloat(#Pdf(r)) => `pdf(${E.Float.toFixed(r)})`
-    | ToFloat(#Sample) => `sample`
-    | ToDist(Normalize) => `normalize`
-    | ToDist(ToPointSet) => `toPointSet`
-    | ToDist(ToSampleSet(r)) => `toSampleSet(${E.I.toString(r)})`
-    | ToDist(Truncate(_, _)) => `truncate`
-    | ToDist(Inspect) => `inspect`
-    | ToString(ToString) => `toString`
-    | ToString(ToSparkline(n)) => `toSparkline(${E.I.toString(n)})`
-    | ToBool(IsNormalized) => `isNormalized`
-    | ToDistCombination(Algebraic, _, _) => `algebraic`
-    | ToDistCombination(Pointwise, _, _) => `pointwise`
-    }
-
-  let toString = (d: genericFunctionCallInfo): string =>
-    switch d {
-    | FromDist(f, _) | FromFloat(f, _) => distCallToString(f)
-    | Mixture(_) => `mixture`
-    }
-}
-
-/*
-It can be a pain to write out the genericFunctionCallInfo. The constructors help with this. 
-This code only covers some of genericFunctionCallInfo: many arguments could be called with either a
-float or a distribution. The "UsingDists" module assumes that everything is a distribution.
-This is a tradeoff of some generality in order to get a bit more simplicity.
-I could see having a longer interface in the future, but it could be messy.
-Like, algebraicAddDistFloat vs. algebraicAddDistDist
-*/
-module Constructors = {
-  type t = Operation.genericFunctionCallInfo
-
-  module UsingDists = {
-    @genType
-    let mean = (dist): t => FromDist(ToFloat(#Mean), dist)
-    let sample = (dist): t => FromDist(ToFloat(#Sample), dist)
-    let cdf = (dist, x): t => FromDist(ToFloat(#Cdf(x)), dist)
-    let inv = (dist, x): t => FromDist(ToFloat(#Inv(x)), dist)
-    let pdf = (dist, x): t => FromDist(ToFloat(#Pdf(x)), dist)
-    let normalize = (dist): t => FromDist(ToDist(Normalize), dist)
-    let isNormalized = (dist): t => FromDist(ToBool(IsNormalized), dist)
-    let toPointSet = (dist): t => FromDist(ToDist(ToPointSet), dist)
-    let toSampleSet = (dist, r): t => FromDist(ToDist(ToSampleSet(r)), dist)
-    let truncate = (dist, left, right): t => FromDist(ToDist(Truncate(left, right)), dist)
-    let inspect = (dist): t => FromDist(ToDist(Inspect), dist)
-    let toString = (dist): t => FromDist(ToString(ToString), dist)
-    let toSparkline = (dist, n): t => FromDist(ToString(ToSparkline(n)), dist)
-    let algebraicAdd = (dist1, dist2: genericDist): t => FromDist(
-      ToDistCombination(Algebraic, #Add, #Dist(dist2)),
-      dist1,
-    )
-    let algebraicMultiply = (dist1, dist2): t => FromDist(
-      ToDistCombination(Algebraic, #Multiply, #Dist(dist2)),
-      dist1,
-    )
-    let algebraicDivide = (dist1, dist2): t => FromDist(
-      ToDistCombination(Algebraic, #Divide, #Dist(dist2)),
-      dist1,
-    )
-    let algebraicSubtract = (dist1, dist2): t => FromDist(
-      ToDistCombination(Algebraic, #Subtract, #Dist(dist2)),
-      dist1,
-    )
-    let algebraicLogarithm = (dist1, dist2): t => FromDist(
-      ToDistCombination(Algebraic, #Logarithm, #Dist(dist2)),
-      dist1,
-    )
-    let algebraicPower = (dist1, dist2): t => FromDist(
-      ToDistCombination(Algebraic, #Power, #Dist(dist2)),
-      dist1,
-    )
-    let pointwiseAdd = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Add, #Dist(dist2)),
-      dist1,
-    )
-    let pointwiseMultiply = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Multiply, #Dist(dist2)),
-      dist1,
-    )
-    let pointwiseDivide = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Divide, #Dist(dist2)),
-      dist1,
-    )
-    let pointwiseSubtract = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Subtract, #Dist(dist2)),
-      dist1,
-    )
-    let pointwiseLogarithm = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Logarithm, #Dist(dist2)),
-      dist1,
-    )
-    let pointwisePower = (dist1, dist2): t => FromDist(
-      ToDistCombination(Pointwise, #Power, #Dist(dist2)),
-      dist1,
-    )
-  }
-}
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
index 6c9cb3fd..5512b5cb 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Continuous.res
@@ -146,7 +146,27 @@ let reduce = (
   continuousShapes,
 ) => continuousShapes |> E.A.fold_left(combinePointwise(~integralSumCachesFn, fn), empty)
 
