-1
This feels particularly ad-hoc and sets a strange precedent for "safe"
functions in base.
The overall better solution is to stop mixing lazy IO with withFile. In the
case that someone absolutely must have this, a local definition will be
best for other purple reading the code.
On Oct 11, 2014 2:11 PM, "David Feuer"
Some care is required to use withFile properly with lazy IO, and people sometimes get it wrong. In some cases, readFile is a suitable replacement. In other cases, however, it may be necessary to ensure the file gets closed in a timely manner, and it may not be necessary to read the whole file. The following seems to do the trick:
safeWithFile :: (NFData a) => String -> IOMode -> (Handle -> IO a) -> IO a safeWithFile name mode f = withFile name mode $ f >=> (return $!!)
Sample use:
*SafeWithFile> safeWithFile "SafeWithFile.hs" ReadMode hGetContents >>= putStr module SafeWithFile (safeWithFile) where import Control.DeepSeq import System.IO import Control.Monad
safeWithFile :: (NFData a) => String -> IOMode -> (Handle -> IO a) -> IO a safeWithFile name mode f = withFile name mode $ f >=> (return $!!)
_______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries