Am Donnerstag, 26. Juni 2008 12:40 schrieb Eric: > Hi all, > > I'm using the Parsec library to parse the following grammar > > expr = atom+ > atom = integer | var | (expr) > > The input to the parser is a list of (Token, SourcePos). I have the > following code for atom: > > atom > = try variable <|> try integerr <|> > do{sat(== Reserved "("); (e,pos) <- expression; sat(==Reserved > ")"); return (e,pos)} > > sat p = do (t,pos) <- item > if p t then return(t,pos) else pzero > > When I run the code on the input "(_ineg_ 0)" the parser fails, but > removing > > sat(==Reserved ")") > > and it succeeds. Can any one see why? > > E. > What does the tokeniser return? I would have to see more of the code to diagnose it.
Cheers, Daniel _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe