import { BaseError } from 'make-error';
import { Constrained } from '../../core';
export declare class InvalidConstantError<T> extends BaseError {
    readonly constantValue: T;
    constructor(constantValue: T);
}
export declare function isConstant<ConstraintSymbol extends symbol, Type>(_symbol: ConstraintSymbol, constantValue: Type, input: unknown): input is Constrained<ConstraintSymbol, Type>;
export declare function constant<ConstraintSymbol extends symbol, Type>(symbol: ConstraintSymbol, constantValue: Type): (input: unknown) => Constrained<ConstraintSymbol, Type>;