%
-% (c) The AQUA Project, Glasgow University, 1996
+% (c) The AQUA Project, Glasgow University, 1996-1998
%
\section[TcTyClsDecls]{Typecheck type and class declarations}
\begin{code}
-#include "HsVersions.h"
-
module TcTyClsDecls (
- tcTyAndClassDecls1
+ tcTyAndClassDecls
) where
-import Ubiq{-uitous-}
+#include "HsVersions.h"
-import HsSyn ( TyDecl(..), ConDecl(..), BangType(..),
- ClassDecl(..), MonoType(..), PolyType(..),
- Sig(..), MonoBinds, Fake, InPat )
-import RnHsSyn ( RenamedTyDecl(..), RenamedClassDecl(..) )
+import HsSyn ( HsDecl(..), TyClDecl(..),
+ HsType(..), HsTyVar,
+ ConDecl(..), ConDetails(..), BangType(..),
+ Sig(..),
+ tyClDeclName, isClassDecl, isSynDecl
+ )
+import RnHsSyn ( RenamedHsDecl, RenamedTyClDecl, listTyCon_name, tupleTyCon_name )
+import BasicTypes ( RecFlag(..), NewOrData(..), Arity )
import TcMonad
-import Inst ( InstanceMapper(..) )
-import TcClassDcl ( tcClassDecl1 )
-import TcEnv ( tcExtendTyConEnv, tcExtendClassEnv,
- tcExtendGlobalValEnv,
- tcTyVarScope, tcGetEnv )
-import TcKind ( TcKind, newKindVars )
-import TcTyDecls ( tcTyDecl )
-
+import Inst ( InstanceMapper )
+import TcClassDcl ( kcClassDecl, tcClassDecl1 )
+import TcEnv ( ValueEnv, TcTyThing(..),
+ tcExtendTypeEnv, getAllEnvTyCons
+ )
+import TcTyDecls ( tcTyDecl, kcTyDecl )
+import TcMonoType ( kcHsTyVar )
+import TcType ( TcKind, newKindVar, newKindVars, kindToTcKind, zonkTcKindToKind )
+
+import Type ( mkArrowKind, boxedTypeKind, mkDictTy )
+ -- next two imports for usage stuff only
+import TyCon ( ArgVrcs, tyConKind, tyConArity, tyConDataCons, tyConTyVars,
+ tyConArgVrcs_maybe, getSynTyConDefn, isSynTyCon, isAlgTyCon )
+import DataCon ( dataConRawArgTys, dataConSig )
+
+import Class ( Class, classBigSig )
+import Type ( Type(..), TyNote(..), tyVarsOfTypes )
+import Var ( TyVar, tyVarKind )
+import FiniteMap
import Bag
-import Class ( Class(..), getClassSelIds )
-import Digraph ( findSCCs, SCC(..) )
-import Name ( Name, isTyConName )
-import PprStyle
-import Pretty
-import UniqSet ( UniqSet(..), emptyUniqSet,
- singletonUniqSet, unionUniqSets,
+import VarSet
+import Digraph ( stronglyConnComp, SCC(..) )
+import Name ( Name, NamedThing(..), getSrcLoc, isTvOcc, nameOccName )
+import Outputable
+import Maybes ( mapMaybe, expectJust )
+import UniqSet ( UniqSet, emptyUniqSet,
+ unitUniqSet, unionUniqSets,
unionManyUniqSets, uniqSetToList )
+import ErrUtils ( Message )
import SrcLoc ( SrcLoc )
-import TyCon ( TyCon, getTyConDataCons )
-import Unique ( Unique )
-import Util ( panic, pprTrace )
-
+import TyCon ( TyCon )
+import Unique ( Unique, Uniquable(..) )
+import UniqFM ( listToUFM, lookupUFM )
\end{code}
The main function
~~~~~~~~~~~~~~~~~
\begin{code}
