Here is an idea that bears both on the proposal
for casual languages and domains for alternate
instruction sets.
In both cases we want something like a domain which can obey languages other than the native instruction set.
We want something like a domain so that all of the good things that pertain to domains will pertain to objects whose behavior is defined in these other languages.
The idea is almost too simple to warrant a note but it did not come to me immediately.
It may not be the best idea.