-module VectType ( vectTyCon, vectType, vectTypeEnv,
- PAInstance, buildPADict )
-where
-#include "HsVersions.h"
+module VectType ( vectTyCon, vectAndLiftType, vectType, vectTypeEnv,
+ mkRepr, arrShapeTys, arrShapeVars, arrSelector,
+ buildPADict,
+ fromVect )
+where
import VectMonad
import VectUtils
import TypeRep
import Coercion
import FamInstEnv ( FamInst, mkLocalFamInst )
-import InstEnv ( Instance, mkLocalInstance, instanceDFunId )
import OccName
import MkId
-import BasicTypes ( StrictnessMark(..), OverlapFlag(..), boolToRecFlag )
-import Var ( Var )
+import BasicTypes ( StrictnessMark(..), boolToRecFlag )
+import Var ( Var, TyVar )
import Id ( mkWildId )
import Name ( Name, getOccName )
import NameEnv
import Unique
import UniqFM
import UniqSet
-import Util ( singleton )
-import Digraph ( SCC(..), stronglyConnComp )
+import Util
+import Digraph ( SCC(..), stronglyConnCompFromEdgedVertices )
import Outputable
+import FastString
import Control.Monad ( liftM, liftM2, zipWithM, zipWithM_, mapAndUnzipM )
import Data.List ( inits, tails, zipWith4, zipWith5 )
| isFunTyCon tc = builtin closureTyCon
| isBoxedTupleTyCon tc = return tc
| isUnLiftedTyCon tc = return tc
- | otherwise = do
- r <- lookupTyCon tc
- case r of
- Just tc' -> return tc'
+ | otherwise = maybeCantVectoriseM "Tycon not vectorised:" (ppr tc)
+ $ lookupTyCon tc
+
+vectAndLiftType :: Type -> VM (Type, Type)
+vectAndLiftType ty | Just ty' <- coreView ty = vectAndLiftType ty'
+vectAndLiftType ty
+ = do
+ mdicts <- mapM paDictArgType tyvars
+ let dicts = [dict | Just dict <- mdicts]
+ vmono_ty <- vectType mono_ty
+ lmono_ty <- mkPArrayType vmono_ty
+ return (abstractType tyvars dicts vmono_ty,
+ abstractType tyvars dicts lmono_ty)
+ where
+ (tyvars, mono_ty) = splitForAllTys ty
- -- FIXME: just for now
- Nothing -> pprTrace "ccTyCon:" (ppr tc) $ return tc
vectType :: Type -> VM Type
vectType ty | Just ty' <- coreView ty = vectType ty'
vectType (AppTy ty1 ty2) = liftM2 AppTy (vectType ty1) (vectType ty2)
vectType (TyConApp tc tys) = liftM2 TyConApp (vectTyCon tc) (mapM vectType tys)
vectType (FunTy ty1 ty2) = liftM2 TyConApp (builtin closureTyCon)
- (mapM vectType [ty1,ty2])
+ (mapM vectAndBoxType [ty1,ty2])
vectType ty@(ForAllTy _ _)
= do
mdicts <- mapM paDictArgType tyvars
mono_ty' <- vectType mono_ty
- return $ tyvars `mkForAllTys` ([dict | Just dict <- mdicts] `mkFunTys` mono_ty')
+ return $ abstractType tyvars [dict | Just dict <- mdicts] mono_ty'
where
(tyvars, mono_ty) = splitForAllTys ty
-vectType ty = pprPanic "vectType:" (ppr ty)
+vectType ty = cantVectorise "Can't vectorise type" (ppr ty)
+
+vectAndBoxType :: Type -> VM Type
+vectAndBoxType ty = vectType ty >>= boxType
+
+abstractType :: [TyVar] -> [Type] -> Type -> Type
+abstractType tyvars dicts = mkForAllTys tyvars . mkFunTys dicts
+
+-- ----------------------------------------------------------------------------
+-- Boxing
+
+boxType :: Type -> VM Type
+boxType ty
+ | Just (tycon, []) <- splitTyConApp_maybe ty
+ , isUnLiftedTyCon tycon
+ = do
+ r <- lookupBoxedTyCon tycon
+ case r of
