Use Control.Applicative as a parser.

[jlouis]

Control.Applicative often simplifies parsers and this is no exception. Use the
applicative <$> and <*> to run the 'getErl' function which simplifies its structure
and makes it more clear what is going on.

While here, destroy a couple of liftM's, now we have started to use applicatives.

Note that Applicatives sits "between" a functor and a monad. They allow for some monad-like operations (and all monads are applicatives, but not vice versa). Here, we can utilize the applicatives to invert the ordering and get a parser which looks more like Erlang binary pattern matching. Also, we avoid having to invent the names for what we parse because it is stuffed directly into the position of the algebraic data type.

Not tested at all, so please don't blindly eat it. It compiles however, and since this is Haskell, it must be correct (snicker). No, really, read through the code and verify I did not miss a putN/putn erroneous swap.

[bookshelfdave]

nice :-)

[joedevivo]

Thanks! This needs more focus than I can give it while I'm at chefconf, but I'll get to it next week :D

[jlouis]

Take your time. I'm going on a vacation which means my network bandwidth is being severly downgraded from 100mbit to 4mbit :)