parser for types + start moving all types to separate modules

examples/parser.js

@@ -0,0 +1,15 @@
+import { parse } from "../parser/parser.js";
+import { prettyGenT, prettyT } from "../util/pretty.js";
+
+console.log(prettyT(parse("Int"))); // Int
+
+console.log(prettyT(parse("Int * Bool"))); // (Int ⨯ Bool)
+
+console.log(prettyT(parse("(((((((Int)))) => ((Bool)))))"))); // (Int => Bool)
+
+console.log(prettyT(parse("#0((Int * #0) + Unit)"))) // #0((Int ⨯ #0) + Unit)
+
+console.log(prettyGenT(parse("∀a: #0((a * #0) + Unit"))); // ∀a: #0((a ⨯ #0) + Unit)
+
+console.log(prettyGenT(parse("∀a,b,c,d: (a*b) + (c*d)"))); // ∀a,b,c,d: ((a ⨯ b) + (c ⨯ d))
+

examples/recursive_types.js

@@ -85,3 +85,12 @@ const unified = unify(
   makeGeneric(() => linkedListOfInt));
 
 console.log(prettyGenT(unified)); // ∀: #0((Int ⨯ #0) + Unit)
+
+// unification (strange case)
+
+const unified2 = unify(
+  makeGeneric(() => listOfSetOfSelf),
+  genericList,
+);
+
+console.log(prettyGenT(unified2)); // ∀: #0[{#0}]

generics/generics.js

@@ -96,7 +96,7 @@ export const mergeTwoWay = (m1, m2) => {
 //   fType, aType: generic types to unify
 //   fStack, aStack: internal use.
 const __unify = (typeVars, fType, aType, fStack=[], aStack=[]) => {
-  console.log("__unify", {typeVars, fType, aType, fStack, aStack});
+  // console.log("__unify", {typeVars, fType, aType, fStack, aStack});
   if (typeVars.has(fType)) {
     // simplest case: formalType is a type paramater
     //   => substitute with actualType
@@ -182,12 +182,13 @@ const __unify = (typeVars, fType, aType, fStack=[], aStack=[]) => {
 export const unify = (fGenericType, aGenericType) => {
   let allTypeVars;
   [allTypeVars, fGenericType, aGenericType] = safeUnionTypeVars(fGenericType, aGenericType);
-  const {genericType} = __unify(allTypeVars, fGenericType.type, aGenericType.type);
+  const {genericType, substitutions} = __unify(allTypeVars, fGenericType.type, aGenericType.type);
+  // console.log('unification complete! substitutions:', substitutions);
   return recomputeTypeVars(genericType);
 };
 
 export const substitute = (type, substitutions, stack=[]) => {
-  console.log('substitute...', {type, substitutions, stack});
+  // console.log('substitute...', {type, substitutions, stack});
   return substitutions.get(type)
   || {
     symbol: type.symbol,