+ Just tycon' -> return $ mkTyConApp tycon' []
+ Nothing -> return ty
+boxType ty = return ty
-- ----------------------------------------------------------------------------
-- Type definitions
type TyConGroup = ([TyCon], UniqSet TyCon)
-data PAInstance = PAInstance {
- painstDFun :: Var
- , painstOrigTyCon :: TyCon
- , painstVectTyCon :: TyCon
- , painstArrTyCon :: TyCon
- }
-
vectTypeEnv :: TypeEnv -> VM (TypeEnv, [FamInst], [(Var, CoreExpr)])
vectTypeEnv env
= do
mk_map env = listToUFM_Directly [(u, getUnique n /= u) | (u,n) <- nameEnvUniqueElts env]
- keep_tc tc = let dcs = tyConDataCons tc
- in
- defTyCon tc tc >> zipWithM_ defDataCon dcs dcs
-
vectTyConDecls :: [TyCon] -> VM [TyCon]
vectTyConDecls tcs = fixV $ \tcs' ->
do
- mapM_ (uncurry defTyCon) (lazy_zip tcs tcs')
+ mapM_ (uncurry defTyCon) (zipLazy tcs tcs')
mapM vectTyConDecl tcs
- where
- lazy_zip [] _ = []
- lazy_zip (x:xs) ~(y:ys) = (x,y) : lazy_zip xs ys
vectTyConDecl :: TyCon -> VM TyCon
vectTyConDecl tc
= do
name' <- cloneName mkVectTyConOcc name
- rhs' <- vectAlgTyConRhs (algTyConRhs tc)
+ rhs' <- vectAlgTyConRhs tc (algTyConRhs tc)
liftDs $ buildAlgTyCon name'
tyvars
tyvars = tyConTyVars tc
rec_flag = boolToRecFlag (isRecursiveTyCon tc)
-vectAlgTyConRhs :: AlgTyConRhs -> VM AlgTyConRhs
-vectAlgTyConRhs (DataTyCon { data_cons = data_cons
- , is_enum = is_enum
- })
+vectAlgTyConRhs :: TyCon -> AlgTyConRhs -> VM AlgTyConRhs
+vectAlgTyConRhs _ (DataTyCon { data_cons = data_cons
+ , is_enum = is_enum
+ })
= do
data_cons' <- mapM vectDataCon data_cons
zipWithM_ defDataCon data_cons data_cons'
return $ DataTyCon { data_cons = data_cons'
, is_enum = is_enum
}
+vectAlgTyConRhs tc _ = cantVectorise "Can't vectorise type definition:" (ppr tc)
vectDataCon :: DataCon -> VM DataCon
vectDataCon dc
- | not . null $ dataConExTyVars dc = pprPanic "vectDataCon: existentials" (ppr dc)
- | not . null $ dataConEqSpec dc = pprPanic "vectDataCon: eq spec" (ppr dc)
+ | not . null $ dataConExTyVars dc
+ = cantVectorise "Can't vectorise constructor (existentials):" (ppr dc)
+ | not . null $ dataConEqSpec dc
+ = cantVectorise "Can't vectorise constructor (eq spec):" (ppr dc)
| otherwise
= do
name' <- cloneName mkVectDataConOcc name
liftDs $ buildSynTyCon name
tyvars
(SynonymTyCon rhs_ty)
+ (typeKind rhs_ty)
(Just $ mk_fam_inst prepr_tc vect_tc)
where
tyvars = tyConTyVars vect_tc
, void_bottom = Var var
}
+{-
enumRepr :: VM Repr
enumRepr
= do
- (arr_tycon, _) <- parrayReprTyCon intTy
+ tycon <- builtin enumerationTyCon
+ let [data_con] = tyConDataCons tycon
+ (arr_tycon, _) <- parrayReprTyCon (mkTyConApp tycon [])
let [arr_data_con] = tyConDataCons arr_tycon
return $ EnumRepr {
, enum_arr_tycon = arr_tycon
, enum_arr_data_con = arr_data_con
}
- where
- tycon = intTyCon
- data_con = intDataCon
+-}
unboxedProductRepr :: [Type] -> VM Repr
unboxedProductRepr [] = voidRepr
tycon <- builtin (prodTyCon arity)
let [data_con] = tyConDataCons tycon
- (arr_tycon, _) <- parrayReprTyCon $ mkTyConApp tycon tys
+ tys' <- mapM boxType tys
+ (arr_tycon, _) <- parrayReprTyCon $ mkTyConApp tycon tys'
