value-supply 0.3 → 0.4

raw patch · 2 files changed

+25/−9 lines, 2 files

Files

• Data/Supply.hs +24/−8
• value-supply.cabal +1/−1

@@ -21,6 +21,7 @@   , newSupply   , newEnumSupply   , newNumSupply+  , unsafeNewIntSupply    -- * Obtaining values from supplies   , supplyValue@@ -36,14 +37,18 @@   ) where  -- Usinga an IORef is thread-safe because we update it with 'atomicModifyIORef'.+-- XXX: Is the atomic necessary? import Data.IORef(IORef,newIORef,atomicModifyIORef)+import System.IO.Unsafe(unsafePerformIO,unsafeInterleaveIO)  #if __GLASGOW_HASKELL__ >= 608-import GHC.IOBase(unsafeDupableInterleaveIO)+import GHC.IOBase(unsafeDupableInterleaveIO,unsafeDupablePerformIO) #else-import System.IO.Unsafe(unsafeInterleaveIO) unsafeDupableInterleaveIO :: IO a -> IO a unsafeDupableInterleaveIO = unsafeInterleaveIO++unsafeDupablePerformIO :: IO a -> a+unsafeDupablePerformIO = unsafePerformIO #endif  -- Basics ----------------------------------------------------------------------@@ -72,12 +77,10 @@ {-# INLINE genericNewSupply #-} genericNewSupply :: b -> (IORef b -> IO a) -> IO (Supply a) genericNewSupply start genSym = gen =<< newIORef start--  where gen r = unsafeDupableInterleaveIO-              $ do v <- unsafeDupableInterleaveIO (genSym r)-                   ls <- gen r+  where gen r = unsafeInterleaveIO+              $ do ls <- gen r                    rs <- gen r-                   return (Node v ls rs)+                   return (Node (unsafePerformIO (genSym r)) ls rs)  -- | Creates a new supply of values. -- The arguments specify how to generate values:@@ -98,7 +101,21 @@ newNumSupply   :: (Num a) => IO (Supply a) newNumSupply    = genericNewSupply 0 numGenSym +-- | Create a supply of ints.+-- WARNING: In general, this is not thread safe!+-- It should be OK, as long as the supply is not accessed by different threads.+-- So, if you are in a multi-threaded setting, first split+-- the supply, and give /different/ supply values to the different threads.+unsafeNewIntSupply :: IO (Supply Int)+unsafeNewIntSupply = gen =<< newIORef 0+  where gen r = unsafeDupableInterleaveIO+              $ do ls <- gen r+                   rs <- gen r+                   return (Node (unsafeDupablePerformIO (enumGenSym r)) ls rs) +++ -- Different ways to generate new values: listGenSym     :: IORef [a] -> IO a listGenSym r    = atomicModifyIORef r (\(a:as) -> (as,a))@@ -108,7 +125,6 @@  numGenSym      :: Num a => IORef a -> IO a numGenSym r     = atomicModifyIORef r (\a -> let n = 1 + a in seq n (n,a))-   -- | Generate a new supply by systematically applying a function

@@ -1,5 +1,5 @@ Name:           value-supply-Version:        0.3+Version:        0.4 License:        BSD3 License-file:   LICENSE Author:         Iavor S. Diatchki