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/*
* esodata - data structures and other things, of varying utility
* Copyright 2022, Ben Culkin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package bjc.optics;
import java.util.function.Function;
import java.util.function.UnaryOperator;
import bjc.typeclasses.BiContainer;
/**
* A type-invariant var Laarhoven lens.
*
* @author bjcul
*
* @param <Whole> The item this lens can focus on
* @param <Part> The field this lens focuses on
*/
public interface Lens<Whole, Part> extends LensX<Whole, Whole, Part, Part>, BiContainer<Whole, Part, Lens<Whole, Part>> {
/**
* Modify a given whole using an operation
*
* @param source The whole to modify.
* @param mod The operation to use for modifying a part
*
* @return A modified whole
*/
default Whole modify(Whole source, UnaryOperator<Part> mod) {
return set(source, mod.apply(get(source)));
}
/**
* Create a function which sets the part of a given whole.
*
* @param part The part to set
*
* @return A function that sets the given part on a whole.
*/
default Function<Whole, Whole> setting(Part part) {
return (whole) -> set(whole, part);
}
/**
* Lift a function that modifies parts to one that modifies wholes.
*
* @param f The function which operates on parts
*
* @return A corresponding function which applies the given modification to a part.
*/
default Function<Whole, Whole> lift(UnaryOperator<Part> f) {
// modify will be more efficient for some lenses
return (whole) -> modify(whole, f);
}
}
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