S - the state typeM - the monadic embeddingA - the result typepublic final class StateT<S,M extends MonadRec<?,M>,A> extends Object implements MonadT<M,A,StateT<S,M,?>,StateT<S,?,?>>, MonadReader<S,A,StateT<S,M,?>>, MonadWriter<S,A,StateT<S,M,?>>
State monad transformer.State| Modifier and Type | Method and Description |
|---|---|
StateT<S,M,A> |
censor(Fn1<? super S,? extends S> fn)
Update the accumulated state.
|
<B> StateT<S,M,B> |
discardL(Applicative<B,StateT<S,M,?>> appB)
Sequence both this
Applicative and appB, discarding this Applicative's
result and returning appB. |
<B> StateT<S,M,A> |
discardR(Applicative<B,StateT<S,M,?>> appB)
Sequence both this
Applicative and appB, discarding appB's result and
returning this Applicative. |
<MA extends Monad<A,M>> |
evalT(S s)
Run the stateful computation embedded in the
Monad, returning the result. |
<MS extends Monad<S,M>> |
execT(S s)
Run the stateful computation embedded in the
Monad, returning the final state. |
<B> StateT<S,M,B> |
flatMap(Fn1<? super A,? extends Monad<B,StateT<S,M,?>>> f)
Chain dependent computations that may continue or short-circuit based on previous results.
|
<B> StateT<S,M,B> |
fmap(Fn1<? super A,? extends B> fn)
Covariantly transmute this functor's parameter using the given mapping function.
|
static <A,M extends MonadRec<?,M>> |
get(Pure<M> pureM)
|
static <S,M extends MonadRec<?,M>,A> |
gets(Fn1<? super S,? extends MonadRec<A,M>> fn)
Given a function that produces a value inside a
monadic effect from a state, produce a
StateT that simply passes its state to the function and applies it. |
<B> Lazy<StateT<S,M,B>> |
lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,StateT<S,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 <S> Lift<StateT<S,?,?>> |
liftStateT()
|
<B> StateT<S,M,Tuple2<A,B>> |
listens(Fn1<? super S,? extends B> fn)
Map the accumulation into a value and pair it with the current output.
|
StateT<S,M,A> |
local(Fn1<? super S,? extends S> fn)
Modify this
MonadReader's environment after reading it but before running the effect. |
<N extends MonadRec<?,N>,B> |
mapStateT(Fn1<? super MonadRec<Tuple2<A,S>,M>,? extends MonadRec<Tuple2<B,S>,N>> fn)
Map both the result and the final state to a new result and final state inside the
Monad. |
static <S,M extends MonadRec<?,M>> |
modify(Fn1<? super S,? extends MonadRec<S,M>> updateFn)
|
<B> StateT<S,M,B> |
pure(B b)
Lift the value
b into this applicative functor. |
static <S,M extends MonadRec<?,M>> |
pureStateT(Pure<M> pureM)
|
static <S,M extends MonadRec<?,M>> |
put(MonadRec<S,M> ms)
Lift a
monadic state into StateT. |
<MAS extends MonadRec<Tuple2<A,S>,M>> |
runStateT(S s)
|
static <S,M extends MonadRec<?,M>,A> |
stateT(Fn1<? super S,? extends MonadRec<Tuple2<A,S>,M>> stateFn)
Lift a state-sensitive
monadically embedded computation into StateT. |
static <S,M extends MonadRec<?,M>,A> |
stateT(MonadRec<A,M> ma)
Lift a
monadic value into StateT. |
<B> StateT<S,M,B> |
trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,StateT<S,M,?>>> fn)
Given some operation yielding a
RecursiveResult inside this MonadRec, internally trampoline the
operation until it yields a termination instruction. |
StateT<S,M,A> |
withStateT(Fn1<? super S,? extends MonadRec<S,M>> fn)
Map the final state to a new final state inside the same
monadic effect using the provided
function. |
<B> StateT<S,M,B> |
zip(Applicative<Fn1<? super A,? extends B>,StateT<S,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 <MA extends Monad<A,M>> MA evalT(S s)
Monad, returning the result.MA - the inferred Monad results - the initial statepublic <MS extends Monad<S,M>> MS execT(S s)
Monad, returning the final state.MS - the inferred Monad results - the initial statepublic <N extends MonadRec<?,N>,B> StateT<S,N,B> mapStateT(Fn1<? super MonadRec<Tuple2<A,S>,M>,? extends MonadRec<Tuple2<B,S>,N>> fn)
Monad.N - the new monadic embedding for this StateTB - the new state typefn - the mapping functionStateTpublic StateT<S,M,A> withStateT(Fn1<? super S,? extends MonadRec<S,M>> fn)
monadic effect using the provided
function.fn - the state-mapping functionStateTpublic <B> StateT<S,M,Tuple2<A,B>> listens(Fn1<? super S,? extends B> fn)
listens in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>B - the mapped outputfn - the mapping functionMonadWriterpublic StateT<S,M,A> censor(Fn1<? super S,? extends S> fn)
censor in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>fn - the update functionMonadWriterpublic StateT<S,M,A> local(Fn1<? super S,? extends S> fn)
MonadReader's environment after reading it but before running the effect.local in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>fn - the modification functionMonadReader with a modified environmentpublic <B> StateT<S,M,B> flatMap(Fn1<? super A,? extends Monad<B,StateT<S,M,?>>> f)
