Re: [Haskell-cafe] Safe way to parse arguments?

21 Jun 2008

      On Saturday 21 June 2008, Don Stewart wrote:
...
maybeRead :: Read a => String -> Maybe a
      maybeRead s = case reads s of
          [(x, "")] -> Just x
          _         -> Nothing
Note, if you want to match the behavior of read, you'll probably want 
something like:

    maybeRead :: Read a => String -> Maybe a
    maybeRead s = case reads s of
        [(x, str)] | all isSpace str -> Just x
        _                            -> Nothing

Otherwise, trailing spaces will yield a bad parse.

-- Dan

Re: [Haskell-cafe] Safe way to parse arguments?

Dan Doel