turn the function for creating new types (or type constructors) into a DOPE function

generics/generics.js

@@ -23,7 +23,7 @@ export const makeGeneric = callback => {
 
 // From the given set of type variables, return only those that occur in the given type.
 export const occurring = (type, typeVars) => {
-  console.log("occurring", type, typeVars);
+  // console.log("occurring", type);
   
   if (typeVars.has(type)) {
     // type IS a type variable:

lib/symbol.js

@@ -1,4 +1,4 @@
-import { constructSymbol, eqSymbol, getName } from "../primitives/symbol.js";
+import { eqSymbol, getName } from "../primitives/symbol.js";
 import { Bool, SymbolT, Type } from "../primitives/types.js";
 import { String } from "../structures/list.js";
 import { typedFnType } from "../structures/types.js";
@@ -6,11 +6,11 @@ import { typedFnType } from "../structures/types.js";
 export const ModuleSymbol = {l:[
   {i: SymbolT, t: Type},
 
-  ...typedFnType(constructSymbol, fnType =>
-    fnType
-      (String)
-      (SymbolT)
-  ),
+  // ...typedFnType(constructSymbol, fnType =>
+  //   fnType
+  //     (String)
+  //     (SymbolT)
+  // ),
 
   ...typedFnType(getName, fnType =>
     fnType

primitives/symbol.js

@@ -1,7 +1,7 @@
 // The functions are only defined here. For their types, see lib/symbol.js
 
-// The point of having an explicit constructor for SymbolT, is that we can later swap it out for something that is (de-)serializable.
-export const constructSymbol = name => Symbol(name);
+// Cannot turn the constructor into a DOPE function, because it is NOT PURE:
+// export const constructSymbol = name => Symbol(name);
 
 export const getName = symbol => symbol.description;
 

primitives/types.js

@@ -1,17 +1,37 @@
 // to break up dependency cycles, primitive types are defined in their own JS module
 
 import { makeTypeConstructor } from "../type_constructor.js";
-import { constructSymbol } from "./symbol.js";
 
-export const Int     = makeTypeConstructor(constructSymbol('Int'), 0);
-export const Bool    = makeTypeConstructor(constructSymbol('Bool'), 0);
-export const Double  = makeTypeConstructor(constructSymbol('Double'), 0);
-export const Byte    = makeTypeConstructor(constructSymbol('Byte'), 0);
-export const Char    = makeTypeConstructor(constructSymbol('Char'), 0);
+const SymbolInt    = Symbol('Int');
+const SymbolBool   = Symbol('Bool');
+const SymbolDouble = Symbol('Double');
+const SymbolByte   = Symbol('Byte');
+const SymbolChar   = Symbol('Char');
+const SymbolUnit   = Symbol('Unit');
+const SymbolSymbol = Symbol('Symbol');
+const SymbolType   = Symbol('Type');
+
+export const Int     = makeTypeConstructor(SymbolInt)(0);
+export const Bool    = makeTypeConstructor(SymbolBool)(0);
+export const Double  = makeTypeConstructor(SymbolDouble)(0);
+export const Byte    = makeTypeConstructor(SymbolByte)(0);
+export const Char    = makeTypeConstructor(SymbolChar)(0);
 
 // Unit type has only 1 instance, the empty tuple.
-export const Unit    = makeTypeConstructor(constructSymbol('Unit'), 0);
+export const Unit    = makeTypeConstructor(SymbolUnit)(0);
 
-export const SymbolT = makeTypeConstructor(constructSymbol('Symbol'), 0);
+export const SymbolT = makeTypeConstructor(SymbolSymbol)(0);
 
-export const Type    = makeTypeConstructor(constructSymbol('Type'), 0);
+export const Type    = makeTypeConstructor(SymbolType)(0);
+
+
+export const ModuleSymbols = {l:[
+  {i: SymbolInt   , t: SymbolT},
+  {i: SymbolBool  , t: SymbolT},
+  {i: SymbolDouble, t: SymbolT},
+  {i: SymbolByte  , t: SymbolT},
+  {i: SymbolChar  , t: SymbolT},
+  {i: SymbolUnit  , t: SymbolT},
+  {i: SymbolSymbol, t: SymbolT},
+  {i: SymbolType  , t: SymbolT},
+]};

scripts/main.js

@@ -1,10 +1,10 @@
-import { select, number } from '@inquirer/prompts';
+import { select, number, input } from '@inquirer/prompts';
 import { ModulePoint } from "../lib/point.js";
 import { DefaultMap } from "../util/defaultmap.js";
 import { pretty } from '../util/pretty.js';
 import { isFunction, prettyT } from '../structures/types.js';
 import { ModuleStd } from '../stdlib.js';
-import { Double, Int, Type } from "../primitives/types.js";
+import { Double, Int, SymbolT, Type } from "../primitives/types.js";
 import { eqType } from '../type.js';
 
