Merge pull request #2351 from quantified-uncertainty/list-methods-all…

…ow-empty-lists

Specific List functions can accept 0 elements

.changeset/slimy-seals-teach.md

@@ -0,0 +1,5 @@
+---
+"@quri/squiggle-lang": patch
+---
+
+Number.sum, product, sort, cumsum, cumprod, should all accept lists with 0 elements

packages/squiggle-lang/__tests__/library/number_test.ts

@@ -6,21 +6,30 @@ describe("Numbers", () => {
   testEvalToBe("floor(5.5)", "5");
   testEvalToBe("ceil(5.5)", "6");
   testEvalToBe("Number.abs(5.5)", "5.5");
+  testEvalToBe("Number.abs(-5.5)", "5.5");
+  testEvalToBe("Number.abs(0)", "0");
   testEvalToBe("abs(5.5)", "5.5");
   testEvalToBe("Number.exp(10)", "22026.465794806718");
   testEvalToBe("Number.log10(10)", "1");
   testEvalToBe("Number.log2(10)", "3.321928094887362");
+  testEvalToBe("Number.sum([])", "0");
   testEvalToBe("Number.sum([2,5,3])", "10");
+  testEvalToBe("sum([])", "0");
   testEvalToBe("sum([2,5,3])", "10");
+  testEvalToBe("Number.product([])", "1");
   testEvalToBe("Number.product([2,5,3])", "30");
   testEvalToBe("Number.min([2,5,3])", "2");
   testEvalToBe("Number.max([2,5,3])", "5");
   testEvalToBe("Number.mean([0,5,10])", "5");
   testEvalToBe("Number.geomean([1,5,18])", "4.481404746557164");
   testEvalToBe("Number.stdev([0,5,10,15])", "5.5901699437494745");
   testEvalToBe("Number.variance([0,5,10,15])", "31.25");
+  testEvalToBe("Number.sort([])", "[]");
   testEvalToBe("Number.sort([10,0,15,5])", "[0,5,10,15]");
+  testEvalToBe("Number.cumsum([])", "[]");
   testEvalToBe("Number.cumsum([1,5,3])", "[1,6,9]");
+  testEvalToBe("Number.cumprod([])", "[]");
   testEvalToBe("Number.cumprod([1,5,3])", "[1,5,15]");
+  testEvalToBe("Number.diff([1])", "[]");
   testEvalToBe("Number.diff([1,5,3])", "[4,-2]");
 });

packages/squiggle-lang/src/fr/number.ts

@@ -15,20 +15,24 @@ const throwEmptyList = (): never => {
   throw new REArgumentError("List is empty");
 };
 
-function makeNumberArrayToNumberDefinition(fn: (arr: number[]) => number) {
+function makeNumberArrayToNumberDefinition(
+  fn: (arr: number[]) => number,
+  throwIfEmpty = true
+) {
   return makeDefinition([frArray(frNumber)], ([arr]) => {
-    if (arr.length === 0) {
+    if (arr.length === 0 && throwIfEmpty) {
       return throwEmptyList();
     }
     return vNumber(fn(arr));
   });
 }
 
 function makeNumberArrayToNumberArrayDefinition(
-  fn: (arr: number[]) => number[]
+  fn: (arr: number[]) => number[],
+  throwIfEmpty = true
 ) {
   return makeDefinition([frArray(frNumber)], ([arr]) => {
-    if (arr.length === 0) {
+    if (arr.length === 0 && throwIfEmpty) {
       return throwEmptyList();
     }
     return vArray(fn(arr).map(vNumber));
@@ -83,15 +87,18 @@ export const library = [
     output: "Number",
     examples: [`sum([3,5,2])`],
     definitions: [
-      makeNumberArrayToNumberDefinition((arr) => E_A_Floats.sum(arr)),
+      makeNumberArrayToNumberDefinition((arr) => E_A_Floats.sum(arr), false),
     ],
   }),
   maker.make({
     name: "product",
     output: "Number",
     examples: [`product([3,5,2])`],
     definitions: [
-      makeNumberArrayToNumberDefinition((arr) => E_A_Floats.product(arr)),
+      makeNumberArrayToNumberDefinition(
+        (arr) => E_A_Floats.product(arr),
+        false
+      ),
     ],
   }),
   maker.make({
@@ -145,22 +152,29 @@ export const library = [
     output: "Array",
     examples: [`sort([3,5,2,3,5])`],
     definitions: [
-      makeNumberArrayToNumberArrayDefinition((arr) => E_A_Floats.sort(arr)),
+      makeNumberArrayToNumberArrayDefinition(
+        (arr) => E_A_Floats.sort(arr),
+        false
+      ),
     ],
   }),
   maker.make({
     name: "cumsum",
     output: "Array",
     description: "cumulative sum",
     examples: [`cumsum([3,5,2,3,5])`],
-    definitions: [makeNumberArrayToNumberArrayDefinition(E_A_Floats.cumSum)],
+    definitions: [
+      makeNumberArrayToNumberArrayDefinition(E_A_Floats.cumSum, false),
+    ],
   }),
   maker.make({
     name: "cumprod",
     description: "cumulative product",
     output: "Array",
     examples: [`cumprod([3,5,2,3,5])`],
-    definitions: [makeNumberArrayToNumberArrayDefinition(E_A_Floats.cumProd)],
+    definitions: [
+      makeNumberArrayToNumberArrayDefinition(E_A_Floats.cumProd, false),
+    ],
   }),
   maker.make({
     name: "diff",