- from_alts :: [FromAlt]
- (from_alts, to_pat, to_body) = mk_sum_stuff init_us datacons
- init_us = 1::Int -- Unique supply
-
-----------------------------------------------------
--- Dealing with sums
-----------------------------------------------------
-
-mk_sum_stuff :: US -- Base for generating unique names
- -> [DataCon] -- The data constructors
- -> ([FromAlt], -- Alternatives for the T->Trep "from" function
- InPat RdrName, LHsExpr RdrName) -- Arg and body of the Trep->T "to" function
-
--- For example, given
--- data T = C | D Int Int Int
---
--- mk_sum_stuff v [C,D] = ([C -> Inl Unit, D a b c -> Inr (a :*: (b :*: c))],
--- case cd of { Inl u -> C;
--- Inr abc -> case abc of { a :*: bc ->
--- case bc of { b :*: c ->
--- D a b c }} },
--- cd)
-
-mk_sum_stuff us [datacon]
- = ([from_alt], to_pat, to_body_fn app_exp)
- where
- n_args = dataConSourceArity datacon -- Existentials already excluded
-
- datacon_vars = map mkGenericLocal [us .. us+n_args-1]
- us' = us + n_args
-
- datacon_rdr = getRdrName datacon
- app_exp = nlHsVarApps datacon_rdr datacon_vars
- from_alt = (nlConVarPat datacon_rdr datacon_vars, from_alt_rhs)
-
- (_, from_alt_rhs, to_pat, to_body_fn) = mk_prod_stuff us' datacon_vars
-
-mk_sum_stuff us datacons
- = (wrap inlDataCon_RDR l_from_alts ++ wrap inrDataCon_RDR r_from_alts,
- nlVarPat to_arg,
- noLoc (HsCase (nlHsVar to_arg)
- (mkMatchGroup [mkSimpleHsAlt (nlConPat inlDataCon_RDR [l_to_pat]) l_to_body,
- mkSimpleHsAlt (nlConPat inrDataCon_RDR [r_to_pat]) r_to_body])))
+ from0_alts, to0_alts :: [Alt]
+ (from0_alts, to0_alts) = mkSum init_us tycon datacons
+ init_us = 1 :: US -- Unique supply
+-}
+
+--------------------------------------------------------------------------------
+-- Type representation
+--------------------------------------------------------------------------------
+{-
+mkRep0Ty :: TyCon -> LHsType Name
+mkRep0Ty tycon = res
+ where
+ res = d1 `nlHsAppTy` (cons datacons)
+ d1 = nlHsTyVar d1TyConName `nlHsAppTy` nlHsTyVar d1TyConName -- TODO
+ c1 = nlHsTyVar c1TyConName `nlHsAppTy` nlHsTyVar c1TyConName -- TODO
+ s1 = nlHsTyVar s1TyConName `nlHsAppTy` nlHsTyVar noSelTyConName -- TODO
+ plus a b = nlHsTyVar sumTyConName `nlHsAppTy` a `nlHsAppTy` b
+ times a b = nlHsTyVar prodTyConName `nlHsAppTy` a `nlHsAppTy` b
+ k1 x = nlHsTyVar k1TyConName `nlHsAppTy` nlHsTyVar x
+
+ datacons = tyConDataCons tycon
+ n_args datacon = dataConSourceArity datacon
+ datacon_vars datacon = map mkGenericLocal [1 .. n_args datacon]
+
+ cons ds = c1 `nlHsAppTy` sum ds
+ sum [] = nlHsTyVar v1TyConName
+ sum l = foldBal plus (map sel l)
+ sel d = s1 `nlHsAppTy` prod (dataConOrigArgTys d)
+ prod [] = nlHsTyVar u1TyConName
+ prod l = foldBal times (map arg l)
+ arg :: Type -> LHsType Name
+ -- TODO
+ arg t = nlHsTyVar k1TyConName `nlHsAppTy` nlHsTyVar v1TyConName -- TODO
+-}
+
+tc_mkRep0Ty :: -- The type to generate representation for
+ TyCon
+ -- Metadata datatypes to refer to
+ -> MetaTyCons
