\begin{code}
module BuildTyCl (
- buildSynTyCon, buildAlgTyCon, buildDataCon,
- buildClass,
- mkAbstractTyConRhs, mkOpenDataTyConRhs,
- mkNewTyConRhs, mkDataTyConRhs
+ buildSynTyCon,
+ buildAlgTyCon,
+ buildDataCon,
+ TcMethInfo, buildClass,
+ mkAbstractTyConRhs,
+ mkNewTyConRhs, mkDataTyConRhs
) where
#include "HsVersions.h"
import VarSet
import BasicTypes
import Name
-import OccName
import MkId
import Class
import TyCon
import Coercion
import TcRnMonad
-import Util ( count )
+import Data.List ( partition )
import Outputable
-
-import Data.List
\end{code}
\begin{code}
------------------------------------------------------
buildSynTyCon :: Name -> [TyVar]
- -> SynTyConRhs
- -> Kind -- Kind of the RHS
- -> Maybe (TyCon, [Type]) -- family instance if applicable
+ -> SynTyConRhs
+ -> Kind -- ^ Kind of the RHS
+ -> TyConParent
+ -> Maybe (TyCon, [Type]) -- ^ family instance if applicable
-> TcRnIf m n TyCon
-
-buildSynTyCon tc_name tvs rhs@(OpenSynTyCon {}) rhs_kind _
- = let
- kind = mkArrowKinds (map tyVarKind tvs) rhs_kind
- in
- return $ mkSynTyCon tc_name kind tvs rhs NoParentTyCon
-
-buildSynTyCon tc_name tvs rhs@(SynonymTyCon {}) rhs_kind 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
- { parent <- mkParentInfo mb_family tc_name tvs tycon_rec
- ; let { tycon = mkSynTyCon tc_name kind tvs rhs parent
- ; kind = mkArrowKinds (map tyVarKind tvs) rhs_kind
- }
- ; return tycon
- })
- ; return tycon
- }
+buildSynTyCon tc_name tvs rhs rhs_kind parent mb_family
+ | Just fam_inst_info <- mb_family
+ = ASSERT( isNoParent parent )
+ fixM $ \ tycon_rec -> do
+ { fam_parent <- mkFamInstParentInfo tc_name tvs fam_inst_info tycon_rec
+ ; return (mkSynTyCon tc_name kind tvs rhs fam_parent) }
+
+ | otherwise
+ = return (mkSynTyCon tc_name kind tvs rhs parent)
+ where
+ kind = mkArrowKinds (map tyVarKind tvs) rhs_kind
------------------------------------------------------
buildAlgTyCon :: Name -> [TyVar]
- -> ThetaType -- Stupid theta
+ -> ThetaType -- ^ Stupid theta
-> AlgTyConRhs
-> RecFlag
- -> Bool -- True <=> want generics functions
- -> Bool -- True <=> was declared in GADT syntax
- -> Maybe (TyCon, [Type]) -- family instance if applicable
+ -> Bool -- ^ True <=> want generics functions
+ -> Bool -- ^ True <=> was declared in GADT syntax
+ -> TyConParent
+ -> Maybe (TyCon, [Type]) -- ^ family instance if applicable
-> TcRnIf m n TyCon
buildAlgTyCon tc_name tvs stupid_theta rhs is_rec want_generics gadt_syn
- 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
- { parent <- mkParentInfo mb_family tc_name tvs tycon_rec
- ; let { tycon = mkAlgTyCon tc_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
- }
-
--- If a family tycon with instance types is given, the current tycon is an
+ parent mb_family
+ | Just fam_inst_info <- mb_family
+ = -- We need to tie a knot as the coercion of a data instance depends
+ -- on the instance representation tycon and vice versa.
+ ASSERT( isNoParent parent )
+ fixM $ \ tycon_rec -> do
+ { fam_parent <- mkFamInstParentInfo tc_name tvs fam_inst_info tycon_rec
+ ; return (mkAlgTyCon tc_name kind tvs stupid_theta rhs
+ fam_parent is_rec want_generics gadt_syn) }
+
+ | otherwise
+ = return (mkAlgTyCon tc_name kind tvs stupid_theta rhs
+ parent is_rec want_generics gadt_syn)
+ where
+ kind = mkArrowKinds (map tyVarKind tvs) liftedTypeKind
+
+-- | If a family tycon with instance types is given, the current tycon is an
-- instance of that family and we need to
--
-- (1) create a coercion that identifies the family instance type and the
-- (2) produce a `TyConParent' value containing the parent and coercion
-- information.
