began value api

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);
+  });
+});

value.mjs

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+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));