-let mapY = (~integralSumCacheFn=_ => None, ~integralCacheFn=_ => None, ~fn, t: t) =>
+let mapYResult = (
+  ~integralSumCacheFn=_ => None,
+  ~integralCacheFn=_ => None,
+  ~fn: float => result<float, 'e>,
+  t: t,
+): result<t, 'e> =>
+  XYShape.T.mapYResult(fn, getShape(t))->E.R2.fmap(x =>
+    make(
+      ~interpolation=t.interpolation,
+      ~integralSumCache=t.integralSumCache |> E.O.bind(_, integralSumCacheFn),
+      ~integralCache=t.integralCache |> E.O.bind(_, integralCacheFn),
+      x,
+    )
+  )
+
+let mapY = (
+  ~integralSumCacheFn=_ => None,
+  ~integralCacheFn=_ => None,
+  ~fn: float => float,
+  t: t,
+): t =>
   make(
     ~interpolation=t.interpolation,
     ~integralSumCache=t.integralSumCache |> E.O.bind(_, integralSumCacheFn),
@@ -170,6 +190,7 @@ module T = Dist({
   let minX = shapeFn(XYShape.T.minX)
   let maxX = shapeFn(XYShape.T.maxX)
   let mapY = mapY
+  let mapYResult = mapYResult
   let updateIntegralCache = updateIntegralCache
   let toDiscreteProbabilityMassFraction = _ => 0.0
   let toPointSetDist = (t: t): PointSetTypes.pointSetDist => Continuous(t)
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
index 4037338d..92fdc7f0 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Discrete.res
@@ -103,7 +103,26 @@ let combineAlgebraically = (op: Operation.convolutionOperation, t1: t, t2: t): t
   make(~integralSumCache=combinedIntegralSum, combinedShape)
 }
 
-let mapY = (~integralSumCacheFn=_ => None, ~integralCacheFn=_ => None, ~fn, t: t) =>
+let mapYResult = (
+  ~integralSumCacheFn=_ => None,
+  ~integralCacheFn=_ => None,
+  ~fn: float => result<float, 'e>,
+  t: t,
+): result<t, 'e> =>
+  XYShape.T.mapYResult(fn, getShape(t))->E.R2.fmap(x =>
+    make(
+      ~integralSumCache=t.integralSumCache |> E.O.bind(_, integralSumCacheFn),
+      ~integralCache=t.integralCache |> E.O.bind(_, integralCacheFn),
+      x,
+    )
+  )
+
+let mapY = (
+  ~integralSumCacheFn=_ => None,
+  ~integralCacheFn=_ => None,
+  ~fn: float => float,
+  t: t,
+): t =>
   make(
     ~integralSumCache=t.integralSumCache |> E.O.bind(_, integralSumCacheFn),
     ~integralCache=t.integralCache |> E.O.bind(_, integralCacheFn),
@@ -143,6 +162,7 @@ module T = Dist({
   let maxX = shapeFn(XYShape.T.maxX)
   let toDiscreteProbabilityMassFraction = _ => 1.0
   let mapY = mapY
+  let mapYResult = mapYResult
   let updateIntegralCache = updateIntegralCache
   let toPointSetDist = (t: t): PointSetTypes.pointSetDist => Discrete(t)
   let toContinuous = _ => None
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Distributions.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Distributions.res
index 0821611c..407eae85 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Distributions.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Distributions.res
@@ -9,6 +9,12 @@ module type dist = {
     ~fn: float => float,
     t,
   ) => t
+  let mapYResult: (
+    ~integralSumCacheFn: float => option<float>=?,
+    ~integralCacheFn: PointSetTypes.continuousShape => option<PointSetTypes.continuousShape>=?,
+    ~fn: float => result<float, 'e>,
+    t,
+  ) => result<t, 'e>
   let xToY: (float, t) => PointSetTypes.mixedPoint
   let toPointSetDist: t => PointSetTypes.pointSetDist
   let toContinuous: t => option<PointSetTypes.continuousShape>
@@ -37,6 +43,7 @@ module Dist = (T: dist) => {
   let integral = T.integral
   let xTotalRange = (t: t) => maxX(t) -. minX(t)
   let mapY = T.mapY
+  let mapYResult = T.mapYResult
   let xToY = T.xToY
   let downsample = T.downsample
   let toPointSetDist = T.toPointSetDist
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Mixed.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Mixed.res
index 223c55e2..4d441a9a 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Mixed.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/Mixed.res
@@ -164,7 +164,12 @@ module T = Dist({
   // This pipes all ys (continuous and discrete) through fn.
   // If mapY is a linear operation, we might be able to update the integralSumCaches as well;
   // if not, they'll be set to None.
-  let mapY = (~integralSumCacheFn=_ => None, ~integralCacheFn=_ => None, ~fn, t: t): t => {
+  let mapY = (
+    ~integralSumCacheFn=_ => None,
+    ~integralCacheFn=_ => None,
+    ~fn: float => float,
+    t: t,
+  ): t => {
     let yMappedDiscrete: PointSetTypes.discreteShape =
       t.discrete
       |> Discrete.T.mapY(~fn)
@@ -187,6 +192,41 @@ module T = Dist({
     }
   }
 
