In practice I use a lot more than just two symbols. The point is the repeated qualification quickly introduces more noise and obscures the intent of the code.
Well, qualification is only necessary for the symbols that conflict, right? It seems to me that if you want an EDSL with a certain prelude, you have to make sure the prelude symbols are all distinct. If you want to compose two DSLs, then you could make a third prelude that imports the other two, but renames colliding symbols. Unless there are many collisions... in which case, maybe don't define your EDSLs like that in the first place? Currently if you want to figure out all imports you parse the top of the file and can stop at the first definition. But with this feature you have to parse the whole file and thus understand all haskell grammar, including all extensions in use. I'd have to give up on my fast deps chaser and switch to slow ghc -M... which is maybe the right way anyway, I don't know. Ok, to be fair, I wouldn't, because I could choose to not use that feature, but in *theory* :) And while "you don't have to use it" is always brought up, it seems to me the more successful the feature is the more likely you do have to use it. On the other hand, lots of languages have a "local open" feature like this. I think many of them make you first import the module, and then you can "open" it in a local scope. This would address both my "parse the whole file for imports" objection and the "what about instances", because module importing would be unchanged.