Const

java.lang.Object
- com.jnape.palatable.lambda.functor.builtin.Const<A,B>

Type Parameters:

A - the left parameter type, and the type of the stored value

B - the right (phantom) parameter type

All Implemented Interfaces:

Applicative<B,Const<A,?>>, Bifunctor<A,B,Const<?,?>>, BoundedBifunctor<A,B,Object,Object,Const<?,?>>, Functor<B,Const<A,?>>, Monad<B,Const<A,?>>, MonadRec<B,Const<A,?>>, Traversable<B,Const<A,?>>
```
public final class Const<A,B>
extends Object
implements MonadRec<B,Const<A,?>>, Bifunctor<A,B,Const<?,?>>, Traversable<B,Const<A,?>>
```
A (surprisingly useful) functor over some phantom type B, retaining a value of type A that can be retrieved later. This is useful in situations where it is desirable to retain constant information throughout arbitrary functor transformations, such that at the end of the chain, regardless of how B has been altered, A is still pristine and retrievable.

Constructor Summary

Constructors
Constructor and Description

Const(A a)

Constructors
Constructor and Description
`Const(A a)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`<C,D> Const<C,D>`	`biMap(Fn1<? super A,? extends C> lFn, Fn1<? super B,? extends D> rFn)` Dually map covariantly over both the left and right parameters.
`<Z> Const<Z,B>`	`biMapL(Fn1<? super A,? extends Z> fn)` Covariantly map over the left parameter.
`<C> Const<A,C>`	`biMapR(Fn1<? super B,? extends C> fn)` Covariantly map over the right parameter.
`<C> Const<A,C>`	`discardL(Applicative<C,Const<A,?>> appB)` Sequence both this `Applicative` and `appB`, discarding this `Applicative's` result and returning `appB`.
`<C> Const<A,B>`	`discardR(Applicative<C,Const<A,?>> appB)` Sequence both this `Applicative` and `appB`, discarding `appB's` result and returning this `Applicative`.
`boolean`	`equals(Object other)`
`<C> Const<A,C>`	`flatMap(Fn1<? super B,? extends Monad<C,Const<A,?>>> f)` Chain dependent computations that may continue or short-circuit based on previous results.
`<C> Const<A,C>`	`fmap(Fn1<? super B,? extends C> fn)` Map over the right parameter.
`int`	`hashCode()`
`<C> Lazy<Const<A,C>>`	`lazyZip(Lazy<? extends Applicative<Fn1<? super B,? extends C>,Const<A,?>>> 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.
`<C> Const<A,C>`	`pure(C c)` Lift the value `b` into this applicative functor.
`static <A> Pure<Const<A,?>>`	`pureConst(A a)` The canonical `Pure` instance for `Const`.
`A`	`runConst()` Retrieve the stored value.
`String`	`toString()`
`<C> Const<A,C>`	`trampolineM(Fn1<? super B,? extends MonadRec<RecursiveResult<B,C>,Const<A,?>>> fn)` Given some operation yielding a `RecursiveResult` inside this `MonadRec`, internally trampoline the operation until it yields a `termination` instruction.
`<C,App extends Applicative<?,App>,TravB extends Traversable<C,Const<A,?>>,AppTrav extends Applicative<TravB,App>> AppTrav`	`traverse(Fn1<? super B,? extends Applicative<C,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.
`<C> Const<A,C>`	`zip(Applicative<Fn1<? super B,? extends C>,Const<A,?>> 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.monad.Monad
join

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

- Constructor Detail
  - Const
```
public Const(A a)
```
- Method Detail
  - runConst
```
public A runConst()
```
    Retrieve the stored value.
    
    Returns:
    
    the value
  - fmap
```
public <C> Const<A,C> fmap(Fn1<? super B,? extends C> fn)
```
    Map over the right parameter. Note that because B is never actually known quantity outside of a type signature, this is effectively a no-op that serves only to alter Const's type signature.
    
    Specified by:
    
    fmap in interface Applicative<B,Const<A,?>>
    
    Specified by:
    
    fmap in interface Functor<B,Const<A,?>>
    
    Specified by:
    
    fmap in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    fmap in interface MonadRec<B,Const<A,?>>
    
    Specified by:
    
    fmap in interface Traversable<B,Const<A,?>>
    
    Type Parameters:
    
    C - the new right parameter type
    
    Parameters:
    
    fn - the mapping function
    
    Returns:
    
    a Const over A (the same value) and C (the new phantom parameter)
  - pure
```
public <C> Const<A,C> pure(C c)
```
    Lift the value b into this applicative functor.
    
