On Jan 31, 2013, at 10:47 , Jan Stolarek <jan.stola...@p.lodz.pl> wrote:
> Thanks for replies guys. I indeed didn't notice that there are monads and
> applicatives used in
> this parser. My thought that monadic parsers are more verbose came from
> Hutton's paper where the
> code is definitely less readable than in example I provided.
>
> There is one more thing that bothers me. It is easy to write a parser that
> returns Nothing when
> parsing fails. But I can't figure out a way to add meaningful error messages
> so that the user
> knows where did the parsing fail. I experimented with using Either so that I
> can use Left to pass
> error messages but this turned out to be inflexible and clutered the code. I
> will be greatful for
> any ideas.
Use the uu-parsinglib library, which provides error messages, repairs your
errors and using its idioms definition you can even write:
inParens c = iI '(' c ')' Ii
I think you cannot get it shorter and with more functionality.
Doaitse
> Janek
>
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