Olivier Galibert <galibert(a)pobox.com&gt; writes: I don't think we need to worry about binary compatibility at all. It's clear that, given the current state of affairs, it is impossible to maintain anything close to that. As for the source compatibility, the only sane way of handling modules I can think of is to define and document a *minimum* set of primitives that are allowed in modules. But not even these should be cast in stone, I think -- modules are pretty much meddling with the implementation (more convenient meddling, but still meddling), and we should always have a right to change it.