--
-mkParentInfo :: Maybe (TyCon, [Type])
- -> Name -> [TyVar]
- -> TyCon
- -> TcRnIf m n TyConParent
-mkParentInfo Nothing _ _ _ =
- return NoParentTyCon
-mkParentInfo (Just (family, instTys)) tc_name tvs rep_tycon =
- do { -- Create the coercion
- ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc
- ; let co_tycon = mkFamInstCoercion co_tycon_name tvs
+mkFamInstParentInfo :: Name -> [TyVar]
+ -> (TyCon, [Type])
+ -> TyCon
+ -> TcRnIf m n TyConParent
+mkFamInstParentInfo tc_name tvs (family, instTys) rep_tycon
+ = do { -- Create the coercion
+ ; co_tycon_name <- newImplicitBinder tc_name mkInstTyCoOcc
+ ; let co_tycon = mkFamInstCoercion co_tycon_name tvs
family instTys rep_tycon
- ; return $ FamilyTyCon family instTys co_tycon
- }
+ ; return $ FamInstTyCon family instTys co_tycon }
------------------------------------------------------
mkAbstractTyConRhs :: AlgTyConRhs
mkAbstractTyConRhs = AbstractTyCon
-mkOpenDataTyConRhs :: AlgTyConRhs
-mkOpenDataTyConRhs = OpenTyCon Nothing
-
mkDataTyConRhs :: [DataCon] -> AlgTyConRhs
mkDataTyConRhs cons
- = DataTyCon { data_cons = cons, is_enum = all isNullarySrcDataCon cons }
+ = DataTyCon {
+ data_cons = cons,
+ is_enum = not (null cons) && all is_enum_con cons
+ -- See Note [Enumeration types] in TyCon
+ }
+ where
+ is_enum_con con
+ | (_tvs, theta, arg_tys, _res) <- dataConSig con
+ = null theta && null arg_tys
+
mkNewTyConRhs :: Name -> TyCon -> DataCon -> TcRnIf m n AlgTyConRhs
--- Monadic because it makes a Name for the coercion TyCon
--- We pass the Name of the parent TyCon, as well as the TyCon itself,
--- because the latter is part of a knot, whereas the former is not.
+-- ^ Monadic because it makes a Name for the coercion TyCon
+-- We pass the Name of the parent TyCon, as well as the TyCon itself,
+-- because the latter is part of a knot, whereas the former is not.
mkNewTyConRhs tycon_name tycon con
= do { co_tycon_name <- newImplicitBinder tycon_name mkNewTyCoOcc
; let co_tycon = mkNewTypeCoercion co_tycon_name tycon etad_tvs etad_rhs
------------------------------------------------------
buildDataCon :: Name -> Bool
- -> [StrictnessMark]
+ -> [HsBang]
-> [Name] -- Field labels
-> [TyVar] -> [TyVar] -- Univ and ext
-> [(TyVar,Type)] -- Equality spec
arg_tyvars = tyVarsOfTypes arg_tys
in_arg_tys pred = not $ isEmptyVarSet $
tyVarsOfPred pred `intersectVarSet` arg_tyvars
-
-------------------------------------------------------
-mkTyConSelIds :: TyCon -> AlgTyConRhs -> [Id]
-mkTyConSelIds tycon rhs
- = [ mkRecordSelId tycon fld
- | fld <- nub (concatMap dataConFieldLabels (visibleDataCons rhs)) ]
- -- We'll check later that fields with the same name
- -- from different constructors have the same type.
