dope2/generics/generics.test.js
2025-03-23 13:25:47 +01:00

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JavaScript

import { Bool, Int } from "../primitives/types.js";
import { lsType } from "../structures/types.js";
import { fnType } from "../structures/function.js";
import { assign, makeGeneric, unify } from "./generics.js";
import { pretty } from "../util.js";
// a -> Int
const a_to_Int = makeGeneric(a => fnType({in: a, out: Int}));
// Bool -> Int
const Bool_to_Int = makeGeneric(() => fnType({in: lsType(Bool), out: Int}));
console.log("should be: [Bool] -> Int")
console.log(pretty(unify(a_to_Int, Bool_to_Int)));
// (a -> a) -> b
const fnType2 = makeGeneric((a,b) => fnType({in: fnType({in: a, out: a}), out: b}));
// (Bool -> Bool) -> a
const fnType3 = makeGeneric(a => fnType({in: fnType({in: Bool, out: Bool}), out: a}));
console.log("should be: (Bool -> Bool) -> a");
console.log(pretty(unify(fnType2, fnType3)));
// (a -> b) -> [a] -> [b]
const mapFnType = makeGeneric((a,b) =>
fnType({
in: fnType({in: a, out: b}),
out: fnType({in: lsType(a), out: lsType(b)}),
}));
// a -> a
const idFnType = makeGeneric(a =>
fnType({in: a, out: a}));
console.log("should be: [a] -> [a]");
console.log(pretty(assign(mapFnType, idFnType)));
// (a -> Int) -> [a] -> a
const weirdFnType = makeGeneric(a =>
fnType({
in: fnType({in: a, out: Int}),
out: fnType({in: lsType(a), out: a}),
}));
console.log("should be: [Int] -> Int");
console.log(pretty(assign(weirdFnType, idFnType)));