From eafdfdc7b7462a9d00d61f151b859ba1baf90ac0 Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Mon, 16 May 2022 20:11:38 -0400
Subject: [PATCH] Cleanup to samplesMap() code

---
 .../rescript/Distributions/DistributionTypes.res  |  1 +
 .../Distributions/SampleSetDist/SampleSetDist.res | 15 ++++++++-------
 .../Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res |  2 +-
 packages/squiggle-lang/src/rescript/Utility/E.res |  7 +++++--
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
index a9f7dfbe..5a6865fc 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/DistributionTypes.res
@@ -37,6 +37,7 @@ module Error = {
     | LogarithmOfDistributionError(s) => `Logarithm of input error: ${s}`
     | SampleSetError(TooFewSamples) => "Too Few Samples"
     | SampleSetError(NonNumericInput(err)) => `Found a non-number in input: ${err}`
+    | SampleSetError(OperationError(err)) => Operation.Error.toString(err)
     | OperationError(err) => Operation.Error.toString(err)
     | PointSetConversionError(err) => SampleSetDist.pointsetConversionErrorToString(err)
     | SparklineError(err) => PointSetTypes.sparklineErrorToString(err)
diff --git a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
index 001c581b..834008f5 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SampleSetDist/SampleSetDist.res
@@ -1,12 +1,14 @@
 @genType
 module Error = {
   @genType
-  type sampleSetError = TooFewSamples | NonNumericInput(string)
+  type sampleSetError =
+    TooFewSamples | NonNumericInput(string) | OperationError(Operation.operationError)
 
   let sampleSetErrorToString = (err: sampleSetError): string =>
     switch err {
     | TooFewSamples => "Too few samples when constructing sample set"
     | NonNumericInput(err) => `Found a non-number in input: ${err}`
+    | OperationError(err) => Operation.Error.toString(err)
     }
 
   @genType
@@ -16,6 +18,8 @@ module Error = {
     switch err {
     | TooFewSamplesForConversionToPointSet => "Too Few Samples to convert to point set"
     }
+
+  let fromOperationError = e => OperationError(e)
 }
 
 include Error
@@ -85,13 +89,10 @@ let sampleN = (t: t, n) => {
 
 let samplesMap = (~fn: float => result<float, Operation.Error.t>, t: t): result<
   t,
-  Operation.Error.t,
+  sampleSetError,
 > => {
   let samples = T.get(t)->E.A2.fmap(fn)
-
-  E.A.R.firstErrorOrOpen(samples)->E.R2.fmap(x =>
-    E.R.toExn("Input of samples should be larger than 5", make(x))
-  )
+  E.A.R.firstErrorOrOpen(samples)->E.R2.errMap(Error.fromOperationError) |> E.R2.bind(make)
 }
 
 //TODO: Figure out what to do if distributions are different lengths. ``zip`` is kind of inelegant for this.
@@ -107,7 +108,7 @@ let map2 = (~fn: (float, float) => result<float, Operation.Error.t>, ~t1: t, ~t2
   // 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.toExn("Input of samples should be larger than 5", make(x))
+    E.R.toExnFnString(Error.sampleSetErrorToString, make(x))
   )
 }
 
diff --git a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
index 232c4364..cd16e1fe 100644
--- a/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
+++ b/packages/squiggle-lang/src/rescript/Reducer/Reducer_Dispatch/Reducer_Dispatch_BuiltIn.res
@@ -107,7 +107,7 @@ let callInternal = (call: functionCall, environment, reducer: ExpressionT.reduce
       }
     switch SampleSetDist.samplesMap(~fn, sampleSetDist) {
     | Ok(r) => Ok(EvDistribution(SampleSet(r)))
-    | Error(r) => Error(REOperationError(r))
+    | Error(r) => Error(REDistributionError(SampleSetError(r)))
     }
   }
 
diff --git a/packages/squiggle-lang/src/rescript/Utility/E.res b/packages/squiggle-lang/src/rescript/Utility/E.res
index 15678e1a..fb682f78 100644
--- a/packages/squiggle-lang/src/rescript/Utility/E.res
+++ b/packages/squiggle-lang/src/rescript/Utility/E.res
@@ -235,13 +235,16 @@ module R = {
     | Ok(a) => f(a)
     | Error(err) => Error(err)
     }
-
   let toExn = (msg: string, x: result<'a, 'b>): 'a =>
     switch x {
     | Ok(r) => r
     | Error(_) => raise(Assertion(msg))
     }
-
+  let toExnFnString = (errorToStringFn, o) =>
+    switch o {
+    | Ok(r) => r
+    | Error(r) => raise(Assertion(errorToStringFn(r)))
+    }
   let default = (default, res: Belt.Result.t<'a, 'b>) =>
     switch res {
     | Ok(r) => r