let [arr_data_con] = tyConDataCons arr_tycon
return $ ProdRepr {
arrReprType = mkPArrayType . reprType
arrShapeTys :: Repr -> VM [Type]
-arrShapeTys (SumRepr {})
- = do
- int_arr <- builtin parrayIntPrimTyCon
- return [intPrimTy, mkTyConApp int_arr [], mkTyConApp int_arr []]
+arrShapeTys (SumRepr {}) = sumShapeTys
arrShapeTys (ProdRepr {}) = return [intPrimTy]
arrShapeTys (IdRepr _) = return []
arrShapeTys (VoidRepr {}) = return [intPrimTy]
-arrShapeTys (EnumRepr {}) = return [intPrimTy]
+arrShapeTys (EnumRepr {}) = sumShapeTys
+
+sumShapeTys :: VM [Type]
+sumShapeTys = do
+ int_arr <- builtin intPrimArrayTy
+ return [intPrimTy, int_arr, int_arr]
+
arrShapeVars :: Repr -> VM [Var]
-arrShapeVars repr = mapM (newLocalVar FSLIT("sh")) =<< arrShapeTys repr
+arrShapeVars repr = mapM (newLocalVar (fsLit "sh")) =<< arrShapeTys repr
replicateShape :: Repr -> CoreExpr -> CoreExpr -> VM [CoreExpr]
-replicateShape (ProdRepr {}) len _ = return [len]
-replicateShape (SumRepr {}) len tag
+replicateShape (ProdRepr {}) len _ = return [len]
+replicateShape (SumRepr {}) len tag = replicateSumShape len tag
+replicateShape (IdRepr _) _ _ = return []
+replicateShape (VoidRepr {}) len _ = return [len]
+replicateShape (EnumRepr {}) len tag = replicateSumShape len tag
+
+replicateSumShape :: CoreExpr -> CoreExpr -> VM [CoreExpr]
+replicateSumShape len tag
= do
rep <- builtin replicatePAIntPrimVar
up <- builtin upToPAIntPrimVar
return [len, Var rep `mkApps` [len, tag], Var up `App` len]
-replicateShape (IdRepr _) _ _ = return []
-replicateShape (VoidRepr {}) len _ = return [len]
-replicateShape (EnumRepr {}) len _ = return [len]
+
+arrSelector :: Repr -> [CoreExpr] -> VM (CoreExpr, CoreExpr, CoreExpr)
+arrSelector (SumRepr {}) [len, sel, is] = return (len, sel, is)
+arrSelector (EnumRepr {}) [len, sel, is] = return (len, sel, is)
+arrSelector _ _ = panic "arrSelector"
emptyArrRepr :: Repr -> VM [CoreExpr]
emptyArrRepr (SumRepr { sum_components = prods })
= liftM singleton $ emptyPA ty
emptyArrRepr (VoidRepr { void_tycon = tycon })
= liftM singleton $ emptyPA (mkTyConApp tycon [])
-emptyArrRepr (EnumRepr { enum_tycon = tycon })
- = liftM singleton $ emptyPA (mkTyConApp tycon [])
+emptyArrRepr (EnumRepr {})
+ = return []
arrReprTys :: Repr -> VM [Type]
arrReprTys (SumRepr { sum_components = reprs })
arrReprTys (VoidRepr { void_tycon = tycon })
= liftM singleton $ mkPArrayType (mkTyConApp tycon [])
arrReprTys (EnumRepr {})
- = liftM singleton $ mkPArrayType intPrimTy
+ = return []
arrReprTys' :: Repr -> VM [[Type]]
arrReprTys' (SumRepr { sum_components = reprs })
arrReprVars :: Repr -> VM [[Var]]
arrReprVars repr
- = mapM (mapM (newLocalVar FSLIT("rs"))) =<< arrReprTys' repr
+ = mapM (mapM (newLocalVar (fsLit "rs"))) =<< arrReprTys' repr
mkRepr :: TyCon -> VM Repr
mkRepr vect_tc
| [tys] <- rep_tys = boxedProductRepr tys
- | all null rep_tys = enumRepr
+ -- removed: | all null rep_tys = enumRepr
| otherwise = sumRepr =<< mapM unboxedProductRepr rep_tys
where
rep_tys = map dataConRepArgTys $ tyConDataCons vect_tc