+ -- Generated representation0 type
+ -> TcM Type
+tc_mkRep0Ty tycon metaDts =
+ do
+ d1 <- tcLookupTyCon d1TyConName
+ c1 <- tcLookupTyCon c1TyConName
+ s1 <- tcLookupTyCon s1TyConName
+ rec0 <- tcLookupTyCon rec0TyConName
+ u1 <- tcLookupTyCon u1TyConName
+ v1 <- tcLookupTyCon v1TyConName
+ plus <- tcLookupTyCon sumTyConName
+ times <- tcLookupTyCon prodTyConName
+ noSel <- tcLookupTyCon noSelTyConName
+ freshTy <- newMetaTyVar TauTv liftedTypeKind
+
+ let mkSum a b = mkTyConApp plus [a,b]
+ mkProd a b = mkTyConApp times [a,b]
+ mkRec0 a = mkTyConApp rec0 [a]
+ mkD a = mkTyConApp d1 [metaDTyCon, sum (tyConDataCons a)]
+ mkC i d a = mkTyConApp c1 [d, prod i (dataConOrigArgTys a)]
+ mkS d a = mkTyConApp s1 [d, a]
+
+ sum [] = mkTyConTy v1
+ sum l = ASSERT (length metaCTyCons == length l)
+ foldBal mkSum [ mkC i d a
+ | (d,(a,i)) <- zip metaCTyCons (zip l [0..]) ]
+ prod :: Int -> [Type] -> Type
+ prod i [] = ASSERT (length metaSTyCons > i)
+ ASSERT (length (metaSTyCons !! i) == 0)
+ mkTyConTy u1
+ prod i l = ASSERT (length metaSTyCons > i)
+ ASSERT (length l == length (metaSTyCons !! i))
+ foldBal mkProd [ arg d a
+ | (d,a) <- zip (metaSTyCons !! i) l ]
+
+ arg d t = mkS d (mkRec0 t)
+
+ metaDTyCon = mkTyConTy (metaD metaDts)
+ metaCTyCons = map mkTyConTy (metaC metaDts)
+ metaSTyCons = map (map mkTyConTy) (metaS metaDts)
+
+ return (mkD tycon)
+
+tc_mkRep0TyCon :: TyCon -- The type to generate representation for
+ -> MetaTyCons -- Metadata datatypes to refer to
+ -> TcM TyCon -- Generated representation0 type
+tc_mkRep0TyCon tycon metaDts =
+-- Consider the example input tycon `D`, where data D a b = D_ a
+ do
+ uniq1 <- newUnique
+ uniq2 <- newUnique
+ -- `rep0Ty` = D1 ... (C1 ... (S1 ... (Rec0 a))) :: * -> *
+ rep0Ty <- tc_mkRep0Ty tycon metaDts
+ -- `rep0` = GHC.Generics.Rep0 (type family)
+ rep0 <- tcLookupTyCon rep0TyConName
+
+ let mod = nameModule (tyConName tycon)
+ loc = nameSrcSpan (tyConName tycon)
+ -- `repName` is a name we generate for the synonym
+ repName = mkExternalName uniq1 mod (mkGenR0 (nameOccName (tyConName tycon))) loc
+ -- `coName` is a name for the coercion
+ coName = mkExternalName uniq2 mod (mkGenR0 (nameOccName (tyConName tycon))) loc
+ -- `tyvars` = [a,b]
+ tyvars = tyConTyVars tycon
+ -- `appT` = D a b
+ appT = [mkTyConApp tycon (mkTyVarTys tyvars)]
+ -- Result
+ res = mkSynTyCon repName
+ -- rep0Ty has kind `kind of D` -> *
+ (tyConKind tycon `mkArrowKind` liftedTypeKind)
+ tyvars (SynonymTyCon rep0Ty)
+ (FamInstTyCon rep0 appT
+ (mkCoercionTyCon coName (tyConArity tycon)
+ -- co : forall a b. Rep0 (D a b) ~ `rep0Ty` a b
+ (CoAxiom tyvars (mkTyConApp rep0 appT) rep0Ty)))
+
+ return res
+
+--------------------------------------------------------------------------------
+-- Meta-information
+--------------------------------------------------------------------------------
+
+data MetaTyCons = MetaTyCons { -- One meta datatype per dataype
+ metaD :: TyCon
+ -- One meta datatype per constructor
