Dear GHC-ers, I'm looking into the inerts of the renamer and I'm trying to get a feel for where things are bound. I thought it would be useful to have a look at how the renamer works on something known, so I compiled the following program (with HEAD): class Foo x where type FooTy x y foo :: x t -> FooTy x t instance Foo [] where type FooTy [] a = a foo (x:xs) = x main = print "Done" In the output of -ddump-rn-trace, I see this around the declaration of the class Foo: bhtv [x, y] [] ([(v1A, x), (v1C, y)], [(afy, x), (afz, y)]) bhtv [t] [] ([(v1A, x), (vjW, t)], [(afy, x), (afA, t)]) rnTycl [(class Foo x where type family FooTy x y foo :: x t -> FooTy x t, [(rfv, FooTy)])] [REC class Foo x where type family FooTy x y foo :: x t -> FooTy x t] I had expected that the 'x' and 'y' would have had the same uniques. The last tuple of bhtv is a LocalRdrEnv, which is (OccEnv Name, NameSet). Can someone explain to me the uses of both of these parts and why the names mentioned in each have different uniques? Regards, Philip