import { Value, Var } from "../value";
export declare class Subst {
    private map;
    constructor(map: Map<Var, Value>);
    static create(): Subst;
    clone(): Subst;
    extend(v: Var, value: Value): Subst;
    find(v: Var): Value | undefined;
    walk(value: Value): Value;
    occur(v: Var, value: Value): boolean;
    unify(x: Value, y: Value): Subst | null;
    private unifyObject;
    private coverObject;
    private unifyArray;
    deepWalk(x: Value): Value;
    reify(x: Value): Value;
    assertFound(v: Var, value: Value): void;
}