From 04abeb7cd10d5081d72d93de0a7b97cbae4908b7 Mon Sep 17 00:00:00 2001
From: Ozzie Gooen <ozzieagooen@gmail.com>
Date: Mon, 28 Mar 2022 07:56:20 -0400
Subject: [PATCH] Added todo list to GenericDist repo

---
 .../src/rescript/GenericDist/GenericDist.res  | 31 ++++++++++++-------
 .../src/rescript/GenericDist/README.md        | 15 ++++++++-
 .../rescript/pointSetDist/PointSetDist.res    |  1 +
 .../rescript/symbolicDist/SymbolicDist.res    |  1 +
 4 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/packages/squiggle-lang/src/rescript/GenericDist/GenericDist.res b/packages/squiggle-lang/src/rescript/GenericDist/GenericDist.res
index 84259de3..7cb714e6 100644
--- a/packages/squiggle-lang/src/rescript/GenericDist/GenericDist.res
+++ b/packages/squiggle-lang/src/rescript/GenericDist/GenericDist.res
@@ -100,6 +100,8 @@ module Truncate = {
   }
 }
 
+let truncate = Truncate.run
+
 /* Given two random variables A and B, this returns the distribution
    of a new variable that is the result of the operation on A and B.
    For instance, normal(0, 1) + normal(1, 1) -> normal(1, 2).
@@ -136,8 +138,9 @@ module AlgebraicCombination = {
     t1: t,
     t2: t,
   ) => {
+    let operation = Operation.Algebraic.toFn(operation)
     E.R.merge(toSampleSet(t1), toSampleSet(t2)) |> E.R.fmap(((a, b)) => {
-      Belt.Array.zip(a, b) |> E.A.fmap(((a, b)) => Operation.Algebraic.toFn(operation, a, b))
+      Belt.Array.zip(a, b) |> E.A.fmap(((a, b)) => operation(a, b))
     })
   }
 
@@ -178,6 +181,8 @@ module AlgebraicCombination = {
   }
 }
 
+let algebraicCombination = AlgebraicCombination.run
+
 //TODO: Add faster pointwiseCombine fn
 let pointwiseCombination = (toPointSet: toPointSetFn, operation, t2: t, t1: t): result<
   t,
@@ -219,14 +224,18 @@ let mixture = (
   pointwiseAdd: (genericDist, genericDist) => result<genericDist, error>,
   values: array<(genericDist, float)>,
 ) => {
-  let properlyWeightedValues =
-    values |> E.A.fmap(((dist, weight)) => scaleMultiply(dist, weight)) |> E.A.R.firstErrorOrOpen
-  properlyWeightedValues |> E.R.bind(_, values => {
-    values
-    |> Js.Array.sliceFrom(1)
-    |> E.A.fold_left(
-      (acc, x) => E.R.bind(acc, acc => pointwiseAdd(acc, x)),
-      Ok(E.A.unsafe_get(values, 0)),
-    )
-  })
+  if E.A.length(values) == 0 {
+    Error(GenericDist_Types.Other("mixture must have at least 1 element"))
+  } else {
+    let properlyWeightedValues =
+      values |> E.A.fmap(((dist, weight)) => scaleMultiply(dist, weight)) |> E.A.R.firstErrorOrOpen
+    properlyWeightedValues |> E.R.bind(_, values => {
+      values
+      |> Js.Array.sliceFrom(1)
+      |> E.A.fold_left(
+        (acc, x) => E.R.bind(acc, acc => pointwiseAdd(acc, x)),
+        Ok(E.A.unsafe_get(values, 0)),
+      )
+    })
+  }
 }
diff --git a/packages/squiggle-lang/src/rescript/GenericDist/README.md b/packages/squiggle-lang/src/rescript/GenericDist/README.md
index 9a3ca6ce..382de2b9 100644
--- a/packages/squiggle-lang/src/rescript/GenericDist/README.md
+++ b/packages/squiggle-lang/src/rescript/GenericDist/README.md
@@ -29,4 +29,17 @@ graph TD
     D --> Float(Float)
     D --> Exponential(Exponential)
     D --> Cauchy(Cauchy)
-```
\ No newline at end of file
+```
+
+## Todo
+- [ ] Lots of cleanup 
+- [ ] Add interface files
+- [ ] Simple test story
+- [ ] Provide decent stack traces for key calls in GenericOperation. This could be very useful for debugging.
+- [ ] Cleanup Sample Set library
+- [ ] Add memoization for calculations
+- [ ] Performance bechmarking reports
+- [ ] Remove most of DistPlus, much of which is not needed anymore
+- [ ] More functions for Sample Set, which is very minimal now
+- [ ] Allow these functions to be run on web workers
+- [ ] Refactor interpreter to use GenericDist. This might not be necessary, as the new reducer-inspired interpreter is integrated.
\ No newline at end of file
diff --git a/packages/squiggle-lang/src/rescript/pointSetDist/PointSetDist.res b/packages/squiggle-lang/src/rescript/pointSetDist/PointSetDist.res
index 59bead6b..834b244f 100644
--- a/packages/squiggle-lang/src/rescript/pointSetDist/PointSetDist.res
+++ b/packages/squiggle-lang/src/rescript/pointSetDist/PointSetDist.res
@@ -34,6 +34,7 @@ let toMixed = mapToAll((
     ),
 ))
 
+//TODO WARNING: The combineAlgebraicallyWithDiscrete will break for subtraction and division, like, discrete - continous
 let combineAlgebraically = (op: Operation.algebraicOperation, t1: t, t2: t): t =>
   switch (t1, t2) {
   | (Continuous(m1), Continuous(m2)) =>
diff --git a/packages/squiggle-lang/src/rescript/symbolicDist/SymbolicDist.res b/packages/squiggle-lang/src/rescript/symbolicDist/SymbolicDist.res
index 3da6bd02..d31a8393 100644
--- a/packages/squiggle-lang/src/rescript/symbolicDist/SymbolicDist.res
+++ b/packages/squiggle-lang/src/rescript/symbolicDist/SymbolicDist.res
@@ -145,6 +145,7 @@ module Uniform = {
   let mean = (t: t) => Ok(Jstat.Uniform.mean(t.low, t.high))
   let toString = ({low, high}: t) => j`Uniform($low,$high)`
   let truncate = (low, high, t: t): t => {
+//todo: add check
     let newLow = max(E.O.default(neg_infinity, low), t.low)
     let newHigh = min(E.O.default(infinity, high), t.high)
     {low: newLow, high: newHigh}