\end{code}
------------------------------------------------------
\begin{code}
-buildClass :: Bool -- True <=> do not include unfoldings
- -- on dict selectors
- -- Used when importing a class without -O
+type TcMethInfo = (Name, DefMethSpec, Type) -- A temporary intermediate, to communicate
+ -- between tcClassSigs and buildClass
+
+buildClass :: Bool -- True <=> do not include unfoldings
+ -- on dict selectors
+ -- Used when importing a class without -O
-> Name -> [TyVar] -> ThetaType
- -> [FunDep TyVar] -- Functional dependencies
- -> [TyThing] -- Associated types
- -> [(Name, DefMeth, Type)] -- Method info
- -> RecFlag -- Info for type constructor
+ -> [FunDep TyVar] -- Functional dependencies
+ -> [TyThing] -- Associated types
+ -> [TcMethInfo] -- Method info
+ -> RecFlag -- Info for type constructor
-> TcRnIf m n Class
buildClass no_unf class_name tvs sc_theta fds ats sig_stuff tc_isrec
; fixM (\ rec_clas -> do { -- Only name generation inside loop
- let { rec_tycon = classTyCon rec_clas
- ; op_tys = [ty | (_,_,ty) <- sig_stuff]
- ; op_items = [ (mkDictSelId no_unf op_name rec_clas, dm_info)
- | (op_name, dm_info, _) <- sig_stuff ] }
+ ; op_items <- mapM (mk_op_item rec_clas) sig_stuff
-- Build the selector id and default method id
- ; dict_con <- buildDataCon datacon_name
- False -- Not declared infix
- (map (const NotMarkedStrict) op_tys)
- [{- No labelled fields -}]
- tvs [{- no existentials -}]
- [{- No GADT equalities -}] sc_theta
- op_tys
- (mkTyConApp rec_tycon (mkTyVarTys tvs))
- rec_tycon
+ ; let (eq_theta, dict_theta) = partition isEqPred sc_theta
- ; let n_value_preds = count (not . isEqPred) sc_theta
- all_value_preds = n_value_preds == length sc_theta
-- We only make selectors for the *value* superclasses,
-- not equality predicates
-
; sc_sel_names <- mapM (newImplicitBinder class_name . mkSuperDictSelOcc)
- [1..n_value_preds]
- ; let sc_sel_ids = [mkDictSelId no_unf sc_name rec_clas | sc_name <- sc_sel_names]
+ [1..length dict_theta]
+ ; let sc_sel_ids = [ mkDictSelId no_unf sc_name rec_clas
+ | sc_name <- sc_sel_names]
-- We number off the Dict superclass selectors, 1, 2, 3 etc so that we
-- can construct names for the selectors. Thus
-- class (C a, C b) => D a b where ...
-- D_sc1, D_sc2
-- (We used to call them D_C, but now we can have two different
-- superclasses both called C!)
- --
- ; let use_newtype = (n_value_preds + length sig_stuff == 1) && all_value_preds
+ ; let use_newtype = null eq_theta && (length dict_theta + length sig_stuff == 1)
-- Use a newtype if the data constructor has
-- (a) exactly one value field
-- (b) no existential or equality-predicate fields
-- i.e. exactly one operation or superclass taken together
-- See note [Class newtypes and equality predicates]
+ -- We play a bit fast and loose by treating the dictionary
+ -- superclasses as ordinary arguments. That means that in
+ -- the case of
+ -- class C a => D a
+ -- we don't get a newtype with no arguments!
+ args = sc_sel_names ++ op_names
+ op_tys = [ty | (_,_,ty) <- sig_stuff]
+ op_names = [op | (op,_,_) <- sig_stuff]
+ arg_tys = map mkPredTy dict_theta ++ op_tys
+ rec_tycon = classTyCon rec_clas
+
+ ; dict_con <- buildDataCon datacon_name
+ False -- Not declared infix
+ (map (const HsNoBang) args)
+ [{- No fields -}]
+ tvs [{- no existentials -}]
+ [{- No GADT equalities -}]
+ eq_theta
+ arg_tys
+ (mkTyConApp rec_tycon (mkTyVarTys tvs))
+ rec_tycon
+
; rhs <- if use_newtype
then mkNewTyConRhs tycon_name rec_tycon dict_con
else return (mkDataTyConRhs [dict_con])
; atTyCons = [tycon | ATyCon tycon <- ats]
; result = mkClass class_name tvs fds
- sc_theta sc_sel_ids atTyCons
+ (eq_theta ++ dict_theta) -- Equalities first
+ (length eq_theta) -- Number of equalities
+ sc_sel_ids atTyCons
op_items tycon
}
; traceIf (text "buildClass" <+> ppr tycon)
; return result
})}
+ where
+ mk_op_item :: Class -> TcMethInfo -> TcRnIf n m ClassOpItem
+ mk_op_item rec_clas (op_name, dm_spec, _)
+ = do { dm_info <- case dm_spec of
+ NoDM -> return NoDefMeth
+ GenericDM -> return GenDefMeth
+ VanillaDM -> do { dm_name <- newImplicitBinder op_name mkDefaultMethodOcc
+ ; return (DefMeth dm_name) }
+ ; return (mkDictSelId no_unf op_name rec_clas, dm_info) }
\end{code}
Note [Class newtypes and equality predicates]