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-- !!! Test file positioning
module Main(main) where
import Control.Monad
import System.Directory (removeFile, doesFileExist)
import System.IO
import System.IO.Error
main = do
hIn <- openFile "hGetPosn001.in" ReadMode
f <- doesFileExist "hGetPosn001.out"
when f (removeFile "hGetPosn001.out")
hOut <- openFile "hGetPosn001.out" ReadWriteMode
bof <- hGetPosn hIn
putStrLn (show bof) -- you can show HandlePosns
copy hIn hOut
hSetPosn bof
copy hIn hOut
hSeek hOut AbsoluteSeek 0
stuff <- hGetContents hOut
putStr stuff
copy :: Handle -> Handle -> IO ()
copy hIn hOut =
try (hGetChar hIn) >>=
either (\ err -> if isEOFError err then return () else error "copy")
( \ x -> hPutChar hOut x >> copy hIn hOut)
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