 class Context {
@@ -260,33 +260,49 @@ async function functionOptions(fn, fnT) {
 async function callFunction(fn, fnT) {
   const {strI, strT} = prettyIT({i: fn, t: fnT});
   const inType = fnT.params[0];
-  const choice = await (async () => {
+  const choice = await select({
+    message: `select parameter for function ${strI} :: ${strT}`,
+    choices: [
+      "(go back)",
+      "(new)",
+      ... [...ctx.instances.getdefault(inType)].flatMap(i => toChoices([i, ctx.types.getdefault(i)])),
+    ],
+  });
+  let i;
+  if (choice === "(go back)") {
+    return;
+  }
+  if (choice === "(new)") {
     if (eqType(inType)(Int)) {
       const n = await number({
         message: `enter an integer (leave empty to go back):`,
         step: 1, // only integers
       });
-      return (n === undefined) ? "(go back)" : {i: BigInt(n), t: Int};
+      if (n === undefined) {
+        return;
+      }
+      i = BigInt(n);
     }
-    if (eqType(inType)(Double)) {
+    else if (eqType(inType)(Double)) {
       const n = await number({
         message: `enter a number (leave empty to go back):`,
         step: 'any',
       });
-      return (n === undefined) ? "(go back)" : {i: n, t: Int};
+      if (n === undefined) {
+        return;
+      }
+      i = n;
+    }
+    else if (eqType(inType)(SymbolT)) {
+      console.log("Note: you are creating a new Symbol. Even if the description matches that of another symbol (e.g., \"Int\"), a new Symbol will be created that is unique and only equal to itself.");
+      const symbolDescr = await input({message: "enter symbol description:"});
+      i = Symbol(symbolDescr);
+    }
+    else {
+      console.log("no prompt handler for creating new", prettyT(inType));
+      return callFunction(fn, fnT);
     }
-    return select({
-      message: `select parameter for function ${strI} :: ${strT}`,
-      choices: [
-        "(go back)",
-        ... [...ctx.instances.getdefault(inType)].flatMap(i => toChoices([i, ctx.types.getdefault(i)])),
-      ],
-    });
-  })();
-  if (choice === "(go back)") {
-    return;
   }
-  const {i, t} = choice;
   await apply(i, fn, fnT);
   return callFunction(fn, fnT);
 }
@@ -327,6 +343,7 @@ async function transform(i, t) {
   if (choice === "(go back)") {
     return;
   }
+
   const {i:fn,t:fnT} = choice;
   await apply(i, fn, fnT);
   return transform(i, t);
@@ -334,6 +351,7 @@ async function transform(i, t) {
 
 async function apply(i, fn, fnT) {
   const result = fn(i);
+  // console.log(fn, '(', i, ')', '=', result);
   const resultType = fnT.params[1];
   // update context with newly produced value
   ctx = ctx.addToCtx({i: result, t: resultType});

stdlib.js

@@ -5,6 +5,7 @@ import { ModuleByte } from "./primitives/byte.js";
 import { ModuleChar } from "./primitives/char.js";
 import { ModuleDouble } from "./primitives/double.js";
 import { ModuleInt } from "./primitives/int.js";
+import { ModuleSymbols } from "./primitives/types.js";
 import { ModuleUnit } from "./primitives/unit.js";
 import { ModuleFunction } from "./structures/function.js";
 import { ModuleList } from "./structures/list.js";
@@ -18,6 +19,7 @@ export const ModuleStd = {l:[
   ...ModuleTyped.l,
 
   ...ModuleTypeConstructor.l,
+  ...ModuleSymbols.l,
 
   // Primitive types
   ...ModuleBool.l,

structures/function.js

@@ -2,8 +2,6 @@ import { Type } from "../primitives/types.js";
 import { typedFnType } from "./types.js";
 import { fnType } from "./types.js";
 
