Hi Ruben,
I imagine, free applicative would allow you to easily insert
whitespace/comment eaters afterwards. For instance, say you have Parser
applicative for parsing. Then Ap Parser would represent the same parser,
but with parsing combinators separated with Ap constructors. You would use
Ap Parser when defining your grammar. Then you could "intersperse"
whitespace eaters in between the combinators and "retract" the resulting Ap
Parser into just Parser. That would probably be a cleaner approach compared
to having every combinator wrapped in trimWhiteSpacesAndComments combinator.
Kind regards,
Nick
On Tue, 18 Oct 2016 at 15:12 Ruben Astudillo
Hi all
on [1] it is said the following
"Dealing with whitespace and comments is awkward in the parser; you need to wrap everything in a token combinator. (If you decide to do that, at least use a free applicative functor to ensure that you don’t forget to consume that whitespace)."
Reading on `free` the def of Ap, frankly I don't see how can the free applicative be used for this. Anybody could drop a hint? I would appreciate it.
[1]: https://ro-che.info/articles/2015-01-02-lexical-analysis -- Ruben _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.