[Haskell-beginners] parsec problem

[Christian Maeder]

Hi Tobias,

the "proper" way is to skip white spaces after each token.
Leading white spaces are skipped only once at the beginning.

lex :: Parser a -> Parser a
lex = (<* spaces) -- skip trailing blanks

sentence = many (lex word) <* lex (oneOf ".?!")

-- finally
alltext = spaces *> many sentence

HTH Christian

Am 12.10.2012 19:20, schrieb Tobias:
> Hello,
>
> I would like to parse the input "word1 word2 word3 ." into
> ["word1","word2","word3"] using Parsec.
>
> My code below fails with:
> /> unexpected "."//
> //> expecting letter or digit
>
> /I guess the problem is that the blank before the dot is considered as
> belonging to the "sepBy word blank" parsing and therefore a next word is
> expected, and it is missing.
> I would like the "sepBy word blank" parsing to stop after "word3".
> How can I do this?
> /
> //sentence :: Parser [String]//
> //sentence =  do words <- word `sepBy` blank//
> //                         blank//
> //                         oneOf ".?!"//
> //                         return words//
> //
> //word :: Parser String//
> //word = many1 (letter <|> digit) //
> //
> //blank :: Parser String//
> //blank = string " "
>
> /Regards,
> Tobias
>
>