rivo/Num/Nat/IsNat.d.ts

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// @ts-ignore - Only used in doc comments
import type { Nat } from ".";
import type { Args, Fn } from "../../HKT";
import type { Every } from "../../List/Every";
import type IsDigitFn from "../../Str/IsDigit";
import type { ToChars } from "../../Str/ToChars";
import type { AssertBool } from "../../helpers";

/**
 * Check if a value is {@link Nat}.
 *
 * Sig: `(x: unknown) => boolean`
 */
export type IsNat<T> = AssertBool<
  T extends string | number | bigint ? Every<IsDigitFn, ToChars<`${T}`>> : false
>;

/**
 * [Fn] Check if a value is {@link Nat}.
 *
 * Sig: `(x: unknown) => boolean`
 */
export default interface IsNatFn extends Fn<[unknown], boolean> {
  def: ([x]: Args<this>) => IsNat<typeof x>;
}