[Haskell-cafe] MIDI-controlled application

[Tim Baumgartner]

Hi Haskellers!

I'm writing my first non-trivial Haskell application. I have an electronic
drum set that generates MIDI events that I process with Haskell. A simple
application of this kind might have fixed drums associated with fixed
commands (I've done that). The next step would be to display menus (with
very large font...) that show commands and the associated drums. The menu
structure should be derived from the commands active in each context. Up to
this point, I implemented this already in Java. But now after some
successful attempts in Haskell, I plan for more features: the user should
ultimately be able to record his own "triggers", i.e. short drum rhythms,
and associate them with actions. Since I'm still a beginner with only some
basic experience in Monads, Arrows and their transformers, there is
infinite knowledge to be gained by working on this problem (both library
and concrete apps).

Currently I'm using a monad that combines Parsec (with MIDI event stream)
and a Writer (that writes commands that should result in IO). It's done in
a way that during running the monad, many parses can be done and failing
parses roll back the parser state so that a new parse can be tried.

Now my questions:
I have read about Yampa, but I have not mastered it yet. E.g. I don't
understand switches. Could my "triggers" be realized with Yampa's events
and switches?
Would you recommend any other approach?
Is there something similar somewhere?

Regards
Tim
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