/**
 * @hidden
 */
export type Combinator = <T, U>(acc: U, curr: T) => U;

/**
 * @hidden
 */
export type Reducer = (reduce: Combinator) => Transformer;

/**
 * @hidden
 */
export type TransformerResult<T> = { __value: T, reduced: boolean };

/**
 * @hidden
 */
export type Transformer = <T, U>(acc: U, curr: T, index: number) => U | TransformerResult<U>;

/**
 * A type which represents a function that returns a Boolean value.
 *
 * @example
 * ```ts-no-run
 * const isGreaterThanTen: Predicate = (num: number) => num > 10;
 * isGreaterThanTen(2); // false
 * isGreaterThanTen(20); // true
 * ```
 */
export type Predicate = <T>(x: T) => boolean;

export type Preprocessors<T> = {
    [P in keyof T]?: (value: T[P]) => any;
};