Adding better error messages to XYShape validator

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

@@ -584,6 +584,7 @@ module A = {
 module A2 = {
   let fmap = (a, b) => A.fmap(b, a)
   let joinWith = (a, b) => A.joinWith(b, a)
+  let filter = (a,b) => A.filter(b, a)
 }
 
 module JsArray = {

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

@@ -0,0 +1,29 @@
+type property = {fnName: string, propertyName: string}
+
+type rec error =
+  | NotSorted(property)
+  | IsEmpty(property)
+  | NotFinite(property, float)
+  | DifferentLengths({fnName: string, p1Name: string, p2Name: string, p1Length: int, p2Length: int})
+  | Multiple(array<error>)
+
+let mapErrorArrayToError = (errors: array<error>): option<error> => {
+  switch errors {
+  | [] => None
+  | [error] => Some(error)
+  | _ => Some(Multiple(errors))
+  }
+}
+
+let rec toString = (t: error) =>
+  switch t {
+  | NotSorted({fnName, propertyName}) => `${fnName} ${propertyName} is not sorted`
+  | IsEmpty({fnName, propertyName}) => `${fnName} ${propertyName} is empty`
+  | NotFinite({fnName, propertyName}, exampleValue) =>
+    `${fnName}  ${propertyName} is not finite. Example value: ${E.Float.toString(exampleValue)}`
+  | DifferentLengths({fnName, p1Name, p2Name, p1Length, p2Length}) =>
+    `${fnName} ${p1Name} and ${p2Name} have different lengths. ${p1Name} has length ${E.I.toString(
+        p1Length,
+      )} and ${p2Name} has length ${E.I.toString(p2Length)}`
+  | Multiple(errors) => `Multiple Errors: ${E.A2.fmap(errors, toString) |> E.A.joinWith(", ")}`
+  }

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

@@ -62,13 +62,39 @@ module T = {
   let toJs = (t: t) => {"xs": t.xs, "ys": t.ys}
 }
 
-module Validates = {
+module Validator = {
   type t = T.t
+  let fnName = "XYShape validate"
+  let property = (propertyName: string): Errors.property => {
+    fnName: fnName,
+    propertyName: propertyName,
+  }
+  let notSortedError = (p: string): Errors.error => NotSorted(property(p))
+  let notFiniteError = (p, exampleValue): Errors.error => NotFinite(property(p), exampleValue)
+  let isEmptyError = (propertyName): Errors.error => IsEmpty(property(propertyName))
+  let differentLengthsError = (t): Errors.error => DifferentLengths({
+    fnName: fnName,
+    p1Name: "Xs",
+    p2Name: "Ys",
+    p1Length: E.A.length(T.xs(t)),
+    p2Length: E.A.length(T.ys(t)),
+  })
+
   let areXsSorted = (t: t) => E.A.Floats.isSorted(T.xs(t))
+  let areXsEmpty = (t: t) => E.A.length(t.xs) == 0
+  let getNonFiniteXs = (t: t) => t->T.xs->E.A.Floats.getNonFinite
+  let getNonFiniteYs = (t: t) => t->T.ys->E.A.Floats.getNonFinite
+
   let validate = (t: t) => {
-    let xsNotSorted = E.A.Floats.isSorted(T.xs(t)) ? None : Some("Xs are not sorted")
-    let xsNotFinite = E.A.Floats.getNonFinite(T.xs(t)) |> E.O.fmap(r => `Xs contain non-finite values: ${E.Float.toString(r)}`)
-    let ysNotFinite = E.A.Floats.getNonFinite(T.ys(t)) |> E.O.fmap(r => `Ys contain non-finite values: ${E.Float.toString(r)}`)
+    let xsNotSorted = areXsSorted(t) ? None : Some(notSortedError("Xs"))
+    let xsEmpty = areXsEmpty(t) ? None : Some(isEmptyError("Xs"))
+    let differentLengths =
+      E.A.length(T.xs(t)) !== E.A.length(T.ys(t)) ? Some(differentLengthsError(t)) : None
+    let xsNotFinite = getNonFiniteXs(t)->E.O2.fmap(notFiniteError("Xs"))
+    let ysNotFinite = getNonFiniteYs(t)->E.O2.fmap(notFiniteError("Ys"))
+    [xsNotSorted, xsEmpty, differentLengths, xsNotFinite, ysNotFinite]
+    ->E.A.O.concatSomes
+    ->Errors.mapErrorArrayToError
   }
 }