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],
73 Int) -- Just (family, tys, index)
74 -- <=> instance of `family' at `tys'
77 buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
79 = do { -- We need to tie a knot as the coercion of a data instance depends
80 -- on the instance representation tycon and vice versa.
81 ; tycon <- fixM (\ tycon_rec -> do
82 { (final_name, parent) <- maybeComputeFamilyInfo mb_family tycon_rec
83 ; let { tycon = mkAlgTyCon final_name kind tvs stupid_theta rhs
84 fields parent is_rec want_generics gadt_syn
85 ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
86 ; fields = mkTyConSelIds tycon rhs
93 -- If a family tycon with instance types is given, the current tycon is an
94 -- instance of that family and we have to perform three extra tasks:
96 -- (1) The instance tycon (representing the family at a particular type
97 -- instance) need to get a new, derived name - we may not reuse the
99 -- (2) Create a coercion that identifies the family instance type and the
100 -- representation type from Step (1); ie, it is of the form
101 -- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion,
102 -- `F' the family tycon and `R' the (derived) representation tycon.
103 -- (3) Produce a `AlgTyConParent' value containing the parent and coercion
106 maybeComputeFamilyInfo Nothing rep_tycon =
107 return (tc_name, NoParentTyCon)
108 maybeComputeFamilyInfo (Just (family, instTys, index)) rep_tycon =
109 do { -- (1) New, derived name for the instance tycon
110 ; final_name <- newImplicitBinder tc_name (mkInstTyTcOcc index)
112 -- (2) Create the coercion.
113 ; co_tycon_name <- newImplicitBinder tc_name (mkInstTyCoOcc index)
114 ; let co_tycon = mkDataInstCoercion co_tycon_name tvs
115 family instTys rep_tycon
117 -- (3) Produce parent information.
118 ; return (final_name, FamilyTyCon family instTys co_tycon index)
122 ------------------------------------------------------
123 mkAbstractTyConRhs :: AlgTyConRhs
124 mkAbstractTyConRhs = AbstractTyCon
126 mkOpenDataTyConRhs :: AlgTyConRhs
127 mkOpenDataTyConRhs = OpenDataTyCon
129 mkOpenNewTyConRhs :: AlgTyConRhs
130 mkOpenNewTyConRhs = OpenNewTyCon
132 mkDataTyConRhs :: [DataCon] -> AlgTyConRhs
134 = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons }
136 mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
137 -- Monadic because it makes a Name for the coercion TyCon
138 -- We pass the Name of the parent TyCon, as well as the TyCon itself,
139 -- because the latter is part of a knot, whereas the former is not.
140 mkNewTyConRhs tycon_name tycon con
141 = do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc
142 ; let co_tycon = mkNewTypeCoercion co_tycon_name tycon tvs rhs_ty
144 | all_coercions || isRecursiveTyCon tycon
148 ; return (NewTyCon { data_con = con,
150 -- Coreview looks through newtypes with a Nothing
151 -- for nt_co, or uses explicit coercions otherwise
153 nt_etad_rhs = eta_reduce tvs rhs_ty,
154 nt_rep = mkNewTyConRep tycon rhs_ty }) }
156 -- if all_coercions is True then we use coercions for all newtypes
157 -- otherwise we use coercions for recursive newtypes and look through
158 -- non-recursive newtypes
160 tvs = tyConTyVars tycon
161 rhs_ty = head (dataConInstOrigArgTys con (mkTyVarTys tvs))
162 -- Instantiate the data con with the
163 -- type variables from the tycon
165 eta_reduce [] ty = ([], ty)
166 eta_reduce (a:as) ty | null as',
167 Just (fun, arg) <- splitAppTy_maybe ty',
168 Just tv <- getTyVar_maybe arg,
170 not (a `elemVarSet` tyVarsOfType fun)
171 = ([], fun) -- Successful eta reduction
175 (as', ty') = eta_reduce as ty
177 mkNewTyConRep :: TyCon -- The original type constructor
178 -> Type -- The arg type of its constructor
179 -> Type -- Chosen representation type
180 -- The "representation type" is guaranteed not to be another newtype
181 -- at the outermost level; but it might have newtypes in type arguments
183 -- Find the representation type for this newtype TyCon
184 -- Remember that the representation type is the *ultimate* representation
185 -- type, looking through other newtypes.
