reorganize directory and file structure

lib/structures/enum.js

@@ -0,0 +1,37 @@
+import { capitalizeFirstLetter } from "../util/util.js";
+import { newProduct as newProduct, getLeft } from "./product.js";
+import { newLeft, newRight, match } from "./sum.js";
+
+const eatParameters = (numParams, result) => {
+  if (numParams === 0) {
+    return result;
+  }
+  else return () => eatParameters(numParams-1, result);
+}
+
+export const makeMatchFn = variants => {
+  if (variants.length === 0) {
+    return undefined;
+  }
+  const [_, ...remainingVariants] = variants;
+  return sum => handler => {
+    return match(sum)
+        (leftValue => eatParameters(remainingVariants.length, handler(leftValue)))
+        (rightValue => makeMatchFn(remainingVariants)(rightValue));
+  };
+};
+
+export const makeConstructors = variants => {
+  if (variants.length === 0) {
+    return [];
+  }
+  const [variant, ...remainingVariants] = variants;
+  const name = getLeft(variant);
+  const ctorName = `new${capitalizeFirstLetter(name)}`;
+  const constructor = { [ctorName]: val => newLeft(val) }[ctorName];
+  return [
+    constructor,
+    ...makeConstructors(remainingVariants).map(ctor =>
+      ({[ctor.name]: val => newRight(ctor(val))}[ctor.name])),
+  ];
+}