Remove NaN from pointwise operations

packages/squiggle-lang/__tests__/Distributions/Invariants/Means_test.res

@@ -50,7 +50,11 @@ module Internals = {
     let dist1 = dist1'->DistributionTypes.Symbolic
     let dist2 = dist2'->DistributionTypes.Symbolic
     let received =
-      distOp(dist1, dist2)->E.R2.fmap(mean)->E.R2.fmap(run)->E.R2.fmap(toFloat)->E.R.toExn("Expected float", _)
+      distOp(dist1, dist2)
+      ->E.R2.fmap(mean)
+      ->E.R2.fmap(run)
+      ->E.R2.fmap(toFloat)
+      ->E.R.toExn("Expected float", _)
     let expected = floatOp(runMean(dist1), runMean(dist2))
     switch received {
     | None => expectImpossiblePath(description)

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

@@ -97,12 +97,6 @@ describe("eval on distribution functions", () => {
     testEval("log10(uniform(5,8))", "Ok(Sample Set Distribution)")
   })
 
-  describe("dotLog", () => {
-    testEval("dotLog(normal(5,2), 3)", "Ok(Point Set Distribution)")
-    testEval("dotLog(normal(5,2), 3)", "Ok(Point Set Distribution)")
-    testEval("dotLog(normal(5,2), normal(10,1))", "Ok(Point Set Distribution)")
-  })
-
   describe("dotAdd", () => {
     testEval("dotAdd(normal(5,2), lognormal(10,2))", "Ok(Point Set Distribution)")
     testEval("dotAdd(normal(5,2), 3)", "Ok(Point Set Distribution)")

packages/squiggle-lang/jest.config.js

@@ -2,6 +2,7 @@
 module.exports = {
   preset: "ts-jest",
   testEnvironment: "node",
+  bail: true,
   setupFilesAfterEnv: [
     "<rootdir>/../../node_modules/bisect_ppx/src/runtime/js/jest.bs.js",
   ],

packages/squiggle-lang/src/rescript/Distributions/DistributionOperation/DistributionOperation.res

@@ -160,14 +160,14 @@ let rec run = (~env, functionCallInfo: functionCallInfo): outputType => {
       ->GenericDist.algebraicCombination(~toPointSetFn, ~toSampleSetFn, ~arithmeticOperation, ~t2)
       ->E.R2.fmap(r => Dist(r))
       ->OutputLocal.fromResult
-    | ToDistCombination(Pointwise, arithmeticOperation, #Dist(t2)) =>
+    | ToDistCombination(Pointwise, algebraicCombination, #Dist(t2)) =>
       dist
-      ->GenericDist.pointwiseCombination(~toPointSetFn, ~arithmeticOperation, ~t2)
+      ->GenericDist.pointwiseCombination(~toPointSetFn, ~algebraicCombination, ~t2)
       ->E.R2.fmap(r => Dist(r))
       ->OutputLocal.fromResult
-    | ToDistCombination(Pointwise, arithmeticOperation, #Float(f)) =>
+    | ToDistCombination(Pointwise, algebraicCombination, #Float(f)) =>
       dist
-      ->GenericDist.pointwiseCombinationFloat(~toPointSetFn, ~arithmeticOperation, ~f)
+      ->GenericDist.pointwiseCombinationFloat(~toPointSetFn, ~algebraicCombination, ~f)
       ->E.R2.fmap(r => Dist(r))
       ->OutputLocal.fromResult
     }

packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res

@@ -46,30 +46,14 @@ module Error = {
 }
 
 @genType
-module Operation = {
+module DistributionOperation = {
+  @genType
+  type pointsetXSelection = [#Linear | #ByWeight]
+
   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)
@@ -78,11 +62,6 @@ module Operation = {
     | #Sample
   ]
 