flatMap in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>flatMap in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>flatMap in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>flatMap in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>flatMap in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the resulting monad parameter typef - the dependent computation over Apublic <B> StateT<S,M,B> pure(B b)
b into this applicative functor.pure in interface Applicative<A,StateT<S,M extends MonadRec<?,M>,?>>pure in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>pure in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>pure in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>pure in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>pure in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the type of the returned applicative's parameterb - the valuepublic <B> StateT<S,M,B> fmap(Fn1<? super A,? extends B> fn)
fmap in interface Applicative<A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface Functor<A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>fmap in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the new parameter typefn - the mapping functionpublic <B> StateT<S,M,B> zip(Applicative<Fn1<? super A,? extends B>,StateT<S,M,?>> appFn)
zip in interface Applicative<A,StateT<S,M extends MonadRec<?,M>,?>>zip in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>zip in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>zip in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>zip in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>zip in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the resulting applicative parameter typeappFn - the other applicative instancepublic <B> Lazy<StateT<S,M,B>> lazyZip(Lazy<? extends Applicative<Fn1<? super A,? extends B>,StateT<S,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,StateT<S,M extends MonadRec<?,M>,?>>lazyZip in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>lazyZip in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>lazyZip in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>lazyZip in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>lazyZip in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the resulting applicative parameter typelazyAppFn - the lazy other applicative instanceMaybe,
Eitherpublic <B> StateT<S,M,B> discardL(Applicative<B,StateT<S,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,StateT<S,M extends MonadRec<?,M>,?>>discardL in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>discardL in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>discardL in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>discardL in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>discardL in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the type of the returned Applicative's parameterappB - the other Applicativepublic <B> StateT<S,M,A> discardR(Applicative<B,StateT<S,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,StateT<S,M extends MonadRec<?,M>,?>>discardR in interface Monad<A,StateT<S,M extends MonadRec<?,M>,?>>discardR in interface MonadReader<S,A,StateT<S,M extends MonadRec<?,M>,?>>discardR in interface MonadRec<A,StateT<S,M extends MonadRec<?,M>,?>>discardR in interface MonadWriter<S,A,StateT<S,M extends MonadRec<?,M>,?>>discardR in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the type of appB's parameterappB - the other Applicativepublic <B,N extends MonadRec<?,N>> StateT<S,N,B> lift(MonadRec<B,N> mb)
lift in interface MonadBase<M extends MonadRec<?,M>,A,StateT<S,?,?>>lift in interface MonadT<M extends MonadRec<?,M>,A,StateT<S,M extends MonadRec<?,M>,?>,StateT<S,?,?>>B - the MonadRec carrier typeN - the argument MonadRec witnessmb - the argument MonadRecMonadBasepublic <B> StateT<S,M,B> trampolineM(Fn1<? super A,? extends MonadRec<RecursiveResult<A,B>,StateT<S,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,StateT<S,M extends MonadRec<?,M>,?>>B - the ultimate resulting carrier typefn - the function to internally trampolineMonadRecfor 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} implementationpublic static <S,M extends MonadRec<?,M>,A> StateT<S,M,A> gets(Fn1<? super S,? extends MonadRec<A,M>> fn)
monadic effect from a state, produce a
StateT that simply passes its state to the function and applies it.public static <S,M extends MonadRec<?,M>> StateT<S,M,Unit> modify(Fn1<? super S,? extends MonadRec<S,M>> updateFn)
public static <S,M extends MonadRec<?,M>> StateT<S,M,Unit> put(MonadRec<S,M> ms)
monadic state into StateT.public static <S,M extends MonadRec<?,M>,A> StateT<S,M,A> stateT(MonadRec<A,M> ma)
monadic value into StateT.public static <S,M extends MonadRec<?,M>,A> StateT<S,M,A> stateT(Fn1<? super S,? extends MonadRec<Tuple2<A,S>,M>> stateFn)
monadically embedded computation into StateT.