buildToPRepr :: Repr -> TyCon -> TyCon -> TyCon -> VM CoreExpr
buildToPRepr repr vect_tc prepr_tc _
= do
- arg <- newLocalVar FSLIT("x") arg_ty
+ arg <- newLocalVar (fsLit "x") arg_ty
result <- to_repr repr (Var arg)
return . Lam arg
to_unboxed (ProdRepr { prod_components = tys
, prod_data_con = data_con })
= do
- vars <- mapM (newLocalVar FSLIT("r")) tys
+ vars <- mapM (newLocalVar (fsLit "r")) tys
return (vars, mkConApp data_con (map Type tys ++ map Var vars))
to_unboxed (IdRepr ty)
= do
- var <- newLocalVar FSLIT("y") ty
+ var <- newLocalVar (fsLit "y") ty
return ([var], Var var)
to_unboxed (VoidRepr { void_bottom = bottom })
= return ([], bottom)
+ to_unboxed _ = panic "buildToPRepr/to_unboxed"
+
buildFromPRepr :: Repr -> TyCon -> TyCon -> TyCon -> VM CoreExpr
buildFromPRepr repr vect_tc prepr_tc _
= do
arg_ty <- mkPReprType res_ty
- arg <- newLocalVar FSLIT("x") arg_ty
+ arg <- newLocalVar (fsLit "x") arg_ty
liftM (Lam arg)
. from_repr repr
, sum_tycon = tycon })
expr
= do
- vars <- mapM (newLocalVar FSLIT("x")) (map reprType prods)
+ vars <- mapM (newLocalVar (fsLit "x")) (map reprType prods)
bodies <- sequence . zipWith3 from_unboxed prods cons
$ map Var vars
return . Case expr (mkWildId (reprType repr)) res_ty
from_repr repr@(EnumRepr { enum_data_con = data_con }) expr
= do
- var <- newLocalVar FSLIT("n") intPrimTy
+ var <- newLocalVar (fsLit "n") intPrimTy
let res = Case (Var var) (mkWildId intPrimTy) res_ty
$ (DEFAULT, [], error_expr)
con
expr
= do
- vars <- mapM (newLocalVar FSLIT("y")) tys
+ vars <- mapM (newLocalVar (fsLit "y")) tys
return $ Case expr (mkWildId (reprType prod)) res_ty
[(DataAlt data_con, vars, con `mkVarApps` vars)]
from_unboxed (IdRepr _) con expr
= return $ con `App` expr
- from_unboxed (VoidRepr {}) con expr
+ from_unboxed (VoidRepr {}) con _
= return con
+ from_unboxed _ _ _ = panic "buildFromPRepr/from_unboxed"
+
buildToArrPRepr :: Repr -> TyCon -> TyCon -> TyCon -> VM CoreExpr
buildToArrPRepr repr vect_tc prepr_tc arr_tc
= do
arg_ty <- mkPArrayType el_ty
- arg <- newLocalVar FSLIT("xs") arg_ty
+ arg <- newLocalVar (fsLit "xs") arg_ty
res_ty <- mkPArrayType (reprType repr)
[arr_dc] = tyConDataCons arr_tc
- to_repr shape_vars@(len_var : _)
+ to_repr shape_vars@(_ : _)
repr_vars
(SumRepr { sum_components = prods
, sum_arr_tycon = tycon
. mkConApp data_con
$ map Type tys ++ map Var (len_var : repr_vars)
- to_repr [len_var]
- [[repr_var]]
+ to_repr shape_vars
+ _
(EnumRepr { enum_arr_tycon = tycon
, enum_arr_data_con = data_con })
= return . wrapFamInstBody tycon []
- $ mkConApp data_con [Var len_var, Var repr_var]
+ . mkConApp data_con
+ $ map Var shape_vars
+
+ to_repr _ _ _ = panic "buildToArrPRepr/to_repr"
to_prod repr_vars@(r : _)
(ProdRepr { prod_components = tys@(ty : _)
. mkConApp data_con
$ map Type tys ++ len : map Var repr_vars
- to_prod [var] (IdRepr ty) = return (Var var)
+ to_prod [var] (IdRepr _) = return (Var var)
to_prod [var] (VoidRepr {}) = return (Var var)
+ to_prod _ _ = panic "buildToArrPRepr/to_prod"
buildFromArrPRepr :: Repr -> TyCon -> TyCon -> TyCon -> VM CoreExpr
