Monomemo

A memoization utility.

Installation

npm install monomemo

or

yarn add monomemo

or

pnpm add monomemo

Usage

The library provides a function memoize,

import { memoize } from "monomemo";

that takes two arguments: a function whose results we want to memoize, and which takes a single argument, and a map to be used as cache - any object such as Map and WeakMap that implements MapLike interface.

// foo(1) will return 2, and add key 1, value 2 to the map, so that the
// next time foo is called the same argument, we will use the cached result.
const foo = memoize((a: number) => a + 1, new Map());

// Typechecking error, because a WeakMap cannot have numbers as keys.
const foo = memoize((a: number) => a + 1, new WeakMap());

// Objects on the other hand are fine. In this case we are able to use WeakMap
// to help prevent memory leaks.
const foo = memoize(({ a }: { a: number }) => a + 1, new WeakMap());

Memoizing results of functions that take multiple arguments

const undecorated = (x: number, y: { a: number }) => x + y.a;

// We use WeakMap in the outer call so that the Maps created in the inner call
// would be garbage-collected as soon as `{ a: number }` objects are no longer
// referenced.
const decorated = memoize(
  (y: { a: number }) => memoize((x: number) => undecorated(x, y), new Map()),
  new WeakMap()
);

const withRestoredSignature = (x: number, y: { a: number }) => decorated(y)(x);

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Contributing guidelines