On Sun, 2008-04-20 at 14:24 -0700, Bryan O'Sullivan wrote:
Doh! For all that I wrote about encodeFile, substitute decodeFile.
Indeed the version of encodeFile you wrote should be exactly identical to the original because the lazy bytestring writeFile already uses bracket like that: writeFile :: FilePath -> ByteString -> IO () writeFile f txt = bracket (openBinaryFile f WriteMode) hClose (\hdl -> hPut hdl txt)
strictDecodeFile :: Binary a => FilePath -> (a -> b) -> IO () strictDecodeFile path force = bracket (openFile path ReadMode) hClose $ \h -> do c <- L.hGetContents h force (decode c) `seq` return ()
Yes, the problem with Ben's program was that decodeFile is lazily reading the file and lazily decoding. If the decoding consumes all the input then it should be possible to avoid rewriting decodeFile and use: dat2 <- decodeFile fname evaluate dat2 removeFile fname It's not immediately clear to me if we can make the decodeFile behave like your version. I'd have to go think about whether running the Get monad can lazily return values or if it always consumes all the input it'll ever need. Duncan