Simon Marlow
http://hackage.haskell.org/trac/ghc/wiki/GhcPackagesWithGrafting
Please correct me if I get anything wrong:
- the proposal is to let you specify grafting in the source code
This is not the main focus of the proposal. Grafting is one oft-requested feature that is not currently supported, but yet it seems very close to the idea of specifying a package dependency in the source code. So my intention is merely to take it into account when designing the latter facility. If one mechanism (with a little tweaking) can achieve both aims, so much the better. The central plank of my proposal is to introduce an explicit concept of "namespace". Namespaces can be managed separately from the imports that range over them. That's it.
- you graft a *sub-hierarchy* of a package anywhere in the global module namespace (the sub-hiearchy bit is new, I haven't seen this proposed before).
The ability to graft hierarchies is just a side-effect. I would phrase this point as - a "namespace" is a sub-hierarchy of the modules contained in a package. (The sub-hierarchy bit is indeed new.)
- you can also graft a sub-hierarchy of a package onto the *current module*, so that it becomes available when importing this module. This is new too.
Again, I would rephrase this: - "namespaces" can be imported and exported, separately from the modules they contain. (Yes, this is new too.) Regards, Malcolm