Uncurry a function

Call a curried function with several arguments at once.

JavaScriptNode.js & browsers Version 1.0.0 · MIT · .md

function uncurry(fn, depth = 1) { return (...args) => args.slice(0, depth).reduce((next, arg) => next(arg), fn); }

Usage

const sum = a => b => c => a + b + c;
uncurry(sum, 1)(1)(2)(3); // → 6
uncurry(sum, 2)(1, 2)(3); // → 6
uncurry(sum, 3)(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.

Know the limits

• Arguments beyond depth are ignored, as in the original. depth must not exceed the curried function’s depth.

The function above is the code the usage lines run. It does not validate its arguments; add checks where it receives untrusted input.

Keep exploring

• Logical xor operator — True when exactly one of two values is truthy.
• Identity function — Return the argument unchanged.
• Box handler — Chain transformations on a value, then unwrap the result.