) where
-import CmdLineOpts ( opt_Generics )
import RnHsSyn ( RenamedHsExpr )
import HsSyn ( HsExpr(..), InPat(..), mkSimpleMatch )
import Type ( Type, isUnLiftedType, applyTys, tyVarsOfType, tyVarsOfTypes,
- mkTyVarTys, mkForAllTys, mkTyConApp, splitFunTys,
- mkFunTy, funResultTy, isTyVarTy, splitForAllTys,
- splitSigmaTy, getTyVar, splitTyConApp_maybe, funTyCon
+ mkTyVarTys, mkForAllTys, mkTyConApp,
+ mkFunTy, isTyVarTy, getTyVar_maybe,
+ splitSigmaTy, splitTyConApp_maybe, funTyCon
)
-import DataCon ( DataCon, dataConOrigArgTys, dataConWrapId, dataConId )
+import DataCon ( DataCon, dataConOrigArgTys, dataConWrapId, dataConId, isExistentialDataCon )
import TyCon ( TyCon, tyConTyVars, tyConDataConsIfAvailable,
tyConGenInfo, isNewTyCon, newTyConRep, isBoxedTupleTyCon
)
import Name ( Name, mkSysLocalName )
import CoreSyn ( mkLams, Expr(..), CoreExpr, AltCon(..), Note(..),
- mkConApp, Alt, Bind (..), mkTyApps, mkVarApps )
-import BasicTypes ( RecFlag(..), EP(..), Boxity(..) )
+ mkConApp, Alt, mkTyApps, mkVarApps )
+import BasicTypes ( EP(..), Boxity(..) )
import Var ( TyVar )
-import VarSet ( isEmptyVarSet )
-import Id ( Id, mkTemplateLocal, mkTemplateLocals, idType, idName,
- mkTemplateLocalsNum, mkVanillaId, mkId
+import VarSet ( varSetElems )
+import Id ( Id, mkTemplateLocal, idType, idName,
+ mkTemplateLocalsNum, mkId
)
import TysWiredIn ( genericTyCons,
genUnitTyCon, genUnitDataCon, plusTyCon, inrDataCon,
inlDataCon, crossTyCon, crossDataCon
)
-import IdInfo ( vanillaIdInfo, setUnfoldingInfo )
+import IdInfo ( constantIdInfo, setUnfoldingInfo )
import CoreUnfold ( mkTopUnfolding )
-import Unique ( Uniquable(..), mkBuiltinUnique )
-import SrcLoc ( mkBuiltinSrcLoc )
-import Maybes ( maybeToBool, expectJust )
+import Unique ( mkBuiltinUnique )
+import SrcLoc ( builtinSrcLoc )
+import Maybes ( expectJust )
import Outputable
#include "HsVersions.h"
-- * function arrow
-- * boxed tuples
-- * an arbitrary type not involving the class type variables
-validGenericMethodType ty = valid ty
-
-valid ty
- | isTyVarTy ty = True
- | not (null arg_tys) = all valid arg_tys && valid res_ty
- | no_tyvars_in_ty = True
- | otherwise = isBoxedTupleTyCon tc && all valid tys
+ -- e.g. this is ok: forall b. Ord b => [b] -> a
+ -- where a is the class variable
+validGenericMethodType ty
+ = valid tau
where
- (arg_tys, res_ty) = splitFunTys ty
- no_tyvars_in_ty = isEmptyVarSet (tyVarsOfType ty)
- Just (tc,tys) = splitTyConApp_maybe ty
+ (local_tvs, _, tau) = splitSigmaTy ty
+
+ valid ty
+ | isTyVarTy ty = True
+ | no_tyvars_in_ty = True
+ | otherwise = case splitTyConApp_maybe ty of
+ Just (tc,tys) -> valid_tycon tc && all valid tys
+ Nothing -> False
+ where
+ no_tyvars_in_ty = all (`elem` local_tvs) (varSetElems (tyVarsOfType ty))
+
+ valid_tycon tc = tc == funTyCon || isBoxedTupleTyCon tc
+ -- Compare bimapApp, below
\end{code}
-- for the fromT and toT conversion functions.
mkTyConGenInfo tycon from_name to_name
- | not opt_Generics
- = Nothing
-
| null datacons -- Abstractly imported types don't have
= Nothing -- to/from operations, (and should not need them)
- -- If any of the constructor has an unboxed type as argument
+ -- If any of the constructor has an unboxed type as argument,
-- then we can't build the embedding-projection pair, because
-- it relies on instantiating *polymorphic* sum and product types
-- at the argument types of the constructors
- | any (any isUnLiftedType . dataConOrigArgTys) datacons
+ -- Nor can we do the job if it's an existential data constructor,
+ | or [ any isUnLiftedType (dataConOrigArgTys dc) || isExistentialDataCon dc
+ | dc <- datacons ]
= Nothing
| otherwise
tycon_ty = mkTyConApp tycon tyvar_tys -- T a b c
tyvar_tys = mkTyVarTys tyvars
- from_id_info = vanillaIdInfo `setUnfoldingInfo` mkTopUnfolding from_fn
- to_id_info = vanillaIdInfo `setUnfoldingInfo` mkTopUnfolding to_fn
+ from_id_info = constantIdInfo `setUnfoldingInfo` mkTopUnfolding from_fn
+ to_id_info = constantIdInfo `setUnfoldingInfo` mkTopUnfolding to_fn
from_ty = mkForAllTys tyvars (mkFunTy tycon_ty rep_ty)
to_ty = mkForAllTys tyvars (mkFunTy rep_ty tycon_ty)
Generating the Generic default method. Uses the bimaps to generate the
actual method. All of this is rather incomplete, but it would be nice
-to make even this work.
