2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
7 buildSynTyCon, buildAlgTyCon, buildDataCon,
9 mkAbstractTyConRhs, mkOpenDataTyConRhs, mkOpenNewTyConRhs,
10 mkNewTyConRhs, mkDataTyConRhs
13 #include "HsVersions.h"
15 import IfaceEnv ( newImplicitBinder )
18 import DataCon ( DataCon, isNullarySrcDataCon, dataConUnivTyVars,
19 mkDataCon, dataConFieldLabels, dataConInstOrigArgTys,
21 import Var ( tyVarKind, TyVar, Id )
22 import VarSet ( isEmptyVarSet, intersectVarSet, elemVarSet )
23 import TysWiredIn ( unitTy )
24 import BasicTypes ( RecFlag, StrictnessMark(..) )
26 import OccName ( mkDataConWrapperOcc, mkDataConWorkerOcc,
27 mkClassTyConOcc, mkClassDataConOcc,
28 mkSuperDictSelOcc, mkNewTyCoOcc, mkInstTyTcOcc,
30 import MkId ( mkDataConIds, mkRecordSelId, mkDictSelId )
31 import Class ( mkClass, Class( classTyCon), FunDep, DefMeth(..) )
32 import TyCon ( mkSynTyCon, mkAlgTyCon, visibleDataCons,
33 tyConStupidTheta, tyConDataCons, isNewTyCon,
34 mkClassTyCon, TyCon( tyConTyVars ),
35 isRecursiveTyCon, tyConArity, AlgTyConRhs(..),
36 SynTyConRhs(..), newTyConRhs, AlgTyConParent(..) )
37 import Type ( mkArrowKinds, liftedTypeKind, typeKind,
38 tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
39 splitTyConApp_maybe, splitAppTy_maybe,
41 mkPredTys, mkTyVarTys, ThetaType, Type, Kind,
43 substTyWith, zipTopTvSubst, substTheta, mkForAllTys,
44 mkTyConApp, mkTyVarTy )
45 import Coercion ( mkNewTypeCoercion, mkDataInstCoercion )
53 ------------------------------------------------------
54 buildSynTyCon :: Name -> [TyVar] -> SynTyConRhs -> TyCon
55 buildSynTyCon name tvs rhs@(OpenSynTyCon rhs_ki)
56 = mkSynTyCon name kind tvs rhs
58 kind = mkArrowKinds (map tyVarKind tvs) rhs_ki
59 buildSynTyCon name tvs rhs@(SynonymTyCon rhs_ty)
60 = mkSynTyCon name kind tvs rhs
62 kind = mkArrowKinds (map tyVarKind tvs) (typeKind rhs_ty)
65 ------------------------------------------------------
66 buildAlgTyCon :: Name -> [TyVar]
67 -> ThetaType -- Stupid theta
70 -> Bool -- True <=> want generics functions
71 -> Bool -- True <=> was declared in GADT syntax
72 -> Maybe (TyCon, [Type]) -- family instance if applicable
75 buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
77 = do { -- We need to tie a knot as the coercion of a data instance depends
78 -- on the instance representation tycon and vice versa.
79 ; tycon <- fixM (\ tycon_rec -> do
80 { parent <- parentInfo mb_family tycon_rec
81 ; let { tycon = mkAlgTyCon tc_name kind tvs stupid_theta rhs
82 fields parent is_rec want_generics gadt_syn
83 ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
84 ; fields = mkTyConSelIds tycon rhs
91 -- If a family tycon with instance types is given, the current tycon is an
92 -- instance of that family and we need to
94 -- (1) create a coercion that identifies the family instance type and the
95 -- representation type from Step (1); ie, it is of the form
96 -- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion,
97 -- `F' the family tycon and `R' the (derived) representation tycon,
99 -- (2) produce a `AlgTyConParent' value containing the parent and coercion
102 parentInfo Nothing rep_tycon =
104 parentInfo (Just (family, instTys)) rep_tycon =
105 do { -- Create the coercion
106 ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc
107 ; let co_tycon = mkDataInstCoercion co_tycon_name tvs
108 family instTys rep_tycon
109 ; return $ FamilyTyCon family instTys co_tycon
113 ------------------------------------------------------
114 mkAbstractTyConRhs :: AlgTyConRhs
115 mkAbstractTyConRhs = AbstractTyCon
117 mkOpenDataTyConRhs :: AlgTyConRhs
118 mkOpenDataTyConRhs = OpenDataTyCon
120 mkOpenNewTyConRhs :: AlgTyConRhs
121 mkOpenNewTyConRhs = OpenNewTyCon
123 mkDataTyConRhs :: [DataCon] -> AlgTyConRhs
125 = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons }
127 mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
128 -- Monadic because it makes a Name for the coercion TyCon
129 -- We pass the Name of the parent TyCon, as well as the TyCon itself,
130 -- because the latter is part of a knot, whereas the former is not.
