# Curry a function

Collect arguments across calls until the function has as many as it declares.

Canonical: https://1loc.dev/function/curry-a-function/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Usage lines executed in Node.js 22 and headless Chromium; no external services
Updated: 2026-10-28

## Implementation

```javascript
function curry(fn, ...args) { return fn.length <= args.length ? fn(...args) : (...more) => curry(fn, ...args, ...more); }
```

## Usage

```javascript
const sum = (a, b, c) => a + b + c;
curry(sum)(1)(2)(3); // → 6
curry(sum, 1)(2, 3); // → 6
curry(sum, 1, 2, 3); // → 6
```

Lines marked → were executed in Node.js 22 and in headless Chromium, and each result was compared with the value shown. Lines marked e.g. are illustrative.

## Limits

- The arity comes from fn.length, which stops at the first default or rest parameter: (a, b = 1) => … has length 1.
- The original used curry.bind(null, …); the closure is equivalent.

The function does not validate its arguments. Add checks where it receives untrusted input.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/curry-a-function.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: See original repository history
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Closure instead of bind; arity limits documented. Documented as a reference with executed usage lines. Original MDX retained as inert source evidence.