W
- the accumulation typeM
- the monadic embedding
A
- the result typepublic final class WriterT<W,M extends MonadRec<?,M>,A> extends Object implements MonadWriter<W,A,WriterT<W,M,?>>, MonadT<M,A,WriterT<W,M,?>,WriterT<W,?,?>>
monad transformer
for Writer
.Modifier and Type | Method and Description |
---|---|
WriterT<W,M,A> |
censor(Fn1<? super W,? extends W> fn)
Update the accumulated state.
|
<B> WriterT<W,M,B> |
discardL(Applicative<B,WriterT<W,M,?>> appB)
Sequence both this
Applicative and appB , discarding this Applicative's
result and returning appB . |
<B> WriterT<W,M,A> |
discardR(Applicative<B,WriterT<W,M,?>> appB)
Sequence both this
Applicative and appB , discarding appB's result and
returning this Applicative . |
<B> WriterT<W,M,B> |
flatMap(Fn1<? super A,? extends Monad<B,WriterT<W,M,?>>> f)
Chain dependent computations that may continue or short-circuit based on previous results.
|
<B> WriterT<W,M,B> |
fmap(Fn1<? super A,? extends B> fn)
Covariantly transmute this functor's parameter using the given mapping function.
|
<B> Lazy<WriterT<W,M,B>> |
lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,WriterT<W,M,?>>> 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,N extends MonadRec<?,N>> |
lift(MonadRec<B,N> mb)
|
static <W> Lift<WriterT<W,?,?>> |
liftWriterT()
|
static <W,M extends MonadRec<?,M>,A> |
listen(MonadRec<A,M> ma)
|
<B> WriterT<W,M,Tuple2<A,B>> |
listens(Fn1<? super W,? extends B> fn)
Map the accumulation into a value and pair it with the current output.
|
<B> WriterT<W,M,B> |
pure(B b)
Lift the value
b into this applicative functor. |
static <W,M extends MonadRec<?,M>> |
pureWriterT(Pure<M> pureM)
|
<MAW extends MonadRec<Tuple2<A,W>,M>> |
runWriterT(Monoid<W> monoid)
Given a
Monoid for the accumulation, run the computation represented by this WriterT inside the
monadic effect , accumulate the written output in terms of the Monoid , and produce the
accumulation and the result inside the Monad . |
static <W,M extends MonadRec<?,M>> |
tell(MonadRec<W,M> mw)
|
<B> WriterT<W,M,B> |
trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,WriterT<W,M,?>>> fn)
Given some operation yielding a
RecursiveResult inside this MonadRec , internally trampoline the
operation until it yields a termination instruction. |
static <W,M extends MonadRec<?,M>,A> |
writerT(MonadRec<Tuple2<A,W>,M> maw)
|
<B> WriterT<W,M,B> |
zip(Applicative<Fn1<? super A,? extends B>,WriterT<W,M,?>> appFn)
Given another instance of this applicative over a mapping function, "zip" the two instances together using
whatever application semantics the current applicative supports.
|
public <MAW extends MonadRec<Tuple2<A,W>,M>> MAW runWriterT(Monoid<W> monoid)
Monoid
for the accumulation, run the computation represented by this WriterT
inside the
monadic effect
, accumulate the written output in terms of the Monoid
, and produce the
accumulation and the result inside the Monad
.public <B> WriterT<W,M,Tuple2<A,B>> listens(Fn1<? super W,? extends B> fn)
listens
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
B
- the mapped outputfn
- the mapping functionMonadWriter
public WriterT<W,M,A> censor(Fn1<? super W,? extends W> fn)
censor
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
fn
- the update functionMonadWriter
public <B,N extends MonadRec<?,N>> WriterT<W,N,B> lift(MonadRec<B,N> mb)
lift
in interface MonadBase<M extends MonadRec<?,M>,A,WriterT<W,?,?>>
lift
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the MonadRec
carrier typeN
- the argument MonadRec
witnessmb
- the argument MonadRec
MonadBase
public <B> WriterT<W,M,B> trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,WriterT<W,M,?>>> fn)
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.
trampolineM
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
B
- the ultimate resulting carrier typefn
- the function to internally trampolineMonadRec
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
public <B> WriterT<W,M,B> fmap(Fn1<? super A,? extends B> fn)
fmap
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
fmap
in interface Functor<A,WriterT<W,M extends MonadRec<?,M>,?>>
fmap
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
fmap
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
fmap
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
fmap
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the new parameter typefn
- the mapping functionpublic <B> WriterT<W,M,B> pure(B b)
b
into this applicative functor.pure
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
pure
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
pure
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
pure
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
pure
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the type of the returned applicative's parameterb
- the valuepublic <B> WriterT<W,M,B> flatMap(Fn1<? super A,? extends Monad<B,WriterT<W,M,?>>> f)
flatMap
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
flatMap
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
flatMap
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
flatMap
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the resulting monad parameter typef
- the dependent computation over Apublic <B> WriterT<W,M,B> zip(Applicative<Fn1<? super A,? extends B>,WriterT<W,M,?>> appFn)
zip
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
zip
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
zip
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
zip
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
zip
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the resulting applicative parameter typeappFn
- the other applicative instancepublic <B> Lazy<WriterT<W,M,B>> lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,WriterT<W,M,?>>> lazyAppFn)
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.lazyZip
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
lazyZip
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
lazyZip
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
lazyZip
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
lazyZip
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the resulting applicative parameter typelazyAppFn
- the lazy other applicative instanceMaybe
,
Either
public <B> WriterT<W,M,B> discardL(Applicative<B,WriterT<W,M,?>> appB)
Applicative
and appB
, discarding this Applicative's
result and returning appB
. This is generally useful for sequentially performing side-effects.discardL
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardL
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardL
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardL
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
discardL
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the type of the returned Applicative's parameterappB
- the other Applicativepublic <B> WriterT<W,M,A> discardR(Applicative<B,WriterT<W,M,?>> appB)
Applicative
and appB
, discarding appB's
result and
returning this Applicative
. This is generally useful for sequentially performing side-effects.discardR
in interface Applicative<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardR
in interface Monad<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardR
in interface MonadRec<A,WriterT<W,M extends MonadRec<?,M>,?>>
discardR
in interface MonadWriter<W,A,WriterT<W,M extends MonadRec<?,M>,?>>
discardR
in interface MonadT<M extends MonadRec<?,M>,A,WriterT<W,M extends MonadRec<?,M>,?>,WriterT<W,?,?>>
B
- the type of appB's parameterappB
- the other Applicativepublic static <W,M extends MonadRec<?,M>,A> WriterT<W,M,A> writerT(MonadRec<Tuple2<A,W>,M> maw)
public static <W,M extends MonadRec<?,M>> Pure<WriterT<W,M,?>> pureWriterT(Pure<M> pureM)