Ki

Scope

data Scope

A scope delimits the lifetime of all threads created within it.

scoped :: (Scope -> IO a) -> IO a

Open a scope, perform an IO action with it, then close the scope.

When the scope is closed, all remaining threads created within it are killed.

Throws:

• The exception thrown by the callback to scoped itself, if any.
• ThreadFailed containing the first exception a thread created with fork throws, if any.

Examples

scoped \scope -> do
  fork_ scope worker1
  fork_ scope worker2
  wait scope

wait :: Scope -> IO ()

Wait until all threads created within a scope finish.

waitSTM :: Scope -> STM ()

STM variant of wait.

waitFor :: Scope -> Duration -> IO ()

Variant of wait that waits for up to the given duration.

Spawning threads

There are two variants of thread-creating functions with different exception-propagation semantics.

• If a thread created with fork throws an exception, it is immediately propagated up the call tree to the thread that created its scope.
• If a thread created with async throws an exception, it is not propagated up the call tree, but can be observed by await.

data Thread a

A running thread.

Instances

Functor Thread

Defined in Ki.Thread

Methods

fmap :: (a -> b) -> Thread a -> Thread b

(<$) :: a -> Thread b -> Thread a

Eq (Thread a)

Defined in Ki.Thread

Methods

(==) :: Thread a -> Thread a -> Bool

(/=) :: Thread a -> Thread a -> Bool

Ord (Thread a)

Defined in Ki.Thread

Methods

compare :: Thread a -> Thread a -> Ordering

(<) :: Thread a -> Thread a -> Bool

(<=) :: Thread a -> Thread a -> Bool

(>) :: Thread a -> Thread a -> Bool

(>=) :: Thread a -> Thread a -> Bool

max :: Thread a -> Thread a -> Thread a

min :: Thread a -> Thread a -> Thread a

Generic (Thread a)

Defined in Ki.Thread

Associated Types

type Rep (Thread a) :: Type -> Type

Methods

from :: Thread a -> Rep (Thread a) x

to :: Rep (Thread a) x -> Thread a

type Rep (Thread a)

Defined in Ki.Thread

type Rep (Thread a) = D1 ('MetaData "Thread" "Ki.Thread" "ki-0.1.0.1-JNrPe1BCZVBCx0CA2xJxNk" 'False) (C1 ('MetaCons "Thread" 'PrefixI 'True) (S1 ('MetaSel ('Just "threadId") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 ThreadId) :*: S1 ('MetaSel ('Just "action") 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 (STM a))))

Fork

fork :: Scope -> IO a -> IO (Thread a)

Create a thread within a scope to compute a value concurrently.

If the thread throws an exception, the exception is wrapped in ThreadFailed and immediately propagated up the call tree to the thread that opened its scope.

Throws:

• Calls error if the scope is closed.

fork_ :: Scope -> IO () -> IO ()

Variant of fork that does not return a handle to the created thread.

Throws:

• Calls error if the scope is closed.

forkWithUnmask :: Scope -> ((forall x. IO x -> IO x) -> IO a) -> IO (Thread a)

Variant of fork that provides the thread a function that unmasks asynchronous exceptions.

Throws:

• Calls error if the scope is closed.

forkWithUnmask_ :: Scope -> ((forall x. IO x -> IO x) -> IO ()) -> IO ()

Variant of forkWithUnmask that does not return a handle to the created thread.

Throws:

• Calls error if the scope is closed.

Async

async :: Scope -> IO a -> IO (Thread (Either ThreadFailed a))

Create a thread within a scope to compute a value concurrently.

Throws:

• Calls error if the scope is closed.

asyncWithUnmask :: Scope -> ((forall x. IO x -> IO x) -> IO a) -> IO (Thread (Either ThreadFailed a))

Variant of async that provides the thread a function that unmasks asynchronous exceptions.

Throws:

• Calls error if the scope is closed.

Await

await :: Thread a -> IO a

Wait for a thread to finish.

Throws:

• ThreadFailed if the thread threw an exception and was created with fork.

awaitSTM :: Thread a -> STM a

STM variant of await.

Throws:

• ThreadFailed if the thread threw an exception and was created with fork.

awaitFor :: Thread a -> Duration -> IO (Maybe a)

Variant of await that waits for up to the given duration.

Throws:

• ThreadFailed if the thread threw an exception and was created with fork.

