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Functional Java is an open source library that supports closures for the Java programming language
package fj;
import fj.control.parallel.Actor;
import fj.control.parallel.Promise;
import fj.control.parallel.Strategy;
import fj.data.*;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.TreeSet;
import java.util.concurrent.*;
import static fj.data.Option.some;
import static fj.data.Stream.iterableStream;
import static fj.data.Zipper.fromStream;
/**
* Created by MarkPerry on 6/04/2014.
*/
public final class F1Functions {
private F1Functions() {
}
/**
* Function composition
*
* @param g A function to compose with this one.
* @return The composed function such that this function is applied last.
*/
public static F o(final F f, final F g) {
return c -> f.f(g.f(c));
}
/**
* First-class function composition
*
* @return A function that composes this function with another.
*/
public static F, F> o(final F f) {
return g -> o(f, g);
}
/**
* Function composition flipped.
*
* @param g A function with which to compose this one.
* @return The composed function such that this function is applied first.
*/
@SuppressWarnings("unchecked")
public static F andThen(final F f, final F g) {
return o(g, f);
}
/**
* First-class composition flipped.
*
* @return A function that invokes this function and then a given function on the result.
*/
public static F, F> andThen(final F f) {
return g -> andThen(f, g);
}
/**
* Binds a given function across this function (Reader Monad).
*
* @param g A function that takes the return value of this function as an argument, yielding a new function.
* @return A function that invokes this function on its argument and then the given function on the result.
*/
public static F bind(final F f, final F> g) {
return a -> g.f(f.f(a)).f(a);
}
/**
* First-class function binding.
*
* @return A function that binds another function across this function.
*/
public static F>, F> bind(final F f) {
return g -> bind(f, g);
}
/**
* Function application in an environment (Applicative Functor).
*
* @param g A function with the same argument type as this function, yielding a function that takes the return
* value of this function.
* @return A new function that invokes the given function on its argument, yielding a new function that is then
* applied to the result of applying this function to the argument.
*/
public static F apply(final F f, final F> g) {
return a -> g.f(a).f(f.f(a));
}
/**
* First-class function application in an environment.
*
* @return A function that applies a given function within the environment of this function.
*/
public static F>, F> apply(final F f) {
return g -> apply(f, g);
}
/**
* Applies this function over the arguments of another function.
*
* @param g The function over whose arguments to apply this function.
* @return A new function that invokes this function on its arguments before invoking the given function.
*/
public static F> on(final F f, final F> g) {
return a1 -> a2 -> g.f(f.f(a1)).f(f.f(a2));
}
/**
* Applies this function over the arguments of another function.
*
* @return A function that applies this function over the arguments of another function.
*/
public static F>, F>> on(final F f) {
return g -> on(f, g);
}
/**
* Promotes this function so that it returns its result in a product-1. Kleisli arrow for P1.
*
* @return This function promoted to return its result in a product-1.
*/
public static F> lazy(final F f) {
return a -> P.lazy(() -> f.f(a));
}
/**
* Partial application.
*
* @param a The A to which to apply this function.
* @return The function partially applied to the given argument to return a lazy value.
*/
public static P1 f(final F f, final A a) {
return P.lazy(() -> f.f(a));
}
/**
* Promotes this function to map over a product-1.
*
* @return This function promoted to map over a product-1.
*/
public static F, P1> mapP1(final F f) {
return p -> p.map(f);
}
/**
* Promotes this function so that it returns its result in an Option. Kleisli arrow for Option.
*
* @return This function promoted to return its result in an Option.
*/
public static F> optionK(final F f) {
return a -> some(f.f(a));
}
/**
* Promotes this function to map over an optional value.
*
* @return This function promoted to map over an optional value.
*/
public static F, Option> mapOption(final F f) {
return o -> o.map(f);
}
/**
* Promotes this function so that it returns its result in a List. Kleisli arrow for List.
*
* @return This function promoted to return its result in a List.
*/
public static F> listK(final F f) {
return a -> List.single(f.f(a));
}
/**
* Promotes this function to map over a List.
*
* @return This function promoted to map over a List.
