Without looking into the precise details, this looks dangerous to me. Why do you want this? The danger I see lurking is that you might find two RdrNames that give the same answer to getUnique but represent different things:
foo x = x + (\x -> x) 3
I see two `x`s there that will have the same Unique attached to their RdrNames but will be very different. In fact, I'm surprised that OccName has a Uniquable instance, which seems similarly dangerous to me.
Richard
On Jun 16, 2014, at 7:45 AM, Jan Stolarek
Hi all,
I just found myself in the need of Uniquable instance for RdrName. I'm surprised that such instance does not exist already because other datatypes like Name or OccName already have Uniquable instances. So, is there a reason why Uniquable instance for RdrName does not exist already (other than "it wasn't needed")? How should such an instance look like? I made an attempt:
rdrNameUnique :: RdrName -> Unique rdrNameUnique (Unqual occName) = getUnique occName rdrNameUnique (Qual _ occName) = getUnique occName rdrNameUnique (Orig _ occName) = getUnique occName rdrNameUnique (Exact name ) = getUnique name
But I suspect this might be wrong: - cases 1 and 4 simply return a Unique for the OccName/Name stored inside RdrName. I think this will assign the same Unique to RdrName and corresponding OccName/Name. Is this allowed? - cases 2 and 3 ignore the Module stored inside RdrName. Again, this assigns the RdrName with a Unique identical to OccNames stored inside it.
Help appreciated.
Janek _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/mailman/listinfo/ghc-devs