import type { DeepPartial } from './util';
/**
  Shortcut function
  Replace only existing fields in {a} with {b}
  When field from {b} is truthy

  ex: ({ a: 0, b: 0 }, { a: 1, x: 1 }) -> { a: 1, b: 0 }
*/
export declare function mergeLeftTruthy<T extends Record<string, any>>(source: T, target?: DeepPartial<T>, customLogic?: (key: keyof T, source: T, target: DeepPartial<T>) => boolean): T;