Box

Boxes that emit, transduce & commit

This library follows the ideas and code from pipes-concurrency and mvc but with some polymorphic tweaks and definitively more pretentious names.

Documentation

>>> :set -XOverloadedStrings
>>> :set -XGADTs
>>> import Protolude
>>> import Box
>>> import qualified Streaming.Prelude as S
>>> import Control.Monad.Conc.Class as C
>>> let committer' = cStdout 100
>>> let emitter' = toEmit (S.each ["hi","bye","q","x"])
>>> let box' = Box <$> committer' <*> emitter'
>>> let transducer' = Transducer $ \s -> s & S.takeWhile (/="q") & S.map ("echo: " <>)

committing

>>> with (cStdout 100) $ \c -> C.atomically (commit c "something")
something
True

The monoid instance sends each commit to both mappended committers. Delaying effects are introduced to these examples to keep stdout clear of race effects.

turned off in doctest until the muddled upedness is sorted... > let cDelay = cmap (b -> sleep 0.1 >> pure (Just b)) $ (liftC $ cStdout 100) > let cImmediate = liftC $ cStdout 100 > (etcM () transducer' $ (Box $ (cImmediate <> cDelay) * (liftE $ emitter'))) >> sleep 1 echo: hi echo: hi echo: bye echo: bye

>>> let c = fmap liftC $ cStdout 10
>>> let e = fmap liftE $ toEmit (S.each ["hi","bye","q","x"])
>>> let c' = cmap (\a -> if a=="q" then (sleep 1 >> putStrLn "stolen!" >> sleep 1 >> pure (Nothing)) else (pure (Just a))) <$> c :: Cont IO (Committer IO Text)
>>> fuse (pure . pure) $ Box <$> c' <*> e
hi
bye
stolen!
x

prism handler

>>> import Control.Lens (_Right)
>>> let e2 = (fmap (\x -> Right (x <> "_right")) <$> e) <> (fmap (\x -> Left (x <> "_left")) <$> e)
>>> let cright = handles _Right <$> c
>>> fuse (pure . pure) $ Box <$> cright <*> e2
hi_right
bye_right
q_right
x_right

>>> with (S.each [0..] & toEmit) (C.atomically . emit) >>= print
Just 0

>>> let c = fmap liftC $ cStdout 10
>>> let e = fmap liftE $ toEmit (S.each ["hi","bye","q","x"])
>>> let e' = emap (\a -> if a=="q" then (sleep 0.1 >> putStrLn "stole a q!" >> sleep 0.1 >> pure (Nothing)) else (pure (Just a))) <$> e :: Cont IO (Emitter IO Text)
>>> fuse (pure . pure) $ Box <$> c <*> e'
hi
bye
stole a q!
x

>>> let e1 = fmap show <$> (toEmit $ delayTimed (S.each (zip (fromIntegral <$> [1..10]) ['a'..]))) :: Cont IO (Emitter (C.STM IO) Text)
>>> let e2 = fmap show <$> (toEmit $ delayTimed (S.each (zip ((\x -> fromIntegral x + 0.1) <$> [1..10]) (reverse ['a'..'z'])))) :: Cont IO (Emitter (C.STM IO) Text)
>>> let e12 = e1 <> e2
>>> etc () (Transducer identity) $ Box <$> cStdout 6 <*> emerge ((,) <$> e1 <*> e2)
'a'
'z'
'b'
'y'
'c'
'x'

>>> etc () (Transducer identity) $ Box <$> cStdout 6 <*> (liftA2 (<>) e1 e2)
'a'
'z'
'b'
'y'
'c'
'x'

>>> etc () transducer' box'
echo: hi
echo: bye

module Box.Box

module Box.Committer

module Box.Connectors

module Box.Cont

module Box.Emitter

module Box.IO

module Box.Plugs

module Box.Queue

module Box.Stream

module Box.Time

module Box.Transducer