import { Kind, Type } from '..';
type _$uppercaseLetter = 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' | 'K' | 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U' | 'V' | 'W' | 'X' | 'Y' | 'Z';
/**
 * `_$isUppercaseLetter` is a type-level function that takes in a string `S` and
 * returns a boolean indicating whether the string is an uppercase letter.
 *
 * @template {string} S - The string to check.
 *
 * @example
 * ```ts
 * import { String } from "hkt-toolbelt";
 *
 * type Result = String._$isUppercaseLetter<'A'>; // true
 * ```
 */
export type _$isUppercaseLetter<S extends string> = S extends _$uppercaseLetter ? true : false;
/**
 * `IsUppercaseLetter` is a type-level function that takes in a string `S` and
 * returns a boolean indicating whether the string is an uppercase letter.
 *
 * @template {string} S - The string to check.
 *
 * @example
 * ```ts
 * import { $, String } from "hkt-toolbelt";
 *
 * type Result = $<String.IsUppercaseLetter, 'A'>; // true
 * ```
 */
export interface IsUppercaseLetter extends Kind.Kind {
    f(x: Type._$cast<this[Kind._], string>): _$isUppercaseLetter<typeof x>;
}
/**
 * Given a string, return a boolean indicating whether the string is an
 * uppercase letter.
 *
 * @param {string} x - The string to check.
 *
 * @example
 * ```ts
 * import { String } from "hkt-toolbelt";
 *
 * const result = String.isUppercaseLetter('A')
 * //    ^? true
 * ```
 */
export declare const isUppercaseLetter: Kind._$reify<IsUppercaseLetter>;
export {};