Class Lazy<A>
- java.lang.Object
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- com.jnape.palatable.lambda.functor.builtin.Lazy<A>
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- Type Parameters:
A
- the value type
- All Implemented Interfaces:
Applicative<A,Lazy<?>>
,Functor<A,Lazy<?>>
,Monad<A,Lazy<?>>
,MonadRec<A,Lazy<?>>
,Traversable<A,Lazy<?>>
- Direct Known Subclasses:
Lazy.Compose
,Lazy.Later
public abstract class Lazy<A> extends java.lang.Object implements MonadRec<A,Lazy<?>>, Traversable<A,Lazy<?>>
AMonad
representing a lazily-computed value. Stack-safe.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
Lazy.Compose<A>
private static class
Lazy.Later<A>
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Constructor Summary
Constructors Modifier Constructor Description private
Lazy()
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description <B> Lazy<B>
discardL(Applicative<B,Lazy<?>> appB)
Sequence both thisApplicative
andappB
, discarding thisApplicative's
result and returningappB
.<B> Lazy<A>
discardR(Applicative<B,Lazy<?>> appB)
Sequence both thisApplicative
andappB
, discardingappB's
result and returning thisApplicative
.boolean
equals(java.lang.Object other)
<B> Lazy<B>
flatMap(Fn1<? super A,? extends Monad<B,Lazy<?>>> f)
Chain dependent computations that may continue or short-circuit based on previous results.<B> Lazy<B>
fmap(Fn1<? super A,? extends B> fn)
Covariantly transmute this functor's parameter using the given mapping function.int
hashCode()
static <A> Lazy<A>
lazy(A value)
Lift a pure value into a lazy computation.static <A> Lazy<A>
lazy(Fn0<A> fn0)
Wrap a computation in a lazy computation.<B> Lazy<B>
pure(B b)
Lift the valueb
into this applicative functor.static Pure<Lazy<?>>
pureLazy()
java.lang.String
toString()
<B> Lazy<B>
trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Lazy<?>>> fn)
Given some operation yielding aRecursiveResult
inside thisMonadRec
, internally trampoline the operation until it yields atermination
instruction.<B,App extends Applicative<?,App>,TravB extends Traversable<B,Lazy<?>>,AppTrav extends Applicative<TravB,App>>
AppTravtraverse(Fn1<? super A,? extends Applicative<B,App>> fn, Fn1<? super TravB,? extends AppTrav> pure)
Applyfn
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.abstract A
value()
Returns the value represented by this lazy computation.<B> Lazy<B>
zip(Applicative<Fn1<? super A,? extends B>,Lazy<?>> appFn)
Given another instance of this applicative over a mapping function, "zip" the two instances together using whatever application semantics the current applicative supports.
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Method Detail
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value
public abstract A value()
Returns the value represented by this lazy computation.- Returns:
- the value
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flatMap
public <B> Lazy<B> flatMap(Fn1<? super A,? extends Monad<B,Lazy<?>>> f)
Chain dependent computations that may continue or short-circuit based on previous results.
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traverse
public <B,App extends Applicative<?,App>,TravB extends Traversable<B,Lazy<?>>,AppTrav extends Applicative<TravB,App>> AppTrav traverse(Fn1<? super A,? extends Applicative<B,App>> fn, Fn1<? super TravB,? extends AppTrav> pure)
Applyfn
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 interfaceTraversable<A,Lazy<?>>
- Type Parameters:
B
- the resulting element typeApp
- the result applicative typeTravB
- this Traversable instance over BAppTrav
- the full inferred resulting type from the traversal- Parameters:
fn
- the function to applypure
- the applicative pure function- Returns:
- the traversed Traversable, wrapped inside an applicative
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pure
public final <B> Lazy<B> pure(B b)
Lift the valueb
into this applicative functor.- Specified by:
pure
in interfaceApplicative<A,Lazy<?>>
- Specified by:
pure
in interfaceMonad<A,Lazy<?>>
- Specified by:
pure
in interfaceMonadRec<A,Lazy<?>>
- Type Parameters:
B
- the type of the returned applicative's parameter- Parameters:
b
- the value- Returns:
- an instance of this applicative over b
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fmap
public final <B> Lazy<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 interfaceApplicative<A,Lazy<?>>
- Specified by:
fmap
in interfaceFunctor<A,Lazy<?>>
- Specified by:
fmap
in interfaceMonad<A,Lazy<?>>
- Specified by:
fmap
in interfaceMonadRec<A,Lazy<?>>
- Specified by:
fmap
in interfaceTraversable<A,Lazy<?>>
- Type Parameters:
B
- the new parameter type- Parameters:
fn
- the mapping function- Returns:
- a functor over B (the new parameter type)
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zip
public <B> Lazy<B> zip(Applicative<Fn1<? super A,? extends B>,Lazy<?>> 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 interfaceApplicative<A,Lazy<?>>
- Specified by:
zip
in interfaceMonad<A,Lazy<?>>
- Specified by:
zip
in interfaceMonadRec<A,Lazy<?>>
- Type Parameters:
B
- the resulting applicative parameter type- Parameters:
appFn
- the other applicative instance- Returns:
- the mapped applicative
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discardL
public final <B> Lazy<B> discardL(Applicative<B,Lazy<?>> appB)
Sequence both thisApplicative
andappB
, discarding thisApplicative's
result and returningappB
. This is generally useful for sequentially performing side-effects.
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discardR
public final <B> Lazy<A> discardR(Applicative<B,Lazy<?>> appB)
Sequence both thisApplicative
andappB
, discardingappB's
result and returning thisApplicative
. This is generally useful for sequentially performing side-effects.
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trampolineM
public <B> Lazy<B> trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,Lazy<?>>> fn)
Given some operation yielding aRecursiveResult
inside thisMonadRec
, internally trampoline the operation until it yields atermination
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 interfaceMonadRec<A,Lazy<?>>
- 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
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equals
public boolean equals(java.lang.Object other)
- Overrides:
equals
in classjava.lang.Object
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hashCode
public int hashCode()
- Overrides:
hashCode
in classjava.lang.Object
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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lazy
public static <A> Lazy<A> lazy(A value)
Lift a pure value into a lazy computation.- Type Parameters:
A
- the value type- Parameters:
value
- the value- Returns:
- the new
Lazy
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lazy
public static <A> Lazy<A> lazy(Fn0<A> fn0)
Wrap a computation in a lazy computation.- Type Parameters:
A
- the value type- Parameters:
fn0
- the computation- Returns:
- the new
Lazy
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