/**
 * Predicate that always returns true
 */
export const always = (...args: any[]) => true;

/**
 * Predicate that always returns false
 */
export const never = (...args: any[]) => false;

/**
 * Negate a predicate
 */
export function not<A extends any[]>(
  predicate: (...args: A) => boolean,
): (...args: A) => boolean {
  return (...args) => !predicate(...args);
}

/**
 * Apply a boolean "and" to merge predicates
 */
export function and<A extends any[]>(
  ...predicates: ((...args: A) => boolean)[]
): (...args: A) => boolean {
  return (...args) => {
    for (let p of predicates) {
      if (!p(...args)) {
        return false;
      }
    }
    return true;
  };
}

/**
 * Apply a boolean "or" to merge predicates
 */
export function or<A extends any[]>(
  ...predicates: ((...args: A) => boolean)[]
): (...args: A) => boolean {
  return (...args) => {
    for (let p of predicates) {
      if (p(...args)) {
        return true;
      }
    }
    return false;
  };
}