Added map3 to samplesMap

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

@@ -100,7 +100,25 @@ let map2 = (~fn: (float, float) => result<float, Operation.Error.t>, ~t1: t, ~t2
   t,
   Operation.Error.t,
 > => {
-  let samples = Belt.Array.zip(get(t1), get(t2))->E.A2.fmap(((a, b)) => fn(a, b))
+  let samples = E.A.zip(get(t1), get(t2))->E.A2.fmap(((a, b)) => fn(a, b))
+
+  // 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.toExnFnString(Error.sampleSetErrorToString, make(x))
+  )
+}
+
+let map3 = (
+  ~fn: (float, float, float) => result<float, Operation.Error.t>,
+  ~t1: t,
+  ~t2: t,
+  ~t3: t,
+): result<t, Operation.Error.t> => {
+  let samples = E.A.zip3(get(t1), get(t2), get(t3))->E.A2.fmap(((a, b, c)) => fn(a, b, c))
 
   // 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

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

@@ -101,15 +101,33 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
     rMappedList->Result.map(mappedList => mappedList->Belt.List.toArray->EvArray)
   }
 
-  let doMapSampleSetDist = (sampleSetDist: SampleSetDist.t, aLambdaValue) => {
-    let fn = r =>
-      switch Lambda.doLambdaCall(aLambdaValue, list{EvNumber(r)}, environment, reducer) {
+  module SampleMap = {
+    type t = SampleSetDist.t
+    let doLambdaCall = (aLambdaValue, list) =>
+      switch Lambda.doLambdaCall(aLambdaValue, list, environment, reducer) {
       | Ok(EvNumber(f)) => Ok(f)
       | _ => Error(Operation.SampleMapNeedsNtoNFunction)
       }
-    switch SampleSetDist.samplesMap(~fn, sampleSetDist) {
-    | Ok(r) => Ok(EvDistribution(SampleSet(r)))
-    | Error(r) => Error(REDistributionError(SampleSetError(r)))
+
+    let toType = r =>
+      switch r {
+      | Ok(r) => Ok(EvDistribution(SampleSet(r)))
+      | Error(r) => Error(REDistributionError(SampleSetError(r)))
+      }
+
+    let map1 = (sampleSetDist: t, aLambdaValue) => {
+      let fn = r => doLambdaCall(aLambdaValue, list{EvNumber(r)})
+      toType(SampleSetDist.samplesMap(~fn, sampleSetDist))
+    }
+
+    let map2 = (t1: t, t2: t, aLambdaValue) => {
+      let fn = (a, b) => doLambdaCall(aLambdaValue, list{EvNumber(a), EvNumber(b)})
+      SampleSetDist.map2(~fn, ~t1, ~t2)->E.R2.errMap(SampleSetDist.Error.fromOperationError)->toType
+    }
+
+    let map3 = (t1: t, t2: t, t3: t, aLambdaValue) => {
+      let fn = (a, b, c) => doLambdaCall(aLambdaValue, list{EvNumber(a), EvNumber(b), EvNumber(c)})
+      SampleSetDist.map3(~fn, ~t1, ~t2, ~t3)->E.R2.errMap(SampleSetDist.Error.fromOperationError)->toType
     }
   }
 
@@ -143,7 +161,22 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
     doKeepArray(aValueArray, aLambdaValue)
   | ("map", [EvArray(aValueArray), EvLambda(aLambdaValue)]) => doMapArray(aValueArray, aLambdaValue)
   | ("mapSamples", [EvDistribution(SampleSet(dist)), EvLambda(aLambdaValue)]) =>
-    doMapSampleSetDist(dist, aLambdaValue)
+    SampleMap.map1(dist, aLambdaValue)
+  | (
+      "mapSamples2",
+      [EvDistribution(SampleSet(dist1)), EvDistribution(SampleSet(dist2)), EvLambda(aLambdaValue)],
+    ) =>
+    SampleMap.map2(dist1, dist2, aLambdaValue)
+  | (
+      "mapSamples3",
+      [
+        EvDistribution(SampleSet(dist1)),
+        EvDistribution(SampleSet(dist2)),
+        EvDistribution(SampleSet(dist3)),
+        EvLambda(aLambdaValue),
+      ],
+    ) =>
+    SampleMap.map3(dist1, dist2, dist3, aLambdaValue)
   | ("reduce", [EvArray(aValueArray), initialValue, EvLambda(aLambdaValue)]) =>
     doReduceArray(aValueArray, initialValue, aLambdaValue)
   | ("reduceReverse", [EvArray(aValueArray), initialValue, EvLambda(aLambdaValue)]) =>

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

@@ -567,6 +567,10 @@ module A = {
   let tail = Belt.Array.sliceToEnd(_, 1)
 
   let zip = Belt.Array.zip
+  let zip3 = (a, b, c) =>
+    Belt.Array.zip(a, b)
+    -> Belt.Array.zip(c)
+    -> Belt.Array.map((((v1, v2), v3)) => (v1, v2, v3))
   // This zips while taking the longest elements of each array.
   let zipMaxLength = (array1, array2) => {
     let maxLength = Int.max(length(array1), length(array2))