35 lines
No EOL
1.1 KiB
TypeScript
35 lines
No EOL
1.1 KiB
TypeScript
//#region src/fp/array/head.d.ts
|
|
/**
|
|
* Creates a function that returns the first element of a non-empty array.
|
|
*
|
|
* This overload preserves the non-empty tuple guarantee: the returned function
|
|
* always returns T when the piped array has at least one element.
|
|
*
|
|
* @template T - The type of elements in the array.
|
|
* @returns A function that maps a non-empty readonly array to its first element.
|
|
*
|
|
* @example
|
|
* import { head, pipe } from 'es-toolkit/fp';
|
|
*
|
|
* pipe([1, 2, 3] as const, head());
|
|
* // => 1
|
|
*/
|
|
declare function head<T>(): (array: readonly [T, ...T[]]) => T;
|
|
/**
|
|
* Creates a function that returns the first element of an array, or undefined.
|
|
*
|
|
* Empty arrays return undefined, matching the main {@link head} behavior. Use
|
|
* the returned function with {@link pipe}.
|
|
*
|
|
* @template T - The type of elements in the array.
|
|
* @returns A function that maps a readonly array to its first element, or undefined.
|
|
*
|
|
* @example
|
|
* import { head, pipe } from 'es-toolkit/fp';
|
|
*
|
|
* pipe([] as number[], head());
|
|
* // => undefined
|
|
*/
|
|
declare function head<T>(): (array: readonly T[]) => T | undefined;
|
|
//#endregion
|
|
export { head }; |