reorganize directory and file structure

lib/structures/struct.js

@@ -0,0 +1,33 @@
+import { unit } from "../primitives/unit.js";
+import { capitalizeFirstLetter } from "../util/util.js";
+import { newProduct, getLeft, getRight } from "./product.js";
+
+export const makeConstructor = nParams => {
+  const internal = (nParams, ret) => {
+    if (nParams === 0) {
+      const result = ret(unit);
+      return result;
+    }
+    return nextParam => {
+      const wrappedName = 'wrapped_' + ret.name;
+      const newRet = {
+        [wrappedName]: inner => newProduct(nextParam)(ret(inner)),
+      }[wrappedName];
+      return internal(nParams-1, newRet);
+    }
+  };
+  const id = x => x;
+  return internal(nParams, id);
+};
+
+export const makeGetters = fieldNames => {
+  if (fieldNames.length === 0) {
+    return [];
+  }
+  const [fieldName, ...rest] = fieldNames;
+  const getterName = `get${capitalizeFirstLetter(fieldName)}`;
+  return [
+    { [getterName]: obj => getLeft(obj) }[getterName],
+    ...makeGetters(rest).map(getter => ({[getter.name]: obj => getter(getRight(obj))}[getter.name])),
+  ];
+};