parser/parser.js

@@ -0,0 +1,174 @@
+import { Bool, Char, Double, Int, Unit } from "../primitives/types.js";
+import { dictType, fnType, lsType, prodType, setType, sumType } from "../structures/types.js";
+
+const bracketOperators = new Map([
+  ['(', [')', null]],
+  ['[', [']', lsType]],
+  ['{', ['}', setType]],
+
+  // can only occur at beginning
+  // we use these to extract the type variables
+  ['∀', [':', null]],
+]);
+
+const infixOperators = new Map([
+  ['+', sumType],
+  ['|', sumType],
+  ['⨯', prodType],
+  ['*', prodType],
+  ['→', fnType],
+  ['->', fnType],
+  ['⇒', dictType],
+  ['=>', dictType],
+
+  // only used for type variables (e.g., ∀a,b,c:)
+  [',', fnX => fnY => {
+    const x = fnX();
+    const y = fnY();
+    return Array.isArray(x) ? x.concat(y) : [x].concat(y)
+  }],
+]);
+
+const a = Symbol('a');
+const b = Symbol('b');
+const c = Symbol('c');
+const d = Symbol('d');
+const e = Symbol('e');
+
+const primitives = new Map([
+  ['Int', Int],
+  ['Double', Double],
+  ['Bool', Bool],
+  ['Char', Char],
+  ['Unit', Unit],
+  ['a', a],
+  ['b', b],
+  ['c', c],
+  ['d', d],
+  ['e', e],
+]);
+
+const TOKENS = [
+  ...bracketOperators.keys(),
+  ...[...bracketOperators.values()].map(v => v[0]),
+  ...infixOperators.keys(),
+  ...primitives.keys(),
+];
+
+// console.log('TOKENS =', TOKENS);
+
+const tokenize = expr => {
+  const tokens = [];
+  let i=0;
+  outerloop: while (i<expr.length) {
+    if (/\s/.test(expr[i])) {
+      i++;
+      continue outerloop; // skip whitespace
+    }
+    if (expr[i] === '#') {
+      const label = '#' + parseInt(expr.slice(i+1));
+      tokens.push(label);
+      i += label.length;
+      continue outerloop;
+    }
+    for (const token of TOKENS) {
+      if (expr.startsWith(token, i)) {
+        tokens.push(token);
+        i += token.length;
+        continue outerloop;
+      }
+    }
+    throw new Error(`Couldn't match any token at position ${i} in\n  ${expr}\n  ${' '.repeat(i)}^`);
+  }
+  // console.log({tokens});
+  return tokens;
+}
+
+const consumeGroup = (tokens) => {
+  const bracket = bracketOperators.get(tokens[0]);
+  if (bracket === undefined) {
+    // no group, just a single token:
+    const [firstToken, ...rest] = tokens;
+    return [[firstToken], null, rest];
+  }
+  else {
+    // find where group ends:
+    const [closing, fn] = bracket;
+    const opening = tokens[0]
+    let depth = 1;
+    let i = 1;
+    for (; i<tokens.length; i++) {
+      if (tokens[i] === opening) {
+        depth++;
+      }
+      else if (tokens[i] === closing) {
+        depth--;
+      }
+      if (depth === 0) {
+        break;
+      }
+    }
+    const tokensInGroup = tokens.slice(1, i); // don't include brackets
+    const rest = tokens.slice(i+1);
+    return [tokensInGroup, fn, rest];
+  }
+}
+
+const parseGroup = (tokensInGroup, fn, labels, label) => {
+  // console.log('parseGroup ', tokensInGroup, fn);
+  return (fn === null)
+    ? __parse(tokensInGroup, labels, label)
+    : fn(self => {
+        return __parse(tokensInGroup, extendLabels(labels, label, self));
+      });
+}
+
+const extendLabels = (labels, label, self) => {
+  return (label === null) ? labels : new Map([...labels, [label, self]])
+};
+
+const __parse = (tokens, labels = new Map(), label = null) => {
+  // console.log('parse ', tokens);
+  if (tokens[0].startsWith('#')) {
+    if (labels.has(tokens[0])) {
+      return labels.get(tokens[0]);
+    }
+    else {
+      // pass label and parse 'rest'
+      return __parse(tokens.slice(1), labels, tokens[0]);
+    }
+  }
+  if (tokens.length === 1) {
+    return primitives.get(tokens[0]);
+  }
+  else {
+    const [lhsTokens, fnGrp, rest] = consumeGroup(tokens);
+    if (rest.length === 0) {
+      return parseGroup(lhsTokens, fnGrp, labels, label);
+    }
+    const [operator, ...rhsTokens] = rest;
+    for (const [operatorChar, fn] of infixOperators) {
+      if (operator === operatorChar) {
+        return fn
+          (self => {
+            return parseGroup(lhsTokens, fnGrp, extendLabels(labels, label, self));
+          })(self => {
+            return __parse(rhsTokens, extendLabels(labels, label, self));
+          });
+      }
+    }
+    throw new Error("unknown operator: "+operator)
+  }
+};
+
+export const parse = expr => {
+  const tokens = tokenize(expr);
+  if (tokens[0] === '∀') {
+    // generic type
+    const [typeVarTokens, _, rest] = consumeGroup(tokens);
+    const typeVars = [].concat(__parse(typeVarTokens))
+    const type = __parse(rest);
+    return { typeVars, type };
+  }
+  return __parse(tokens);
+}

structures/product.js

@@ -3,52 +3,8 @@
 // A Product-type always has only two fields, called "left" and "right".
 // Product-types of more fields (called Structs) can be constructed by nesting Product-types.
 