*/
public static F, List> mapList(final F f) {
return x -> x.map(f);
}
/**
* Promotes this function so that it returns its result in a Stream. Kleisli arrow for Stream.
*
* @return This function promoted to return its result in a Stream.
*/
public static F> streamK(final F f) {
return a -> Stream.single(f.f(a));
}
/**
* Promotes this function to map over a Stream.
*
* @return This function promoted to map over a Stream.
*/
public static F, Stream> mapStream(final F f) {
return x -> x.map(f);
}
/**
* Promotes this function so that it returns its result in a Array. Kleisli arrow for Array.
*
* @return This function promoted to return its result in a Array.
*/
public static F> arrayK(final F f) {
return a -> Array.single(f.f(a));
}
/**
* Promotes this function to map over a Array.
*
* @return This function promoted to map over a Array.
*/
public static F, Array> mapArray(final F f) {
return x -> x.map(f);
}
/**
* Returns a function that contramaps over a given actor.
*
* @return A function that contramaps over a given actor.
*/
public static F, Actor> contramapActor(final F f) {
return a -> a.contramap(f);
}
/**
* Promotes this function to a concurrent function that returns a Promise of a value.
*
* @param s A parallel strategy for concurrent execution.
* @return A concurrent function that returns a Promise of a value.
*/
public static F> promiseK(final F f, final Strategy s) {
return Promise.promise(s, f);
}
/**
* Promotes this function to map over a Promise.
*
* @return This function promoted to map over Promises.
*/
public static F, Promise> mapPromise(final F f) {
return p -> p.fmap(f);
}
/**
* Promotes this function so that it returns its result on the left side of an Either.
* Kleisli arrow for the Either left projection.
*
* @return This function promoted to return its result on the left side of an Either.
*/
@SuppressWarnings("unchecked")
public static F> eitherLeftK(final F f) {
return o(Either.left_(), f);
}
/**
* Promotes this function so that it returns its result on the right side of an Either.
* Kleisli arrow for the Either right projection.
*
* @return This function promoted to return its result on the right side of an Either.
*/
@SuppressWarnings("unchecked")
public static F> eitherRightK(final F f) {
return o(Either.right_(), f);
}
/**
* Promotes this function to map over the left side of an Either.
*
* @return This function promoted to map over the left side of an Either.
*/
@SuppressWarnings("unchecked")
public static F, Either> mapLeft(final F f) {
return Either.leftMap_().f(f);
}
/**
* Promotes this function to map over the right side of an Either.
*
* @return This function promoted to map over the right side of an Either.
*/
@SuppressWarnings("unchecked")
public static F, Either> mapRight(final F f) {
return Either.rightMap_().f(f);
}
/**
* Returns a function that returns the left side of a given Either, or this function applied to the right side.
*
* @return a function that returns the left side of a given Either, or this function applied to the right side.
*/
public static F, B> onLeft(final F f) {
return e -> e.left().on(f);
}
/**
* Returns a function that returns the right side of a given Either, or this function applied to the left side.
*
* @return a function that returns the right side of a given Either, or this function applied to the left side.
*/
public static F, B> onRight(final F f) {
return e -> e.right().on(f);
}
/**
* Promotes this function to return its value in an Iterable.
*
* @return This function promoted to return its value in an Iterable.
*/
@SuppressWarnings("unchecked")
public static F> iterableK(final F f) {
return IterableW.arrow().f(f);
}
/**
* Promotes this function to map over Iterables.
*
* @return This function promoted to map over Iterables.
*/
@SuppressWarnings("unchecked")
public static F, IterableW> mapIterable(final F f) {
return o(IterableW.map().f(f), IterableW.wrap());
}
/**
* Promotes this function to return its value in a NonEmptyList.
*
* @return This function promoted to return its value in a NonEmptyList.
*/
@SuppressWarnings("unchecked")
public static F> nelK(final F f) {
return o(NonEmptyList.nel(), f);
}
/**
* Promotes this function to map over a NonEmptyList.
*
* @return This function promoted to map over a NonEmptyList.
*/
public static F, NonEmptyList> mapNel(final F f) {
return list -> list.map(f);
}
/**
* Promotes this function to return its value in a Set.
