Unwanted memoization effect

[arthurpaulino]

(begin (emit 42) (emit 42)) only emits 42 once (the first time) because the second one is skipped by due to memoization.

One solution is plumbing an emit_counter through evaluation so that each emit increases this (kind of) global variable. It's not really a global variable because it would have to be passed on.

Another solution is accumulating emitted data and make it part of the eval coroutine arguments as well as the public values. The first (emit 42) would make the emitted list grow from nil to (42). This solution would have the advantage of making emitted data provable altogether.