can auto-generate comparison functions for composed types

compare/registry.js

@@ -0,0 +1,25 @@
+import { SymbolBool, SymbolChar, SymbolDouble, SymbolInt, SymbolUnit } from "../primitives/types.js";
+import { symbolList, symbolProduct, symbolSet, symbolSum } from "../structures/types.js";
+import { compareBools, compareNumbers, compareStrings, compareUnits } from "./primitives.js";
+import { compareLists, compareProducts, compareSets, compareSums } from "./structures.js";
+
+const typeSymbolToCmp = new Map([
+  [SymbolInt   , compareNumbers],
+  [SymbolChar  , compareStrings],
+  [SymbolDouble, compareNumbers],
+  [SymbolBool  , compareBools],
+  [SymbolUnit  , compareUnits],
+
+  // these functions take extra comparison callbacks:
+  [symbolList   , compareLists],
+  [symbolProduct, compareProducts],
+  [symbolSum    , compareSums],
+  [symbolSet    , compareSets],
+])
+
+export const makeCompareFn = type => {
+  return type.params.reduce(
+    (acc, cur) => acc(makeCompareFn(cur)),
+    typeSymbolToCmp.get(type.symbol)
+  );
+}