Likewise, to what extent aside from syntactic nicety does implicit parameters and the punning extensions not suffice?
At the definition and instantiation sites I mostly miss defaults. At the application sites I would love to have specialisation for certain arguments. For example I would like to be able to tell GHC that I would like to have a version of my function `f` with a certain argument inlined. Note that I don't want to inline `f` itself. Rather I'd like to preapply certain arguments: f :: X -> Y -> Z {-# SPECIALISE f SomeX #-} {-# SPECIALISE f SomeOtherX #-} This would generate two specialised versions of `f` with exactly the given arguments inlined. That way I can get a very efficient `f` without having to inline it at the application sites. And as long as `f` is INLINABLE I can put those pragmas pretty much everywhere. I believe this is exactly what happens for type class dictionaries. This can (and probably should) be a separate feature though. For some of my applications I need to inline a huge chunk of code multiple times to compensate for the lack of this feature.