+  let mapYResult = (
+    ~integralSumCacheFn=_ => None,
+    ~integralCacheFn=_ => None,
+    ~fn: float => result<float, 'e>,
+    t: t,
+  ): result<t, 'e> => {
+    E.R.merge(
+      Discrete.T.mapYResult(~fn, t.discrete),
+      Continuous.T.mapYResult(~fn, t.continuous),
+    )->E.R2.fmap(((discreteMapped, continuousMapped)) => {
+      let yMappedDiscrete: PointSetTypes.discreteShape =
+        discreteMapped
+        |> Discrete.updateIntegralSumCache(
+          E.O.bind(t.discrete.integralSumCache, integralSumCacheFn),
+        )
+        |> Discrete.updateIntegralCache(E.O.bind(t.discrete.integralCache, integralCacheFn))
+
+      let yMappedContinuous: PointSetTypes.continuousShape =
+        continuousMapped
+        |> Continuous.updateIntegralSumCache(
+          E.O.bind(t.continuous.integralSumCache, integralSumCacheFn),
+        )
+        |> Continuous.updateIntegralCache(E.O.bind(t.continuous.integralCache, integralCacheFn))
+
+      (
+        {
+          discrete: yMappedDiscrete,
+          continuous: yMappedContinuous,
+          integralSumCache: E.O.bind(t.integralSumCache, integralSumCacheFn),
+          integralCache: E.O.bind(t.integralCache, integralCacheFn),
+        }: t
+      )
+    })
+  }
+
   let mean = ({discrete, continuous}: t): float => {
     let discreteMean = Discrete.T.mean(discrete)
     let continuousMean = Continuous.T.mean(continuous)
diff --git a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/PointSetDist.res b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/PointSetDist.res
index 0035d646..b654c890 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/PointSetDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/PointSetDist/PointSetDist.res
@@ -16,6 +16,13 @@ let fmap = ((fn1, fn2, fn3), t: t): t =>
   | Continuous(m) => Continuous(fn3(m))
   }
 
