import type { StructType } from './struct.js';
import { type DecodeContext, type RTError, Type } from './type.js';
import { type Result } from './utils.js';
export declare class KeyOfType<T extends {
    [K: string]: unknown;
}> extends Type<keyof T> {
    struct: StructType<T>;
    constructor(struct: StructType<T>);
    print(): string;
    decode(u: unknown, _opts: DecodeContext): import("./utils.js").Err<RTError> | import("./utils.js").Ok<keyof T>;
    validate(v: keyof T, opts: DecodeContext): Promise<Result<keyof T, RTError>>;
    validateSync(v: keyof T, opts: DecodeContext): Result<keyof T, RTError>;
    in(...list: (keyof T)[]): this;
}
export declare function keyOf<T extends {
    [K: string]: unknown;
}>(struct: StructType<T>): KeyOfType<T>;