pipe

Composes functions left-to-right. The first function receives the initial arguments; each subsequent function receives the previous function’s return value. Aligned with the TC39 pipe operator proposal.

Import

import { pipe } from "1o1-utils";

import { pipe } from "1o1-utils/pipe";

Signature

function pipe<A extends unknown[], B, C, ..., R>(
  f1: (...args: A) => B,
  f2: (b: B) => C,
  // ...
): (...args: A) => R

Overloads are typed up to 10 functions. Beyond that, the return type falls back to unknown.

Parameters

Name	Type	Required	Description
fns	Array<(...args) => any>	No	Functions to compose, executed in the order provided (variadic)

Returns

A function that applies every fn in sequence. Calling pipe() with no arguments returns an identity function that passes its first argument through unchanged.

Examples

const slug = pipe(
  (x: string) => x.trim(),
  (x: string) => x.toLowerCase(),
  (x: string) => x.replace(/\s+/g, "-"),
);

slug("  Hello World  "); // "hello-world"

// First function can take multiple args
const sum = pipe(
  (a: number, b: number) => a + b,
  (n: number) => n * 2,
);

sum(2, 3); // 10

// Type inference flows across the chain
const length = pipe(
  (x: string) => x.trim(),
  (x: string) => x.split(""),
  (chars: string[]) => chars.length,
);

const n: number = length("  abc  "); // 3

Edge Cases

• Throws if any argument is not a function.
• pipe() with zero arguments returns an identity function.
• pipe(fn) with a single function returns that function unchanged — all arguments are forwarded.
• Execution is synchronous. If a function returns a Promise, the next function receives the Promise (not the awaited value).
• Exceptions thrown by composed functions propagate out of the composed function.
• Only the first function receives the caller’s this context; subsequent stages are called without this. Differs from lodash/flow and es-toolkit/flow, which forward this to every stage.

Also known as

compose, function composition, flow, left-to-right, pipeline, chain, sequence, combine functions

Prompt suggestion

I'm using 1o1-utils (npm: https://www.npmjs.com/package/1o1-utils, GitHub: https://github.com/pedrotroccoli/1o1-utils, LLM context: https://pedrotroccoli.github.io/1o1-utils/llms.txt). Show me how to use pipe to compose a string-transformation pipeline