+let fmapResult = ((fn1, fn2, fn3), t: t): result<t, 'e> =>
+  switch t {
+  | Mixed(m) => fn1(m)->E.R2.fmap(x => PointSetTypes.Mixed(x))
+  | Discrete(m) => fn2(m)->E.R2.fmap(x => PointSetTypes.Discrete(x))
+  | Continuous(m) => fn3(m)->E.R2.fmap(x => PointSetTypes.Continuous(x))
+  }
+
 let toMixed = mapToAll((
   m => m,
   d =>
@@ -130,13 +137,26 @@ module T = Dist({
   let integralYtoX = f =>
     mapToAll((Mixed.T.Integral.yToX(f), Discrete.T.Integral.yToX(f), Continuous.T.Integral.yToX(f)))
   let maxX = mapToAll((Mixed.T.maxX, Discrete.T.maxX, Continuous.T.maxX))
-  let mapY = (~integralSumCacheFn=_ => None, ~integralCacheFn=_ => None, ~fn) =>
+  let mapY = (~integralSumCacheFn=_ => None, ~integralCacheFn=_ => None, ~fn: float => float): (
+    t => t
+  ) =>
     fmap((
       Mixed.T.mapY(~integralSumCacheFn, ~integralCacheFn, ~fn),
       Discrete.T.mapY(~integralSumCacheFn, ~integralCacheFn, ~fn),
       Continuous.T.mapY(~integralSumCacheFn, ~integralCacheFn, ~fn),
     ))
 
+  let mapYResult = (
+    ~integralSumCacheFn=_ => None,
+    ~integralCacheFn=_ => None,
+    ~fn: float => result<float, 'e>,
+  ): (t => result<t, 'e>) =>
+    fmapResult((
+      Mixed.T.mapYResult(~integralSumCacheFn, ~integralCacheFn, ~fn),
+      Discrete.T.mapYResult(~integralSumCacheFn, ~integralCacheFn, ~fn),
+      Continuous.T.mapYResult(~integralSumCacheFn, ~integralCacheFn, ~fn),
+    ))
+
   let mean = (t: t): float =>
     switch t {
     | Mixed(m) => Mixed.T.mean(m)
@@ -195,8 +215,16 @@ let operate = (distToFloatOp: Operation.distToFloatOperation, s): float =>
   | #Mean => T.mean(s)
   }
 
-let toSparkline = (t: t, bucketCount) =>
+@genType
+type sparklineError = CannotSparklineDiscrete
+
+let sparklineErrorToString = (err: sparklineError): string =>
+  switch err {
+  | CannotSparklineDiscrete => "Cannot find the sparkline of a discrete distribution"
+  }
+
+let toSparkline = (t: t, bucketCount): result<string, sparklineError> =>
   T.toContinuous(t)
   ->E.O2.fmap(Continuous.downsampleEquallyOverX(bucketCount))
-  ->E.O2.toResult("toContinous Error: Could not convert into continuous distribution")
+  ->E.O2.toResult(CannotSparklineDiscrete)
   ->E.R2.fmap(r => Continuous.getShape(r).ys->Sparklines.create())
diff --git a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
index fcd4055d..b775c8ac 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
@@ -1,3 +1,11 @@
+@genType
+type sampleSetError = TooFewSamples
+
+let sampleSetErrorToString = (err: sampleSetError): string =>
+  switch err {
+  | TooFewSamples => "Too few samples when constructing sample set"
+  }
+
 /*
 This is used as a smart constructor. The only way to create a SampleSetDist.t is to call
 this constructor.
@@ -8,7 +16,7 @@ module T: {
   //When we get a good functional library in TS, we could refactor that out.
   @genType
   type t = array<float>
-  let make: array<float> => result<t, string>
+  let make: array<float> => result<t, sampleSetError>
   let get: t => array<float>
 } = {
   type t = array<float>
@@ -16,7 +24,7 @@ module T: {
     if E.A.length(a) > 5 {
       Ok(a)
     } else {
-      Error("too small")
+      Error(TooFewSamples)
     }
   let get = (a: t) => a
 }
@@ -25,19 +33,27 @@ include T
 
 let length = (t: t) => get(t)->E.A.length
 
+@genType
+type pointsetConversionError = TooFewSamplesForConversionToPointSet
+
+let pointsetConversionErrorToString = (err: pointsetConversionError) =>
+  switch err {
+  | TooFewSamplesForConversionToPointSet => "Too Few Samples to convert to point set"
+  }
+
 /*
 TODO: Refactor to get a more precise estimate. Also, this code is just fairly messy, could use 
 some refactoring.
 */
 let toPointSetDist = (~samples: t, ~samplingInputs: SamplingInputs.samplingInputs): result<
   PointSetTypes.pointSetDist,
-  string,
+  pointsetConversionError,
 > =>
   SampleSetDist_ToPointSet.toPointSetDist(
     ~samples=get(samples),
     ~samplingInputs,
     (),
-  ).pointSetDist->E.O2.toResult("Failed to convert to PointSetDist")
+  ).pointSetDist->E.O2.toResult(TooFewSamplesForConversionToPointSet)
 
