seqid-streams 0.3.2 → 0.3.3

raw patch · 2 files changed

+29/−3 lines, 2 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• seqid-streams.cabal +1/−1
• src/System/IO/Streams/SequenceId.hs +28/−2

@@ -1,5 +1,5 @@ name:                seqid-streams-version:             0.3.2+version:             0.3.3 synopsis:            Sequence ID IO-Streams description:         Uniquely identify elements in a sequenced stream License:             BSD3

@@ -1,6 +1,12 @@-module System.IO.Streams.SequenceId where+{-# LANGUAGE BangPatterns #-} +module System.IO.Streams.SequenceId+       ( sequenceIdInputStream+       , sequenceIdOutputStream+       ) where+ import           Control.Applicative ((<$>))+import           Data.IORef          (newIORef, readIORef, writeIORef) import           Data.SequenceId     (SequenceId, SequenceIdError, checkSeqId,                                       incrementSeqId) import           System.IO.Streams   (InputStream, OutputStream)@@ -48,5 +54,25 @@ sequenceIdOutputStream :: SequenceId                         -- ^ Initial sequence ID                        -> OutputStream a                     -- ^ 'System.IO.Streams.OutputStream' to count the elements of                        -> IO (OutputStream a, IO SequenceId) -- ^ ('IO' 'SequenceId') is the action to run to get the current sequence ID-sequenceIdOutputStream = Streams.outputFoldM count+sequenceIdOutputStream = outputFoldM count   where count a _ = return $ incrementSeqId a+++outputFoldM :: (a -> b -> IO a)           -- ^ fold function+            -> a                          -- ^ initial seed+            -> OutputStream b             -- ^ output stream+            -> IO (OutputStream b, IO a)  -- ^ returns a new stream as well as+                                          -- an IO action to fetch the updated+                                          -- seed value.+outputFoldM f initial stream = do+    ref <- newIORef initial+    os  <- Streams.makeOutputStream (wr ref)+    return (os, readIORef ref)++  where+    wr _ Nothing       = Streams.write Nothing stream+    wr ref mb@(Just x) = do+        !z  <- readIORef ref+        !z' <- f z x+        writeIORef ref z'+        Streams.write mb stream