131 mkNewTyConRhs tycon_name tycon con
132 = do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc
133 ; let co_tycon = mkNewTypeCoercion co_tycon_name tycon tvs rhs_ty
135 | all_coercions || isRecursiveTyCon tycon
139 ; return (NewTyCon { data_con = con,
141 -- Coreview looks through newtypes with a Nothing
142 -- for nt_co, or uses explicit coercions otherwise
144 nt_etad_rhs = eta_reduce tvs rhs_ty,
145 nt_rep = mkNewTyConRep tycon rhs_ty }) }
147 -- if all_coercions is True then we use coercions for all newtypes
148 -- otherwise we use coercions for recursive newtypes and look through
149 -- non-recursive newtypes
151 tvs = tyConTyVars tycon
152 rhs_ty = head (dataConInstOrigArgTys con (mkTyVarTys tvs))
153 -- Instantiate the data con with the
154 -- type variables from the tycon
156 eta_reduce [] ty = ([], ty)
157 eta_reduce (a:as) ty | null as',
158 Just (fun, arg) <- splitAppTy_maybe ty',
159 Just tv <- getTyVar_maybe arg,
161 not (a `elemVarSet` tyVarsOfType fun)
162 = ([], fun) -- Successful eta reduction
166 (as', ty') = eta_reduce as ty
168 mkNewTyConRep :: TyCon -- The original type constructor
169 -> Type -- The arg type of its constructor
170 -> Type -- Chosen representation type
171 -- The "representation type" is guaranteed not to be another newtype
172 -- at the outermost level; but it might have newtypes in type arguments
174 -- Find the representation type for this newtype TyCon
175 -- Remember that the representation type is the *ultimate* representation
176 -- type, looking through other newtypes.
178 -- splitTyConApp_maybe no longer looks through newtypes, so we must
179 -- deal explicitly with this case
181 -- The trick is to to deal correctly with recursive newtypes
182 -- such as newtype T = MkT T
184 mkNewTyConRep tc rhs_ty
185 | null (tyConDataCons tc) = unitTy
186 -- External Core programs can have newtypes with no data constructors
187 | otherwise = go [tc] rhs_ty
189 -- Invariant: tcs have been seen before
191 = case splitTyConApp_maybe rep_ty of
193 | tc `elem` tcs -> unitTy -- Recursive loop
195 if isRecursiveTyCon tc then
196 go (tc:tcs) (substTyWith tvs tys rhs_ty)
198 substTyWith tvs tys rhs_ty
200 (tvs, rhs_ty) = newTyConRhs tc
204 ------------------------------------------------------
205 buildDataCon :: Name -> Bool
207 -> [Name] -- Field labels
208 -> [TyVar] -> [TyVar] -- Univ and ext
209 -> [(TyVar,Type)] -- Equality spec
210 -> ThetaType -- Does not include the "stupid theta"
211 -- or the GADT equalities
213 -> TcRnIf m n DataCon
214 -- A wrapper for DataCon.mkDataCon that
215 -- a) makes the worker Id
216 -- b) makes the wrapper Id if necessary, including
217 -- allocating its unique (hence monadic)
218 buildDataCon src_name declared_infix arg_stricts field_lbls
219 univ_tvs ex_tvs eq_spec ctxt arg_tys tycon
220 = do { wrap_name <- newImplicitBinder src_name mkDataConWrapperOcc
221 ; work_name <- newImplicitBinder src_name mkDataConWorkerOcc
222 -- This last one takes the name of the data constructor in the source
223 -- code, which (for Haskell source anyway) will be in the DataName name
224 -- space, and puts it into the VarName name space
227 stupid_ctxt = mkDataConStupidTheta tycon arg_tys univ_tvs
228 data_con = mkDataCon src_name declared_infix
229 arg_stricts field_lbls
230 univ_tvs ex_tvs eq_spec ctxt
233 dc_ids = mkDataConIds wrap_name work_name data_con
238 -- The stupid context for a data constructor should be limited to
239 -- the type variables mentioned in the arg_tys
240 -- ToDo: Or functionally dependent on?