 //Randomly get one sample from the distribution
 let sample = (t: t): float => {
@@ -62,7 +78,19 @@ let sampleN = (t: t, n) => {
 }
 
 //TODO: Figure out what to do if distributions are different lengths. ``zip`` is kind of inelegant for this.
-let map2 = (~fn: (float, float) => float, ~t1: t, ~t2: t) => {
+let map2 = (
+  ~fn: (float, float) => result<float, Operation.invalidOperationError>,
+  ~t1: t,
+  ~t2: t,
+): result<t, Operation.invalidOperationError> => {
   let samples = Belt.Array.zip(get(t1), get(t2))->E.A2.fmap(((a, b)) => fn(a, b))
-  make(samples)
+
+  // This assertion should never be reached. In order for it to be reached, one
+  // of the input parameters would need to be a sample set distribution with less
+  // than 6 samples. Which should be impossible due to the smart constructor.
+  // I could prove this to the type system (say, creating a {first: float, second: float, ..., fifth: float, rest: array<float>}
+  // But doing so would take too much time, so I'll leave it as an assertion
+  E.A.R.firstErrorOrOpen(samples)->E.R2.fmap(x =>
+    E.R.assertOk("Input of samples should be larger than 5", make(x))
+  )
 }
diff --git a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist_ToPointSet.res b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist_ToPointSet.res
index 59b4fa46..3916e6fe 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist_ToPointSet.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist_ToPointSet.res
@@ -83,7 +83,7 @@ let toPointSetDist = (
   ~samples: Internals.T.t,
   ~samplingInputs: SamplingInputs.samplingInputs,
   (),
-) => {
+): Internals.Types.outputs => {
   Array.fast_sort(compare, samples)
   let (continuousPart, discretePart) = E.A.Sorted.Floats.split(samples)
   let length = samples |> E.A.length |> float_of_int
diff --git a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
index a6eda12b..7ce95721 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
@@ -379,7 +379,7 @@ module T = {
   ): analyticalSimplificationResult =>
     switch (d1, d2) {
     | (#Float(v1), #Float(v2)) =>
-      switch Operation.Algebraic.applyFn(op, v1, v2) {
+      switch Operation.Algebraic.toFn(op, v1, v2) {
       | Ok(r) => #AnalyticalSolution(#Float(r))
       | Error(n) => #Error(n)
       }
diff --git a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDistTypes.res b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDistTypes.res
index 4625867d..121ff0b9 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDistTypes.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDistTypes.res
@@ -45,6 +45,6 @@ type symbolicDist = [
 
 type analyticalSimplificationResult = [
   | #AnalyticalSolution(symbolicDist)
-  | #Error(string)
+  | #Error(Operation.invalidOperationError)
   | #NoSolution
 ]
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res
index 4ad60732..48fae58c 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_ErrorValue.res
@@ -9,6 +9,7 @@ type errorValue =
   | RERecordPropertyNotFound(string, string)
   | RESymbolNotFound(string)
   | RESyntaxError(string)
+  | REDistributionError(DistributionTypes.error)
   | RETodo(string) // To do
 
 type t = errorValue
@@ -20,6 +21,7 @@ let errorToString = err =>
   | REAssignmentExpected => "Assignment expected"
   | REExpressionExpected => "Expression expected"
   | REFunctionExpected(msg) => `Function expected: ${msg}`
+  | REDistributionError(err) => `Math Error: ${DistributionTypes.Error.toString(err)}`
   | REJavaScriptExn(omsg, oname) => {
       let answer = "JS Exception:"
       let answer = switch oname {
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res
index 2a8dc2e1..0470543d 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_ExpressionValue.res
@@ -10,7 +10,7 @@ type rec expressionValue =
   | EvArray(array<expressionValue>)
   | EvBool(bool)
   | EvCall(string) // External function call
-  | EvDistribution(GenericDist_Types.genericDist)
+  | EvDistribution(DistributionTypes.genericDist)
   | EvNumber(float)
   | EvRecord(Js.Dict.t<expressionValue>)
   | EvString(string)
diff --git a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res
index f21010e2..68ac7393 100644
--- a/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res
+++ b/packages/squiggle-lang/src/rescript/ReducerInterface/ReducerInterface_GenericDistribution.res
@@ -29,8 +29,8 @@ module Helpers = {
     }
 