-import { makeGeneric } from "../generics/generics.js";
-import { GenericType, Type } from "../primitives/types.js";
-import { typedFnType } from "./types.js";
-import { prodType } from "./types.js";
 
 // In JS, all products are encoded in the same way:
 export const newProduct = l => r => ({l, r});
 export const getLeft     = product => product.l;
 export const getRight    = product => product.r;
-
-export const ModuleProduct = {l: [
-  // binary type constructor
-  // Type -> Type -> Type
-  ...typedFnType(prodType, fnType =>
-    fnType
-      (Type)
-      (fnType
-        (Type)
-        (Type)
-      )
-  ),
-
-  // a -> b -> (a, b)
-  ...typedFnType(newProduct, fnType =>
-    makeGeneric((a, b) =>
-      fnType
-        (a)
-        (fnType
-          (b)
-          (prodType(() => a)(() => b))
-        )
-    ), GenericType),
-
-  // (a, b) -> a
-  ...typedFnType(getLeft, fnType =>
-    makeGeneric((a, b) =>
-      fnType
-        (prodType(() => a)(() => b))
-        (a)
-    ), GenericType),
-
-  // (a, b) -> b
-  ...typedFnType(getRight, fnType =>
-    makeGeneric((a, b) =>
-      fnType
-        (prodType(() => a)(() => b))
-        (b)
-    ), GenericType),
-]};

structures/product.types.js

@@ -0,0 +1,27 @@
+import { makeGeneric } from "../generics/generics.js";
+import { Type, GenericType } from "../primitives/types.js";
+import { newProduct, getLeft, getRight } from "./product.js";
+import { typedFnType, prodType } from "./types.js";
+
+export const ModuleProduct = {
+  l: [
+    // binary type constructor
+    // Type -> Type -> Type
+    ...typedFnType(prodType, fnType => fnType(Type)(fnType(Type)(Type)
+    )
+    ),
+
+    // a -> b -> (a, b)
+    ...typedFnType(newProduct, fnType => makeGeneric((a, b) => fnType(a)(fnType(b)(prodType(() => a)(() => b))
+    )
+    ), GenericType),
+
+    // (a, b) -> a
+    ...typedFnType(getLeft, fnType => makeGeneric((a, b) => fnType(prodType(() => a)(() => b))(a)
+    ), GenericType),
+
+    // (a, b) -> b
+    ...typedFnType(getRight, fnType => makeGeneric((a, b) => fnType(prodType(() => a)(() => b))(b)
+    ), GenericType),
+  ]
+};

structures/set.js

@@ -1,7 +1,3 @@
-import { fnType, setType } from "./types.js";
-import { Int } from "../primitives/types.js";
-import { makeGeneric } from "../generics/generics.js";
-
 import createRBTree from "functional-red-black-tree";
 import { inspect } from "node:util";
 
@@ -9,6 +5,7 @@ export class RBTreeWrapper {
   constructor(tree) {
     this.tree = tree;
   }
+  // pretty print to console
   [inspect.custom](depth, options, inspect) {
     const entries = [];
     this.tree.forEach((key,val) => {entries.push(`${inspect(key)} => ${inspect(val)}`);});
@@ -19,7 +16,6 @@ export class RBTreeWrapper {
 // (a -> a -> Int) -> Set(a)
 export const emptySet = compareFn => new RBTreeWrapper(createRBTree((x, y) => compareFn(x)(y)));
 
