import { HttpMessage } from "@http4t/core/contract";
import { MessageLens, RoutingResult } from "../lenses";
export declare class UnionLens<A extends object | undefined, B extends object | undefined, TMessage extends HttpMessage = HttpMessage> implements MessageLens<TMessage, A | B> {
    private a;
    private b;
    private isA;
    constructor(a: MessageLens<TMessage, A>, b: MessageLens<TMessage, B>, isA: (value: A | B) => value is A);
    get(from: TMessage): Promise<RoutingResult<A | B>>;
    set<SetInto extends TMessage>(into: SetInto, value: A | B): Promise<SetInto>;
}
export declare function union<A extends object | undefined, B extends object | undefined, TMessage extends HttpMessage = HttpMessage>(a: MessageLens<TMessage, A>, b: MessageLens<TMessage, A>, isA: (value: A | B) => value is A): MessageLens<TMessage, A | B>;
//# sourceMappingURL=UnionLens.d.ts.map