-- | Simple resource management functions {-# LANGUAGE RankNTypes #-} module Pipes.Safe.Prelude ( -- * Handle management withFile, -- * String I/O -- $strings readFile, writeFile ) where import Control.Monad.IO.Class (MonadIO(liftIO)) import Pipes (Producer', Consumer') import Pipes.Safe (bracket, MonadSafe) import qualified Pipes.Prelude as P import qualified System.IO as IO import Prelude hiding (readFile, writeFile) -- | Acquire a 'IO.Handle' within 'MonadSafe' withFile :: (MonadSafe m) => FilePath -> IO.IOMode -> (IO.Handle -> m r) -> m r withFile file ioMode = bracket (liftIO $ IO.openFile file ioMode) (liftIO . IO.hClose) {-# INLINABLE withFile #-} {- $strings Note that 'String's are very inefficient, and I will release future separate packages with 'Data.ByteString.ByteString' and 'Data.Text.Text' operations. I only provide these to allow users to test simple I/O without requiring any additional library dependencies. -} {-| Read lines from a file, automatically opening and closing the file as necessary -} readFile :: (MonadSafe m) => FilePath -> Producer' String m () readFile file = withFile file IO.ReadMode P.fromHandle {-# INLINABLE readFile #-} {-| Write lines to a file, automatically opening and closing the file as necessary -} writeFile :: (MonadSafe m) => FilePath -> Consumer' String m r writeFile file = withFile file IO.WriteMode P.toHandle {-# INLINABLE writeFile #-}