mems

A memoization utility.

Usage

A simple example exhibiting how the same exact value is returned for each invocation of makeDoubleArray, although the function itself would generate a brand new array without memoization.

import mems from 'mems'

const makeDoubleArray = mems((a, b) => [a * 2, b * 2]);

const main = () => {
  const a = makeDoubleArray(1, 2);
  const b = makeDoubleArray(1, 2);
  const c = makeDoubleArray(1, 2);

  // NOTE: Without memoization, each of the returned values
  // would be an entirely new array, so the following strict
  // eqality checks would all evaluate to false.
  console.log(a === b, b === c, a === c);
  // true, true, true
};

main();

We see here that even when the main function is invoked multiple times, the cached makeDoubleArray function/result persists.

At the end, when we log the size of each of the results Sets, we see that they are all 1, because a Set will not allow multiple of the same value to live inside of it, meaning that the second invocation of main resulted in the same values produced by the first.

import mems from 'mems'

const makeDoubleArray = mems((a, b) => [a * 2, b * 2]);

const aResults = new Set();
const bResults = new Set();
const cResults = new Set();

const main = () => {
  const a = makeDoubleArray(1, 1);
  const b = makeDoubleArray(1, 2);
  const c = makeDoubleArray(1, 3);

  console.log(aResults.has(a), bResults.has(b), cResults.has(c));

  aResults.add(a);
  bResults.add(b);
  cResults.add(c);
};

main();
// false false false

main();
// true true true

console.log(aResults.size, bResults.size, cResults.size);
// 1 1 1