pipes-interleave (empty) → 0.1

raw patch · 4 files changed

+172/−0 lines, 4 filesdep +basedep +containersdep +pipessetup-changed

Dependencies added: base, containers, pipes

Files

LICENSE +30/−0
Pipes/Interleave.hs +120/−0
Setup.hs +2/−0
pipes-interleave.cabal +20/−0

+ LICENSE view

@@ -0,0 +1,30 @@+Copyright (c) 2013, Ben Gamari++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions are met:++    * Redistributions of source code must retain the above copyright+      notice, this list of conditions and the following disclaimer.++    * Redistributions in binary form must reproduce the above+      copyright notice, this list of conditions and the following+      disclaimer in the documentation and/or other materials provided+      with the distribution.++    * Neither the name of Ben Gamari nor the names of other+      contributors may be used to endorse or promote products derived+      from this software without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+ Pipes/Interleave.hs view

@@ -0,0 +1,120 @@+module Pipes.Interleave ( interleave+                        , combine+                        , combineM+                        , merge+                        , mergeM+                        , groupBy+                        ) where+                        +import Control.Monad (liftM)+import Data.List (sortBy)+import Data.Function (on)+import Data.Either (rights)+import qualified Data.Sequence as Seq+import Data.Foldable (toList)+import Pipes++-- $setup+-- >>> import Pipes.Prelude+-- >>> import Data.Function+-- >>> import Data.Functor.Identity++-- | Interleave elements from a set of 'Producers' such that the interleaved+-- stream is increasing with respect to the given ordering.+-- +-- >>> toList $ interleave compare [each [1,3..10], each [1,5..20]] +-- [1,1,3,5,5,7,9,9,13,17]+-- +interleave :: (Monad m)+           => (a -> a -> Ordering)   -- ^ ordering on elements+           -> [Producer a m ()]      -- ^ element producers+           -> Producer a m ()+interleave compare producers = do+    xs <- lift $ rights `liftM` mapM Pipes.next producers+    go xs+  where --go :: (Monad m, Functor m) => [(a, Producer a m ())] -> Producer a m ()+        go [] = return ()+        go xs = do let (a,producer):xs' = sortBy (compare `on` fst) xs+                   yield a+                   x' <- lift $ next producer+                   go $ either (const xs') (:xs') x'+{-# INLINABLE interleave #-}++-- | Given a stream of increasing elements, combine those equal under the +-- given equality relation+--+-- >>> let append (k,v) (_,v') = return (k, v+v')+-- >>> toList $ combine ((==) `on` fst) append (each [(1,1), (1,4), (2,3), (3,10)])+-- [(1,5),(2,3),(3,10)]+--+combine :: (Monad m)+        => (a -> a -> Bool)    -- ^ equality test+        -> (a -> a -> a)       -- ^ combine operation+        -> Producer a m r -> Producer a m r+combine eq append = combineM eq (\a b->return $ append a b)+{-# INLINEABLE combine #-}+        +-- | 'combine' with monadic side-effects in combine operation.+combineM :: (Monad m)+         => (a -> a -> Bool)    -- ^ equality test+         -> (a -> a -> m a)     -- ^ combine operation+         -> Producer a m r -> Producer a m r+combineM eq append producer = lift (next producer) >>= either return (uncurry go)+  where go a producer' = do+          n <- lift $ next producer'+          case n of+            Left r                 -> yield a >> return r+            Right (a', producer'')+              | a `eq` a'          -> do a'' <- lift $ append a a'+                                         go a'' producer''+              | otherwise          -> yield a >> go a' producer''+{-# INLINABLE combineM #-}+   +-- | Equivalent to 'combine' composed with 'interleave'+--+-- >>> let append (k,v) (_,v') = return (k, v+v')+-- >>> let producers = [ each [(i,2) | i <- [1,3..10]], each [(i,10) | i <- [1,5..20]] ] :: [Producer (Int,Int) Identity ()]+-- >>> toList $ merge (compare `on` fst) append producers+-- [(1,12),(3,2),(5,12),(7,2),(9,12),(13,10),(17,10)]+-- +merge :: (Monad m)+      => (a -> a -> Ordering)    -- ^ ordering on elements+      -> (a -> a -> a)           -- ^ combine operation+      -> [Producer a m ()]       -- ^ producers of elements+      -> Producer a m ()+merge compare append = mergeM compare (\a b->return $ append a b)+{-# INLINABLE merge #-}++-- | Merge with monadic side-effects in combine operation.+mergeM :: (Monad m)+       => (a -> a -> Ordering)    -- ^ ordering on elements+       -> (a -> a -> m a)         -- ^ combine operation+       -> [Producer a m ()]       -- ^ producers of elements+       -> Producer a m ()+mergeM compare append =+    combineM (\a b->compare a b == EQ) append . interleave compare+{-# INLINABLE mergeM #-}++-- | Split stream into groups of equal elements.+-- Note that this is a non-local operation: if the 'Producer' generates+-- a large run of equal elements, all of them will remain in memory until the+-- run ends.+--+-- >>> toList $ groupBy ((==) `on` fst) (each [(1,1), (1,4), (2,3), (3,10)])+-- [[(1,1),(1,4)],[(2,3)],[(3,10)]]+-- +groupBy :: (Monad m)+        => (a -> a -> Bool)    -- ^ equality test+        -> Producer a m r -> Producer [a] m r+groupBy eq producer =+    lift (next producer) >>= either return (\(x,producer)->go (Seq.singleton x) producer)+  where -- go :: Monad m => Seq.Seq a -> Producer a m r -> Producer [a] m r+        go xs producer' = do+          n <- lift $ next producer'+          case n of+            Left r                 -> yield (toList xs) >> return r+            Right (x, producer'')+              | x `eq` x0     -> go (xs Seq.|> x) producer''+              | otherwise     -> yield (toList xs) >> go (Seq.singleton x) producer''+              where x0 Seq.:< _ = Seq.viewl xs+{-# INLINABLE groupBy #-}

+ Setup.hs view

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

+ pipes-interleave.cabal view

@@ -0,0 +1,20 @@+name:                pipes-interleave+version:             0.1+synopsis:            Interleave and merge streams of elements+description:         Interleave and merge streams of elements+homepage:            http://github.com/bgamari/pipes-interleave+license:             BSD3+license-file:        LICENSE+author:              Ben Gamari+maintainer:          bgamari.foss@gmail.com+-- copyright:           +category:            Data+build-type:          Simple+cabal-version:       >=1.10++library+  exposed-modules:     Pipes.Interleave+  build-depends:       base >=4.6 && <4.7,+                       containers >=0.5 && < 0.6,+                       pipes >=4.0 && <4.1+  default-language:    Haskell2010