From de395700afa73065a2ec69ba5e3cc3ec1a474d11 Mon Sep 17 00:00:00 2001 From: Łukasz Hanuszczak Date: Wed, 29 Jul 2015 15:13:26 +0200 Subject: Introduce alternative type for family declarations. --- haddock-api/src/Haddock/Types.hs | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'haddock-api/src') diff --git a/haddock-api/src/Haddock/Types.hs b/haddock-api/src/Haddock/Types.hs index ac073036..90672c9d 100644 --- a/haddock-api/src/Haddock/Types.hs +++ b/haddock-api/src/Haddock/Types.hs @@ -341,6 +341,37 @@ instance OutputableBndr a => Outputable (InstType a) where ppr (TypeInst a) = text "TypeInst" <+> ppr a ppr (DataInst a) = text "DataInst" <+> ppr a + +-- | Almost the same as 'FamilyDecl' except for type binders. +-- +-- In order to perform type specialization for class instances, we need to +-- substitute class variables to appropriate type. However, type variables in +-- associated type are specified using 'LHsTyVarBndrs' instead of 'HsType'. +-- This makes type substitution impossible and to overcome this issue, +-- 'PseudoFamilyDecl' type is introduced. +data PseudoFamilyDecl name = PseudoFamilyDecl + { pfdInfo :: FamilyInfo name + , pfdLName :: Located name + , pfdTyVars :: [LHsType name] + , pfdKindSig :: Maybe (LHsKind name) + } + + +mkPseudoFamilyDecl :: FamilyDecl name -> PseudoFamilyDecl name +mkPseudoFamilyDecl (FamilyDecl { .. }) = PseudoFamilyDecl + { pfdInfo = fdInfo + , pfdLName = fdLName + , pfdTyVars = [ L loc (mkType bndr) | L loc bndr <- hsq_tvs fdTyVars ] + , pfdKindSig = fdKindSig + } + where + mkType (KindedTyVar (L loc name) lkind) = + HsKindSig tvar lkind + where + tvar = L loc (HsTyVar name) + mkType (UserTyVar name) = HsTyVar name + + -- | An instance head that may have documentation and a source location. type DocInstance name = (InstHead name, Maybe (MDoc name), Located name) -- cgit v1.2.3