2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
8 buildSynTyCon, buildAlgTyCon, buildDataCon,
10 mkAbstractTyConRhs, mkOpenDataTyConRhs, mkOpenNewTyConRhs,
11 mkNewTyConRhs, mkDataTyConRhs
14 #include "HsVersions.h"
38 ------------------------------------------------------
39 buildSynTyCon :: Name -> [TyVar] -> SynTyConRhs -> TyCon
40 buildSynTyCon name tvs rhs@(OpenSynTyCon rhs_ki)
41 = mkSynTyCon name kind tvs rhs
43 kind = mkArrowKinds (map tyVarKind tvs) rhs_ki
44 buildSynTyCon name tvs rhs@(SynonymTyCon rhs_ty)
45 = mkSynTyCon name kind tvs rhs
47 kind = mkArrowKinds (map tyVarKind tvs) (typeKind rhs_ty)
50 ------------------------------------------------------
51 buildAlgTyCon :: Name -> [TyVar]
52 -> ThetaType -- Stupid theta
55 -> Bool -- True <=> want generics functions
56 -> Bool -- True <=> was declared in GADT syntax
57 -> Maybe (TyCon, [Type]) -- family instance if applicable
60 buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
62 = do { -- We need to tie a knot as the coercion of a data instance depends
63 -- on the instance representation tycon and vice versa.
64 ; tycon <- fixM (\ tycon_rec -> do
65 { parent <- parentInfo mb_family tycon_rec
66 ; let { tycon = mkAlgTyCon tc_name kind tvs stupid_theta rhs
67 fields parent is_rec want_generics gadt_syn
68 ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
69 ; fields = mkTyConSelIds tycon rhs
76 -- If a family tycon with instance types is given, the current tycon is an
77 -- instance of that family and we need to
79 -- (1) create a coercion that identifies the family instance type and the
80 -- representation type from Step (1); ie, it is of the form
81 -- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion,
82 -- `F' the family tycon and `R' the (derived) representation tycon,
84 -- (2) produce a `AlgTyConParent' value containing the parent and coercion
87 parentInfo Nothing rep_tycon =
89 parentInfo (Just (family, instTys)) rep_tycon =
90 do { -- Create the coercion
91 ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc
92 ; let co_tycon = mkDataInstCoercion co_tycon_name tvs
93 family instTys rep_tycon
94 ; return $ FamilyTyCon family instTys co_tycon
98 ------------------------------------------------------
99 mkAbstractTyConRhs :: AlgTyConRhs
100 mkAbstractTyConRhs = AbstractTyCon
102 mkOpenDataTyConRhs :: AlgTyConRhs
103 mkOpenDataTyConRhs = OpenDataTyCon
105 mkOpenNewTyConRhs :: AlgTyConRhs
106 mkOpenNewTyConRhs = OpenNewTyCon
108 mkDataTyConRhs :: [DataCon] -> AlgTyConRhs
110 = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons }
112 mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
113 -- Monadic because it makes a Name for the coercion TyCon
114 -- We pass the Name of the parent TyCon, as well as the TyCon itself,
115 -- because the latter is part of a knot, whereas the former is not.
116 mkNewTyConRhs tycon_name tycon con
117 = do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc
118 ; let co_tycon = mkNewTypeCoercion co_tycon_name tycon etad_tvs etad_rhs
119 cocon_maybe | all_coercions || isRecursiveTyCon tycon
123 ; return (NewTyCon { data_con = con,
125 nt_etad_rhs = (etad_tvs, etad_rhs),
127 -- Coreview looks through newtypes with a Nothing
128 -- for nt_co, or uses explicit coercions otherwise
129 nt_rep = mkNewTyConRep tycon rhs_ty }) }
131 -- If all_coercions is True then we use coercions for all newtypes
132 -- otherwise we use coercions for recursive newtypes and look through
133 -- non-recursive newtypes
135 tvs = tyConTyVars tycon
136 rhs_ty = head (dataConInstOrigArgTys con (mkTyVarTys tvs))
137 -- Instantiate the data con with the
138 -- type variables from the tycon
140 etad_tvs :: [TyVar] -- Matched lazily, so that mkNewTypeCoercion can
141 etad_rhs :: Type -- return a TyCon without pulling on rhs_ty
142 -- See Note [Tricky iface loop] in LoadIface
143 (etad_tvs, etad_rhs) = eta_reduce (reverse tvs) rhs_ty
145 eta_reduce :: [TyVar] -- Reversed
147 -> ([TyVar], Type) -- Eta-reduced version (tyvars in normal order)
148 eta_reduce (a:as) ty | Just (fun, arg) <- splitAppTy_maybe ty,
149 Just tv <- getTyVar_maybe arg,
151 not (a `elemVarSet` tyVarsOfType fun)
153 eta_reduce tvs ty = (reverse tvs, ty)
156 mkNewTyConRep :: TyCon -- The original type constructor
157 -> Type -- The arg type of its constructor
158 -> Type -- Chosen representation type
159 -- The "representation type" is guaranteed not to be another newtype
160 -- at the outermost level; but it might have newtypes in type arguments
162 -- Find the representation type for this newtype TyCon
163 -- Remember that the representation type is the *ultimate* representation
164 -- type, looking through other newtypes.
