import { Optional } from "./Optional.js";
/**
 * This is the identity function - it returns whatever you pass in
 *
 * @category Utilities
 */
export declare const identity: <T>(t: T) => T;
/**
 * A synonym for {@link identity}
 *
 * @category Utilities
 */
export declare const asIs: <T>(t: T) => T;
/**
 * This function returns undefined, whatever you pass in
 *
 * @category Utilities
 */
export declare const drop: (t: unknown) => void;
/**
 * This does the same as {@link drop}, but is typed to return undefined (rather than void)
 *
 * @category Utilities
 */
export declare const asUndefined: (t: unknown) => undefined;
/**
 * Logs an error and moves on
 *
 * @category Utilities
 */
export declare const logError: (e: Error) => void;
/**
 * This is a handy utility function that just throws an error
 * that exists in an Either. Useful for Either.apply
 *
 * @category Utilities
 */
export declare const throwError: (e: Error) => never;
/**
 * Sometimes, all you're looking to do is extract a single property from and object.
 * That's what this function does
 *
 * @category Utilities
 */
export declare const extractProperty: <O extends object>(key: keyof O) => (o: O) => O[keyof O];
/**
 * Sometimes, you want a subset of an object, with just a few properties
 * That's what this function does
 *
 * @category Utilities
 */
export declare const pickProperties: <O extends object>(keys: (keyof O)[]) => (o: O) => Partial<O>;
/**
 * Take function that returns a value and make that return an Optional
 *
 * @category Utilities
 */
export declare const asOptional: <A extends any[], R>(f: (...args: A) => R) => (...args: A) => Optional<NonNullable<R>>;