-  @genType
-  type pointsetXSelection = [#Linear | #ByWeight]
-}
-
-module DistributionOperation = {
   type toDist =
     | Normalize
     | ToPointSet
@@ -99,13 +78,9 @@ module DistributionOperation = {
     | ToSparkline(int)
 
   type fromDist =
-    | ToFloat(Operation.toFloat)
+    | ToFloat(toFloat)
     | ToDist(toDist)
-    | ToDistCombination(
-        Operation.direction,
-        Operation.arithmeticOperation,
-        [#Dist(genericDist) | #Float(float)],
-      )
+    | ToDistCombination(direction, Operation.Algebraic.t, [#Dist(genericDist) | #Float(float)])
     | ToString(toString)
     | ToBool(toBool)
 

packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.res

@@ -68,7 +68,7 @@ let toPointSet = (
   t,
   ~xyPointLength,
   ~sampleCount,
-  ~xSelection: DistributionTypes.Operation.pointsetXSelection=#ByWeight,
+  ~xSelection: DistributionTypes.DistributionOperation.pointsetXSelection=#ByWeight,
   (),
 ): result<PointSetTypes.pointSetDist, error> => {
   switch (t: t) {
@@ -148,7 +148,7 @@ let truncate = Truncate.run
 */
 module AlgebraicCombination = {
   let tryAnalyticalSimplification = (
-    arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+    arithmeticOperation: Operation.algebraicOperation,
     t1: t,
     t2: t,
   ): option<result<SymbolicDistTypes.symbolicDist, Operation.Error.invalidOperationError>> =>
@@ -174,7 +174,7 @@ module AlgebraicCombination = {
 
   let runMonteCarlo = (
     toSampleSet: toSampleSetFn,
-    arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+    arithmeticOperation: Operation.algebraicOperation,
     t1: t,
     t2: t,
   ): result<t, error> => {
@@ -241,27 +241,23 @@ let algebraicCombination = AlgebraicCombination.run
 let pointwiseCombination = (
   t1: t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation,
+  ~algebraicCombination: Operation.algebraicOperation,
   ~t2: t,
 ): result<t, error> => {
-  E.R.merge(toPointSetFn(t1), toPointSetFn(t2))
-  ->E.R2.fmap(((t1, t2)) =>
-    PointSetDist.combinePointwise(
-      DistributionTypes.Operation.arithmeticToFn(arithmeticOperation),
-      t1,
-      t2,
-    )
+  E.R.merge(toPointSetFn(t1), toPointSetFn(t2))->E.R.bind(((t1, t2)) =>
+    PointSetDist.combinePointwise(Operation.Algebraic.toFn(algebraicCombination), t1, t2)
+    ->E.R2.fmap(r => DistributionTypes.PointSet(r))
+    ->E.R2.errMap(err => DistributionTypes.OperationError(err))
   )
-  ->E.R2.fmap(r => DistributionTypes.PointSet(r))
 }
 
 let pointwiseCombinationFloat = (
   t: t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~algebraicCombination: Operation.algebraicOperation,
   ~f: float,
 ): result<t, error> => {
-  let m = switch arithmeticOperation {
+  let m = switch algebraicCombination {
   | #Add | #Subtract => Error(DistributionTypes.DistributionVerticalShiftIsInvalid)
   | (#Multiply | #Divide | #Power | #Logarithm) as arithmeticOperation =>
     toPointSetFn(t)->E.R.bind(t => {

packages/squiggle-lang/src/rescript/Distributions/GenericDist/GenericDist.resi

@@ -28,7 +28,7 @@ let toPointSet: (
   t,
   ~xyPointLength: int,
   ~sampleCount: int,
-  ~xSelection: DistributionTypes.Operation.pointsetXSelection=?,
+  ~xSelection: DistributionTypes.DistributionOperation.pointsetXSelection=?,
   unit,
 ) => result<PointSetTypes.pointSetDist, error>
 let toSparkline: (t, ~sampleCount: int, ~bucketCount: int=?, unit) => result<string, error>
@@ -45,21 +45,21 @@ let algebraicCombination: (
   t,
   ~toPointSetFn: toPointSetFn,
   ~toSampleSetFn: toSampleSetFn,
-  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~arithmeticOperation: Operation.algebraicOperation,
   ~t2: t,
 ) => result<t, error>
 
 let pointwiseCombination: (
   t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~algebraicCombination: Operation.algebraicOperation,
   ~t2: t,
 ) => result<t, error>
 
 let pointwiseCombinationFloat: (
   t,
   ~toPointSetFn: toPointSetFn,
-  ~arithmeticOperation: DistributionTypes.Operation.arithmeticOperation,
+  ~algebraicCombination: Operation.algebraicOperation,
   ~f: float,
 ) => result<t, error>
 

