import TysWiredIn ( unitTy )
import BasicTypes ( RecFlag, StrictnessMark(..) )
import Name ( Name )
-import OccName ( mkDataConWrapperOcc, mkDataConWorkerOcc, mkClassTyConOcc,
- mkClassDataConOcc, mkSuperDictSelOcc, mkNewTyCoOcc )
+import OccName ( mkDataConWrapperOcc, mkDataConWorkerOcc,
+ mkClassTyConOcc, mkClassDataConOcc,
+ mkSuperDictSelOcc, mkNewTyCoOcc, mkInstTyTcOcc,
+ mkInstTyCoOcc )
import MkId ( mkDataConIds, mkRecordSelId, mkDictSelId )
import Class ( mkClass, Class( classTyCon), FunDep, DefMeth(..) )
import TyCon ( mkSynTyCon, mkAlgTyCon, visibleDataCons,
tyConStupidTheta, tyConDataCons, isNewTyCon,
mkClassTyCon, TyCon( tyConTyVars ),
isRecursiveTyCon, tyConArity, AlgTyConRhs(..),
- SynTyConRhs(..), newTyConRhs )
+ SynTyConRhs(..), newTyConRhs, AlgTyConParent(..) )
import Type ( mkArrowKinds, liftedTypeKind, typeKind,
tyVarsOfType, tyVarsOfTypes, tyVarsOfPred,
splitTyConApp_maybe, splitAppTy_maybe,
TyThing(..),
substTyWith, zipTopTvSubst, substTheta, mkForAllTys,
mkTyConApp, mkTyVarTy )
-import Coercion ( mkNewTypeCoercion )
+import Coercion ( mkNewTypeCoercion, mkDataInstCoercion )
import Outputable
import List ( nub )
-> RecFlag
-> Bool -- True <=> want generics functions
-> Bool -- True <=> was declared in GADT syntax
+ -> Maybe (TyCon, [Type]) -- Just (family, tys)
+ -- <=> instance of `family' at `tys'
-> TcRnIf m n TyCon
buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
- = do { let { tycon = mkAlgTyCon tc_name kind tvs stupid_theta
- rhs fields is_rec want_generics gadt_syn
- ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
- ; fields = mkTyConSelIds tycon rhs
- }
- ; return tycon }
+ mb_family
+ = do { -- We need to tie a knot as the coercion of a data instance depends
+ -- on the instance representation tycon and vice versa.
+ ; tycon <- fixM (\ tycon_rec -> do
+ { (final_name, parent) <- maybeComputeFamilyInfo mb_family tycon_rec
+ ; let { tycon = mkAlgTyCon final_name kind tvs stupid_theta rhs
+ fields parent is_rec want_generics gadt_syn
+ ; kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
+ ; fields = mkTyConSelIds tycon rhs
+ }
+ ; return tycon
+ })
+ ; return tycon
+ }
+ where
+ -- If a family tycon with instance types is given, the current tycon is an
+ -- instance of that family and we have to perform three extra tasks:
+ --
+ -- (1) The instance tycon (representing the family at a particular type
+ -- instance) need to get a new, derived name - we may not reuse the
+ -- family name.
+ -- (2) Create a coercion that identifies the family instance type and the
+ -- representation type from Step (1); ie, it is of the form
+ -- `Co tvs :: F ts :=: R tvs', where `Co' is the name of the coercion,
+ -- `F' the family tycon and `R' the (derived) representation tycon.
+ -- (3) Produce a `AlgTyConParent' value containing the parent and coercion
+ -- information.
+ --
+ maybeComputeFamilyInfo Nothing rep_tycon =
+ return (tc_name, NoParentTyCon)
+ maybeComputeFamilyInfo (Just (family, instTys)) rep_tycon =
+ do { -- (1) New, derived name for the instance tycon
+ ; uniq <- newUnique
+ ; final_name <- newImplicitBinder tc_name (mkInstTyTcOcc uniq)
+
+ -- (2) Create the coercion.
+ ; co_tycon_name <- newImplicitBinder tc_name (mkInstTyCoOcc uniq)
+ ; let co_tycon = mkDataInstCoercion co_tycon_name tvs
+ family instTys rep_tycon
+
+ -- (3) Produce parent information.
+ ; return (final_name, FamilyTyCon family instTys co_tycon)
+ }
+
------------------------------------------------------
mkAbstractTyConRhs :: AlgTyConRhs
data_con = mkDataCon src_name declared_infix
arg_stricts field_lbls
univ_tvs ex_tvs eq_spec ctxt
- arg_tys tycon stupid_ctxt dc_ids
+ arg_tys tycon
+ stupid_ctxt dc_ids
dc_ids = mkDataConIds wrap_name work_name data_con
; returnM data_con }