I'm glad to announce the new version of the csound-expression [1] package.
It's the library for electronic music and sound design. Here is a full description [2]
In the new version it supports GUI-widgets. You can not only 
create sound instruments but update parameters onlne with sliders, 
knobs and buttons. There are many other widgets.

You can find out the details in the quick start guide [3] and the examples [4].

Anton

[1] http://hackage.haskell.org/package/csound-expression
[2] https://github.com/anton-k/csound-expression
[3] https://github.com/anton-k/csound-expression/blob/master/tutorial/QuickStart.markdown
[4] https://github.com/anton-k/csound-expression/tree/master/examples/Gui