Haskell High Performance Programming

Streaming with side-effects

Lists are pure, but the streaming property is still useful also in impure I/O settings. Although lazy I/O has its share of problems, it isn't the only streaming I/O technique in Haskell. It's fully possible to use explicit buffers, for example, to read and process iteratively using the low-level functions in System.IO. This program uses a pointer to an integer to stream random numbers from `

-- file: ptr.hsimport System.IO import Foreign.Ptr (Ptr) import Foreign.Storable (Storable(sizeOf, peek)) import Foreign.Marshal (alloca) main = withBinaryFile "/dev/random" ReadMode $ alloca . process where process :: Handle -> Ptr Int -> IO () process h ptr = go where go = do count <- hGetBuf h ptr (sizeOf (undefined :: Int)) if ...