import type { Extended } from './isExtension.js';
export declare const $SUBTRACT: unique symbol;
export type $SUBTRACT = typeof $SUBTRACT;
export type SUBTRACT<A, B> = Extended<{
    [$SUBTRACT]: [A, B];
}>;
export declare const $subtract: <A, B>(a: A, b: B) => SUBTRACT<A, B>;
export declare const isSubtraction: (input: unknown) => input is {
    [$SUBTRACT]: unknown;
};