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// Copyright (c) 2020 Jozty. All rights reserved. MIT license.
import type { PH } from './utils/types.ts';import curryN from './utils/curry_n.ts';
// @typestype LensF_2<T, F> = (setter: LensSetter<T, F>) => Lens<T, F>;
type LensF_1<T, F> = (getter: LensGetter<T, F>) => Lens<T, F>;
type LensF =  & (<T, F>(getter: LensGetter<T, F>) => LensF_2<T, F>)  & (<T, F>(getter: PH, setter: LensSetter<T, F>) => LensF_1<T, F>)  & (<T, F>(getter: LensGetter<T, F>, setter: LensSetter<T, F>) => Lens<T, F>);
export type LensGetter<T, F> = (target: T) => F;
export type LensSetter<T, F> = (focus: F, target: T) => T;
export type GetTransformer<T, F, R> = (  focus: F,) => LensTransformer<T, F, R>;
export type LensTransformer<T, F, R> = {  value: F;  transform: (    setter: LensSetter<T, F>,    target: T,  ) => LensTransformer<never, R, never>;};
export type Lens<T, F> = <R>(  getTransformer: GetTransformer<T, F, R>,) => (target: T) => LensTransformer<never, R, never>;
function _lens<T, F>(  getter: LensGetter<T, F>,  setter: LensSetter<T, F>,): Lens<T, F> {  return function <R>(getTransformer: GetTransformer<T, F, R>) {    return function (target: T) {      const focusedObj = getter(target);      const transformer = getTransformer(focusedObj);      return transformer.transform(setter, target);    };  };}
/** * Returns a lens for the given getter and setter functions. The `getter` "gets" * the value of the focus; the setter "sets" the value of the focus. The `setter` * should not mutate the data structure. */export const lens: LensF = curryN(2, _lens);