import type { Option } from "../Option";
/**
 * Atomically modifies the `FiberRef` with the specified partial function.
 * If the function is undefined on the current value it doesn't change it.
 */
export declare function updateSome<A>(f: (a: A) => Option<A>): (fiberRef: import("./fiberRef").FiberRef<A>) => import("../Effect").UIO<void>;
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