import type { compareFn, mapFn } from './_types';
/**
 * Checks if array has a permutation.
 * @param x an array
 * @param y permutation?
 * @param fc map function (v, i, x)
 * @param fm compare function (a, b)
 */
declare function isPermutation<T, U = T>(x: T[], y: T[], fc?: compareFn<T | U>, fm?: mapFn<T, T | U>): boolean;
export default isPermutation;
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