*
* @param o An order for the set.
* @return This function promoted to return its value in a Set.
*/
public static F> setK(final F f, final Ord o
) {
return a -> Set.single(o, f.f(a));
}
/**
* Promotes this function to map over a Set.
*
* @param o An order for the resulting set.
* @return This function promoted to map over a Set.
*/
public static F, Set> mapSet(final F f, final Ord o) {
return s -> s.map(o, f);
}
/**
* Promotes this function to return its value in a Tree.
*
* @return This function promoted to return its value in a Tree.
*/
public static F> treeK(final F f) {
return a -> Tree.leaf(f.f(a));
}
/**
* Promotes this function to map over a Tree.
*
* @return This function promoted to map over a Tree.
*/
@SuppressWarnings("unchecked")
public static F, Tree> mapTree(final F f) {
return Tree.fmap_().f(f);
}
/**
* Returns a function that maps this function over a tree and folds it with the given monoid.
*
* @param m The monoid with which to fold the mapped tree.
* @return a function that maps this function over a tree and folds it with the given monoid.
*/
public static F, B> foldMapTree(final F f, final Monoid m) {
return Tree.foldMap_(f, m);
}
/**
* Promotes this function to return its value in a TreeZipper.
*
* @return This function promoted to return its value in a TreeZipper.
*/
public static F> treeZipperK(final F f) {
return andThen(treeK(f), TreeZipper.fromTree());
}
/**
* Promotes this function to map over a TreeZipper.
*
* @return This function promoted to map over a TreeZipper.
*/
public static F, TreeZipper> mapTreeZipper(final F f) {
return (z) -> z.map(f);
}
/**
* Promotes this function so that it returns its result on the failure side of a Validation.
* Kleisli arrow for the Validation failure projection.
*
* @return This function promoted to return its result on the failure side of a Validation.
*/
public static F> failK(final F f) {
return a -> Validation.fail(f.f(a));
}
/**
* Promotes this function so that it returns its result on the success side of an Validation.
* Kleisli arrow for the Validation success projection.
*
* @return This function promoted to return its result on the success side of an Validation.
*/
public static F> successK(final F f) {
return a -> Validation.success(f.f(a));
}
/**
* Promotes this function to map over the failure side of a Validation.
*
* @return This function promoted to map over the failure side of a Validation.
*/
public static F, Validation> mapFail(final F f) {
return v -> v.f().map(f);
}
/**
* Promotes this function to map over the success side of a Validation.
*
* @return This function promoted to map over the success side of a Validation.
*/
public static F, Validation> mapSuccess(final F f) {
return v -> v.map(f);
}
/**
* Returns a function that returns the failure side of a given Validation,
* or this function applied to the success side.
*
* @return a function that returns the failure side of a given Validation,
* or this function applied to the success side.
*/
public static F, B> onFail(final F f) {
return v -> v.f().on(f);
}
/**
* Returns a function that returns the success side of a given Validation,
* or this function applied to the failure side.
*
* @return a function that returns the success side of a given Validation,
* or this function applied to the failure side.
*/
public static F, B> onSuccess(final F f) {
return v -> v.on(f);
}
/**
* Promotes this function to return its value in a Zipper.
*
* @return This function promoted to return its value in a Zipper.
*/
public static F> zipperK(final F f) {
return andThen(streamK(f), s -> fromStream(s).some());
}
/**
* Promotes this function to map over a Zipper.
*
* @return This function promoted to map over a Zipper.
*/
public static F, Zipper> mapZipper(final F f) {
return z -> z.map(f);
}
/**
* Promotes this function to map over an Equal as a contravariant functor.
*
* @return This function promoted to map over an Equal as a contravariant functor.
*/
public static F, Equal> contramapEqual(final F f) {
return e -> e.contramap(f);
}
/**
* Promotes this function to map over a Hash as a contravariant functor.
*
* @return This function promoted to map over a Hash as a contravariant functor.
*/
public static F, Hash> contramapHash(final F f) {
return h -> h.contramap(f);
}
/**
* Promotes this function to map over a Show as a contravariant functor.
