Refactor and rename checkOrdered

packages/squiggle-lang/__tests__/Distributions/AlgebraicShapeCombination_test.res

@@ -4,7 +4,7 @@ open TestHelpers
 describe("combine with discrete", () => {
   makeTest(
     "keep order when multiplying by negative number",
-    AlgebraicShapeCombination.checkOrdered(
+    AlgebraicShapeCombination.isOrdered(
       AlgebraicShapeCombination.combineShapesContinuousDiscrete(
         #Multiply,
         {xs: [0., 1.], ys: [1., 1.]},

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

@@ -255,4 +255,4 @@ let combineShapesContinuousDiscrete = (
   )
 }
 
-let checkOrdered = (a: XYShape.T.t): bool => a.xs[0] < a.xs[1]
+let isOrdered = (a: XYShape.T.t): bool => E.A.Sorted.Floats.isSorted(a.xs)

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

@@ -363,6 +363,9 @@ module A = {
       |> Rationale.Result.return
     }
 
+  let tail = Belt.Array.sliceToEnd(_, 1)
+
+  let zip = Belt.Array.zip
   // This zips while taking the longest elements of each array.
   let zipMaxLength = (array1, array2) => {
     let maxLength = Int.max(length(array1), length(array2))
@@ -506,6 +509,9 @@ module A = {
     }
 
     module Floats = {
+      let isSorted = (ar: array<float>): bool =>
+        reduce(zip(ar, tail(ar)), true, (acc, (first, second)) => acc && first < second)
+
       let makeIncrementalUp = (a, b) =>
         Array.make(b - a + 1, a) |> Array.mapi((i, c) => c + i) |> Belt.Array.map(_, float_of_int)