buildFromArrPRepr repr vect_tc prepr_tc arr_tc
= do
arg_ty <- mkPArrayType =<< mkPReprType el_ty
- arg <- newLocalVar FSLIT("xs") arg_ty
+ arg <- newLocalVar (fsLit "xs") arg_ty
res_ty <- mkPArrayType el_ty
res_ty
body
= do
- vars <- mapM (newLocalVar FSLIT("xs")) =<< mapM arrReprType prods
+ vars <- mapM (newLocalVar (fsLit "xs")) =<< mapM arrReprType prods
result <- go prods repr_vars vars body
let scrut = unwrapFamInstScrut tycon ty_args expr
go [] [] [] body = return body
go (prod : prods) (repr_vars : rss) (var : vars) body
= do
- shape_vars <- mapM (newLocalVar FSLIT("s")) =<< arrShapeTys prod
+ shape_vars <- mapM (newLocalVar (fsLit "s")) =<< arrShapeTys prod
from_prod prod (Var var) shape_vars repr_vars res_ty
=<< go prods rss vars body
+ go _ _ _ _ = panic "buildFromArrPRepr/go"
from_repr repr expr shape_vars [repr_vars] res_ty body
= from_prod repr expr shape_vars repr_vars res_ty body
- from_prod prod@(ProdRepr { prod_components = tys
- , prod_arr_tycon = tycon
- , prod_arr_data_con = data_con })
+ from_repr _ _ _ _ _ _ = panic "buildFromArrPRepr/from_repr"
+
+ from_prod (ProdRepr { prod_components = tys
+ , prod_arr_tycon = tycon
+ , prod_arr_data_con = data_con })
expr
shape_vars
repr_vars
= do
let scrut = unwrapFamInstScrut tycon tys expr
scrut_ty = mkTyConApp tycon tys
- ty <- arrReprType prod
return $ Case scrut (mkWildId scrut_ty) res_ty
[(DataAlt data_con, shape_vars ++ repr_vars, body)]
from_prod (EnumRepr { enum_arr_tycon = tycon
, enum_arr_data_con = data_con })
expr
- [len_var]
- [repr_var]
+ shape_vars
+ _
res_ty
body
= let scrut = unwrapFamInstScrut tycon [] expr
scrut_ty = mkTyConApp tycon []
in
return $ Case scrut (mkWildId scrut_ty) res_ty
- [(DataAlt data_con, [len_var, repr_var], body)]
+ [(DataAlt data_con, shape_vars, body)]
- from_prod (IdRepr ty)
+ from_prod (IdRepr _)
expr
- shape_vars
+ _shape_vars
[repr_var]
- res_ty
+ _res_ty
body
= return $ Let (NonRec repr_var expr) body
from_prod (VoidRepr {})
expr
- shape_vars
+ _shape_vars
[repr_var]
- res_ty
+ _res_ty
body
= return $ Let (NonRec repr_var expr) body
+ from_prod _ _ _ _ _ _ = panic "buildFromArrPRepr/from_prod"
+
buildPRDictRepr :: Repr -> VM CoreExpr
buildPRDictRepr (VoidRepr { void_tycon = tycon })
= prDFunOfTyCon tycon
dict <- buildPADict repr vect_tc prepr_tc arr_tc dfun
binds <- takeHoisted
return $ (dfun, dict) : binds
- where
- orig_dcs = tyConDataCons orig_tc
- vect_dcs = tyConDataCons vect_tc
- [arr_dc] = tyConDataCons arr_tc
-
- repr_tys = map dataConRepArgTys vect_dcs
vectDataConWorkers :: Repr -> TyCon -> TyCon -> TyCon
-> VM ()
lift_data_con tys pre_reprs post_reprs tag
= do
len <- builtin liftingContext
- args <- mapM (newLocalVar FSLIT("xs"))
+ args <- mapM (newLocalVar (fsLit "xs"))
=<< mapM mkPArrayType tys
shape <- replicateShape repr (Var len) tag
units <- replicatePA len (Var unitDataConId)
return [units]
- mk_arr_repr len arrs = return arrs
+ mk_arr_repr _ arrs = return arrs
def_worker data_con arg_tys mk_body
= do
orig_worker = dataConWorkId data_con
buildPADict :: Repr -> TyCon -> TyCon -> TyCon -> Var -> VM CoreExpr