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

@@ -243,10 +243,13 @@ let combineShapesContinuousDiscrete = (
   outXYShapes
   |> E.A.fmap(XYShape.T.fromZippedArray)
   |> E.A.fold_left(
-    XYShape.PointwiseCombination.combine(
-      \"+.",
-      XYShape.XtoY.continuousInterpolator(#Linear, #UseZero),
-    ),
+    (acc, x) =>
+      XYShape.PointwiseCombination.combine(
+        (a, b) => Ok(a +. b),
+        XYShape.XtoY.continuousInterpolator(#Linear, #UseZero),
+        acc,
+        x,
+      )->E.R.toExn("Error, unexpected failure", _),
     XYShape.T.empty,
   )
 }

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

@@ -88,10 +88,10 @@ let stepwiseToLinear = (t: t): t =>
 let combinePointwise = (
   ~integralSumCachesFn=(_, _) => None,
   ~distributionType: PointSetTypes.distributionType=#PDF,
-  fn: (float, float) => float,
+  fn: (float, float) => result<float, Operation.Error.invalidOperationError>,
   t1: PointSetTypes.continuousShape,
   t2: PointSetTypes.continuousShape,
-): PointSetTypes.continuousShape => {
+): result<PointSetTypes.continuousShape, 'e> => {
   // If we're adding the distributions, and we know the total of each, then we
   // can just sum them up. Otherwise, all bets are off.
   let combinedIntegralSum = Common.combineIntegralSums(
@@ -119,9 +119,8 @@ let combinePointwise = (
 
   let interpolator = XYShape.XtoY.continuousInterpolator(t1.interpolation, extrapolation)
 
-  make(
-    ~integralSumCache=combinedIntegralSum,
-    XYShape.PointwiseCombination.combine(fn, interpolator, t1.xyShape, t2.xyShape),
+  XYShape.PointwiseCombination.combine(fn, interpolator, t1.xyShape, t2.xyShape)->E.R2.fmap(x =>
+    make(~integralSumCache=combinedIntegralSum, x)
   )
 }
 
@@ -140,11 +139,25 @@ let updateIntegralSumCache = (integralSumCache, t: t): t => {
 
 let updateIntegralCache = (integralCache, t: t): t => {...t, integralCache: integralCache}
 
+let sum = (
+  ~integralSumCachesFn: (float, float) => option<float>=(_, _) => None,
+  continuousShapes,
+): t =>
+  continuousShapes |> E.A.fold_left(
+    (x, y) =>
+      combinePointwise(~integralSumCachesFn, (a, b) => Ok(a +. b), x, y)->E.R.toExn(
+        "Addition should never fail",
+        _,
+      ),
+    empty,
+  )
+
 let reduce = (
   ~integralSumCachesFn: (float, float) => option<float>=(_, _) => None,
-  fn,
+  fn: (float, float) => result<float, 'e>,
   continuousShapes,
-) => continuousShapes |> E.A.fold_left(combinePointwise(~integralSumCachesFn, fn), empty)
+): result<t, 'e> =>
+  continuousShapes |> E.A.R.foldM(combinePointwise(~integralSumCachesFn, fn), empty)
 
 let mapYResult = (
   ~integralSumCacheFn=_ => None,

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

@@ -49,11 +49,11 @@ let combinePointwise = (
   make(
     ~integralSumCache=combinedIntegralSum,
     XYShape.PointwiseCombination.combine(
-      \"+.",
+      (a, b) => Ok(a +. b),
       XYShape.XtoY.discreteInterpolator,
       t1.xyShape,
       t2.xyShape,
-    ),
+    )->E.R.toExn("Addition operation should never fail", _),
   )
 }
 

