Re: [Haskell-cafe] [Parsec] A combinator to match between M and N times?

29 Aug 2006


      On Tue, 29 Aug 2006, Tomasz Zielonka wrote:
...
How about this?
countBetween m n p = do
        xs <- count m p
        ys <- count (n - m) $ option Nothing $ do
            y <- p
            return (Just y)
        return (xs ++ catMaybes ys)
Assuming n >= m.
...
Does anyone has a solution? Preferrably one I can understand, which
means not yet with liftM :-)
No liftM, as requested :-)
Although, one is tempted to write

    liftM Just p

 instead of

    do
      y <- p
      return (Just y)


:-)

Re: [Haskell-cafe] [Parsec] A combinator to match between M and N times?

Henning Thielemann