drjoliv.jfunc.contorl.eval

Class Eval<A>

java.lang.Object

drjoliv.jfunc.contorl.eval.Eval<A>

All Implemented Interfaces:

Applicative<Eval.μ,A>, Functor<Eval.μ,A>, Monad<Eval.μ,A>

public abstract class Eval<A>
extends Object
implements Monad<Eval.μ,A>

Delays the evaluation of an expression, caching the value the first time the expression is evaluated.

Author:

Desonte 'drjoliv' Jolivet : drjoliv@gmail.com

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Eval.μ The witness type of Eval.

Constructor Summary

Constructors

Constructor and Description
Eval()

Method Summary

Modifier and Type	Method and Description
<B> Eval<B>	apply(Applicative<Eval.μ,? extends F1<? super A,? extends B>> f) Apply a function contained within an applicative to the contents of this applicative.
<B> Eval<B>	bind(F1<? super A,? extends Monad<Eval.μ,B>> fn) Chains together this computation with a function that produces computations of this type.
static <A> Eval<A>	later(F0<A> fn) Constructs an eval from a supplier of a value.
static <A,B,C> Eval<C>	liftM2(Monad<Eval.μ,A> m, Monad<Eval.μ,B> m1, F2<? super A,? super B,C> fn)
abstract <B> Eval<B>	map(F1<? super A,? extends B> fn) Map applies the function fn to the contents of this Functor, returning a new Functor whose contents is the result of that function application.
static <B> Eval<B>	monad(Monad<Eval.μ,B> monad) A helper function to convert/narrow a reference from a monad to its underlying type.
static <A> Eval<A>	now(A a) Constructs an eval from a value.
ApplicativeFactory<Eval.μ>	pure() Returns a strategy for creating an applicative of this type.
<B> Eval<B>	semi(Monad<Eval.μ,B> mb) Chains together this computation with the given argument, discarding the value within this monad returning a new monad.
abstract A	value() Returns the value witin this eval.
MonadFactory<Eval.μ>	yield() A strategy for creating a monad of this type.

Methods inherited from class java.lang.Object

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

Methods inherited from interface drjoliv.jfunc.monad.Monad

bind, For, For, For, For, For, For, For, forever, join, join, liftM2, liftM3, liftM4, map, map, map, map, unit

Methods inherited from interface drjoliv.jfunc.functor.Functor

replace

Constructor Detail

Eval

public Eval()

Method Detail

apply

public <B> Eval<B> apply(Applicative<Eval.μ,? extends F1<? super A,? extends B>> f)

Description copied from interface: Applicative

Apply a function contained within an applicative to the contents of this applicative.

Specified by:

apply in interface Applicative<Eval.μ,A>

Specified by:

apply in interface Monad<Eval.μ,A>

Parameters:

f - an applicative containing a function.

Returns:

an applicative who contains the result of applying the argument to this applicative.

pure

public ApplicativeFactory<Eval.μ> pure()

Description copied from interface: Applicative

Returns a strategy for creating an applicative of this type.

Specified by:

pure in interface Applicative<Eval.μ,A>

Returns:

a strategy for creating an applicative of this type.

yield

public MonadFactory<Eval.μ> yield()

Description copied from interface: Monad

A strategy for creating a monad of this type.

Specified by:

yield in interface Monad<Eval.μ,A>

Returns:

a strategy for creating a monad of this type.

map

public abstract <B> Eval<B> map(F1<? super A,? extends B> fn)

Description copied from interface: Functor

Map applies the function fn to the contents of this Functor, returning a new Functor whose contents is the result of that function application.

Specified by:

map in interface Applicative<Eval.μ,A>

Specified by:

map in interface Functor<Eval.μ,A>

Specified by:

map in interface Monad<Eval.μ,A>

Type Parameters:

B - the type of the contents of the new Functor.

Parameters:

fn - the function that will map over the contents of this functor.

Returns:

a Functor containing the result of fn.

bind

public <B> Eval<B> bind(F1<? super A,? extends Monad<Eval.μ,B>> fn)

Description copied from interface: Monad

Chains together this computation with a function that produces computations of this type.

Specified by:

bind in interface Monad<Eval.μ,A>

Parameters:

fn - a function that produces monadic computations.

Returns:

A computation created from chaining together this computation with a function that produces computations.

semi

public <B> Eval<B> semi(Monad<Eval.μ,B> mb)

Description copied from interface: Monad

Chains together this computation with the given argument, discarding the value within this monad returning a new monad.

Specified by:

semi in interface Monad<Eval.μ,A>

Parameters:

mb - a computation that wil be chained.

Returns:

a monad obtained from chaining this monad with the argument.

value

public abstract A value()

Returns the value witin this eval.

Returns:

the value within this eval.

now

public static <A> Eval<A> now(A a)

Constructs an eval from a value.

Parameters:

a - a value to be lifted into an eval.

Returns:

an eval.

later

public static <A> Eval<A> later(F0<A> fn)

Constructs an eval from a supplier of a value.

Parameters:

fn - a supplier.

Returns:

an eval.

monad

public static <B> Eval<B> monad(Monad<Eval.μ,B> monad)

A helper function to convert/narrow a reference from a monad to its underlying type.

Parameters:

monad - the monad to be casted to its original type.

Returns:

a eval.

liftM2

public static <A,B,C> Eval<C> liftM2(Monad<Eval.μ,A> m,
                                     Monad<Eval.μ,B> m1,
                                     F2<? super A,? super B,C> fn)

See Also:

Monad.liftM2(Monad,Monad,F2)