Re: [Haskell-beginners] File I/O: reading from, writing to, same file in one function

Chaddai: Thanks for your excellent explanation of why using a temp file is necessary and a good thing to do. The problem also with using withFile and a lambda is that in my infinite Haskell beginnerness, I do not know how to get the contents out of the lambda for use later for the second try of withFile in WriteMode. As in LYAH 1. withFile "girlfriend.txt" ReadMode (\handle -> do 2. contents <- hGetContents handle 3. putStr contents) how to retrieve contents for later use? Scope of contents variable in inside lambda only it would appear. Can I declare an empty contents IO String before the withFile lambda somehow? Thanks On Thu, Feb 5, 2015 at 4:33 PM, Chaddaï Fouché wrote:

On Thu, Feb 5, 2015 at 10:30 PM, Geoffrey Bays wrote:

...

Francesco:

Unfortunately, using withFile I get the same error as before with handles: hPutStr: illegal operation (handle is closed).

This error suggests you're forgetting to reopen your file in WriteMode once withFile closed it (you *did *read the documentation of withFile ?). Trying to write on a closed handle is an exercise in futility.

-- Jedaï

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