Needs more core.typed about slacker

[emiln]

A very powerful feature would be the ability to reason about matching handle and emit! calls.

The following should pass as + happily takes three numbers:

(handle :add +)
(emit! :add 1 2 3)

The following should fail as * doesn't work with Strings:

(handle :multiply *)
(emit! :multiply "hi" "hello")

Is this even possible with core.typed?

Probably not statically. I think a better approach is to maintain a runtime map of topic→type info, which should by updated when calling handle. Any calls to emit! could then look up the types that the arguments must match and ask core.typed to validate whether they match.

[emiln]

This is a won't fix for now.