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

@@ -146,8 +146,7 @@ module T = Dist({
       let discreteIntegral = Continuous.stepwiseToLinear(Discrete.T.Integral.get(t.discrete))
 
       Continuous.make(
-        XYShape.PointwiseCombination.combine(
-          \"+.",
+        XYShape.PointwiseCombination.addCombine(
           XYShape.XtoY.continuousInterpolator(#Linear, #UseOutermostPoints),
           Continuous.getShape(continuousIntegral),
           Continuous.getShape(discreteIntegral),
@@ -280,7 +279,7 @@ let combineAlgebraically = (op: Operation.convolutionOperation, t1: t, t2: t): t
   let ccConvResult = Continuous.combineAlgebraically(op, t1.continuous, t2.continuous)
   let dcConvResult = Continuous.combineAlgebraicallyWithDiscrete(op, t2.continuous, t1.discrete)
   let cdConvResult = Continuous.combineAlgebraicallyWithDiscrete(op, t1.continuous, t2.discrete)
-  let continuousConvResult = Continuous.reduce(\"+.", [ccConvResult, dcConvResult, cdConvResult])
+  let continuousConvResult = Continuous.sum([ccConvResult, dcConvResult, cdConvResult])
 
   // ... finally, discrete (*) discrete => discrete, obviously:
   let discreteConvResult = Discrete.combineAlgebraically(op, t1.discrete, t2.discrete)
@@ -302,10 +301,10 @@ let combineAlgebraically = (op: Operation.convolutionOperation, t1: t, t2: t): t
 let combinePointwise = (
   ~integralSumCachesFn=(_, _) => None,
   ~integralCachesFn=(_, _) => None,
-  fn,
+  fn: (float, float) => result<float, 'e>,
   t1: t,
   t2: t,
-): t => {
+): result<t, 'e> => {
   let reducedDiscrete =
     [t1, t2] |> E.A.fmap(toDiscrete) |> E.A.O.concatSomes |> Discrete.reduce(~integralSumCachesFn)
 
@@ -326,11 +325,12 @@ let combinePointwise = (
     t1.integralCache,
     t2.integralCache,
   )
-
-  make(
-    ~integralSumCache=combinedIntegralSum,
-    ~integralCache=combinedIntegral,
-    ~discrete=reducedDiscrete,
-    ~continuous=reducedContinuous,
+  reducedContinuous->E.R2.fmap(continuous =>
+    make(
+      ~integralSumCache=combinedIntegralSum,
+      ~integralCache=combinedIntegral,
+      ~discrete=reducedDiscrete,
+      ~continuous,
+    )
   )
 }

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

@@ -60,19 +60,28 @@ let combinePointwise = (
     PointSetTypes.continuousShape,
     PointSetTypes.continuousShape,
   ) => option<PointSetTypes.continuousShape>=(_, _) => None,
-  fn,
+  fn: (float, float) => result<float, Operation.Error.invalidOperationError>,
   t1: t,
   t2: t,
-) =>
+): result<PointSetTypes.pointSetDist, Operation.Error.invalidOperationError> =>
   switch (t1, t2) {
   | (Continuous(m1), Continuous(m2)) =>
-    PointSetTypes.Continuous(Continuous.combinePointwise(~integralSumCachesFn, fn, m1, m2))
+    Continuous.combinePointwise(
+      ~integralSumCachesFn,
+      fn,
+      m1,
+      m2,
+    )->E.R2.fmap(x => PointSetTypes.Continuous(x))
   | (Discrete(m1), Discrete(m2)) =>
-    PointSetTypes.Discrete(Discrete.combinePointwise(~integralSumCachesFn, m1, m2))
+    Ok(PointSetTypes.Discrete(Discrete.combinePointwise(~integralSumCachesFn, m1, m2)))
   | (m1, m2) =>
-    PointSetTypes.Mixed(
-      Mixed.combinePointwise(~integralSumCachesFn, ~integralCachesFn, fn, toMixed(m1), toMixed(m2)),
-    )
+    Mixed.combinePointwise(
+      ~integralSumCachesFn,
+      ~integralCachesFn,
+      fn,
+      toMixed(m1),
+      toMixed(m2),
+    )->E.R2.fmap(x => PointSetTypes.Mixed(x))
   }
 