241 -- This whole stupid theta thing is, well, stupid.
242 mkDataConStupidTheta tycon arg_tys univ_tvs
243 | null stupid_theta = [] -- The common case
244 | otherwise = filter in_arg_tys stupid_theta
246 tc_subst = zipTopTvSubst (tyConTyVars tycon) (mkTyVarTys univ_tvs)
247 stupid_theta = substTheta tc_subst (tyConStupidTheta tycon)
248 -- Start by instantiating the master copy of the
249 -- stupid theta, taken from the TyCon
251 arg_tyvars = tyVarsOfTypes arg_tys
252 in_arg_tys pred = not $ isEmptyVarSet $
253 tyVarsOfPred pred `intersectVarSet` arg_tyvars
255 ------------------------------------------------------
256 mkTyConSelIds :: TyCon -> AlgTyConRhs -> [Id]
257 mkTyConSelIds tycon rhs
258 = [ mkRecordSelId tycon fld
259 | fld <- nub (concatMap dataConFieldLabels (visibleDataCons rhs)) ]
260 -- We'll check later that fields with the same name
261 -- from different constructors have the same type.
265 ------------------------------------------------------
267 buildClass :: Name -> [TyVar] -> ThetaType
268 -> [FunDep TyVar] -- Functional dependencies
269 -> [TyThing] -- Associated types
270 -> [(Name, DefMeth, Type)] -- Method info
271 -> RecFlag -- Info for type constructor
274 buildClass class_name tvs sc_theta fds ats sig_stuff tc_isrec
275 = do { tycon_name <- newImplicitBinder class_name mkClassTyConOcc
276 ; datacon_name <- newImplicitBinder class_name mkClassDataConOcc
277 -- The class name is the 'parent' for this datacon, not its tycon,
278 -- because one should import the class to get the binding for
280 ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc)
282 -- We number off the superclass selectors, 1, 2, 3 etc so that we
283 -- can construct names for the selectors. Thus
284 -- class (C a, C b) => D a b where ...
285 -- gives superclass selectors
287 -- (We used to call them D_C, but now we can have two different
288 -- superclasses both called C!)
290 ; fixM (\ rec_clas -> do { -- Only name generation inside loop
292 let { rec_tycon = classTyCon rec_clas
293 ; op_tys = [ty | (_,_,ty) <- sig_stuff]
294 ; sc_tys = mkPredTys sc_theta
295 ; dict_component_tys = sc_tys ++ op_tys
296 ; sc_sel_ids = [mkDictSelId sc_name rec_clas | sc_name <- sc_sel_names]
297 ; op_items = [ (mkDictSelId op_name rec_clas, dm_info)
298 | (op_name, dm_info, _) <- sig_stuff ] }
299 -- Build the selector id and default method id
301 ; dict_con <- buildDataCon datacon_name
302 False -- Not declared infix
303 (map (const NotMarkedStrict) dict_component_tys)
304 [{- No labelled fields -}]
305 tvs [{- no existentials -}]
306 [{- No equalities -}] [{-No context-}]
310 ; rhs <- case dict_component_tys of
311 [rep_ty] -> mkNewTyConRhs tycon_name rec_tycon dict_con
312 other -> return (mkDataTyConRhs [dict_con])
314 ; let { clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
316 ; tycon = mkClassTyCon tycon_name clas_kind tvs
317 rhs rec_clas tc_isrec
318 -- A class can be recursive, and in the case of newtypes
319 -- this matters. For example
320 -- class C a where { op :: C b => a -> b -> Int }
321 -- Because C has only one operation, it is represented by
322 -- a newtype, and it should be a *recursive* newtype.
323 -- [If we don't make it a recursive newtype, we'll expand the
324 -- newtype like a synonym, but that will lead to an infinite
326 ; atTyCons = [tycon | ATyCon tycon <- ats]
328 ; return (mkClass class_name tvs fds
329 sc_theta sc_sel_ids atTyCons op_items