[choeger]

> When a program is decomposed in modules, those are compiled separately

No, they're not. At least not in languages with nontrivial features and optimizations. Consider the identity function id = \\x.x in some module A and it's usage A.id 42 in some module B. Unless you commit to uniform object representation, excluding several optimizations, there's no way to compile A separately from it's use in B (because specialization of A.id is required). That fact excludes the option of creating dynamic libraries because you would expect the dynamic library compiled from A to be used in stead of A (with the necessary type interface data). Similar problems occur with polymorphic data structures.

Separate compilation, modularity, and dynamic linking are all aspects of the same problem.

I think that's why Rust uses a global compilation approach and if I am not completely mistaken, only Swift tries to have dynamic linking with polymorphism.