-// const emptySetType = makeGeneric(a => fnType(() => fnType(a)(fnType(a)(Int)))(() => set(() => a)));
 
 export const has = set => key => set.tree.get(key) === true;
 export const add = set => key => set.tree.get(key) === true ? set : new RBTreeWrapper(set.tree.insert(key, true));
@@ -42,33 +38,3 @@ export const read = iter => ifNotDone => ifDone => {
 export const forEach = set => fn => {
   set.tree.forEach(key => { fn(key); });
 };
-
-export const ModuleSet = {l:[
-  // // Type -> Type
-  // ...typedFnType(setType, fnType =>
-  //   fnType
-  //     /* in  */ (Type)
-  //     /* out */ (Type)
-  // ),
-
-  // {i: emptySet    , t: emptySetType},
-  // {i: emptySetType, t: GenericType },
-
-  // ...typedFnType(has, fnType =>
-  //   makeGeneric(a =>
-  //     fnType
-  //       /* in  */ (set(() => a))
-  //       /* out */ (fnType
-  //         /* in  */ (a)
-  //         /* out */ (Bool)
-  //       )), GenericType),
-
-  // ...typedFnType(add, fnType =>
-  //   makeGeneric(a =>
-  //     fnType
-  //       /* in  */ (set(() => a))
-  //       /* out */ (fnType
-  //         /* in  */ (a)
-  //         /* out */ (set(() => a))
-  //       )), GenericType),
-]};

structures/set.types.js

@@ -0,0 +1,31 @@
+import { makeGeneric } from "../generics/generics.js";
+import { Int } from "../primitives/types.js";
+import { emptySet, has, add } from "./set.js";
+import { fnType, setType } from "./types.js";
+
+const emptySetType = makeGeneric(a =>
+  fnType
+    // comparison function:
+    (_ => fnType
+      (_ => a)
+      (_ => fnType(_ => a)(_ => Int)))
+    // the set:
+    (_ => setType(_ => a))
+);
+
+export const ModuleSet = {
+  l: [
+    // Type -> Type
+    ...typedFnType(setType, fnType => fnType(_ => Type)(_ => Type)
+    ),
+
+    { i: emptySet, t: emptySetType },
+    { i: emptySetType, t: GenericType },
+
+    ...typedFnType(has, fnType => makeGeneric(a => fnType(_ => setType(_ => a))(_ => fnType(_ => a)(_ => Bool)
+    )), GenericType),
+
+    ...typedFnType(add, fnType => makeGeneric(a => fnType(setType(_ => a))(fnType(a)(setType(_ => a))
+    )), GenericType),
+  ]
+};

structures/types.js

@@ -52,3 +52,8 @@ export const lsType = makeTypeConstructor(symbolList)(1);
 
 export const symbolSet = Symbol('Set');
 export const setType = makeTypeConstructor(symbolSet)(1);
+
+// Dict type
+
+export const symbolDict = Symbol('Dict');
+export const dictType = makeTypeConstructor(symbolDict)(2);

type_constructor.js

@@ -39,12 +39,16 @@ const __makeTypeConstructor = (symbol, nAry, params) => {
   if (nAry === 0) {
     return { symbol, params };
   }
-  return typeParam => {
+  // only for debugging, do we give the function a name
+  const fName = `${symbol.description.toLowerCase()}Type${params.length>0?params.length:''}`;
+  return {
+    [fName]: typeParam => {
       if (typeof typeParam !== 'function') {
         throw new Error("all type params must be functions");
       }
       return __makeTypeConstructor(symbol, nAry-1, params.concat([typeParam]));
     }
+  }[fName];
 }
 
 // Creates a new nominal type

util/pretty.js

@@ -1,5 +1,5 @@
 import { inspect } from 'node:util';
-import { symbolFunction, symbolList, symbolProduct, symbolSet, symbolSum } from '../structures/types.js';
+import { symbolDict, symbolFunction, symbolList, symbolProduct, symbolSet, symbolSum } from '../structures/types.js';
 import { mapRecursiveStructure } from './util.js';
 
 export function pretty(obj) {
@@ -35,6 +35,7 @@ const renderType = (symbol, annot, params) => {
     [symbolFunction]: `${annot}(${params[0]} -> ${params[1]})`,
     [symbolSum]     : `${annot}(${params[0]} + ${params[1]})`,
     [symbolProduct] : `${annot}(${params[0]} ⨯ ${params[1]})`,
+    [symbolDict]    : `${annot}(${params[0]} => ${params[1]})`,
   }[symbol] || symbol.description;
 };