 module T = Dist({

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

@@ -24,7 +24,6 @@ module Helpers = {
     | "dotPow" => #Power
     | "multiply" => #Multiply
     | "dotMultiply" => #Multiply
-    | "dotLog" => #Logarithm
     | _ => #Multiply
     }
 
@@ -41,7 +40,7 @@ module Helpers = {
   }
 
   let toFloatFn = (
-    fnCall: DistributionTypes.Operation.toFloat,
+    fnCall: DistributionTypes.DistributionOperation.toFloat,
     dist: DistributionTypes.genericDist,
   ) => {
     FromDist(DistributionTypes.DistributionOperation.ToFloat(fnCall), dist)
@@ -243,15 +242,12 @@ let dispatchToGenericOutput = (call: ExpressionValue.functionCall): option<
       | "dotMultiply"
       | "dotSubtract"
       | "dotDivide"
-      | "dotPow"
-      | "dotLog") as arithmetic,
+      | "dotPow") as arithmetic,
       [_, _] as args,
     ) =>
     Helpers.catchAndConvertTwoArgsToDists(args)->E.O2.fmap(((fst, snd)) =>
       Helpers.twoDiststoDistFn(Pointwise, arithmetic, fst, snd)
     )
-  | ("dotLog", [EvDistribution(a)]) =>
-    Helpers.twoDiststoDistFn(Pointwise, "dotLog", a, GenericDist.fromFloat(Math.e))->Some
   | ("dotExp", [EvDistribution(a)]) =>
     Helpers.twoDiststoDistFn(Pointwise, "dotPow", GenericDist.fromFloat(Math.e), a)->Some
   | _ => None

packages/squiggle-lang/src/rescript/Utility/E.res

@@ -192,6 +192,7 @@ module R = {
     | Ok(f) => fmap(f, a)
     | Error(err) => Error(err)
     }
+
   // (a1 -> a2 -> r) -> m a1 -> m a2 -> m r  // not in Rationale
   let liftM2: (('a, 'b) => 'c, result<'a, 'd>, result<'b, 'd>) => result<'c, 'd> = (op, xR, yR) => {
     ap'(fmap(op, xR), yR)
@@ -444,6 +445,31 @@ module A = {
       bringErrorUp |> Belt.Result.map(_, forceOpen)
     }
     let filterOk = (x: array<result<'a, 'b>>): array<'a> => fmap(R.toOption, x)->O.concatSomes
+
+    let forM = (x: array<'a>, fn: 'a => result<'b, 'c>): result<array<'b>, 'c> =>
+      firstErrorOrOpen(fmap(fn, x))
+
+    let foldM = (fn: ('c, 'a) => result<'b, 'e>, init: 'c, x: array<'a>): result<'c, 'e> => {
+      let acc = ref(init)
+      let final = ref(Ok())
+      let break = ref(false)
+      let i = ref(0)
+
+      while break.contents != true && i.contents < length(x) {
+        switch fn(acc.contents, x[i.contents]) {
+        | Ok(r) => acc := r
+        | Error(err) => {
+            final := Error(err)
+            break := true
+          }
+        }
+        i := i.contents + 1
+      }
+      switch final.contents {
+      | Ok(_) => Ok(acc.contents)
+      | Error(err) => Error(err)
+      }
+    }
   }
 
