I'm trying to use parsec for parsing a custom input stream. As far as I understood the manual correctly I need to define the primitive parser: type MyParser a = GenParser (SourcePos,Tok) () a mytoken :: (Tok -> Maybe a) -> MyParser a mytoken test = token showToken posToken testToken where showToken (pos,tok) = show tok posToken (pos,tok) = pos testToken (pos,tok) = test tok The problem is, since SourcePos is an abstract datatype, how can I actually run this parser without explicitly using values of type SourcePos in the input stream? Many thanks in advance! _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/