Amusingly, I was precisely working today on extra-nice error messages for module type errors in OCaml. :) My reaction to the title was "But they are not exotic

Amusingly, I was precisely working today on extra-nice error messages for module type errors in OCaml. :) My reaction to the title was "But they are not exotic, I use them every day!" It's definitely the feature I miss the most every time I work in other languages, even presumable "advanced" ones, like Haskell. One notable attempt to add them elsewhere is "modular C"[1]. [1]: http://cmod.gforge.inria.fr/ http://cmod.gforge.inria.fr/