froebel/partition.d.ts

TypeScript utility library

declare type Partition = {
    <T, S extends T>(list: T[], predicate: (el: T) => el is S): [
        S[],
        Exclude<T, S>[]
    ];
    <T extends readonly unknown[], S>(list: T, predicate: (el: any) => el is S): Part<T, S>;
    <T>(list: T[], predicate: (el: T) => unknown): [T[], T[]];
};
/**
 * Takes a `list` and returns a pair of lists containing: the elements that
 * match the `predicate` and those that don't, respectively.
 *
 * Think of it as `filter`, but the elements that don't pass the filter aren't
 * discarded but returned in a separate list instead.
 *
 * @example
 * ```
 * const [strings, numbers] = partition(
 *   ['a', 'b', 1, 'c', 2, 3],
 *   (el): el is string => typeof el === 'string'
 * )
 * // strings: ["a", "b", "c"]
 * // numbers: [1, 2, 3]
 * ```
 */
declare const partition: Partition;
export default partition;
declare type Part<T extends readonly unknown[], S> = T extends readonly [
    infer F,
    ...infer R
] ? [
    F extends S ? [F, ...Part<R, S>[0]] : Part<R, S>[0],
    F extends S ? Part<R, S>[1] : [F, ...Part<R, S>[1]]
] : [[], []];