187 -- splitTyConApp_maybe no longer looks through newtypes, so we must
188 -- deal explicitly with this case
190 -- The trick is to to deal correctly with recursive newtypes
191 -- such as newtype T = MkT T
193 mkNewTyConRep tc rhs_ty
194 | null (tyConDataCons tc) = unitTy
195 -- External Core programs can have newtypes with no data constructors
196 | otherwise = go [tc] rhs_ty
198 -- Invariant: tcs have been seen before
200 = case splitTyConApp_maybe rep_ty of
202 | tc `elem` tcs -> unitTy -- Recursive loop
204 if isRecursiveTyCon tc then
205 go (tc:tcs) (substTyWith tvs tys rhs_ty)
207 substTyWith tvs tys rhs_ty
209 (tvs, rhs_ty) = newTyConRhs tc
213 ------------------------------------------------------
214 buildDataCon :: Name -> Bool
216 -> [Name] -- Field labels
217 -> [TyVar] -> [TyVar] -- Univ and ext
218 -> [(TyVar,Type)] -- Equality spec
219 -> ThetaType -- Does not include the "stupid theta"
220 -- or the GADT equalities
222 -> TcRnIf m n DataCon
223 -- A wrapper for DataCon.mkDataCon that
224 -- a) makes the worker Id
225 -- b) makes the wrapper Id if necessary, including
226 -- allocating its unique (hence monadic)
227 buildDataCon src_name declared_infix arg_stricts field_lbls
228 univ_tvs ex_tvs eq_spec ctxt arg_tys tycon
229 = do { wrap_name <- newImplicitBinder src_name mkDataConWrapperOcc
230 ; work_name <- newImplicitBinder src_name mkDataConWorkerOcc
231 -- This last one takes the name of the data constructor in the source
232 -- code, which (for Haskell source anyway) will be in the DataName name
233 -- space, and puts it into the VarName name space
236 stupid_ctxt = mkDataConStupidTheta tycon arg_tys univ_tvs
237 data_con = mkDataCon src_name declared_infix
238 arg_stricts field_lbls
239 univ_tvs ex_tvs eq_spec ctxt
242 dc_ids = mkDataConIds wrap_name work_name data_con
247 -- The stupid context for a data constructor should be limited to
248 -- the type variables mentioned in the arg_tys
249 -- ToDo: Or functionally dependent on?
250 -- This whole stupid theta thing is, well, stupid.
251 mkDataConStupidTheta tycon arg_tys univ_tvs
252 | null stupid_theta = [] -- The common case
253 | otherwise = filter in_arg_tys stupid_theta
255 tc_subst = zipTopTvSubst (tyConTyVars tycon) (mkTyVarTys univ_tvs)
256 stupid_theta = substTheta tc_subst (tyConStupidTheta tycon)
257 -- Start by instantiating the master copy of the
258 -- stupid theta, taken from the TyCon
260 arg_tyvars = tyVarsOfTypes arg_tys
261 in_arg_tys pred = not $ isEmptyVarSet $
262 tyVarsOfPred pred `intersectVarSet` arg_tyvars
264 ------------------------------------------------------
265 mkTyConSelIds :: TyCon -> AlgTyConRhs -> [Id]
266 mkTyConSelIds tycon rhs
267 = [ mkRecordSelId tycon fld
268 | fld <- nub (concatMap dataConFieldLabels (visibleDataCons rhs)) ]
269 -- We'll check later that fields with the same name
270 -- from different constructors have the same type.
274 ------------------------------------------------------
276 buildClass :: Name -> [TyVar] -> ThetaType
277 -> [FunDep TyVar] -- Functional dependencies
278 -> [TyThing] -- Associated types
279 -> [(Name, DefMeth, Type)] -- Method info
280 -> RecFlag -- Info for type constructor
283 buildClass class_name tvs sc_theta fds ats sig_stuff tc_isrec
284 = do { tycon_name <- newImplicitBinder class_name mkClassTyConOcc
285 ; datacon_name <- newImplicitBinder class_name mkClassDataConOcc
286 -- The class name is the 'parent' for this datacon, not its tycon,
287 -- because one should import the class to get the binding for
289 ; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc)
291 -- We number off the superclass selectors, 1, 2, 3 etc so that we
292 -- can construct names for the selectors. Thus
293 -- class (C a, C b) => D a b where ...
294 -- gives superclass selectors
296 -- (We used to call them D_C, but now we can have two different
297 -- superclasses both called C!)
299 ; fixM (\ rec_clas -> do { -- Only name generation inside loop
301 let { rec_tycon = classTyCon rec_clas
302 ; op_tys = [ty | (_,_,ty) <- sig_stuff]
303 ; sc_tys = mkPredTys sc_theta
304 ; dict_component_tys = sc_tys ++ op_tys
305 ; sc_sel_ids = [mkDictSelId sc_name rec_clas | sc_name <- sc_sel_names]
306 ; op_items = [ (mkDictSelId op_name rec_clas, dm_info)
307 | (op_name, dm_info, _) <- sig_stuff ] }
308 -- Build the selector id and default method id
310 ; dict_con <- buildDataCon datacon_name
311 False -- Not declared infix
312 (map (const NotMarkedStrict) dict_component_tys)
313 [{- No labelled fields -}]
314 tvs [{- no existentials -}]
315 [{- No equalities -}] [{-No context-}]
319 ; rhs <- case dict_component_tys of
320 [rep_ty] -> mkNewTyConRhs tycon_name rec_tycon dict_con
321 other -> return (mkDataTyConRhs [dict_con])
323 ; let { clas_kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
325 ; tycon = mkClassTyCon tycon_name clas_kind tvs
326 rhs rec_clas tc_isrec
327 -- A class can be recursive, and in the case of newtypes
328 -- this matters. For example
329 -- class C a where { op :: C b => a -> b -> Int }
330 -- Because C has only one operation, it is represented by
331 -- a newtype, and it should be a *recursive* newtype.
332 -- [If we don't make it a recursive newtype, we'll expand the
333 -- newtype like a synonym, but that will lead to an infinite
335 ; atTyCons = [tycon | ATyCon tycon <- ats]
337 ; return (mkClass class_name tvs fds
338 sc_theta sc_sel_ids atTyCons op_items