Re: [Haskell-beginners] Parse error in pattern

26 Feb 2010


      It doesn't look like a complete piece of code so these comments aren't
backed up by running it through GHCi or anything.

On Fri, Feb 26, 2010 at 16:29, Florian Duret  wrote:
...
Hello,
I try to set up a verification on the number of arguments given to my
program, but keep on getting "Parse error in pattern"
Here is what my code looks like:
main :: IO()
main = do
    -- On commence par ouvrir le fichier SAC en mode binaire
    argsList <- getArgs
    if (length (argsList) == 0)
       then do
             putStrLn $ "No filename given to the program.\n $ ProgramName
file.sac"
             return ()
I believe the 'do' here is unecessary.
...
      else
             sacFile1 <- openBinaryFile fileToOpen ReadMode
Here you do need a 'do' though, I believe.
...
ghci complains, and tells "Parse error in pattern", indicating the 'if' line
number.
Can you please help ?
Thank you very much,
Florian
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