-data Decl = TyD RenamedTyDecl | ClD RenamedClassDecl
-
-tcTyAndClassDecls1 :: InstanceMapper
- -> Bag RenamedTyDecl -> Bag RenamedClassDecl
- -> TcM s (TcEnv s)
+tcTyAndClassDecls :: ValueEnv -> InstanceMapper -- Knot tying stuff
+ -> [RenamedHsDecl]
+ -> TcM s TcEnv
-tcTyAndClassDecls1 inst_mapper rnty_decls rncls_decls
- = sortByDependency syn_decls cls_decls decls `thenTc` \ groups ->
- tcGroups inst_mapper groups
- where
- cls_decls = mapBag ClD rncls_decls
- ty_decls = mapBag TyD rnty_decls
- syn_decls = filterBag is_syn_decl ty_decls
- decls = ty_decls `unionBags` cls_decls
-
- is_syn_decl (TyD (TySynonym _ _ _ _)) = True
- is_syn_decl _ = False
+tcTyAndClassDecls unf_env inst_mapper decls
+ = sortByDependency decls `thenTc` \ groups ->
+ tcGroups unf_env inst_mapper groups
-tcGroups inst_mapper []
- = tcGetEnv `thenNF_Tc` \ env ->
+tcGroups unf_env inst_mapper []
+ = tcGetEnv `thenNF_Tc` \ env ->
returnTc env
-tcGroups inst_mapper (group:groups)
- = tcGroup inst_mapper group `thenTc` \ new_env ->
-
- -- Extend the environment using the new tycons and classes
- tcSetEnv new_env $
-
- -- Do the remaining groups
- tcGroups inst_mapper groups
+tcGroups unf_env inst_mapper (group:groups)
+ = tcGroup unf_env inst_mapper group `thenTc` \ env ->
+ tcSetEnv env $
+ tcGroups unf_env inst_mapper groups
\end{code}
Dealing with a group
~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-tcGroup :: InstanceMapper -> Bag Decl -> TcM s (TcEnv s)
-tcGroup inst_mapper decls
- = pprTrace "tcGroup: " (ppCat (map (fst.fmt_decl) (bagToList decls))) $
-
- -- TIE THE KNOT
- fixTc ( \ ~(tycons,classes,_) ->
-
- -- EXTEND TYPE AND CLASS ENVIRONMENTS
- -- including their data constructors and class operations
- -- NB: it's important that the tycons and classes come back in just
- -- the same order from this fix as from get_binders, so that these
- -- extend-env things work properly. A bit UGH-ish.
- tcExtendTyConEnv tycon_names_w_arities tycons $
- tcExtendClassEnv class_names classes $
- tcExtendGlobalValEnv (concat (map getTyConDataCons tycons)) $
- tcExtendGlobalValEnv (concat (map getClassSelIds classes)) $
-
- -- SNAFFLE ENV TO RETURN
- tcGetEnv `thenNF_Tc` \ final_env ->
-
- -- DEAL WITH TYPE VARIABLES
- tcTyVarScope tyvar_names ( \ tyvars ->
-
- -- DEAL WITH THE DEFINITIONS THEMSELVES
- foldBag combine (tcDecl inst_mapper)
- (returnTc (emptyBag, emptyBag))
- decls
- ) `thenTc` \ (tycons,classes) ->
-
- returnTc (bagToList tycons, bagToList classes, final_env)
- ) `thenTc` \ (_, _, final_env) ->
- returnTc final_env
+The knot-tying parameters: @rec_tyclss@ is an alist mapping @Name@s to
+@TcTyThing@s. @rec_vrcs@ is a finite map from @Name@s to @ArgVrcs@s.