   module Sorted = {

packages/squiggle-lang/src/rescript/Utility/Operation.res

@@ -51,6 +51,31 @@ module Error = {
     }
 }
 
+let power = (a: float, b: float): result<float, Error.invalidOperationError> =>
+  if a >= 0.0 {
+    Ok(a ** b)
+  } else {
+    Error(ComplexNumberError)
+  }
+
+let divide = (a: float, b: float): result<float, Error.invalidOperationError> =>
+  if b != 0.0 {
+    Ok(a /. b)
+  } else {
+    Error(DivisionByZeroError)
+  }
+
+let logarithm = (a: float, b: float): result<float, Error.invalidOperationError> =>
+  if b == 1. {
+    Error(DivisionByZeroError)
+  } else if b == 0. {
+    Ok(0.)
+  } else if a > 0.0 && b > 0.0 {
+    Ok(log(a) /. log(b))
+  } else {
+    Error(ComplexNumberError)
+  }
+
 module Algebraic = {
   type t = algebraicOperation
   let toFn: (t, float, float) => result<float, Error.invalidOperationError> = (x, a, b) =>
@@ -58,26 +83,9 @@ module Algebraic = {
     | #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 b == 1. {
-        Error(DivisionByZeroError)
-      } else if a > 0.0 && b > 0.0 {
-        Ok(log(a) /. log(b))
-      } else {
-        Error(ComplexNumberError)
-      }
+    | #Power => power(a, b)
+    | #Divide => divide(a, b)
+    | #Logarithm => logarithm(a, b)
     }
 
   let toString = x =>
@@ -124,24 +132,9 @@ module Scale = {
   let toFn = (x: t, a: float, b: float): result<float, Error.invalidOperationError> =>
     switch x {
     | #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)
-      }
+    | #Divide => divide(a, b)
+    | #Power => power(a, b)
+    | #Logarithm => logarithm(a, b)
     }
 
   let format = (operation: t, value, scaleBy) =>

packages/squiggle-lang/src/rescript/Utility/XYShape.res

@@ -233,7 +233,12 @@ module Zipped = {
 
 module PointwiseCombination = {
   // t1Interpolator and t2Interpolator are functions from XYShape.XtoY, e.g. linearBetweenPointsExtrapolateFlat.
-  let combine: ((float, float) => float, interpolator, T.t, T.t) => T.t = %raw(`
+  let combine: (
+    (float, float) => result<float, Operation.Error.invalidOperationError>,
+    interpolator,
+    T.t,
+    T.t,
+  ) => result<T.t, Operation.Error.invalidOperationError> = %raw(`
       // This function combines two xyShapes by looping through both of them simultaneously.
       // It always moves on to the next smallest x, whether that's in the first or second input's xs,
       // and interpolates the value on the other side, thus accumulating xs and ys.
@@ -281,13 +286,28 @@ module PointwiseCombination = {
           }
 
           outX.push(x);
-          outY.push(fn(ya, yb));
+
+          // Here I check whether the operation was a success. If it was
+          // keep going. Otherwise, stop and throw the error back to user
+          let newY = fn(ya, yb);
+          if(newY.TAG === 0){
+            outY.push(newY._0);
+          }
+          else {
+            return newY;
+          }
         }
 
-        return {xs: outX, ys: outY};
+        return {TAG: 0, _0: {xs: outX, ys: outY}, [Symbol.for("name")]: "Ok"};
       }
     `)
 
+  let addCombine = (interpolator: interpolator, t1: T.t, t2: T.t): T.t =>
+    combine((a, b) => Ok(a +. b), interpolator, t1, t2)->E.R.toExn(
+      "Add operation should never fail",
+      _,
+    )
+
   let combineEvenXs = (~fn, ~xToYSelection, sampleCount, t1: T.t, t2: T.t) =>
     switch (E.A.length(t1.xs), E.A.length(t2.xs)) {
     | (0, 0) => T.empty

packages/website/docs/Features/Functions.mdx

@@ -255,16 +255,6 @@ dist2 = triangular(1,2,3)
 dist1 .^ dist2`}
 />
 
-### Pointwise logarithm
-
-TODO: write about the semantics and the case handling re scalar vs. dist and log base.
-
-<SquiggleEditor
-  initialSquiggleString={`dist1 = 1 to 10
-dist2 = triangular(1,2,3)
-dotLog(dist1, dist2)`}
-/>
-
 ## Standard functions on distributions
 
 ### Probability density function