com.jnape.palatable.lambda.monoid.builtin

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

Method Summary

Modifier and Type	Method and 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 java.lang.Object

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

Methods inherited from interface com.jnape.palatable.lambda.monoid.Monoid

flip, foldLeft, foldRight, monoid, monoid, reduceLeft, reduceRight

Methods inherited from interface com.jnape.palatable.lambda.functions.Fn2

apply, apply, checkedApply, compose, contraMap, curried, curry, diMapL, discardR, fn2, fromBiFunction, toBiFunction, uncurry, widen

Methods inherited from interface com.jnape.palatable.lambda.functions.Fn1

andThen, carry, cartesian, censor, choose, cocartesian, diMap, diMapR, discardL, flatMap, fmap, fn1, fromFunction, lazyZip, listens, local, pure, pureFn1, thunk, toFunction, trampolineM, zip, zip

Methods inherited from interface com.jnape.palatable.lambda.monad.Monad

join

Methods inherited from interface com.jnape.palatable.lambda.functor.Functor

coerce

Method Detail

identity

public Maybe<A> identity()

Description copied from interface: Monoid

The identity element of this monoid.

Specified by:

identity in interface Monoid<Maybe<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<Maybe<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)