import { _Type } from "./apply";
export { HKT, Contra, Expect };
/** Interfaces extending this type are able to use `hkt` internally. */
type HKT = {
    HKT: [any, ...any[]];
};
/** Expect a free type with contravariant arguments
 * @deprecated use `Expect` instead
 * */
type Contra<$T, $U extends _Type> = _Contra<Extract<$T, _Type>, $U>;
type _Contra<$T extends _Type, $U extends _Type> = $U['constraints'] extends $T['constraints'] ? $T['type'] extends $U['type'] ? _Type : _Type<$T['constraints'], $U['type']> : _Type<[$U['constraints'], 'is not assignable to', $T['constraints']]>;
type Expect<$T, Active extends boolean = true> = Active extends false ? $T : {
    [K in keyof $T]: K extends CovariantKey ? any : $T[K];
};
type CovariantKey = 'namedConstraints' | 'constraints' | 'arg' | 'names';