simplify 'struct'

lib/structures/struct.js

@@ -1,33 +1,30 @@
 import { unit } from "../primitives/unit.js";
 import { capitalizeFirstLetter } from "../util/util.js";
-import { newProduct, getLeft, getRight } from "./product.js";
 
-export const makeConstructor = nParams => {
+export const makeConstructor = fieldNames => {
-  const internal = (nParams, ret) => {
+  const internal = (fieldNames, ret) => {
-    if (nParams === 0) {
+    if (fieldNames.length === 0) {
       const result = ret(unit);
       return result;
     }
     return nextParam => {
-      const wrappedName = 'wrapped_' + ret.name;
+      const [fieldName, ...rest] = fieldNames;
+      const wrappedName = 'ctor_' + fieldName;
       const newRet = {
-        [wrappedName]: inner => newProduct(nextParam)(ret(inner)),
+        [wrappedName]: inner => ({[fieldName]: nextParam, ...ret(inner)}),
       }[wrappedName];
-      return internal(nParams-1, newRet);
+      return internal(rest, newRet);
     }
   };
   const id = x => x;
-  return internal(nParams, id);
+  return internal(fieldNames, id);
 };
 
 export const makeGetters = fieldNames => {
-  if (fieldNames.length === 0) {
+  return fieldNames.map(fieldName => {
-    return [];
+    const getterName = `get${capitalizeFirstLetter(fieldName)}`;
-  }
+    return {
-  const [fieldName, ...rest] = fieldNames;
+      [getterName]: obj => obj[fieldName],
-  const getterName = `get${capitalizeFirstLetter(fieldName)}`;
+    }[getterName];
-  return [
+  })
-    { [getterName]: obj => getLeft(obj) }[getterName],
-    ...makeGetters(rest).map(getter => ({[getter.name]: obj => getter(getRight(obj))}[getter.name])),
-  ];
 };

lib/structures/struct.types.js

@@ -1,40 +1,14 @@
 import { getDefaultTypeParser } from "../parser/type_parser.js";
 import { newDynamic } from "../primitives/dynamic.js";
-import { Type, Unit } from "../primitives/primitive_types.js";
 import { zip } from "../util/util.js";
 import { map } from "./list.js";
 import { getLeft, getRight } from "./product.js";
 import { makeConstructor, makeGetters } from "./struct.js";
-import { fnType, prodType } from "./type_constructors.types.js";
+import { fnType } from "./type_constructors.types.js";
-
-
-// 'fields' is an array of (name: string, type: Type) pairs.
-// e.g.:
-//   [{l: "x", r: Double}, {l: "y", r: Double}]
-//   results in the type (Double × (Double × Unit))
-
-export const structType = (fields, rootSelf) => {
-  // console.log("structType..", fields);
-  if (fields.length === 0) {
-    return Unit;
-  }
-  const [field, ...rest] = fields;
-  const fieldType = getRight(field);
-  return prodType
-    (self => {
-      // console.log("requested left type (of structType)")
-      return fieldType(rootSelf || self);
-    })
-    (self => {
-      // console.log("requested right type (of structType)")
-      return structType(rest, self);
-    });
-};
 
 export const makeConstructorType = type => fields => {
   if (fields.length === 0) {
     return type;
-    // return structType(fields);
   }
   const [field, ...rest] = fields;
   const fieldType = getRight(field);
@@ -42,7 +16,6 @@ export const makeConstructorType = type => fields => {
 };
 
 export const makeGettersTypes = type => fields => {
-  // const type = structType(fields);
   return fields.map(field => {
     const fieldType = getRight(field);
     return fnType(_ => type)(_ => fieldType);
@@ -51,14 +24,11 @@ export const makeGettersTypes = type => fields => {
 
 export const makeModuleStruct = type => fields => {
   const fieldNames = map(fields)(getLeft);
-  // const type = structType(fields);
+  const ctor = makeConstructor(fieldNames);
-  const ctor = makeConstructor(fields.length);
+  const ctorType = makeConstructorType(type)(fields);
-  const ctorType = makeConstructorType(fields);
+  const getterTypes = makeGettersTypes(type)(fields);
-  const getterTypes = makeGettersTypes(fields);
   const getters = makeGetters(fieldNames);
   const module = [
-    // ["type", newDynamic(type)(Type)],
-
     // constructor
     ["ctor", newDynamic(ctor)(ctorType)],
 
@@ -72,6 +42,6 @@ export const makeModuleStruct = type => fields => {
 const mkType = getDefaultTypeParser();
 
 export const ModuleStruct = [
-  ["structType"      , newDynamic(structType      )(mkType("[String*Type] -> Type"     ))],
+  // ["structType"      , newDynamic(structType      )(mkType("[String*Type] -> Type"     ))],
   ["makeModuleStruct", newDynamic(makeModuleStruct)(mkType("[String*Type] -> [Dynamic]"))],
 ];

tests/struct.js

@@ -0,0 +1,38 @@
+import assert from "node:assert";
+
+import { makeTypeConstructor } from "../lib/meta/type_constructor.js";
+import { Bool, Char, Int } from "../lib/primitives/primitive_types.js";
+import { makeModuleStruct } from "../lib/structures/struct.types.js";
+import { lsType } from "../lib/structures/type_constructors.types.js";
+
+
+const symbolPerson = "Person__22a59ca589b4a7efdbe20b52f380e50f";
+
+const Person = makeTypeConstructor(symbolPerson)(0);
+
+const fields = [
+  {l: "name", r: lsType(_ => Char)},
+  {l: "age", r: Int},
+  {l: "isMale", r: Bool},
+];
+
+const [
+  [, {i: newPerson}],
+  [, {i: getName}],
+  [, {i: getAge}],
+  [, {i: getIsMale}],
+] = makeModuleStruct(Person)(fields);
+
+const expectedName = "billy";
+const expectedAge = 99;
+const expectedIsMale = true;
+
+const billy = newPerson(expectedName)(expectedAge)(expectedIsMale);
+
+const actualName = getName(billy);
+const actualAge = getAge(billy);
+const actualIsMale = getIsMale(billy);
+
+assert.equal(actualName, expectedName);
+assert.equal(actualAge, expectedAge);
+assert.equal(actualIsMale, expectedIsMale);