+
+\begin{code}
+tcGroup :: ValueEnv -> InstanceMapper -> SCC RenamedTyClDecl -> TcM s TcEnv
+tcGroup unf_env inst_mapper scc
+ = -- Do kind checking
+ mapNF_Tc getTyBinding1 decls `thenNF_Tc` \ ty_env_stuff1 ->
+ tcExtendTypeEnv ty_env_stuff1 (mapTc kcDecl decls) `thenTc_`
+
+ -- Tie the knot
+-- traceTc (ppr (map fst ty_env_stuff1)) `thenTc_`
+ fixTc ( \ ~(rec_tyclss, rec_vrcs, _) ->
+ let
+ rec_env = listToUFM rec_tyclss
+ in
+
+ -- Do type checking
+ mapNF_Tc (getTyBinding2 rec_env) ty_env_stuff1 `thenNF_Tc` \ ty_env_stuff2 ->
+ tcExtendTypeEnv ty_env_stuff2 $
+ mapTc (tcDecl is_rec_group unf_env inst_mapper rec_vrcs) decls
+ `thenTc` \ tyclss ->
+
+ tcGetEnv `thenTc` \ env ->
+ let
+ tycons = getAllEnvTyCons env
+ vrcs = calcTyConArgVrcs tycons
+ in
+
+ returnTc (tyclss, vrcs, env)
+ ) `thenTc` \ (_, _, env) ->
+-- traceTc (text "done" <+> ppr (map fst ty_env_stuff1)) `thenTc_`
+ returnTc env
where
- (tyvar_names, tycon_names_w_arities, class_names) = get_binders decls
+ is_rec_group = case scc of
+ AcyclicSCC _ -> NonRecursive
+ CyclicSCC _ -> Recursive
- combine do_a do_b
- = do_a `thenTc` \ (a1,a2) ->
- do_b `thenTc` \ (b1,b2) ->
- returnTc (a1 `unionBags` b1, a2 `unionBags` b2)
+ decls = case scc of
+ AcyclicSCC decl -> [decl]
+ CyclicSCC decls -> decls
\end{code}
Dealing with one decl
~~~~~~~~~~~~~~~~~~~~~
\begin{code}
-tcDecl :: InstanceMapper
- -> Decl
- -> TcM s (Bag TyCon, Bag Class)
+kcDecl decl
+ = tcAddDeclCtxt decl $
+ if isClassDecl decl then
+ kcClassDecl decl
+ else
+ kcTyDecl decl
+
+tcDecl :: RecFlag -- True => recursive group
+ -> ValueEnv -> InstanceMapper -> FiniteMap Name ArgVrcs
+ -> RenamedTyClDecl -> TcM s (Name, TcTyThing)
+
+tcDecl is_rec_group unf_env inst_mapper vrcs_env decl
+ = tcAddDeclCtxt decl $
+-- traceTc (text "Starting" <+> ppr name) `thenTc_`
+ if isClassDecl decl then
+ tcClassDecl1 unf_env inst_mapper vrcs_env decl `thenTc` \ clas ->
+-- traceTc (text "Finished" <+> ppr name) `thenTc_`
+ returnTc (getName clas, AClass clas)
+ else
+ tcTyDecl is_rec_group vrcs_env decl `thenTc` \ tycon ->
+-- traceTc (text "Finished" <+> ppr name) `thenTc_`
+ returnTc (getName tycon, ATyCon tycon)
+
+ where
+ name = tyClDeclName decl
+
+
+tcAddDeclCtxt decl thing_inside
+ = tcAddSrcLoc loc $
+ tcAddErrCtxt ctxt $
+ thing_inside
+ where
+ (name, loc, thing)
+ = case decl of
+ (ClassDecl _ name _ _ _ _ _ _ _ loc) -> (name, loc, "class")
+ (TySynonym name _ _ loc) -> (name, loc, "type synonym")
+ (TyData NewType _ name _ _ _ _ loc) -> (name, loc, "data type")
+ (TyData DataType _ name _ _ _ _ loc) -> (name, loc, "newtype")
+
+ ctxt = hsep [ptext SLIT("In the"), text thing,
+ ptext SLIT("declaration for"), quotes (ppr name)]
+\end{code}
+
+
+getTyBinders
+~~~~~~~~~~~
+Extract *binding* names from type and class decls. Type variables are
+bound in type, data, newtype and class declarations,
+ *and* the polytypes in the class op sigs.
+ *and* the existentially quantified contexts in datacon decls
+
+Why do we need to grab all these type variables at once, including
+those locally-quantified type variables in class op signatures?
+
+ [Incidentally, this only works because the names are all unique by now.]
+
+Because we can only commit to the final kind of a type variable when
+we've completed the mutually recursive group. For example:
+
+class C a where
+ op :: D b => a -> b -> b
+
+class D c where
+ bop :: (Monad c) => ...