-buildPADict repr vect_tc prepr_tc arr_tc dfun
+buildPADict repr vect_tc prepr_tc arr_tc _
= polyAbstract tvs $ \abstract ->
do
meth_binds <- mapM (mk_method repr) paMethods
var <- newLocalVar name (exprType body)
return (var, mkInlineMe body)
-paMethods = [(FSLIT("toPRepr"), buildToPRepr),
- (FSLIT("fromPRepr"), buildFromPRepr),
- (FSLIT("toArrPRepr"), buildToArrPRepr),
- (FSLIT("fromArrPRepr"), buildFromArrPRepr),
- (FSLIT("dictPRepr"), buildPRDict)]
+paMethods :: [(FastString, Repr -> TyCon -> TyCon -> TyCon -> VM CoreExpr)]
+paMethods = [(fsLit "toPRepr", buildToPRepr),
+ (fsLit "fromPRepr", buildFromPRepr),
+ (fsLit "toArrPRepr", buildToArrPRepr),
+ (fsLit "fromArrPRepr", buildFromArrPRepr),
+ (fsLit "dictPRepr", buildPRDict)]
-- | Split the given tycons into two sets depending on whether they have to be
-- converted (first list) or not (second list). The first argument contains
classifyTyCons :: UniqFM Bool -> [TyConGroup] -> ([TyCon], [TyCon])
classifyTyCons = classify [] []
where
- classify conv keep cs [] = (conv, keep)
+ classify conv keep _ [] = (conv, keep)
classify conv keep cs ((tcs, ds) : rs)
| can_convert && must_convert
= classify (tcs ++ conv) keep (cs `addListToUFM` [(tc,True) | tc <- tcs]) rs
-- | Compute mutually recursive groups of tycons in topological order
--
tyConGroups :: [TyCon] -> [TyConGroup]
-tyConGroups tcs = map mk_grp (stronglyConnComp edges)
+tyConGroups tcs = map mk_grp (stronglyConnCompFromEdgedVertices edges)
where
edges = [((tc, ds), tc, uniqSetToList ds) | tc <- tcs
, let ds = tyConsOfTyCon tc]
tyConsOfType :: Type -> UniqSet TyCon
tyConsOfType ty
| Just ty' <- coreView ty = tyConsOfType ty'
-tyConsOfType (TyVarTy v) = emptyUniqSet
+tyConsOfType (TyVarTy _) = emptyUniqSet
tyConsOfType (TyConApp tc tys) = extend (tyConsOfTypes tys)
where
extend | isUnLiftedTyCon tc
tyConsOfTypes :: [Type] -> UniqSet TyCon
tyConsOfTypes = unionManyUniqSets . map tyConsOfType
+
+-- ----------------------------------------------------------------------------
+-- Conversions
+
+fromVect :: Type -> CoreExpr -> VM CoreExpr
+fromVect ty expr | Just ty' <- coreView ty = fromVect ty' expr
+fromVect (FunTy arg_ty res_ty) expr
+ = do
+ arg <- newLocalVar (fsLit "x") arg_ty
+ varg <- toVect arg_ty (Var arg)
+ varg_ty <- vectType arg_ty
+ vres_ty <- vectType res_ty
+ apply <- builtin applyClosureVar
+ body <- fromVect res_ty
+ $ Var apply `mkTyApps` [varg_ty, vres_ty] `mkApps` [expr, varg]
+ return $ Lam arg body
+fromVect ty expr
+ = identityConv ty >> return expr
+
+toVect :: Type -> CoreExpr -> VM CoreExpr
+toVect ty expr = identityConv ty >> return expr
+
+identityConv :: Type -> VM ()
+identityConv ty | Just ty' <- coreView ty = identityConv ty'
+identityConv (TyConApp tycon tys)
+ = do
+ mapM_ identityConv tys
+ identityConvTyCon tycon
+identityConv _ = noV
+
+identityConvTyCon :: TyCon -> VM ()
+identityConvTyCon tc
+ | isBoxedTupleTyCon tc = return ()
+ | isUnLiftedTyCon tc = return ()
+ | otherwise = do
+ tc' <- maybeV (lookupTyCon tc)
+ if tc == tc' then return () else noV
+