Roughly: the info of a class during a period.
Compute hashcode relative to enclosing binders
Equality used for hash-consing; uses
eq on all recursive invocations,
except where a BindingType is involved. The latter demand a deep isomorphism check.
this isomorphic to
that, assuming pairs of matching binders
It is assumed that
The full parent types, including all type arguments
The self type of a class is the conjunction of - the explicit self type if given (or the info of a given self symbol), and - the fully applied reference to the class itself.
hash of this type the same for all possible sequences of enclosing binders?