fj
Class P1<A>

java.lang.Object
  fj.P1<A>

public abstract class P1<A>
extends Object

A product-1. Also, the identity monad.

Version:

2.8

• $LastChangedRevision$
• $LastChangedDate$

Constructor Summary

P1()

Method Summary

static <A> F<P1<A>,A>	__1() Returns a function that returns the first element of a product.
abstract A	_1() Access the first element of the product.
static <A,B> P1<B>	apply(P1<A> ca, P1<F<A,B>> cf) Performs function application within a P1 (applicative functor pattern).
static <A,B> P1<B>	bind(P1<A> a, F<A,P1<B>> f) Binds the given function to the value in a product-1 with a final join.
static <A,B,C> P1<C>	bind(P1<A> ca, P1<B> cb, F<A,F<B,C>> f) Binds the given function to the values in the given P1s with a final join.
static <A,B> F<A,P1<B>>	curry(F<A,B> f) Promotes the given function so that it returns its value in a P1.
static <A,B> F<P1<A>,P1<B>>	fmap(F<A,B> f) Promote any function to a transformation between P1s.
static <A> P1<A>	join(P1<P1<A>> a) Joins a P1 of a P1 with a bind operation.
static <A,B,C> F<P1<A>,F<P1<B>,P1<C>>>	liftM2(F<A,F<B,C>> f) Promotes a function of arity-2 to a function on P1s.
<X> P1<X>	map(F<A,X> f) Map the element of the product.
static <A> F<List<P1<A>>,P1<List<A>>>	sequence_() A first-class version of the sequence method for lists of P1s.
static <A> P1<List<A>>	sequence(List<P1<A>> as) Turns a List of P1s into a single P1 of a List.
static <A> P1<Stream<A>>	sequence(Stream<P1<A>> as) Turns a stream of P1s into a single P1 of a stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

P1

public P1()

Method Detail

_1

public abstract A _1()

Access the first element of the product.

Returns:

The first element of the product.

map

public <X> P1<X> map(F<A,X> f)

Map the element of the product.

Parameters:

f - The function to map with.

Returns:

A product with the given function applied.

__1

public static <A> F<P1<A>,A> __1()

Returns a function that returns the first element of a product.

Returns:

A function that returns the first element of a product.

fmap

public static <A,B> F<P1<A>,P1<B>> fmap(F<A,B> f)

Promote any function to a transformation between P1s.

Parameters:

f - A function to promote to a transformation between P1s.

Returns:

A function promoted to operate on P1s.

bind

public static <A,B> P1<B> bind(P1<A> a,
                               F<A,P1<B>> f)

Binds the given function to the value in a product-1 with a final join.

Parameters:

a - A value in a product-1 to which to apply a function.

f - A function to apply to the value in a product-1.

Returns:

The result of applying the given function to the value of given product-1.

curry

public static <A,B> F<A,P1<B>> curry(F<A,B> f)

Promotes the given function so that it returns its value in a P1.

Parameters:

f - A function to have its result wrapped in a P1.

Returns:

A function whose result is wrapped in a P1.

apply

public static <A,B> P1<B> apply(P1<A> ca,
                                P1<F<A,B>> cf)

Performs function application within a P1 (applicative functor pattern).

Parameters:

ca - The P1 to which to apply a function.

cf - The P1 function to apply.

Returns:

A new P1 after applying the given P1 function to the first argument.

bind

public static <A,B,C> P1<C> bind(P1<A> ca,
                                 P1<B> cb,
                                 F<A,F<B,C>> f)

Binds the given function to the values in the given P1s with a final join.

Parameters:

ca - A given P1 to bind the given function with.

cb - A given P1 to bind the given function with.

f - The function to apply to the values in the given P1s.

Returns:

A new P1 after performing the map, then final join.

join

public static <A> P1<A> join(P1<P1<A>> a)

Joins a P1 of a P1 with a bind operation.

Parameters:

a - The P1 of a P1 to join.

Returns:

A new P1 that is the join of the given P1.

liftM2

public static <A,B,C> F<P1<A>,F<P1<B>,P1<C>>> liftM2(F<A,F<B,C>> f)

Promotes a function of arity-2 to a function on P1s.

Parameters:

f - The function to promote.

Returns:

A function of arity-2 promoted to map over P1s.

sequence

public static <A> P1<List<A>> sequence(List<P1<A>> as)

Turns a List of P1s into a single P1 of a List.

Parameters:

as - The list of P1s to transform.

Returns:

A single P1 for the given List.

sequence_

public static <A> F<List<P1<A>>,P1<List<A>>> sequence_()

A first-class version of the sequence method for lists of P1s.

Returns:

A function from a List of P1s to a single P1 of a List.

sequence

public static <A> P1<Stream<A>> sequence(Stream<P1<A>> as)

Turns a stream of P1s into a single P1 of a stream.

Parameters:

as - The stream of P1s to transform.

Returns:

A single P1 for the given stream.