   let catchAndConvertTwoArgsToDists = (args: array<expressionValue>): option<(
-    GenericDist_Types.genericDist,
-    GenericDist_Types.genericDist,
+    DistributionTypes.genericDist,
+    DistributionTypes.genericDist,
   )> => {
     switch args {
     | [EvDistribution(a), EvDistribution(b)] => Some((a, b))
@@ -41,33 +41,41 @@ module Helpers = {
   }
 
   let toFloatFn = (
-    fnCall: GenericDist_Types.Operation.toFloat,
-    dist: GenericDist_Types.genericDist,
+    fnCall: DistributionTypes.Operation.toFloat,
+    dist: DistributionTypes.genericDist,
   ) => {
-    FromDist(GenericDist_Types.Operation.ToFloat(fnCall), dist)->runGenericOperation->Some
+    FromDist(DistributionTypes.DistributionOperation.ToFloat(fnCall), dist)
+    ->runGenericOperation
+    ->Some
   }
 
   let toStringFn = (
-    fnCall: GenericDist_Types.Operation.toString,
-    dist: GenericDist_Types.genericDist,
+    fnCall: DistributionTypes.DistributionOperation.toString,
+    dist: DistributionTypes.genericDist,
   ) => {
-    FromDist(GenericDist_Types.Operation.ToString(fnCall), dist)->runGenericOperation->Some
+    FromDist(DistributionTypes.DistributionOperation.ToString(fnCall), dist)
+    ->runGenericOperation
+    ->Some
   }
 
   let toBoolFn = (
-    fnCall: GenericDist_Types.Operation.toBool,
-    dist: GenericDist_Types.genericDist,
+    fnCall: DistributionTypes.DistributionOperation.toBool,
+    dist: DistributionTypes.genericDist,
   ) => {
-    FromDist(GenericDist_Types.Operation.ToBool(fnCall), dist)->runGenericOperation->Some
+    FromDist(DistributionTypes.DistributionOperation.ToBool(fnCall), dist)
+    ->runGenericOperation
+    ->Some
   }
 
-  let toDistFn = (fnCall: GenericDist_Types.Operation.toDist, dist) => {
-    FromDist(GenericDist_Types.Operation.ToDist(fnCall), dist)->runGenericOperation->Some
+  let toDistFn = (fnCall: DistributionTypes.DistributionOperation.toDist, dist) => {
+    FromDist(DistributionTypes.DistributionOperation.ToDist(fnCall), dist)
+    ->runGenericOperation
+    ->Some
   }
 
   let twoDiststoDistFn = (direction, arithmetic, dist1, dist2) => {
     FromDist(
-      GenericDist_Types.Operation.ToDistCombination(
+      DistributionTypes.DistributionOperation.ToDistCombination(
         direction,
         arithmeticMap(arithmetic),
         #Dist(dist2),
@@ -84,7 +92,7 @@ module Helpers = {
   let parseNumberArray = (ags: array<expressionValue>): Belt.Result.t<array<float>, string> =>
     E.A.fmap(parseNumber, ags) |> E.A.R.firstErrorOrOpen
 
-  let parseDist = (args: expressionValue): Belt.Result.t<GenericDist_Types.genericDist, string> =>
+  let parseDist = (args: expressionValue): Belt.Result.t<DistributionTypes.genericDist, string> =>
     switch args {
     | EvDistribution(x) => Ok(x)
     | EvNumber(x) => Ok(GenericDist.fromFloat(x))
@@ -92,12 +100,12 @@ module Helpers = {
     }
 
   let parseDistributionArray = (ags: array<expressionValue>): Belt.Result.t<
-    array<GenericDist_Types.genericDist>,
+    array<DistributionTypes.genericDist>,
     string,
   > => E.A.fmap(parseDist, ags) |> E.A.R.firstErrorOrOpen
 