+to make even this work. Example
+
+ class Foo a where
+ op :: Op a
+
+ instance Foo T
+
+Then we fill in the RHS for op, RenamedHsExpr, by calling mkGenericRhs:
+
+ instance Foo T where
+ op = <mkGenericRhs op a T>
+
+To do this, we generate a pair of RenamedHsExprs (EP toOp fromOp), where
+
+ toOp :: Op Trep -> Op T
+ fromOp :: Op T -> Op Trep
+
+(the bimap) and then fill in the RHS with
+
+ instance Foo T where
+ op = toOp op
+
+Remember, we're generating a RenamedHsExpr, so the result of all this
+will be fed to the type checker. So the 'op' on the RHS will be
+at the representation type for T, Trep.
+
+
+A note about polymorphism. Suppose the class op is polymorphic:
+
+ class Baz a where
+ op :: forall b. Ord b => a -> b -> b
+
+Then we can still generate a bimap with
+
+ toOP :: forall b. (Trep -> b -> b) -> (T -> b -> b)
+
+and fill in the instance decl thus
+
+ instance Foo T where
+ op = toOp op
+
+By the time the type checker has done its stuff we'll get
+
+ instance Foo T where
+ op = \b. \dict::Ord b. toOp b (op Trep b dict)
\begin{code}
mkGenericRhs :: Id -> TyVar -> TyCon -> RenamedHsExpr
Just (EP from to) = tyConGenInfo tycon -- Caller checked this will succeed
ep = EP (HsVar (idName from)) (HsVar (idName to))
- -- Takes out the ForAll and the Class rstrictions in front of the
- -- type of the method.
+ -- Takes out the ForAll and the Class restrictions
+ -- in front of the type of the method.
(_,_,op_ty) = splitSigmaTy (idType sel_id)
+ -- Do it again! This deals with the case where the method type
+ -- is polymorphic -- see notes above
+ (local_tvs,_,final_ty) = splitSigmaTy op_ty
+
-- Now we probably have a tycon in front
-- of us, quite probably a FunTyCon.
- bimap = generate_bimap (tyvar, ep) op_ty
+ bimap = generate_bimap (tyvar, ep, local_tvs) final_ty
--- EP is the environment of to/from bimaps, but as we only have one type
--- variable at the moment, there is only one EP.
+type EPEnv = (TyVar, -- The class type variable
+ EP RenamedHsExpr, -- The EP it maps to
+ [TyVar] -- Other in-scope tyvars; they have an identity EP
+ )
-------------------
-generate_bimap :: (TyVar, EP RenamedHsExpr) -> Type -> EP RenamedHsExpr
+generate_bimap :: EPEnv
+ -> Type
+ -> EP RenamedHsExpr
-- Top level case - splitting the TyCon.
-generate_bimap (tv,ep) ty | isTyVarTy ty = ASSERT( getTyVar "Generics.generate_bimap" ty == tv) ep
- | otherwise = bimapApp (tv,ep) (splitTyConApp_maybe ty)
+generate_bimap env@(tv,ep,local_tvs) ty
+ = case getTyVar_maybe ty of
+ Just tv1 | tv == tv1 -> ep -- The class tyvar
+ | otherwise -> ASSERT( tv1 `elem` local_tvs) -- One of the polymorphic tyvars of the method
+ idEP
+ Nothing -> bimapApp env (splitTyConApp_maybe ty)
-------------------
-bimapApp :: (TyVar, EP RenamedHsExpr) -> Maybe (TyCon, [Type]) -> EP RenamedHsExpr
-bimapApp ep Nothing = panic "TcClassDecl: Type Application!"
-bimapApp ep (Just (tycon, ty_args))
+bimapApp :: EPEnv -> Maybe (TyCon, [Type]) -> EP RenamedHsExpr
+bimapApp env Nothing = panic "TcClassDecl: Type Application!"
+bimapApp env (Just (tycon, ty_args))
| tycon == funTyCon = bimapArrow arg_eps
| isBoxedTupleTyCon tycon = bimapTuple arg_eps
| otherwise = -- Otherwise validGenericMethodType will
-- have checked that the type is a constant type
- ASSERT( isEmptyVarSet (tyVarsOfTypes ty_args) )
- EP idexpr idexpr
+ ASSERT( all (`elem` local_tvs) (varSetElems (tyVarsOfTypes ty_args)) )
+ idEP
where
- arg_eps = map (generate_bimap ep) ty_args
+ arg_eps = map (generate_bimap env) ty_args
+ (_,_,local_tvs) = env
-------------------
+-- bimapArrow :: [EP a a', EP b b'] -> EP (a->b) (a'->b')
bimapArrow [ep1, ep2]
= EP { fromEP = mk_hs_lam [VarPatIn g1, VarPatIn g2] from_body,
toEP = mk_hs_lam [VarPatIn g1, VarPatIn g2] to_body }
genericNames = [mkSysLocalName (mkBuiltinUnique i) (_PK_ ('g' : show i)) | i <- [1..]]
(g1:g2:g3:_) = genericNames
-mk_hs_lam pats body = HsPar (HsLam (mkSimpleMatch pats body Nothing mkBuiltinSrcLoc))
-idexpr = mk_hs_lam [VarPatIn g3] (HsVar g3)
+mk_hs_lam pats body = HsPar (HsLam (mkSimpleMatch pats body Nothing builtinSrcLoc))
+
+idEP :: EP RenamedHsExpr
+idEP = EP idexpr idexpr
+ where
+ idexpr = mk_hs_lam [VarPatIn g3] (HsVar g3)
\end{code}
projects / ghc-hetmet.git / blobdiff