option-t/esm/nullable/operators/filter.d.ts

A toolkit of Nullable/Option/Result type implementation in ECMAScript. Their APIs are inspired by Rust's `Option<T>` and `Result<T, E>`.

import type { FilterFn, TypePredicateFn } from '../../internal/function.js';
import { type Nullable, type NotNull } from '../core/nullable.js';
/**
 *  Returns `null` if the _input_ is `null`,
 *  otherwise calls _predicate_ with the _input_ `T` and returns:
 *
 *      * `T` if _predicate_ returns `true`.
 *      * `null` if _predicate_ returns `false`.
 */
export declare function filterForNullable<T>(input: Nullable<T>, predicate: FilterFn<T>): Nullable<T>;
/**
 *  Returns `null` if the _input_ is `null`,
 *  otherwise calls _predicate_ with the _input_ `T` and returns:
 *
 *      * The input value as `U` if _predicate_ returns `true` which means that _predicate_ says the input value is U.
 *      * `null` if _predicate_ returns `false`.
 *
 *  Please use {@link filterForNullable} generally if you don't have to narrow the type.
 */
export declare function filterWithEnsureTypeForNullable<T, U extends T>(input: Nullable<T>, predicate: TypePredicateFn<T, NotNull<U>>): Nullable<U>;