   let mixtureWithGivenWeights = (
-    distributions: array<GenericDist_Types.genericDist>,
+    distributions: array<DistributionTypes.genericDist>,
     weights: array<float>,
   ): DistributionOperation.outputType =>
     E.A.length(distributions) == E.A.length(weights)
@@ -107,7 +115,7 @@ module Helpers = {
         )
 
   let mixtureWithDefaultWeights = (
-    distributions: array<GenericDist_Types.genericDist>,
+    distributions: array<DistributionTypes.genericDist>,
   ): DistributionOperation.outputType => {
     let length = E.A.length(distributions)
     let weights = Belt.Array.make(length, 1.0 /. Belt.Int.toFloat(length))
@@ -259,12 +267,7 @@ let genericOutputToReducerValue = (o: DistributionOperation.outputType): result<
   | Float(d) => Ok(EvNumber(d))
   | String(d) => Ok(EvString(d))
   | Bool(d) => Ok(EvBool(d))
-  | GenDistError(NotYetImplemented) => Error(RETodo("Function not yet implemented"))
-  | GenDistError(Unreachable) => Error(RETodo("Unreachable"))
-  | GenDistError(DistributionVerticalShiftIsInvalid) =>
-    Error(RETodo("Distribution Vertical Shift Is Invalid"))
-  | GenDistError(ArgumentError(err)) => Error(RETodo("Argument Error: " ++ err))
-  | GenDistError(Other(s)) => Error(RETodo(s))
+  | GenDistError(err) => Error(REDistributionError(err))
   }
 
 let dispatch = call => {
diff --git a/packages/squiggle-lang/src/rescript/TypescriptInterface.res b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
index 6a0b7bcf..8704bf5e 100644
--- a/packages/squiggle-lang/src/rescript/TypescriptInterface.res
+++ b/packages/squiggle-lang/src/rescript/TypescriptInterface.res
@@ -53,4 +53,4 @@ type continuousShape = PointSetTypes.continuousShape
 let errorValueToString = Reducer_ErrorValue.errorToString
 
 @genType
-let distributionErrorToString = GenericDist_Types.Error.toString
+let distributionErrorToString = DistributionTypes.Error.toString
diff --git a/packages/squiggle-lang/src/rescript/Utility/E.res b/packages/squiggle-lang/src/rescript/Utility/E.res
index 8c6c4511..779ab03a 100644
--- a/packages/squiggle-lang/src/rescript/Utility/E.res
+++ b/packages/squiggle-lang/src/rescript/Utility/E.res
@@ -152,6 +152,8 @@ module I = {
   let toString = Js.Int.toString
 }
 
+exception Assertion(string)
+
 /* R for Result */
 module R = {
   let result = Rationale.Result.result
@@ -159,6 +161,11 @@ module R = {
   let fmap = Rationale.Result.fmap
   let bind = Rationale.Result.bind
   let toExn = Belt.Result.getExn
+  let assertOk = (message: string, x: result<'a, 'b>): 'a =>
+    switch x {
+    | Ok(r) => r
+    | Error(_) => raise(Assertion(message))
+    }
   let default = (default, res: Belt.Result.t<'a, 'b>) =>
     switch res {
     | Ok(r) => r
@@ -210,10 +217,10 @@ module R2 = {
   let bind = (a, b) => R.bind(b, a)
 
   //Converts result type to change error type only
-  let errMap = (a, map) =>
+  let errMap = (a: result<'a, 'b>, map: 'b => 'c): result<'a, 'c> =>
     switch a {
     | Ok(r) => Ok(r)
-    | Error(e) => map(e)
+    | Error(e) => Error(map(e))
     }
 
   let fmap2 = (xR, f) =>
@@ -436,6 +443,7 @@ module A = {
         r |> Belt.Array.map(_, r => Belt.Result.getExn(r))
       bringErrorUp |> Belt.Result.map(_, forceOpen)
     }
+    let filterOk = (x: array<result<'a, 'b>>): array<'a> => fmap(R.toOption, x)->O.concatSomes
   }
 
   module Sorted = {
diff --git a/packages/squiggle-lang/src/rescript/Utility/Operation.res b/packages/squiggle-lang/src/rescript/Utility/Operation.res
index f78a432c..587f2e31 100644
--- a/packages/squiggle-lang/src/rescript/Utility/Operation.res
+++ b/packages/squiggle-lang/src/rescript/Utility/Operation.res
@@ -37,22 +37,42 @@ module Convolution = {
     }
 }
 
