Package com.jnape.palatable.lambda.functions.builtin.fn1

Class Upcast<A extends B,B>

java.lang.Object

com.jnape.palatable.lambda.functions.builtin.fn1.Upcast<A,B>

Type Parameters:

A - the covariant type

B - the contravariant type

All Implemented Interfaces:

Fn1<A,B>, Applicative<B,Fn1<A,?>>, Cartesian<A,B,Fn1<?,?>>, Cocartesian<A,B,Fn1<?,?>>, Contravariant<A,Profunctor<?,B,Fn1<?,?>>>, Functor<B,Fn1<A,?>>, Profunctor<A,B,Fn1<?,?>>, Monad<B,Fn1<A,?>>, MonadReader<A,B,Fn1<A,?>>, MonadRec<B,Fn1<A,?>>, MonadWriter<A,B,Fn1<A,?>>

public final class Upcast<A extends B,B>
extends Object
implements Fn1<A,B>

Upcast a value of type B to a value of type A that B extends. This is principally useful when dealing with parametric types that are invariant in their parameters and a cast is necessary for compatibility purposes.

Example:

 
 Iterable<String> have = new ArrayList<>();
 Iterable<CharSequence> want = map(upcast(), have); // necessary due to invariance in parameter
 
 

Note that this is universally safe.

Field Summary

Fields

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

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Upcast()

Method Summary

Modifier and Type	Method	Description
B	checkedApply(A a)	Invoke this function with the given argument, potentially throwing any Throwable.
static <A extends B, B> Upcast<A,B>	upcast()
static <A extends B, B> B	upcast(A a)

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.functions.Fn1

andThen, apply, carry, cartesian, censor, choose, cocartesian, compose, contraMap, diMap, diMapL, diMapR, discardL, discardR, flatMap, fmap, lazyZip, listens, local, pure, self, thunk, toFunction, trampolineM, widen, zip, zip

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

coerce

Field Details

INSTANCE

private static final Upcast<?,?> INSTANCE

Constructor Details

Upcast

private Upcast()

Method Details

checkedApply

public B checkedApply(A a)

Description copied from interface: Fn1

Invoke this function with the given argument, potentially throwing any Throwable.

Specified by:

checkedApply in interface Fn1<A extends B,B>

Parameters:

a - the argument

Returns:

the result of the function application

upcast

public static <A extends B,
B> Upcast<A,B> upcast()

upcast

public static <A extends B,
B> B upcast(A a)