Stuttering

[ivanperez-keera]

A common need in Copilot is the ability to stutter, or to temporarily hold a sample for more than one step.

For example, assuming that the argument stream below holds numbers, one could do:

delay1 a = ifThenElse (counter == 0) a ([0] ++ a)

In the general case, we could do:

delay1 v a = ifThenElse (counter == 0) a ([v] ++ a)

Or, if we have defaults for some types, we could do:

delayDef a = ifThenElse (counter == 0) a ([0] ++ a)

Just something to think about. Maybe there's a cleaner way to do that, or a cleaner way to define a "default".

Having defaults would also help us to create updating and constructor functions for array and struct elements.

[ivanperez-keera]

One could also define:

stutter :: Typed a => a -> Stream Bool -> Stream a -> Stream a
stutter initial cond stream = g
  where
    g = ifThenElse cond ([initial] ++ g) stream

stutterList :: Stream Bool
stutterList = [True, False, False, False, True] ++ stutterList

stream :: Stream Word8
stream = [1, 2, 3, 4] ++ stream

spec :: Spec
spec = trigger "j" true [arg (stutter 0 stutterList stream)]

The behavior of this should be: hold the last sample for so long as the condition is true, and otherwise give me the current sample.

It doesn't shift the stream that is stuttered indefinitely; that would require unbounded memory and is not (and should not be) allowed in Copilot.