Daniel Fischer wrote:
On Wednesday 29 September 2010 19:10:22, Ben Franksen wrote:
Note the last line mentions only '}'. I would rather like to see
expecting "}" or digit
since the parser could very well accept another digit here.
parsec2 did that, I don't know whether that change is intentional or accidental.
This looks more like a bug than a feature to me. I checked parsec-3.0.1 and it behaves like parsec-2, i.e. behaves as I expected.
(1) What is the reason for this behaviour? (2) Is there another combinator that behaves as I would like? (3) Otherwise, how do I write one myself?
I just saw that Christian Maeder answered a similar question recently. I
tried his suggestion of using manyTill and bingo:
{-# LANGUAGE NoMonomorphismRestriction #-} import Control.Applicative ((*>),(<*)) import Text.Parsec block p = char '{' *> p <* char '}' parser = block (manyTill digit (char '}')) main = parseTest parser "{123a}" You would need
block (manyTill digit (lookAhead (char '}'))
to replicate the behaviour of block (many digit).
Right, so it gets even more complicated.
Is there a non-greedy variant of 'many' so that modularity gets restored and efficiency is not lost?
So many questions... Cheers Ben