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can auto-generate comparison functions for composed types

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This commit is contained in:
Joeri Exelmans 2025-04-17 16:43:28 +02:00
parent 0b262daf7f
commit 4d1fb81492
6 changed files with 72 additions and 35 deletions
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36
structures/enum.js
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@ -1,3 +1,4 @@
import { makeCompareFn } from "../compare/registry.js";
import { Bottom, Int, Unit } from "../primitives/types.js";
import { unit } from "../primitives/unit.js";
import { capitalizeFirstLetter } from "../util/util.js";
@ -66,23 +67,36 @@ const variants = [
constructorProduct("not_found")(Unit),
];
const myEnum = enumType(variants);
const myEnumType = enumType(variants);
console.log(prettyT(myEnum));
console.log("observe the type that was generated:");
console.log(prettyT(myEnumType));
const [newPrice, newPrices, newNotFound] = makeConstructors(variants);
console.log(newPrice(10));
console.log(newPrices([20,30]));
console.log(newNotFound(unit));
const price = newPrice(10);
const prices = newPrices({l:[20,30]});
const notFound = newNotFound(unit);
const myMatchFn = makeMatchFn(variants);
console.log("observe the encoding of different variant instances:");
console.log(price);
console.log(prices);
console.log(notFound);
const matchVariant = x => myMatchFn(x)
const myEnumToString = x => makeMatchFn(variants)(x)
(price => `Price: ${price}`)
(prices => `Prices: ${prices}`)
(prices => `Prices: ${prices.l}`)
(() => "Not found!");
console.log(matchVariant(newPrice(10)));
console.log(matchVariant(newPrices([20,30])));
console.log(matchVariant(newNotFound(unit)));
console.log("observe the generated match function in action:")
console.log(myEnumToString(price));
console.log(myEnumToString(prices));
console.log(myEnumToString(notFound));
const compareMyEnum = makeCompareFn(myEnumType);
console.log(compareMyEnum(price)(prices)); // smaller
console.log(compareMyEnum(prices)(price)); // bigger
console.log(compareMyEnum(notFound)(price)); // bigger
console.log(compareMyEnum(prices)(prices)); // equal
console.log(compareMyEnum(newPrice(5))(newPrice(6))); // smaller

10
structures/types.js
View file

@ -8,7 +8,7 @@ import { getSymbol, makeTypeConstructor } from "../type_constructor.js";
// The registry ensures that we never accidentally create more than one JS object for the same function type.
// 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 symbolFunction = Symbol('Function');
export const fnType = makeTypeConstructor(symbolFunction)(2);
export const isFunction = type => getSymbol(type) === symbolFunction;
@ -35,22 +35,22 @@ export const typedFnType = (instance, callback, typeOfType = Type) => {
// Sum type
const symbolSum = Symbol("Sum");
export const symbolSum = Symbol("Sum");
export const sumType = makeTypeConstructor(symbolSum)(2);
// Product type
const symbolProduct = Symbol("Product");
export const symbolProduct = Symbol("Product");
export const prodType = makeTypeConstructor(symbolProduct)(2);
// List type
const symbolList = Symbol('List');
export const symbolList = Symbol('List');
export const lsType = makeTypeConstructor(symbolList)(1);
// Set type
const symbolSet = Symbol('Set');
export const symbolSet = Symbol('Set');
export const setType = makeTypeConstructor(symbolSet)(1);