DSP Programming for VST Instruments and Effects?

Hey, I currently work in distributed computing especially in the video domain and primarily have been interested in functional programming in the last few years - I'm currently a scala developer.

I'm wondering a couple things:

1) If I wanted to play with producing VSTs/AUs - especially instruments - are there any decent resources for getting into this specific problem domain? It seems a bit aloof relative to more prolific areas like distributed computing.

2) Are there any functional programming approaches - eg languages and libraries - that are widely used in audio DSP? I don't think imperative languages would fit quite as well as functional programming as you can just string a signal through a series of functions, and re-arrange them to produce some sort of signal path - that seems logical to me from what I know of analog signal processing circuitry.

3) What sort of math would i want to get up to speed with if I was to venture in this direction? I'm assuming that there is a lot more mathematics that become apparent when working with digital audio and processing/altering it.

Thanks in advance for any insight - it's hard to research the field as very little information appears to be available. I can see this one book here: http://www.amazon.ca/Designing-Audio-Effect-Plug-Ins-Processing/dp/0240825152

I honestly do not really want to work in C - I'd much prefer to work in a higher level language as it's for interest and enjoyment atm.

I also found some Haskell bits: http://hackage.haskell.org/package/csound-expression-0.3.4/docs/CsoundExpr-Opcodes-Plugin-Vst4cs.html