I'm currently trying to get the interface file bulk imposed by TTypeable down. The branch will currently produce two top-level bindings for each TyCon. For instance, given the type, data Proxy (a :: k) = Proxy the branch will produce (ignoring the promoted datacon for a moment), $tcProxy :: TyCon $tcProxy = GHC.Types.TyCon fpr1 fpr2 -- fingerprints $trModule (GHC.Types.TrNameS "Proxy"#) 1 krep_aebr krep_aebr :: KindRep krep_aebr [InlPrag=NOINLINE CONLIKE] = GHC.Types.KindRepFun (GHC.Types.KindRepVar 0) (GHC.Types.KindRepTYPE GHC.Types.LiftedRep) Note that the KindRep has been marked as NOINLINE; I do this intentionally as these things can grow quite large (consider, for instance, the kind of a promoted tuple constructor). This is especially true as the simplifier tends to float out the constituents of the KindRep. After the first simplifier phase we end up with, krep_sebQ :: GHC.Types.KindRep [LclId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 30 0}] krep_sebQ = GHC.Types.$WKindRepVar (GHC.Types.I# 0#) krep_sebR :: GHC.Types.KindRep [LclId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}] krep_sebR = GHC.Types.$WKindRepTYPE GHC.Types.LiftedRep krep_aebr [InlPrag=NOINLINE CONLIKE] :: GHC.Types.KindRep [LclId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}] krep_aebr = GHC.Types.KindRepFun krep_sebQ krep_sebR This means that GHC will now include each of the bindings floated out from krep_aebr in the interface file, despite the NOINLINE pragma, as they are all depended upon by the exported $tcProxy through their unfoldings. This is Quite Bad. I have observed that the floated bindings are not included in the interface file with -O0. Moreover, the core2core output clearly shows the unfoldings being added after the first simplifier phase. I haven't yet determined where in the simplifier these unfoldings are being introduced, but if anyone has ideas I'd love to hear them. Cheers, - Ben