Miscellaneous

data Duration

A length of time with microsecond precision. Numeric literals are treated as seconds.

Instances

Enum Duration

Defined in Ki.Duration

Methods

succ :: Duration -> Duration

pred :: Duration -> Duration

toEnum :: Int -> Duration

fromEnum :: Duration -> Int

enumFrom :: Duration -> [Duration]

enumFromThen :: Duration -> Duration -> [Duration]

enumFromTo :: Duration -> Duration -> [Duration]

enumFromThenTo :: Duration -> Duration -> Duration -> [Duration]

Eq Duration

Defined in Ki.Duration

Methods

(==) :: Duration -> Duration -> Bool

(/=) :: Duration -> Duration -> Bool

Fractional Duration

Defined in Ki.Duration

Methods

(/) :: Duration -> Duration -> Duration

recip :: Duration -> Duration

fromRational :: Rational -> Duration

Data Duration

Defined in Ki.Duration

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Duration -> c Duration

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Duration

toConstr :: Duration -> Constr

dataTypeOf :: Duration -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Duration)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Duration)

gmapT :: (forall b. Data b => b -> b) -> Duration -> Duration

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Duration -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Duration -> r

gmapQ :: (forall d. Data d => d -> u) -> Duration -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Duration -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Duration -> m Duration

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Duration -> m Duration

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Duration -> m Duration

Num Duration

Defined in Ki.Duration

Methods

(+) :: Duration -> Duration -> Duration

(-) :: Duration -> Duration -> Duration

(*) :: Duration -> Duration -> Duration

negate :: Duration -> Duration

abs :: Duration -> Duration

signum :: Duration -> Duration

fromInteger :: Integer -> Duration

Ord Duration

Defined in Ki.Duration

Methods

compare :: Duration -> Duration -> Ordering

(<) :: Duration -> Duration -> Bool

(<=) :: Duration -> Duration -> Bool

(>) :: Duration -> Duration -> Bool

(>=) :: Duration -> Duration -> Bool

max :: Duration -> Duration -> Duration

min :: Duration -> Duration -> Duration

Read Duration

Defined in Ki.Duration

Methods

readsPrec :: Int -> ReadS Duration

readList :: ReadS [Duration]

readPrec :: ReadPrec Duration

readListPrec :: ReadPrec [Duration]

Real Duration

Defined in Ki.Duration

Methods

toRational :: Duration -> Rational

RealFrac Duration

Defined in Ki.Duration

Methods

properFraction :: Integral b => Duration -> (b, Duration)

truncate :: Integral b => Duration -> b

round :: Integral b => Duration -> b

ceiling :: Integral b => Duration -> b

floor :: Integral b => Duration -> b

Show Duration

Defined in Ki.Duration

Methods

showsPrec :: Int -> Duration -> ShowS

show :: Duration -> String

showList :: [Duration] -> ShowS

Generic Duration

Defined in Ki.Duration

Associated Types

type Rep Duration :: Type -> Type

Methods

from :: Duration -> Rep Duration x

to :: Rep Duration x -> Duration

type Rep Duration

Defined in Ki.Duration

type Rep Duration = D1 ('MetaData "Duration" "Ki.Duration" "ki-0.1.0.1-JNrPe1BCZVBCx0CA2xJxNk" 'True) (C1 ('MetaCons "Duration" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Fixed E6))))

microseconds :: Duration

One microsecond.

milliseconds :: Duration

One millisecond.

seconds :: Duration

One second.

timeoutSTM :: Duration -> STM (IO a) -> IO a -> IO a

Wait for an STM action to return an IO action, or if the given duration elapses, return the given IO action instead.

sleep :: Duration -> IO ()

Duration-based threadDelay.

Exceptions

data ThreadFailed

A thread failed, either by throwing or being thrown an exception.

Constructors

ThreadFailed

Fields

• threadId :: ThreadId
• exception :: SomeException

Instances

Show ThreadFailed

Defined in Ki.ThreadFailed

Methods

showsPrec :: Int -> ThreadFailed -> ShowS

show :: ThreadFailed -> String

showList :: [ThreadFailed] -> ShowS

Exception ThreadFailed

Defined in Ki.ThreadFailed

Methods

toException :: ThreadFailed -> SomeException

fromException :: SomeException -> Maybe ThreadFailed

displayException :: ThreadFailed -> String