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Functional patterns for Java

There is a newer version: 5.5.0

package com.jnape.palatable.lambda.optics.functions;

import com.jnape.palatable.lambda.functions.Fn1;
import com.jnape.palatable.lambda.functions.Fn2;
import com.jnape.palatable.lambda.functor.builtin.Const;
import com.jnape.palatable.lambda.optics.Optic;

/**
 * Given an {@link Optic} and a "larger" value S, retrieve a "smaller" value A by lifting the
 * {@link Optic} into the {@link Const} functor.
 * 
 * More idiomatically, this function can be used to treat a {@link Optic} as a "getter" of As from
 * Ss.
 *
 * @param  the type of the larger value
 * @param  the type of the larger updated value (unused, but necessary for composition)
 * @param  the type of the smaller retrieving value
 * @param  the type of the smaller setting value (unused, but necessary for composition)
 * @see Set
 * @see Over
 */
public final class View implements Fn2, ? super Const, S, T, A, B>, S, A> {

    private static final View INSTANCE = new View<>();

    private View() {
    }

    @Override
    public A checkedApply(Optic, ? super Const, S, T, A, B> optic, S s) {
        return optic., Const, Const, Const, Fn1>, Fn1>>apply(
                Const::new).apply(s).runConst();
    }

    @SuppressWarnings("unchecked")
    public static  View view() {
        return (View) INSTANCE;
    }

    public static  Fn1 view(Optic, ? super Const, S, T, A, B> optic) {
        return View.view().apply(optic);
    }

    public static  A view(Optic, ? super Const, S, T, A, B> optic, S s) {
        return view(optic).apply(s);
    }
}