Type abstract interpreter 2
partial order, glb and lub on the new abstract domain are similar to the previous ones
we might have used the same domain in the monotype interpreter
- without taking instances in applyenv
- abstreq could (correctly) check variance of universally quantified variables only
the new abstract operations are the straightforward adaptation of the previous ones
- quantification prefixes are ignored
- computed type schemes have usually an empty list of quantified variables