-tcDecl inst_mapper (TyD decl)
- = tcTyDecl decl `thenTc` \ tycon ->
- returnTc (unitBag tycon, emptyBag)
+Here, the kind of the locally-polymorphic type variable "b"
+depends on *all the uses of class D*. For example, the use of
+Monad c in bop's type signature means that D must have kind Type->Type.
-tcDecl inst_mapper (ClD decl)
- = tcClassDecl1 inst_mapper decl `thenTc` \ clas ->
- returnTc (emptyBag, unitBag clas)
+
+\begin{code}
+getTyBinding1 :: RenamedTyClDecl -> NF_TcM s (Name, (TcKind, Maybe Arity, TcTyThing))
+getTyBinding1 (TySynonym name tyvars _ _)
+ = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
+ newKindVar `thenNF_Tc` \ result_kind ->
+ returnNF_Tc (name, (foldr mkArrowKind result_kind arg_kinds,
+ Just (length tyvars),
+ ATyCon (pprPanic "ATyCon: syn" (ppr name))))
+
+getTyBinding1 (TyData _ _ name tyvars _ _ _ _)
+ = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
+ returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds,
+ Nothing,
+ ATyCon (error "ATyCon: data")))
+
+getTyBinding1 (ClassDecl _ name tyvars _ _ _ _ _ _ _)
+ = mapNF_Tc kcHsTyVar tyvars `thenNF_Tc` \ arg_kinds ->
+ returnNF_Tc (name, (foldr mkArrowKind boxedTypeKind arg_kinds,
+ Just (length tyvars),
+ AClass (error "AClass")))
+
+-- Zonk the kind to its final form, and lookup the
+-- recursive tycon/class
+getTyBinding2 rec_env (name, (tc_kind, maybe_arity, thing))
+ = zonkTcKindToKind tc_kind `thenNF_Tc` \ kind ->
+ returnNF_Tc (name, (kind, maybe_arity, mk_thing thing (lookupUFM rec_env name)))
+ where
+ mk_thing (ATyCon _) ~(Just (ATyCon tc)) = ATyCon tc
+ mk_thing (AClass _) ~(Just (AClass cls)) = AClass cls
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Dependency analysis}
+%* *
+%************************************************************************
+
Dependency analysis
~~~~~~~~~~~~~~~~~~~
\begin{code}
-sortByDependency :: Bag Decl -> Bag Decl -> Bag Decl -> TcM s [Bag Decl]
-sortByDependency syn_decls cls_decls decls
- = let -- CHECK FOR SYNONYM CYCLES
- syn_sccs = findSCCs mk_edges syn_decls
- syn_cycles = [map fmt_decl (bagToList decls)
- | CyclicSCC decls <- syn_sccs]
-
+sortByDependency :: [RenamedHsDecl] -> TcM s [SCC RenamedTyClDecl]
+sortByDependency decls
+ = let -- CHECK FOR CLASS CYCLES
+ cls_sccs = stronglyConnComp (mapMaybe mk_cls_edges tycl_decls)
+ cls_cycles = [ decls | CyclicSCC decls <- cls_sccs]
in
- checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
+ checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_`
- let -- CHECK FOR CLASS CYCLES
- cls_sccs = findSCCs mk_edges cls_decls
- cls_cycles = [map fmt_decl (bagToList decls)
- | CyclicSCC decls <- cls_sccs]
+ let -- CHECK FOR SYNONYM CYCLES
+ syn_sccs = stronglyConnComp (filter is_syn_decl edges)
+ syn_cycles = [ decls | CyclicSCC decls <- syn_sccs]
in
- checkTc (null cls_cycles) (classCycleErr cls_cycles) `thenTc_`
+ checkTc (null syn_cycles) (typeCycleErr syn_cycles) `thenTc_`
- -- DO THE MAIN DEPENDENCY ANALYSIS
+ -- DO THE MAIN DEPENDENCY ANALYSIS
let
- decl_sccs = findSCCs mk_edges decls
- scc_bags = map bag_acyclic decl_sccs
+ decl_sccs = stronglyConnComp edges
in
- returnTc (scc_bags)
-
+ returnTc decl_sccs
where
- bag_acyclic (AcyclicSCC scc) = unitBag scc
- bag_acyclic (CyclicSCC sccs) = sccs
-
-fmt_decl (TyD (TySynonym name _ _ _)) = (ppr PprForUser name, getSrcLoc name)
-fmt_decl (ClD (ClassDecl _ name _ _ _ _ _)) = (ppr PprForUser name, getSrcLoc name)
+ tycl_decls = [d | TyClD d <- decls]
+ edges = map mk_edges tycl_decls
+
+ is_syn_decl (d, _, _) = isSynDecl d
+ is_cls_decl (d, _, _) = isClassDecl d
\end{code}
Edges in Type/Class decls