+ , metaC :: [TyCon]
+ -- One meta datatype per selector per constructor
+ , metaS :: [[TyCon]] }
+
+instance Outputable MetaTyCons where
+ ppr (MetaTyCons d c s) = ppr d <+> ppr c <+> ppr s
+
+metaTyCons2TyCons :: MetaTyCons -> [TyCon]
+metaTyCons2TyCons (MetaTyCons d c s) = d : c ++ concat s
+
+
+-- Bindings for Datatype, Constructor, and Selector instances
+mkBindsMetaD :: FixityEnv -> TyCon
+ -> ( LHsBinds RdrName -- Datatype instance
+ , [LHsBinds RdrName] -- Constructor instances
+ , [[LHsBinds RdrName]]) -- Selector instances
+mkBindsMetaD fix_env tycon = (dtBinds, allConBinds, allSelBinds)
+ where
+ mkBag l = foldr1 unionBags
+ [ unitBag (L loc (mkFunBind (L loc name) matches))
+ | (name, matches) <- l ]
+ dtBinds = mkBag [ (datatypeName_RDR, dtName_matches)
+ , (moduleName_RDR, moduleName_matches)]
+
+ allConBinds = map conBinds datacons
+ conBinds c = mkBag ( [ (conName_RDR, conName_matches c)]
+ ++ ifElseEmpty (dataConIsInfix c)
+ [ (conFixity_RDR, conFixity_matches c) ]
+ ++ ifElseEmpty (length (dataConFieldLabels c) > 0)
+ [ (conIsRecord_RDR, conIsRecord_matches c) ]
+ ++ ifElseEmpty (isTupleCon c)
+ [(conIsTuple_RDR
+ ,conIsTuple_matches (dataConTyCon c))]
+ )
+
+ ifElseEmpty p x = if p then x else []
+ fixity c = case lookupFixity fix_env (dataConName c) of
+ Fixity n InfixL -> buildFix n leftAssocDataCon_RDR
+ Fixity n InfixR -> buildFix n rightAssocDataCon_RDR
+ Fixity n InfixN -> buildFix n notAssocDataCon_RDR
+ buildFix n assoc = nlHsApps infixDataCon_RDR [nlHsVar assoc
+ , nlHsIntLit (toInteger n)]
+
+ allSelBinds = map (map selBinds) datasels
+ selBinds s = mkBag [(selName_RDR, selName_matches s)]
+
+ loc = srcLocSpan (getSrcLoc tycon)
+ mkStringLHS s = [mkSimpleHsAlt nlWildPat (nlHsLit (mkHsString s))]
+ datacons = tyConDataCons tycon
+ datasels = map dataConFieldLabels datacons
+
+ dtName_matches = mkStringLHS . showPpr . nameOccName . tyConName
+ $ tycon
+ moduleName_matches = mkStringLHS . moduleNameString . moduleName
+ . nameModule . tyConName $ tycon
+
+ conName_matches c = mkStringLHS . showPpr . nameOccName
+ . dataConName $ c
+ conFixity_matches c = [mkSimpleHsAlt nlWildPat (fixity c)]
+ conIsRecord_matches c = [mkSimpleHsAlt nlWildPat (nlHsVar true_RDR)]
+ -- TODO: check that this works
+ conIsTuple_matches c = [mkSimpleHsAlt nlWildPat
+ (nlHsApp (nlHsVar arityDataCon_RDR)
+ (nlHsIntLit
+ (toInteger (tupleTyConArity c))))]
+
+ selName_matches s = mkStringLHS (showPpr (nameOccName s))
+
+
+--------------------------------------------------------------------------------
+-- Dealing with sums
+--------------------------------------------------------------------------------
+
+mkSum :: US -- Base for generating unique names
+ -> TyCon -- The type constructor
+ -> [DataCon] -- The data constructors
+ -> ([Alt], -- Alternatives for the T->Trep "from" function
+ [Alt]) -- Alternatives for the Trep->T "to" function
+
+-- Datatype without any constructors
+mkSum _us tycon [] = ([from_alt], [to_alt])