-// export const pprintFn = fnT => ``
-
 export const ModuleFunction = {l:[
   // binary type constructor: Type -> Type -> Type
   ...typedFnType(fnType, fnType => fnType

structures/nominal.js

@@ -4,7 +4,7 @@ import { sumType, prodType, fnType } from "./types.js";
 
 
 export const createNominalADT = symbol => variants => {
-
+  makeTypeConstructor(symbol, 0, )
 };
 
 export const createNominalADTFnType =

structures/types.js

@@ -9,7 +9,7 @@ import { getSymbol, makeTypeConstructor } from "../type_constructor.js";
 // It is a cheap workaround for JS lacking customizable hash-functions and equality-testing-functions.
 // This same pattern is repeated throughout the code for all non-nullary type constructors (list, sum, product, ...)
 const symbolFunction = Symbol('Function');
-export const fnType = makeTypeConstructor(symbolFunction, 2);
+export const fnType = makeTypeConstructor(symbolFunction)(2);
 
 export const isFunction = type => getSymbol(type) === symbolFunction;
 
@@ -40,25 +40,26 @@ export const typedFnType2 = callback => {
 // Sum type
 
 const symbolSum = Symbol("Sum");
-export const sumType = makeTypeConstructor(symbolSum, 2);
+export const sumType = makeTypeConstructor(symbolSum)(2);
 
 // Product type
 
 const symbolProduct = Symbol("Product");
-export const prodType = makeTypeConstructor(symbolProduct, 2);
+export const prodType = makeTypeConstructor(symbolProduct)(2);
 
 // List type
 
 const symbolList = Symbol('List');
-export const lsType = makeTypeConstructor(symbolList, 1);
+export const lsType = makeTypeConstructor(symbolList)(1);
 
 // Set type
 
 const symbolSet = Symbol('Set');
-export const setType = makeTypeConstructor(symbolSet, 1);
+export const setType = makeTypeConstructor(symbolSet)(1);
 
 // Pretty print type
 export function prettyT(type) {
+  // console.log("pretty:", type);
   if (type.typeVars) {
     if (type.typeVars.size > 0) {
       return `∀${[...type.typeVars].map(prettyT).join(", ")}: ${prettyT(type.type)}`;

structures/versioned.js

@@ -6,7 +6,7 @@ import { eqDictType } from "../typeclasses/eq_type.js";
 import { fnType, setType } from "./types.js";
 
 const symbolVersioned = Symbol("Versioned");
-export const versionedType = makeTypeConstructor(symbolVersioned, 1);
+export const versionedType = makeTypeConstructor(symbolVersioned)(1);
 
 
 export const constructor = parents => value  => {

type_constructor.js

@@ -1,15 +1,30 @@
 import { DefaultMap } from "./util/defaultmap.js";
 
-// Creates a new nominal type
-export const makeTypeConstructor = (name, n_ary, params = []) => {
-  if (n_ary === 0) {
-    return { symbol: Symbol(name), params };
+const nullaryTypeConstructors = new DefaultMap(symbol => ({symbol, params: []})); // symbol -> 0-ary type constructor (= a type, basically)
+
+const makeTypeConstructorInternal = (symbol, n_ary, params = []) => {
+  // console.log("n_ary:", n_ary);
+  if (n_ary === 0 || n_ary === 0n) {
+    // a bit dirty, but otherwise OK
+    if (params.length > 0) {
+      const result = { symbol, params };
+      // console.log("result:", result);
+      return result;
+    }
+    else {
+      const result = nullaryTypeConstructors.getdefault(symbol, true)
+      // console.log("result:", result);
+      return result;
+    }
   }
   else {
-    const m = new DefaultMap(typeParam => makeTypeConstructor(name, n_ary - 1, params.concat([typeParam])));
+    const m = new DefaultMap(typeParam => makeTypeConstructorInternal(symbol, n_ary - 1, params.concat([typeParam])));
     return typeParam => m.getdefault(typeParam, true);
   }
 };
 
+// Creates a new nominal type
+export const makeTypeConstructor = symbol => nAry => makeTypeConstructorInternal(symbol, nAry);
+
 export const getSymbol = type => type.symbol;
 export const getParams = type => ({ l: type.params });

typeclasses/eq.js

@@ -29,15 +29,15 @@ export const ModuleEq = {l:[
 
 const eq = x => y => deepEqual(x,y);
 
-const EqDict = {eq};
+const eqDict = {eq};
 
 export const EqInstances = new Map([
-  [Int    , EqDict],
-  [Bool   , EqDict],
-  [Double , EqDict],
-  [Byte   , EqDict],
-  [Char   , EqDict],
-  [Unit   , EqDict],
-  [Type   , EqDict],
-  [SymbolT, EqDict],
+  [Int    , eqDict],
+  [Bool   , eqDict],
+  [Double , eqDict],
+  [Byte   , eqDict],
+  [Char   , eqDict],
+  [Unit   , eqDict],
+  [Type   , eqDict],
+  [SymbolT, eqDict],
 ]);