Package com.jnape.palatable.lambda.functor.builtin

Class Identity<A>

java.lang.Object

com.jnape.palatable.lambda.functor.builtin.Identity<A>

Type Parameters:

A - the value type

All Implemented Interfaces:

Applicative<A,Identity<?>>, Functor<A,Identity<?>>, Monad<A,Identity<?>>, MonadRec<A,Identity<?>>, Traversable<A,Identity<?>>

public final class Identity<A>
extends java.lang.Object
implements MonadRec<A,Identity<?>>, Traversable<A,Identity<?>>

A functor over some value of type A that can be mapped over and retrieved later.

Field Summary

Fields

Modifier and Type	Field	Description
private A	a

Constructor Summary

Constructors

Constructor	Description
Identity(A a)

Method Summary

Modifier and Type	Method	Description
<B> Identity<B>	discardL(Applicative<B,Identity<?>> appB)	Sequence both this Applicative and appB, discarding this Applicative's result and returning appB.
<B> Identity<A>	discardR(Applicative<B,Identity<?>> appB)	Sequence both this Applicative and appB, discarding appB's result and returning this Applicative.
boolean	equals(java.lang.Object other)
<B> Identity<B>	flatMap(Fn1<? super A,? extends Monad<B,Identity<?>>> f)	Chain dependent computations that may continue or short-circuit based on previous results.
<B> Identity<B>	fmap(Fn1<? super A,? extends B> fn)	Covariantly transmute this functor's parameter using the given mapping function.
int	hashCode()
<B> Lazy<Identity<B>>	lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,Identity<?>>> lazyAppFn)	Given a lazy instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.
<B> Identity<B>	pure(B b)	Lift the value b into this applicative functor.
static Pure<Identity<?>>	pureIdentity()	The canonical Pure instance for Identity.
A	runIdentity()	Retrieve the value.
java.lang.String	toString()
<B> Identity<B>	trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Identity<?>>> fn)	Given some operation yielding a RecursiveResult inside this MonadRec, internally trampoline the operation until it yields a termination instruction.
<B,App extends Applicative<?,App>,TravB extends Traversable<B,Identity<?>>,AppTrav extends Applicative<TravB,App>> AppTrav	traverse(Fn1<? super A,? extends Applicative<B,App>> fn, Fn1<? super TravB,? extends AppTrav> pure)	Apply fn to each element of this traversable from left to right, and collapse the results into a single resulting applicative, potentially with the assistance of the applicative's pure function.
<B> Identity<B>	zip(Applicative<Fn1<? super A,? extends B>,Identity<?>> appFn)	Given another instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

coerce

Field Detail

a

private final A a

Constructor Detail

Identity

public Identity(A a)

Method Detail

runIdentity

public A runIdentity()

Retrieve the value.

Returns:

the value

flatMap

public <B> Identity<B> flatMap(Fn1<? super A,? extends Monad<B,Identity<?>>> f)

Chain dependent computations that may continue or short-circuit based on previous results.

Specified by:

flatMap in interface Monad<A,Identity<?>>

Specified by:

flatMap in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the resulting monad parameter type

Parameters:

f - the dependent computation over A

Returns:

the new monad instance

fmap

public <B> Identity<B> fmap(Fn1<? super A,? extends B> fn)

Covariantly transmute this functor's parameter using the given mapping function. Generally this method is specialized to return an instance of the class implementing Functor.

Specified by:

fmap in interface Applicative<A,Identity<?>>

Specified by:

fmap in interface Functor<A,Identity<?>>

Specified by:

fmap in interface Monad<A,Identity<?>>

Specified by:

fmap in interface MonadRec<A,Identity<?>>

Specified by:

fmap in interface Traversable<A,Identity<?>>

Type Parameters:

B - the new parameter type

Parameters:

fn - the mapping function

Returns:

a functor over B (the new parameter type)

pure

public <B> Identity<B> pure(B b)

Lift the value b into this applicative functor.

Specified by:

pure in interface Applicative<A,Identity<?>>

Specified by:

pure in interface Monad<A,Identity<?>>

Specified by:

pure in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the type of the returned applicative's parameter

Parameters:

b - the value

Returns:

an instance of this applicative over b

zip

public <B> Identity<B> zip(Applicative<Fn1<? super A,? extends B>,Identity<?>> appFn)

Given another instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.

Specified by:

zip in interface Applicative<A,Identity<?>>

Specified by:

zip in interface Monad<A,Identity<?>>

Specified by:

zip in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the resulting applicative parameter type

Parameters:

appFn - the other applicative instance

Returns:

the mapped applicative

lazyZip

public <B> Lazy<Identity<B>> lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,Identity<?>>> lazyAppFn)

Given a lazy instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports. This is useful for applicatives that support lazy evaluation and early termination.

Specified by:

lazyZip in interface Applicative<A,Identity<?>>

Specified by:

lazyZip in interface Monad<A,Identity<?>>

Specified by:

lazyZip in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the resulting applicative parameter type

Parameters:

lazyAppFn - the lazy other applicative instance

Returns:

the mapped applicative

See Also:

Maybe, Either

discardL

public <B> Identity<B> discardL(Applicative<B,Identity<?>> appB)

Sequence both this Applicative and appB, discarding this Applicative's result and returning appB. This is generally useful for sequentially performing side-effects.

Specified by:

discardL in interface Applicative<A,Identity<?>>

Specified by:

discardL in interface Monad<A,Identity<?>>

Specified by:

discardL in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the type of the returned Applicative's parameter

Parameters:

appB - the other Applicative

Returns:

appB

discardR

public <B> Identity<A> discardR(Applicative<B,Identity<?>> appB)

Sequence both this Applicative and appB, discarding appB's result and returning this Applicative. This is generally useful for sequentially performing side-effects.

Specified by:

discardR in interface Applicative<A,Identity<?>>

Specified by:

discardR in interface Monad<A,Identity<?>>

Specified by:

discardR in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the type of appB's parameter

Parameters:

appB - the other Applicative

Returns:

this Applicative

traverse

public <B,App extends Applicative<?,App>,TravB extends Traversable<B,Identity<?>>,AppTrav extends Applicative<TravB,App>> AppTrav traverse(Fn1<? super A,? extends Applicative<B,App>> fn,
                                                                                                                                                                               Fn1<? super TravB,? extends AppTrav> pure)

Apply fn to each element of this traversable from left to right, and collapse the results into a single resulting applicative, potentially with the assistance of the applicative's pure function.

Specified by:

traverse in interface Traversable<A,Identity<?>>

Type Parameters:

B - the resulting element type

App - the result applicative type

TravB - this Traversable instance over B

AppTrav - the full inferred resulting type from the traversal

Parameters:

fn - the function to apply

pure - the applicative pure function

Returns:

the traversed Traversable, wrapped inside an applicative

trampolineM

public <B> Identity<B> trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Identity<?>>> fn)

Given some operation yielding a RecursiveResult inside this MonadRec, internally trampoline the operation until it yields a termination instruction.

Stack-safety depends on implementations guaranteeing that the growth of the call stack is a constant factor independent of the number of invocations of the operation. For various examples of how this can be achieved in stereotypical circumstances, see the referenced types.

Specified by:

trampolineM in interface MonadRec<A,Identity<?>>

Type Parameters:

B - the ultimate resulting carrier type

Parameters:

fn - the function to internally trampoline

Returns:

the trampolined MonadRec

See Also:

for a basic implementation, for a implementation, for an implementation leveraging an already stack-safe , for a implementation

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

pureIdentity

public static Pure<Identity<?>> pureIdentity()

The canonical Pure instance for Identity.

Returns:

the Pure instance