Sun Jan 20 11:42:22 CET 2013

Time delay primitive

Is it enough to just have a time delay primitive?  Needed is both
input and output delay.  Let's try to make a composite integrator
object that way.

I don't think this works..  Since the feedback is local, it can only
be done in the primitives.  Makes sense!  The whole point of the
stream abstraction is to tuck away such feedback.

Maybe this needs a different kind of operator.  Something like the
`rec' operation in ArrowLoop.

I don't see a way around this.  Currenlty it seems best to stick to
biquad, one-pole and z as basic ops, and rely on partial evaluation to
optimize away unnecesary operations.