Add notion of "allowed to be stuck" terms to WP
For some languages it makes sense to distinguish two kinds of "stuck" terms (terms that cannot take a step and aren't a value): some are "bad" and some are "good". For instance, this can be used to model a "halt the program" primitive (though it will only halt the current thread due to the fixed threadpool semantics). Possibly this could also be used to model "blocking" operations.
!825 (closed) started implementing this, but did not get completed. Still some discussion we had around that MR should be taken into account when another attempt is made at implementing this feature, in particular the proposal for naming things.