import type { Predicate } from './Predicate';
import type { Refinement } from './Refinement';
export interface None {
    readonly _tag: 'None';
}
export interface Some<A> {
    readonly _tag: 'Some';
    readonly value: A;
}
export declare type Option<A> = None | Some<A>;
/**
 * @internal
 */
export declare function Some<A>(a: A): Option<A>;
/**
 * @internal
 */
export declare function None<A = never>(): Option<A>;
/**
 * Constructs a new `Option` from a value and the given predicate
 *
 * @category Constructors
 * @since 1.0.0
 * @internal
 */
export declare function fromPredicate_<A, B extends A>(a: A, refinement: Refinement<A, B>): Option<A>;
export declare function fromPredicate_<A>(a: A, predicate: Predicate<A>): Option<A>;
/**
 * Returns a smart constructor based on the given predicate
 *
 * @category Constructors
 * @since 1.0.0
 * @internal
 */
export declare function fromPredicate<A, B extends A>(refinement: Refinement<A, B>): (a: A) => Option<A>;
export declare function fromPredicate<A>(predicate: Predicate<A>): (a: A) => Option<A>;
export declare function fromNullable<A>(a: A | null | undefined): Option<NonNullable<A>>;
/**
 * @internal
 */
export declare function getOrElse_<A, B>(fa: Option<A>, onNone: () => B): A | B;
/**
 * @internal
 */
export declare function getOrElse<B>(onNone: () => B): <A>(fa: Option<A>) => A | B;
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