~~~~~~~~~~~~~~~~~~~~~~~~~
+
\begin{code}
-mk_edges (TyD (TyData ctxt name _ condecls _ _ _))
- = (getItsUnique name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecls))
-mk_edges (TyD (TyNew ctxt name _ condecl _ _ _))
- = (getItsUnique name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_cons condecl))
-mk_edges (TyD (TySynonym name _ rhs _))
- = (getItsUnique name, set_to_bag (get_ty rhs))
-mk_edges (ClD (ClassDecl ctxt name _ sigs _ _ _))
- = (getItsUnique name, set_to_bag (get_ctxt ctxt `unionUniqSets` get_sigs sigs))
-
-get_ctxt ctxt
- = unionManyUniqSets (map (set_name.fst) ctxt)
-
-get_cons cons
- = unionManyUniqSets (map get_con cons)
- where
- get_con (ConDecl _ btys _)
- = unionManyUniqSets (map get_bty btys)
- get_con (ConOpDecl bty1 _ bty2 _)
- = unionUniqSets (get_bty bty1) (get_bty bty2)
- get_con (NewConDecl _ ty _)
- = get_ty ty
- get_con (RecConDecl _ nbtys _)
- = unionManyUniqSets (map (get_bty.snd) nbtys)
-
- get_bty (Banged ty) = get_ty ty
- get_bty (Unbanged ty) = get_ty ty
-
-get_ty (MonoTyVar tv)
- = emptyUniqSet
-get_ty (MonoTyApp name tys)
- = (if isTyConName name then set_name name else emptyUniqSet)
- `unionUniqSets` get_tys tys
+----------------------------------------------------
+-- mk_cls_edges looks only at the context of class decls
+-- Its used when we are figuring out if there's a cycle in the
+-- superclass hierarchy
+
+mk_cls_edges :: RenamedTyClDecl -> Maybe (RenamedTyClDecl, Unique, [Unique])
+
+mk_cls_edges decl@(ClassDecl ctxt name _ _ _ _ _ _ _ _)
+ = Just (decl, getUnique name, map (getUnique . fst) ctxt)
+mk_cls_edges other_decl
+ = Nothing
+
+----------------------------------------------------
+mk_edges :: RenamedTyClDecl -> (RenamedTyClDecl, Unique, [Unique])
+
+mk_edges decl@(TyData _ ctxt name _ condecls derivs _ _)
+ = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
+ get_cons condecls `unionUniqSets`
+ get_deriv derivs))
+
+mk_edges decl@(TySynonym name _ rhs _)
+ = (decl, getUnique name, uniqSetToList (get_ty rhs))
+
+mk_edges decl@(ClassDecl ctxt name _ sigs _ _ _ _ _ _)
+ = (decl, getUnique name, uniqSetToList (get_ctxt ctxt `unionUniqSets`
+ get_sigs sigs))
+
+
+----------------------------------------------------
+get_ctxt ctxt = unionManyUniqSets (map (set_name.fst) ctxt)
+
+----------------------------------------------------
+get_deriv Nothing = emptyUniqSet
+get_deriv (Just clss) = unionManyUniqSets (map set_name clss)
+
+----------------------------------------------------
+get_cons cons = unionManyUniqSets (map get_con cons)
+
+----------------------------------------------------
+get_con (ConDecl _ _ ctxt details _)
+ = get_ctxt ctxt `unionUniqSets` get_con_details details
+
+----------------------------------------------------
+get_con_details (VanillaCon btys) = unionManyUniqSets (map get_bty btys)
+get_con_details (InfixCon bty1 bty2) = unionUniqSets (get_bty bty1) (get_bty bty2)
+get_con_details (NewCon ty _) = get_ty ty
+get_con_details (RecCon nbtys) = unionManyUniqSets (map (get_bty.snd) nbtys)
+
+----------------------------------------------------
+get_bty (Banged ty) = get_ty ty
+get_bty (Unbanged ty) = get_ty ty
+get_bty (Unpacked ty) = get_ty ty
+
+----------------------------------------------------
+get_ty (MonoTyVar name)
+ = if isTvOcc (nameOccName name) then emptyUniqSet else set_name name
+get_ty (MonoTyApp ty1 ty2)
+ = unionUniqSets (get_ty ty1) (get_ty ty2)
get_ty (MonoFunTy ty1 ty2)
= unionUniqSets (get_ty ty1) (get_ty ty2)
get_ty (MonoListTy ty)
- = get_ty ty -- careful when defining [] (,,) etc as
-get_ty (MonoTupleTy tys) -- [ty] (ty,ty,ty) will not give edges!
