Class First<A>

java.lang.Object

com.jnape.palatable.lambda.monoid.builtin.First<A>

Type Parameters:

A - the Maybe value parameter type

All Implemented Interfaces:

Fn1<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>>, Fn2<Maybe<A>,Maybe<A>,Maybe<A>>, Applicative<Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, Cartesian<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>, Fn1<?,?>>, Cocartesian<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>, Fn1<?,?>>, Contravariant<Maybe<A>, Profunctor<?, Fn1<Maybe<A>,Maybe<A>>, Fn1<?,?>>>, Functor<Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, Profunctor<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>, Fn1<?,?>>, Monad<Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, MonadReader<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, MonadRec<Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, MonadWriter<Maybe<A>, Fn1<Maybe<A>,Maybe<A>>, Fn1<Maybe<A>,?>>, Monoid<Maybe<A>>, Semigroup<Maybe<A>>

public final class First<A>
extends Object
implements Monoid<Maybe<A>>

A Monoid instance formed by Maybe<A>. The application to two Maybe values produces the first non-empty value, or Maybe.nothing() if all values are empty.

See Also:

• Last
• Present
• Monoid
• Maybe

Field Summary

Fields

Modifier and Type	Field	Description
private static final First<?>	INSTANCE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	First()

Method Summary

Modifier and Type	Method	Description
Maybe<A>	checkedApply(Maybe<A> x, Maybe<A> y)
static <A> First<A>	first()
static <A> Fn1<Maybe<A>,Maybe<A>>	first(Maybe<A> x)
static <A> Maybe<A>	first(Maybe<A> x, Maybe<A> y)
<B> Maybe<A>	foldMap(Fn1<? super B, ? extends Maybe<A>> fn, Iterable<B> bs)	Homomorphism combined with catamorphism.
Maybe<A>	identity()	The identity element of this monoid.

Methods inherited from class Object

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

Methods inherited from interface Fn1

andThen, carry, cartesian, censor, choose, cocartesian, diMap, diMapR, discardL, flatMap, fmap, lazyZip, listens, local, pure, self, thunk, toFunction, trampolineM, zip, zip

Methods inherited from interface Fn2

apply, apply, checkedApply, compose, contraMap, diMapL, discardR, toBiFunction, uncurry, widen

Methods inherited from interface Functor

coerce

Methods inherited from interface Monoid

flip, foldLeft, foldRight, reduceLeft, reduceRight

Field Details

INSTANCE

private static final First<?> INSTANCE

Constructor Details

First

private First()

Method Details

identity

public Maybe<A> identity()

Description copied from interface: Monoid

The identity element of this monoid.

Specified by:

identity in interface Monoid<A>

Returns:

the identity

checkedApply

public Maybe<A> checkedApply(Maybe<A> x,
 Maybe<A> y)

Specified by:

checkedApply in interface Fn2<Maybe<A>,Maybe<A>,Maybe<A>>

foldMap

public <B> Maybe<A> foldMap(Fn1<? super B, ? extends Maybe<A>> fn,
 Iterable<B> bs)

Description copied from interface: Monoid

Homomorphism combined with catamorphism. Convert an Iterable<B> to an Iterable<A> (that is, an Iterable of elements this monoid is formed over), then reduce the result from left to right. Under algebraic data types, this is isomorphic to a flatMap.

Specified by:

foldMap in interface Monoid<A>

Type Parameters:

B - the input Iterable element type

Parameters:

fn - the mapping function from A to B

bs - the Iterable of Bs

Returns:

the folded result under this Monoid

See Also:

• Map
• Monoid.reduceLeft(Iterable)

first

public static <A> First<A> first()

first

public static <A> Fn1<Maybe<A>,Maybe<A>> first(Maybe<A> x)

first

public static <A> Maybe<A> first(Maybe<A> x,
 Maybe<A> y)