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|
-----------------------------------------------------------------------------
-- |
-- Module : System.IO.Strict
-- Copyright : (c) Don Stewart 2007
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : dons@galois.com
-- Stability : stable
-- Portability : portable
--
-- The standard IO input functions using strict IO.
--
-----------------------------------------------------------------------------
module System.IO.Strict (
-- * Strict Handle IO
hGetContents, -- :: Handle -> IO [Char]
-- * Strict String IO wrappers
getContents, -- :: IO String
readFile, -- :: FilePath -> IO String
interact -- :: (String -> String) -> IO ()
) where
import Prelude ( String, (>>=), seq, return, (.), (=<<), FilePath, length)
import System.IO (IO)
import qualified System.IO as IO
-- -----------------------------------------------------------------------------
-- Strict hGetContents
-- | Computation 'hGetContents' @hdl@ returns the list of characters
-- corresponding to the unread portion of the channel or file managed
-- by @hdl@, which is immediate closed.
--
-- Items are read strictly from the input Handle.
--
-- This operation may fail with:
--
-- * 'isEOFError' if the end of file has been reached.
hGetContents :: IO.Handle -> IO.IO String
hGetContents h = IO.hGetContents h >>= \s -> length s `seq` return s
-- -----------------------------------------------------------------------------
-- Standard IO
-- | The 'getContents' operation returns all user input as a single string,
-- which is read stirctly (same as 'hGetContents' 'stdin').
getContents :: IO String
getContents = hGetContents IO.stdin
{-# INLINE getContents #-}
-- | The 'interact' function takes a function of type @String->String@
-- as its argument. The entire input from the standard input device is
-- passed to this function as its argument, and the resulting string is
-- output on the standard output device.
interact :: (String -> String) -> IO ()
interact f = IO.putStr . f =<< getContents
{-# INLINE interact #-}
-- | The 'readFile' function reads a file and
-- returns the contents of the file as a string.
-- The file is read strictly, as with 'getContents'.
readFile :: FilePath -> IO String
readFile name = IO.openFile name IO.ReadMode >>= hGetContents
{-# INLINE readFile #-}
|