- = get_tys tys
-get_ty other = panic "TcTyClsDecls:get_ty"
-
-get_pty (HsForAllTy _ ctxt mty)
+ = set_name listTyCon_name `unionUniqSets` get_ty ty
+get_ty (MonoTupleTy tys boxed)
+ = set_name (tupleTyCon_name boxed (length tys)) `unionUniqSets` get_tys tys
+get_ty (MonoUsgTy _ ty)
+ = get_ty ty
+get_ty (HsForAllTy _ ctxt mty)
= get_ctxt ctxt `unionUniqSets` get_ty mty
-get_pty other = panic "TcTyClsDecls:get_pty"
+get_ty (MonoDictTy name _)
+ = set_name name
+----------------------------------------------------
get_tys tys
= unionManyUniqSets (map get_ty tys)
+----------------------------------------------------
get_sigs sigs
= unionManyUniqSets (map get_sig sigs)
where
- get_sig (ClassOpSig _ ty _ _) = get_pty ty
+ get_sig (ClassOpSig _ _ ty _) = get_ty ty
+ get_sig (FixSig _) = emptyUniqSet
get_sig other = panic "TcTyClsDecls:get_sig"
-set_name name = singletonUniqSet (getItsUnique name)
-
+----------------------------------------------------
+set_name name = unitUniqSet (getUnique name)
set_to_bag set = listToBag (uniqSetToList set)
\end{code}
-get_binders
-~~~~~~~~~~~
-Extract *binding* names from type and class decls. Type variables are
-bound in type, data, newtype and class declarations and the polytypes
-in the class op sigs.
+\begin{code}
+typeCycleErr, classCycleErr :: [[RenamedTyClDecl]] -> Message
-Why do we need to grab all these type variables at once, including
-those locally-quantified type variables in class op signatures?
-Because we can only commit to the final kind of a type variable when
-we've completed the mutually recursive group. For example:
+typeCycleErr syn_cycles
+ = vcat (map (pp_cycle "Cycle in type declarations:") syn_cycles)
-class C a where
- op :: D b => a -> b -> b
+classCycleErr cls_cycles
+ = vcat (map (pp_cycle "Cycle in class declarations:") cls_cycles)
-class D c where
- bop :: (Monad c) => ...
+pp_cycle str decls
+ = hang (text str)
+ 4 (vcat (map pp_decl decls))
+ where
+ pp_decl decl
+ = hsep [quotes (ppr name), ptext SLIT("at"), ppr (getSrcLoc name)]
+ where
+ name = tyClDeclName decl
+\end{code}
-Here, the kind of the locally-polymorphic type variable "b"
-depends on *all the uses of class D*. For example, the use of
-Monad c in bop's type signature means that D must have kind Type->Type.
+Computing the tyConArgVrcs info
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-get_binders :: Bag Decl
- -> ([Name], -- TyVars; no dups
- [(Name, Maybe Arity)], -- Tycons; no dups; arities for synonyms
- [Name]) -- Classes; no dups
+@tyConArgVrcs@ gives a list of (occPos,occNeg) flags, one for each
+tyvar. For @AlgTyCon@s and @SynTyCon@s, this info must be precomputed
+separately. Note that this is information about occurrences of type
+variables, not usages of term variables.
