@typed/lenses/esm/PathLens.d.ts

Strongly-typed functional lenses

import { Arity1, Head, Tail } from '@typed/lambda';
import { Lens } from './Lens';
export declare const fromPath: <K extends readonly (string | number | symbol)[]>(keys: K) => PathLens<K>;
export interface PathLens<K extends ReadonlyArray<PropertyKey>> extends Lens<PathToRecord<K>, any> {
    readonly get: <R extends PathToRecord<K>>(r: R) => GetPath<R, K>;
    readonly update: {
        <R extends PathToRecord<K>>(update: Arity1<GetPath<R, K>, GetPath<R, K>>, r: R): R;
        <B>(update: Arity1<B, B>): <R extends PathToRecord<K, B>>(r: R) => R;
    };
}
export declare type PathLensKeys<A> = A extends PathLens<infer Keys> ? Keys : never;
export declare type PathToRecord<K extends ReadonlyArray<PropertyKey>, R = any> = Tail<K> extends [] ? {
    readonly [Key in Head<K>]: R;
} : {
    readonly [Key in Head<K>]: PathToRecord<Tail<K>, R>;
};
export declare type GetPath<O, K extends ReadonlyArray<PropertyKey>> = K extends [] ? O : {
    complete: Head<K> extends keyof O ? O[Head<K>] : never;
    continue: Head<K> extends keyof O ? GetPath<O[Head<K>], Tail<K>> : never;
}[[] extends Tail<K> ? 'complete' : 'continue'];
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