I've been thinking about an extension to GHC which would allow creating new module-like namespaces within normal Haskell modules. Because this kind of namespacing system seems quite obvious to me, I ask if it has already been proposed or discussed in detail?
Take a look at Agda's module system as described in the user documentation[1] and Norell's PhD thesis[2]. It supports the features you propose, along with lightweight parameterised modules (subsuming Joachim's "context fixes" proposal) and some additional stuff. At the same time, it doesn't buy into the complexity of ML-style generative module functors, which I think is a good tradeoff. [1] http://agda.readthedocs.io/en/v2.5.2/language/module-system.html [2] http://www.cse.chalmers.se/~ulfn/papers/thesis.pdf (PDF) Cheers, Jannis