+
+The function @calcTyConArgVrcs@ must be passed a list of *algebraic or
+syntycons only* such that all tycons referred to (by mutual recursion)
+appear in the list. The fixpointing will be done on this set of
+tycons as a whole. It returns a list of @tyconVrcInfo@ data, ready to
+be (knot-tyingly?) stuck back into the appropriate fields.
-get_binders decls = (bagToList tyvars, bagToList tycons, bagToList classes)
+\begin{code}
+calcTyConArgVrcs :: [TyCon]
+ -> FiniteMap Name ArgVrcs
+
+calcTyConArgVrcs tycons
+ = let oi = foldl (\fm tc -> addToFM fm tc (initial tc)) emptyFM tycons
+ initial tc = if isAlgTyCon tc && null (tyConDataCons tc) then
+ -- make pessimistic assumption (and warn)
+ take (tyConArity tc) abstractVrcs
+ else
+ replicate (tyConArity tc) (False,False)
+ oi'' = tcaoFix oi
+ go (tc,vrcs) = (getName tc,vrcs)
+ in listToFM (map go (fmToList oi''))
+
where
- (tyvars, tycons, classes) = foldBag union3 get_binders1
- (emptyBag,emptyBag,emptyBag)
- decls
-
- union3 (a1,a2,a3) (b1,b2,b3)
- = (a1 `unionBags` b1, a2 `unionBags` b2, a3 `unionBags` b3)
-
-get_binders1 (TyD (TyData _ name tyvars _ _ _ _))
- = (listToBag tyvars, unitBag (name,Nothing), emptyBag)
-get_binders1 (TyD (TyNew _ name tyvars _ _ _ _))
- = (listToBag tyvars, unitBag (name,Nothing), emptyBag)
-get_binders1 (TyD (TySynonym name tyvars _ _))
- = (listToBag tyvars, unitBag (name, Just (length tyvars)), emptyBag)
-get_binders1 (ClD (ClassDecl _ name tyvar sigs _ _ _))
- = (unitBag tyvar `unionBags` sigs_tvs sigs,
- emptyBag, unitBag name)
-
-sigs_tvs sigs = unionManyBags (map sig_tvs sigs)
- where
- sig_tvs (ClassOpSig _ ty _ _) = pty_tvs ty
- pty_tvs (HsForAllTy tvs _ _) = listToBag tvs -- tvs doesn't include the class tyvar
+
+ tcaoFix :: FiniteMap TyCon ArgVrcs -- initial ArgVrcs per tycon
+ -> FiniteMap TyCon ArgVrcs -- fixpointed ArgVrcs per tycon
+
+ tcaoFix oi = let (changed,oi') = foldFM (\ tc pms
+ (changed,oi')
+ -> let pms' = tcaoIter oi' tc -- seq not simult
+ in (changed || (pms /= pms'),
+ addToFM oi' tc pms'))
+ (False,oi) -- seq not simult for faster fixpting
+ oi
+ in if changed
+ then tcaoFix oi'
+ else oi'
+
+ tcaoIter :: FiniteMap TyCon ArgVrcs -- reference ArgVrcs (initial)
+ -> TyCon -- tycon to update
+ -> ArgVrcs -- new ArgVrcs for tycon
+
+ tcaoIter oi tc | isAlgTyCon tc
+ = let cs = tyConDataCons tc
+ vs = tyConTyVars tc
+ argtys = concatMap dataConRawArgTys cs
+ exdicttys = concatMap ((\ (_,_,_,exth,_,_) -> map (uncurry mkDictTy) exth)
+ . dataConSig) cs
+ myfao tc = lookupWithDefaultFM oi (expectJust "tcaoIter(Alg)" $
+ tyConArgVrcs_maybe tc)
+ tc
+ -- we use the already-computed result for tycons not in this SCC
+ in map (\v -> anyVrc (\ty -> vrcInTy myfao v ty) (exdicttys ++ argtys))
+ vs
+
+ tcaoIter oi tc | isSynTyCon tc
+ = let (tyvs,ty) = getSynTyConDefn tc
+ myfao tc = lookupWithDefaultFM oi (expectJust "tcaoIter(Syn)" $
+ tyConArgVrcs_maybe tc)
+ tc
+ -- we use the already-computed result for tycons not in this SCC
+ in map (\v -> vrcInTy myfao v ty) tyvs
+
+
+abstractVrcs :: ArgVrcs
+-- we pull this out as a CAF so the warning only appears *once*
+abstractVrcs = trace ("WARNING: tyConArgVrc info inaccurate due to unavailable constructors.\n"
+ ++ "\tUse -fno-prune-tydecls to fix.") $
+ repeat (True,True)
\end{code}
+And a general variance-check function. We pass a function for
+determining the @ArgVrc@s of a tycon; when fixpointing this refers to
+the current value; otherwise this should be looked up from the tycon's
+own tyConArgVrcs.