*
* @return This function promoted to map over a Show as a contravariant functor.
*/
public static F, Show> contramapShow(final F f) {
return s -> s.contramap(f);
}
/**
* Promotes this function to map over the first element of a pair.
*
* @return This function promoted to map over the first element of a pair.
*/
public static F, P2> mapFst(final F f) {
return P2.map1_(f);
}
/**
* Promotes this function to map over the second element of a pair.
*
* @return This function promoted to map over the second element of a pair.
*/
public static F, P2> mapSnd(final F f) {
return P2.map2_(f);
}
/**
* Promotes this function to map over both elements of a pair.
*
* @return This function promoted to map over both elements of a pair.
*/
public static F, P2> mapBoth(final F f) {
return p2 -> P2.map(f, p2);
}
/**
* Maps this function over a SynchronousQueue.
*
* @param as A SynchronousQueue to map this function over.
* @return A new SynchronousQueue with this function applied to each element.
*/
public static SynchronousQueue mapJ(final F f, final SynchronousQueue as) {
final SynchronousQueue bs = new SynchronousQueue<>();
bs.addAll(iterableStream(as).map(f).toCollection());
return bs;
}
/**
* Maps this function over a PriorityBlockingQueue.
*
* @param as A PriorityBlockingQueue to map this function over.
* @return A new PriorityBlockingQueue with this function applied to each element.
*/
public static PriorityBlockingQueue mapJ(final F f, final PriorityBlockingQueue as) {
return new PriorityBlockingQueue<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a LinkedBlockingQueue.
*
* @param as A LinkedBlockingQueue to map this function over.
* @return A new LinkedBlockingQueue with this function applied to each element.
*/
public static LinkedBlockingQueue mapJ(final F f, final LinkedBlockingQueue as) {
return new LinkedBlockingQueue<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a CopyOnWriteArraySet.
*
* @param as A CopyOnWriteArraySet to map this function over.
* @return A new CopyOnWriteArraySet with this function applied to each element.
*/
public static CopyOnWriteArraySet mapJ(final F f, final CopyOnWriteArraySet as) {
return new CopyOnWriteArraySet<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a CopyOnWriteArrayList.
*
* @param as A CopyOnWriteArrayList to map this function over.
* @return A new CopyOnWriteArrayList with this function applied to each element.
*/
public static CopyOnWriteArrayList mapJ(final F f, final CopyOnWriteArrayList as) {
return new CopyOnWriteArrayList<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a ConcurrentLinkedQueue.
*
* @param as A ConcurrentLinkedQueue to map this function over.
* @return A new ConcurrentLinkedQueue with this function applied to each element.
*/
public static ConcurrentLinkedQueue mapJ(final F f, final ConcurrentLinkedQueue as) {
return new ConcurrentLinkedQueue<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over an ArrayBlockingQueue.
*
* @param as An ArrayBlockingQueue to map this function over.
* @return A new ArrayBlockingQueue with this function applied to each element.
*/
public static ArrayBlockingQueue mapJ(final F f, final ArrayBlockingQueue as) {
final ArrayBlockingQueue bs = new ArrayBlockingQueue<>(as.size());
bs.addAll(iterableStream(as).map(f).toCollection());
return bs;
}
/**
* Maps this function over a TreeSet.
*
* @param as A TreeSet to map this function over.
* @return A new TreeSet with this function applied to each element.
*/
public static TreeSet mapJ(final F f, final TreeSet as) {
return new TreeSet<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a PriorityQueue.
*
* @param as A PriorityQueue to map this function over.
* @return A new PriorityQueue with this function applied to each element.
*/
public static PriorityQueue mapJ(final F f, final PriorityQueue as) {
return new PriorityQueue<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over a LinkedList.
*
* @param as A LinkedList to map this function over.
* @return A new LinkedList with this function applied to each element.
*/
public static LinkedList mapJ(final F f, final LinkedList as) {
return new LinkedList<>(iterableStream(as).map(f).toCollection());
}
/**
* Maps this function over an ArrayList.
*
* @param as An ArrayList to map this function over.
* @return A new ArrayList with this function applied to each element.
*/
public static ArrayList