[steveklabnik]

The language would still have to understand all of that in order to write that kernel side allocator in safe code.

[jacquesm]

I don't see how that follows. The language can't possibly understand the intricacies of what the MMU is capable of (besides, every MMU is different), and as far as the language is concerned what is returned is simply a valid offset and a length to go with it to indicate where the allocated segment ends.

[steveklabnik]

I think you're strongly agreeing with me. It's not feasible to have in the language.