Safe Haskell | Safe |
---|---|

Language | Haskell2010 |

- class MonadTrans t => Interruptible t where
- inEitherTCtx :: a -> RSt (EitherT e) a
- peelEitherTCtx :: RSt (EitherT e) a -> Either e a
- inStateTCtx :: st -> a -> RSt (StateT st) a
- peelStateTCtx :: RSt (StateT st) a -> (a, st)
- inWriterTCtx :: Monoid w => a -> RSt (WriterT w) a
- peelWriterTCtx :: RSt (WriterT w) a -> (a, w)
- inReaderTCtx :: r -> a -> RSt (ReaderT r) a
- peelReaderTCtx :: RSt (ReaderT r) a -> a
- inRWSTCtx :: Monoid w => r -> s -> a -> RSt (RWST r w s) a
- peelRWSTCtx :: RSt (RWST r w s) a -> (a, w, s)
- resume2 :: (Monad m, Interruptible t, Monad (t m), Interruptible u) => (a -> u (t m) b) -> RSt t (RSt u a) -> m (RSt t (RSt u b))
- resume3 :: (Monad m, Interruptible t0, Monad (t0 m), Interruptible t1, Monad (t1 (t0 m)), Interruptible t2) => (a -> t2 (t1 (t0 m)) b) -> RSt t0 (RSt t1 (RSt t2 a)) -> m (RSt t0 (RSt t1 (RSt t2 b)))
- resume4 :: (Monad m, Interruptible t0, Interruptible t1, Interruptible t2, Interruptible t3, Monad (t0 m), Monad (t1 (t0 m)), Monad (t2 (t1 (t0 m)))) => (a -> t3 (t2 (t1 (t0 m))) b) -> RSt t0 (RSt t1 (RSt t2 (RSt t3 a))) -> m (RSt t0 (RSt t1 (RSt t2 (RSt t3 b))))
- resume5 :: (Monad m, Interruptible t0, Interruptible t1, Interruptible t2, Interruptible t3, Interruptible t4, Monad (t0 m), Monad (t1 (t0 m)), Monad (t2 (t1 (t0 m))), Monad (t3 (t2 (t1 (t0 m))))) => (a -> t4 (t3 (t2 (t1 (t0 m)))) b) -> RSt t0 (RSt t1 (RSt t2 (RSt t3 (RSt t4 a)))) -> m (RSt t0 (RSt t1 (RSt t2 (RSt t3 (RSt t4 b)))))
- intercalateWith :: Monad m => ((a -> t a) -> rsta -> m rsta) -> (b -> a -> t a) -> [b] -> [rsta] -> m [rsta]

# Documentation

class MonadTrans t => Interruptible t where Source #

Interruptible monad transformers.

A monad transformer can be made interruptible if it returns its final context from its type creator, and if it is possible to hoist this context again into the monad at the begining of its execution.

For example, `StateT`

can be interrupted because
`runStateT`

returns its final state, and because its state
can be set again at creation simply by passing it as an
parameter to `runStateT`

. An Error context can not be hoisted
back at the transformer, thus Error can not be interrupted.

When instantiating, do not forget to create the corresponding inCtx and peelCtx functions, for documenting the RSt format and keeping the class consistent.

resume :: Monad m => (a -> t m b) -> RSt t a -> m (RSt t b) Source #

Resumes the execution of an interruptible transformer

Interruptible (EitherT e) Source # | |

Interruptible (StateT st) Source # | |

Monoid w => Interruptible (WriterT w) Source # | |

Interruptible (ReaderT * r) Source # | |

Monoid w => Interruptible (RWST r w s) Source # | |

# Instance accessors

inEitherTCtx :: a -> RSt (EitherT e) a Source #

Cretes an interrupted EitherT context

inStateTCtx :: st -> a -> RSt (StateT st) a Source #

Creates an interrupted StateT context

peelStateTCtx :: RSt (StateT st) a -> (a, st) Source #

Unwraps an interrupted StateT context

peelWriterTCtx :: RSt (WriterT w) a -> (a, w) Source #

Unwraps an interrupted WriterT context

inReaderTCtx :: r -> a -> RSt (ReaderT r) a Source #

Creates an interrupted ReaderT context

peelReaderTCtx :: RSt (ReaderT r) a -> a Source #

Unwraps an interrupted WriterT context

inRWSTCtx :: Monoid w => r -> s -> a -> RSt (RWST r w s) a Source #

Creates an interrupted RWST context

peelRWSTCtx :: RSt (RWST r w s) a -> (a, w, s) Source #

Unwraps an interrupted RWST context

# Resumers for stacks of interruptibles

resume2 :: (Monad m, Interruptible t, Monad (t m), Interruptible u) => (a -> u (t m) b) -> RSt t (RSt u a) -> m (RSt t (RSt u b)) Source #

resume3 :: (Monad m, Interruptible t0, Monad (t0 m), Interruptible t1, Monad (t1 (t0 m)), Interruptible t2) => (a -> t2 (t1 (t0 m)) b) -> RSt t0 (RSt t1 (RSt t2 a)) -> m (RSt t0 (RSt t1 (RSt t2 b))) Source #

resume4 :: (Monad m, Interruptible t0, Interruptible t1, Interruptible t2, Interruptible t3, Monad (t0 m), Monad (t1 (t0 m)), Monad (t2 (t1 (t0 m)))) => (a -> t3 (t2 (t1 (t0 m))) b) -> RSt t0 (RSt t1 (RSt t2 (RSt t3 a))) -> m (RSt t0 (RSt t1 (RSt t2 (RSt t3 b)))) Source #

resume5 :: (Monad m, Interruptible t0, Interruptible t1, Interruptible t2, Interruptible t3, Interruptible t4, Monad (t0 m), Monad (t1 (t0 m)), Monad (t2 (t1 (t0 m))), Monad (t3 (t2 (t1 (t0 m))))) => (a -> t4 (t3 (t2 (t1 (t0 m)))) b) -> RSt t0 (RSt t1 (RSt t2 (RSt t3 (RSt t4 a)))) -> m (RSt t0 (RSt t1 (RSt t2 (RSt t3 (RSt t4 b))))) Source #

# Interruptible applications

intercalateWith :: Monad m => ((a -> t a) -> rsta -> m rsta) -> (b -> a -> t a) -> [b] -> [rsta] -> m [rsta] Source #

Folds the second list with the function applied to the first, intercalating the evaluation. That is:

intercalateWith resume f [a00, a10, a20] [b1, b2] = do a01 <- resume (f b1) a00 a11 <- resume (f b1) a10 a21 <- resume (f b1) a20 a02 <- resume (f b2) a11 a12 <- resume (f b2) a21 a22 <- resume (f b2) a31 return [a02, a12, a22]

Usefull for consuming lazy sequences.

The resume function is parametric for allowing resuming deeper Interruptible chains, with resume2, resume3, etc.