diff --git a/test/value.test.mjs b/test/value.test.mjs new file mode 100644 index 00000000..f68ff36c --- /dev/null +++ b/test/value.test.mjs @@ -0,0 +1,18 @@ +import { strict as assert } from 'assert'; +import { map, valued, mul } from '../value.mjs'; + +describe('Value', () => { + it('unionWith', () => { + const { value } = valued({ freq: 2000, distortion: 1.2 }).unionWith({ distortion: 2 }, mul); + assert.deepStrictEqual(value, { freq: 2000, distortion: 2.4 }); + }); + + it('experiments', () => { + assert.equal(map(mul(5), valued(3)).value, 15); + assert.equal(map(mul(null), valued(3)).value, 0); + assert.equal(map(mul(3), valued(null)).value, null); + assert.equal(valued(3).map(mul).ap(3).value, 9); + assert.equal(valued(mul).ap(3).ap(3).value, 9); + assert.equal(valued(3).mul(3).value, 9); + }); +}); diff --git a/value.mjs b/value.mjs new file mode 100644 index 00000000..0a077077 --- /dev/null +++ b/value.mjs @@ -0,0 +1,52 @@ +import { curry } from 'ramda'; + +function unionWithObj(a, b, func) { + const common = Object.keys(a).filter((k) => Object.keys(b).includes(k)); + return Object.assign({}, a, b, Object.fromEntries(common.map((k) => [k, func(a[k], b[k])]))); +} + +export const mul = curry((a, b) => a * b); + +export const valued = (value) => { + if (value?.constructor?.name === 'Value') { + return value; + } + return Value.of(value); +}; + +export class Value { + constructor(value) { + this.value = value; + } + static of(x) { + return new Value(x); + } + get isNothing() { + return this.value === null || this.value === undefined; + } + map(f) { + if (this.isNothing) { + return this; + } + return Value.of(f(this.value)); + } + mul(n) { + return this.map(mul).ap(n); + } + ap(other) { + return valued(other).map(this.value); + } + unionWith(other, func) { + const type = typeof this.value; + other = valued(other); + if (type !== typeof other.value) { + throw new Error('unionWith: both Values must have same type!'); + } + if (Array.isArray(type) || type !== 'object') { + throw new Error('unionWith: expected objects'); + } + return this.map((v) => unionWithObj(v, other.value, func)); + } +} + +export const map = curry((f, anyFunctor) => anyFunctor.map(f));