\begin{code}
-typeCycleErr syn_cycles sty
- = ppAboves (map (pp_cycle sty "Cycle in type declarations ...") syn_cycles)
+vrcInTy :: (TyCon -> ArgVrcs) -- function to get argVrcs of a tycon (break out of recursion)
+ -> TyVar -- tyvar to check Vrcs of
+ -> Type -- type to check for occ in
+ -> (Bool,Bool) -- (occurs positively, occurs negatively)
+
+vrcInTy fao v (NoteTy (UsgNote _) ty) = vrcInTy fao v ty
+
+vrcInTy fao v (NoteTy (SynNote _) ty) = vrcInTy fao v ty
+ -- SynTyCon doesn't neccessarily have vrcInfo at this point,
+ -- so don't try and use it
+
+vrcInTy fao v (NoteTy (FTVNote ftv) ty) = if elemVarSet v ftv
+ then vrcInTy fao v ty
+ else (False,False)
+ -- note that ftv cannot be calculated as occPos||occNeg,
+ -- since if a tyvar occurs only as unused tyconarg,
+ -- occPos==occNeg==False, but ftv=True
+
+vrcInTy fao v (TyVarTy v') = if v==v'
+ then (True,False)
+ else (False,False)
+
+vrcInTy fao v (AppTy ty1 ty2) = if vrcInTy fao v ty2 /= (False,False)
+ then (True,True)
+ else vrcInTy fao v ty1
+ -- ty1 is probably unknown (or it would have been beta-reduced);
+ -- hence if v occurs in ty2 at all then it could occur with
+ -- either variance. Otherwise it occurs as it does in ty1.
+
+vrcInTy fao v (FunTy ty1 ty2) = let (p1,m1) = vrcInTy fao v ty1
+ (p2,m2) = vrcInTy fao v ty2
+ in (m1||p2,p1||m2)
+
+vrcInTy fao v (ForAllTy v' ty) = if v==v'
+ then (False,False)
+ else vrcInTy fao v ty
+
+vrcInTy fao v (TyConApp tc tys) = let pms1 = map (vrcInTy fao v) tys
+ pms2 = fao tc
+ in orVrcs (zipWith timesVrc pms1 pms2)
+
+orVrc :: (Bool,Bool) -> (Bool,Bool) -> (Bool,Bool)
+orVrc (p1,m1) (p2,m2) = (p1||p2,m1||m2)
+
+orVrcs :: [(Bool,Bool)] -> (Bool,Bool)
+orVrcs = foldl orVrc (False,False)
+
+anyVrc :: (a -> (Bool,Bool)) -> [a] -> (Bool,Bool)
+anyVrc p as = foldl (\pm a -> pm `orVrc` p a) (False,False) as
+
+timesVrc :: (Bool,Bool) -> (Bool,Bool) -> (Bool,Bool)
+timesVrc (p1,m1) (p2,m2) = (p1 && p2 || m1 && m2,
+ p1 && m2 || m1 && p2)
+\end{code}
-classCycleErr cls_cycles sty
- = ppAboves (map (pp_cycle sty "Cycle in class declarations ...") cls_cycles)
-pp_cycle sty str things
- = ppHang (ppStr str)
- 4 (ppAboves (map pp_thing things))
- where
- pp_thing (pp_name, loc)
- = ppCat [pp_name, ppr sty loc]
-\end{code}