166 -- splitTyConApp_maybe no longer looks through newtypes, so we must
167 -- deal explicitly with this case
169 -- The trick is to to deal correctly with recursive newtypes
170 -- such as newtype T = MkT T
172 mkNewTyConRep tc rhs_ty
173 | null (tyConDataCons tc) = unitTy
174 -- External Core programs can have newtypes with no data constructors
175 | otherwise = go [tc] rhs_ty
177 -- Invariant: tcs have been seen before
179 = case splitTyConApp_maybe rep_ty of
181 | tc `elem` tcs -> unitTy -- Recursive loop
183 if isRecursiveTyCon tc then
184 go (tc:tcs) (substTyWith tvs tys rhs_ty)
186 substTyWith tvs tys rhs_ty
188 (tvs, rhs_ty) = newTyConRhs tc
192 ------------------------------------------------------
193 buildDataCon :: Name -> Bool
195 -> [Name] -- Field labels
196 -> [TyVar] -> [TyVar] -- Univ and ext
197 -> [(TyVar,Type)] -- Equality spec
198 -> ThetaType -- Does not include the "stupid theta"
199 -- or the GADT equalities
201 -> TcRnIf m n DataCon
202 -- A wrapper for DataCon.mkDataCon that
203 -- a) makes the worker Id
204 -- b) makes the wrapper Id if necessary, including
205 -- allocating its unique (hence monadic)
206 buildDataCon src_name declared_infix arg_stricts field_lbls
207 univ_tvs ex_tvs eq_spec ctxt arg_tys tycon
208 = do { wrap_name <- newImplicitBinder src_name mkDataConWrapperOcc
209 ; work_name <- newImplicitBinder src_name mkDataConWorkerOcc
210 -- This last one takes the name of the data constructor in the source
211 -- code, which (for Haskell source anyway) will be in the DataName name
212 -- space, and puts it into the VarName name space
215 stupid_ctxt = mkDataConStupidTheta tycon arg_tys univ_tvs
216 data_con = mkDataCon src_name declared_infix
217 arg_stricts field_lbls
218 univ_tvs ex_tvs eq_spec ctxt
221 dc_ids = mkDataConIds wrap_name work_name data_con
226 -- The stupid context for a data constructor should be limited to
227 -- the type variables mentioned in the arg_tys
228 -- ToDo: Or functionally dependent on?
229 -- This whole stupid theta thing is, well, stupid.
230 mkDataConStupidTheta tycon arg_tys univ_tvs
231 | null stupid_theta = [] -- The common case
232 | otherwise = filter in_arg_tys stupid_theta
234 tc_subst = zipTopTvSubst (tyConTyVars tycon) (mkTyVarTys univ_tvs)
235 stupid_theta = substTheta tc_subst (tyConStupidTheta tycon)
236 -- Start by instantiating the master copy of the
237 -- stupid theta, taken from the TyCon
239 arg_tyvars = tyVarsOfTypes arg_tys
240 in_arg_tys pred = not $ isEmptyVarSet $
241 tyVarsOfPred pred `intersectVarSet` arg_tyvars
243 ------------------------------------------------------
244 mkTyConSelIds :: TyCon -> AlgTyConRhs -> [Id]
245 mkTyConSelIds tycon rhs
246 = [ mkRecordSelId tycon fld
247 | fld <- nub (concatMap dataConFieldLabels (visibleDataCons rhs)) ]
248 -- We'll check later that fields with the same name
249 -- from different constructors have the same type.
253 ------------------------------------------------------
255 buildClass :: Name -> [TyVar] -> ThetaType
256 -> [FunDep TyVar] -- Functional dependencies
257 -> [TyThing] -- Associated types
258 -> [(Name, DefMeth, Type)] -- Method info
259 -> RecFlag -- Info for type constructor
262 buildClass class_name tvs sc_theta fds ats sig_stuff tc_isrec
263 = do { tycon_name <- newImplicitBinder class_name mkClassTyConOcc
264 ; datacon_name <- newImplicitBinder class_name mkClassDataConOcc
265 -- The class name is the 'parent' for this datacon, not its tycon,
266 -- because one should import the class to get the binding for
268 ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc)
270 -- We number off the superclass selectors, 1, 2, 3 etc so that we
271 -- can construct names for the selectors. Thus
272 -- class (C a, C b) => D a b where ...
273 -- gives superclass selectors
275 -- (We used to call them D_C, but now we can have two different
276 -- superclasses both called C!)
278 ; fixM (\ rec_clas -> do { -- Only name generation inside loop
280 let { rec_tycon = classTyCon rec_clas
281 ; op_tys = [ty | (_,_,ty) <- sig_stuff]
282 ; sc_tys = mkPredTys sc_theta
283 ; dict_component_tys = sc_tys ++ op_tys
284 ; sc_sel_ids = [mkDictSelId sc_name rec_clas | sc_name <- sc_sel_names]
285 ; op_items = [ (mkDictSelId op_name rec_clas, dm_info)
286 | (op_name, dm_info, _) <- sig_stuff ] }
287 -- Build the selector id and default method id
289 ; dict_con <- buildDataCon datacon_name
290 False -- Not declared infix
291 (map (const NotMarkedStrict) dict_component_tys)
292 [{- No labelled fields -}]
293 tvs [{- no existentials -}]
294 [{- No equalities -}] [{-No context-}]
298 ; rhs <- case dict_component_tys of
299 [rep_ty] -> mkNewTyConRhs tycon_name rec_tycon dict_con
300 other -> return (mkDataTyConRhs [dict_con])
302 ; let { clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
304 ; tycon = mkClassTyCon tycon_name clas_kind tvs
305 rhs rec_clas tc_isrec
306 -- A class can be recursive, and in the case of newtypes
307 -- this matters. For example
308 -- class C a where { op :: C b => a -> b -> Int }
309 -- Because C has only one operation, it is represented by
310 -- a newtype, and it should be a *recursive* newtype.
311 -- [If we don't make it a recursive newtype, we'll expand the
312 -- newtype like a synonym, but that will lead to an infinite
314 ; atTyCons = [tycon | ATyCon tycon <- ats]
316 ; return (mkClass class_name tvs fds
317 sc_theta sc_sel_ids atTyCons op_items