Surely you do want this. It's the biggest problem with the original haskell-src package, that it cannot print out any useful Haskell code obtained from the parser, because it forgets all the brackets.
I should point out that haskell-src-exts already fixes this for code obtained from the parser, by making the parser and AST remember the brackets. Or as you put it:
It probably wants to be a combination of the parser, AST and pretty printer.
Yes indeed. But the problem at hand here is auto-generated AST code, where we cannot rely on the parser to do the right thing. There's help in the AST such that it's possible to explicitly insert brackets where needed, but I agree with Dominic that it shouldn't really be necessary in his case. Neil's point is well taken though - to do it correctly (or rather, minimally) for infix application, the pretty printer would need to be aware of the respective fixities involved. However, that doesn't mean we can't do better than what it is now, but be conservative about it. Only insert brackets where it's clear that brackets must be inserted, which would be the case for Dominic's example. If the argument to an application is non-atomic, it needs brackets, there's nothing ambiguous about that. Nothing can be said so categorically for infix applications, so there we should assume that the fixities are already done in the correct way, or that brackets are inserted manually where needed. Does that sound reasonable? Cheers, /Niklas