    Specified by:
    
    pure in interface Applicative<B,Const<A,?>>
    
    Specified by:
    
    pure in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    pure in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the type of the returned applicative's parameter
    
    Parameters:
    
    c - the value
    
    Returns:
    
    an instance of this applicative over b
  - zip
```
public <C> Const<A,C> zip(Applicative<Fn1<? super B,? extends C>,Const<A,?>> 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<B,Const<A,?>>
    
    Specified by:
    
    zip in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    zip in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the resulting applicative parameter type
    
    Parameters:
    
    appFn - the other applicative instance
    
    Returns:
    
    the mapped applicative
  - lazyZip
```
public <C> Lazy<Const<A,C>> lazyZip(Lazy<? extends Applicative<Fn1<? super B,? extends C>,Const<A,?>>> 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<B,Const<A,?>>
    
    Specified by:
    
    lazyZip in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    lazyZip in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the resulting applicative parameter type
    
    Parameters:
    
    lazyAppFn - the lazy other applicative instance
    
    Returns:
    
    the mapped applicative
    
    See Also:
    
    Maybe, Either
  - discardL
```
public <C> Const<A,C> discardL(Applicative<C,Const<A,?>> 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<B,Const<A,?>>
    
    Specified by:
    
    discardL in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    discardL in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the type of the returned Applicative's parameter
    
    Parameters:
    
    appB - the other Applicative
    
    Returns:
    
    appB
  - discardR
```
public <C> Const<A,B> discardR(Applicative<C,Const<A,?>> 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<B,Const<A,?>>
    
    Specified by:
    
    discardR in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    discardR in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the type of appB's parameter
    
    Parameters:
    
    appB - the other Applicative
    
    Returns:
    
    this Applicative
  - flatMap
```
public <C> Const<A,C> flatMap(Fn1<? super B,? extends Monad<C,Const<A,?>>> f)
```
    Chain dependent computations that may continue or short-circuit based on previous results.
    
    Specified by:
    
    flatMap in interface Monad<B,Const<A,?>>
    
    Specified by:
    
    flatMap in interface MonadRec<B,Const<A,?>>
    
    Type Parameters:
    
    C - the resulting monad parameter type
    
    Parameters:
    
    f - the dependent computation over A
    
    Returns:
    
    the new monad instance
  - trampolineM
```
public <C> Const<A,C> trampolineM(Fn1<? super B,? extends MonadRec<RecursiveResult<B,C>,Const<A,?>>> 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<B,Const<A,?>>
    
    Type Parameters:
    
    C - the ultimate resulting carrier type
    
    Parameters:
    
    fn - the function to internally trampoline
    
    Returns:
    
    the trampolined MonadRec
    
    See Also:
    
    for a basic implementation, for a {@link CoProduct2 coproduct} implementation, for an implementation leveraging an already stack-safe {@link Monad#flatMap(Fn1)}, for a {@link MonadT monad transformer} implementation
  - traverse
```
public <C,App extends Applicative<?,App>,TravB extends Traversable<C,Const<A,?>>,AppTrav extends Applicative<TravB,App>> AppTrav traverse(Fn1<? super B,? extends Applicative<C,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<B,Const<A,?>>
    
    Type Parameters:
    
    C - 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
  - biMapL
```
public <Z> Const<Z,B> biMapL(Fn1<? super A,? extends Z> fn)
```
    Covariantly map over the left parameter.
    
    Specified by:
    
    biMapL in interface Bifunctor<A,B,Const<?,?>>
    
    Specified by:
    
    biMapL in interface BoundedBifunctor<A,B,Object,Object,Const<?,?>>
    
    Type Parameters:
    
    Z - the new left parameter type
    
    Parameters:
    
    fn - the mapping function
    
    Returns:
    
    a bifunctor over C (the new left parameter) and B (the same right parameter)
  - biMapR
```
public <C> Const<A,C> biMapR(Fn1<? super B,? extends C> fn)
```
    Covariantly map over the right parameter. For all bifunctors that are also functors, it should hold that biMapR(f) == fmap(f).
    
    Specified by:
    
    biMapR in interface Bifunctor<A,B,Const<?,?>>
    
    Specified by:
    
    biMapR in interface BoundedBifunctor<A,B,Object,Object,Const<?,?>>
    
    Type Parameters:
    
    C - the new right parameter type
    
    Parameters:
    
    fn - the mapping function
    
    Returns:
    
    a bifunctor over A (the same left parameter) and C (the new right parameter)
  - biMap
```
public <C,D> Const<C,D> biMap(Fn1<? super A,? extends C> lFn,
                              Fn1<? super B,? extends D> rFn)
```
    Dually map covariantly over both the left and right parameters. This is isomorphic to biMapL(lFn).biMapR(rFn).
    
    Specified by:
    
    biMap in interface Bifunctor<A,B,Const<?,?>>
    
    Specified by:
    
    biMap in interface BoundedBifunctor<A,B,Object,Object,Const<?,?>>
    
    Type Parameters:
    
    C - the new left parameter type
    
    D - the new right parameter type
    
    Parameters:
    
    lFn - the left parameter mapping function
    
    rFn - the right parameter mapping function
    
    Returns:
    
    a bifunctor over C (the new left parameter type) and D (the new right parameter type)
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - pureConst
```
public static <A> Pure<Const<A,?>> pureConst(A a)
```
    The canonical Pure instance for Const.
    
    Type Parameters:
    
    A - the left parameter type, and the type of the stored value
    
    Parameters:
    
    a - the stored value
    
    Returns:
    
    the Pure instance

Class Const<A,B>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

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

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

Constructor Detail

Const

Method Detail

runConst

fmap

pure

zip

lazyZip

discardL

discardR

flatMap

trampolineM

traverse

biMapL

biMapR

biMap

equals

hashCode

toString

pureConst