+@genType
+type invalidOperationError =
+  | DivisionByZeroError
+  | ComplexNumberError
+
+let invalidOperationErrorToString = (err: invalidOperationError): string =>
+  switch err {
+  | DivisionByZeroError => "Cannot divide by zero"
+  | ComplexNumberError => "Operation returned complex result"
+  }
+
 module Algebraic = {
   type t = algebraicOperation
-  let toFn: (t, float, float) => float = x =>
+  let toFn: (t, float, float) => result<float, invalidOperationError> = (x, a, b) =>
     switch x {
-    | #Add => \"+."
-    | #Subtract => \"-."
-    | #Multiply => \"*."
-    | #Power => \"**"
-    | #Divide => \"/."
-    | #Logarithm => (a, b) => log(a) /. log(b)
-    }
-
-  let applyFn = (t, f1, f2) =>
-    switch (t, f1, f2) {
-    | (#Divide, _, 0.) => Error("Cannot divide $v1 by zero.")
-    | _ => Ok(toFn(t, f1, f2))
+    | #Add => Ok(a +. b)
+    | #Subtract => Ok(a -. b)
+    | #Multiply => Ok(a *. b)
+    | #Power =>
+      if a > 0.0 {
+        Ok(a ** b)
+      } else {
+        Error(ComplexNumberError)
+      }
+    | #Divide =>
+      if b != 0.0 {
+        Ok(a /. b)
+      } else {
+        Error(DivisionByZeroError)
+      }
+    | #Logarithm =>
+      if a > 0.0 && b > 0.0 {
+        Ok(log(a) /. log(b))
+      } else {
+        Error(ComplexNumberError)
+      }
     }
 
   let toString = x =>
@@ -96,12 +116,27 @@ module DistToFloat = {
 // Note that different logarithms don't really do anything.
 module Scale = {
   type t = scaleOperation
-  let toFn = x =>
+  let toFn = (x: t, a: float, b: float): result<float, invalidOperationError> =>
     switch x {
-    | #Multiply => \"*."
-    | #Divide => \"/."
-    | #Power => \"**"
-    | #Logarithm => (a, b) => log(a) /. log(b)
+    | #Multiply => Ok(a *. b)
+    | #Divide =>
+      if b != 0.0 {
+        Ok(a /. b)
+      } else {
+        Error(DivisionByZeroError)
+      }
+    | #Power =>
+      if a > 0.0 {
+        Ok(a ** b)
+      } else {
+        Error(ComplexNumberError)
+      }
+    | #Logarithm =>
+      if a > 0.0 && b > 0.0 {
+        Ok(log(a) /. log(b))
+      } else {
+        Error(DivisionByZeroError)
+      }
     }
 
   let format = (operation: t, value, scaleBy) =>
diff --git a/packages/squiggle-lang/src/rescript/Utility/XYShape.res b/packages/squiggle-lang/src/rescript/Utility/XYShape.res
index 020acd42..d792f70e 100644
--- a/packages/squiggle-lang/src/rescript/Utility/XYShape.res
+++ b/packages/squiggle-lang/src/rescript/Utility/XYShape.res
@@ -43,6 +43,10 @@ module T = {
   let xTotalRange = (t: t) => maxX(t) -. minX(t)
   let mapX = (fn, t: t): t => {xs: E.A.fmap(fn, t.xs), ys: t.ys}
   let mapY = (fn, t: t): t => {xs: t.xs, ys: E.A.fmap(fn, t.ys)}
+  let mapYResult = (fn: float => result<float, 'e>, t: t): result<t, 'e> => {
+    let mappedYs = E.A.fmap(fn, t.ys)
+    E.A.R.firstErrorOrOpen(mappedYs)->E.R2.fmap(y => {xs: t.xs, ys: y})
+  }
   let square = mapX(x => x ** 2.0)
   let zip = ({xs, ys}: t) => Belt.Array.zip(xs, ys)
   let fromArray = ((xs, ys)): t => {xs: xs, ys: ys}