Categorical instance to return value rather than index?

[baskaransri]

I'd quite like if there was an analogue of categorical like:

discrete :: (Foldable f, PrimMonad m) => f (Double, a) -> Prob m a

which would sample from the container, choosing each a with the associated probability.

[jtobin]

I have an unequal probability sampling implementation in a slightly less well-known library called sampling (see psample, presample), but I agree an implementation would be nice here too. I'll add it.