[Haskell-cafe] Conditional IO ?

[Dmitri O.Kondratiev]

Hi,
What is right way to do conditional IO?
For example, I need to write to file errors only in case they exist,
otherwise my function should do nothing:

handleParseErrors errors
  | (not . null) errors =  writeFile "parse-errors.txt" (show errors)
  | otherwise = ?

What should be an 'otherwise' case ?

Thanks!
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