@thi.ng/memoize

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• About
  • Available memoization functions
• Status
• Related packages
• Installation
• Dependencies
• Usage examples
• API
  • Optimized version for single arg functions
  • Arbitrary args
  • Via JSON.stringify()
• Authors
• License

About

Function memoization with configurable caching and support for async functions.

This package provides different function memoization implementations for functions with arbitrary arguments and custom result caching using ES6 Map API like implementations. Unlike native ES6 Maps, the implementations MUST support value, not just referential, equality semantics (e.g. those provided by @thi.ng/associative) or @thi.ng/cache). The latter also support automatically pruning of memoization caches, based on different strategies. See doc strings for further details.

Available memoization functions

• defOnce()
• delay()
• doOnce()
• memoize() / memoizeAsync()
• memoize1() / memoizeAsync1()
• memoizeJ() / memoizeAsyncJ()
• memoizeO() / memoizeAsyncO()

Status

STABLE - used in production

Search or submit any issues for this package

Related packages

• @thi.ng/cache - In-memory cache implementations with ES6 Map-like API and different eviction strategies

Installation

yarn add @thi.ng/memoize

ESM import:

import * as mem from "@thi.ng/memoize";

Browser ESM import:

<script type="module" src="https://esm.run/@thi.ng/memoize"></script>

JSDelivr documentation

For Node.js REPL:

const mem = await import("@thi.ng/memoize");

Package sizes (brotli'd, pre-treeshake): ESM: 507 bytes

Dependencies

• @thi.ng/api

Note: @thi.ng/api is in most cases a type-only import (not used at runtime)

Usage examples

Three projects in this repo's /examples directory are using this package:

Screenshot	Description	Live demo	Source
	Isolated, component-local DOM updates	Demo	Source
	Basic rstream-gestures multi-touch demo	Demo	Source
	rstream based spreadsheet w/ S-expression formula DSL	Demo	Source

API

Generated API docs

import * as m from "@thi.ng/memoize";

// (optional, for custom caching)
import { EquivMap } from "@thi.ng/associative";
import { LRUCache } from "@thi.ng/cache";

Optimized version for single arg functions

import { memoize1 } from "@thi.ng/memoize";

foo = memoize1((x: number) => {
    console.log("exec");
    return x * 10;
});

foo(1);
// exec
// 10
foo(1);
// 10

import { EquivMap } from "@thi.ng/associative";

// with custom cache
foo = memoize1(
    (x: number[]) => (console.log("exec"), x[0] * 10),
    // custom ES6 Map impl which compares by value, not by reference
    new EquivMap()
);

foo([1]);
// exec
// 10

// would be a cache miss w/ native ES6 Map
// due to lack of value equality semantics
foo([1]);
// 10

import { LRUCache } from "@thi.ng/cache";

// use LRU cache to limit cache size
foo = memoize1(
    (x: number[]) => (console.log("exec"), x[0] * 10),
    new LRUCache(null, { maxlen: 3 })
);

Arbitrary args

import { memoize } from "@thi.ng/memoize";
import { EquivMap } from "@thi.ng/associative";

const dotProduct = memoize(
    (x: number[], y: number[]) => {
        console.log("exec");
        return x[0] * y[0] + x[1] * y[1];
    },
    new EquivMap()
);

dotProduct([1,2], [3,4]);
// exec
// 11
dotProduct([1,2], [3,4]);
// 11

Via JSON.stringify()

import { memoizeJ } from "@thi.ng/memoize";

const dotProduct = memoizeJ(
    (x: number[], y: number[]) => {
        console.log("exec");
        return x[0] * y[0] + x[1] * y[1];
    }
);

dotProduct([1, 2], [3, 4]);
// exec
// 11

dotProduct([1, 2], [3, 4]);
// 11

Authors

• Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-memoize,
  title = "@thi.ng/memoize",
  author = "Karsten Schmidt",
  note = "https://thi.ng/memoize",
  year = 2018
}

License

© 2018 - 2025 Karsten Schmidt // Apache License 2.0