Is your feature request related to a problem? Please describe.

My use case is rather complex, so I hope you'll excuse me for not going into gory details right away.

I'd rather just say that while Kanata now provides various handy devices/hacks that allow to store and reuse "state" for complex scenarios, like key-history, noop keys, virtual keys, etc, I feel like sometimes it would just make more sense to piggyback on Kanata's own wonderful layer model, keeping config cleaner and saner. Also just for completeness' sake.

So we already have a predicate that checks the current layer in switch statements, thanks to #1060. How hard would it be to also make one for the current base layer (the one Kanata goes back to when you release layer-while-held)?

Describe the solution you'd like.

a check for current base layer, like this:

(defalias
  sw (switch
    ((base-layer base-layer-1)) a break
    ((base-layer base-layer-2)) b fallthrough
    () c break
  )
)

Describe alternatives you've considered.

Defining dummy virtual keys and using them as flags that other bool expressions can query.

Additional context

No response