\section[TcClassDcl]{Typechecking class declarations}
\begin{code}
-module TcClassDcl ( tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where
+module TcClassDcl ( kcClassDecl, tcClassDecl1, tcClassDecls2, tcMethodBind, badMethodErr ) where
#include "HsVersions.h"
-import HsSyn ( HsDecl(..), ClassDecl(..), Sig(..), MonoBinds(..),
- InPat(..), HsBinds(..), GRHSsAndBinds(..),
+import HsSyn ( HsDecl(..), TyClDecl(..), Sig(..), MonoBinds(..),
+ InPat(..), HsBinds(..), GRHSs(..),
HsExpr(..), HsLit(..), HsType(..), pprClassAssertion,
- unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName
+ unguardedRHS, andMonoBinds, andMonoBindList, getTyVarName,
+ isClassDecl
)
import HsPragmas ( ClassPragmas(..) )
import BasicTypes ( NewOrData(..), TopLevelFlag(..), RecFlag(..), StrictnessMark(..) )
-import RnHsSyn ( RenamedClassDecl, RenamedClassPragmas,
+import RnHsSyn ( RenamedTyClDecl, RenamedClassPragmas,
RenamedClassOpSig, RenamedMonoBinds,
RenamedContext, RenamedHsDecl, RenamedSig
)
import TcHsSyn ( TcMonoBinds )
import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, newDicts, newMethod )
-import TcEnv ( TcIdOcc(..), GlobalValueEnv, tcAddImportedIdInfo,
- tcLookupClass, tcLookupTyVar,
- tcExtendGlobalTyVars, tcExtendLocalValEnv
+import TcEnv ( TcId, ValueEnv, TcTyThing(..), tcAddImportedIdInfo,
+ tcLookupClass, tcLookupTy, tcExtendTyVarEnvForMeths, tcExtendGlobalTyVars,
+ tcExtendLocalValEnv
)
import TcBinds ( tcBindWithSigs, tcPragmaSigs )
import TcUnify ( unifyKinds )
import TcMonad
-import TcMonoType ( tcHsType, tcContext, checkSigTyVars, sigCtxt, mkTcSig )
+import TcMonoType ( tcHsType, tcHsTopType, tcExtendTopTyVarScope,
+ tcContext, checkSigTyVars, sigCtxt, mkTcSig
+ )
import TcSimplify ( tcSimplifyAndCheck, bindInstsOfLocalFuns )
-import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr )
+import TcType ( TcType, TcTyVar, tcInstTyVars, zonkTcTyVarBndr, tcGetTyVar )
import PrelVals ( nO_METHOD_BINDING_ERROR_ID )
import FieldLabel ( firstFieldLabelTag )
import Bag ( unionManyBags )
Death to "ExpandingDicts".
+%************************************************************************
+%* *
+\subsection{Kind checking}
+%* *
+%************************************************************************
+
\begin{code}
-tcClassDecl1 rec_env rec_inst_mapper
- (ClassDecl context class_name
+kcClassDecl (ClassDecl context class_name
tyvar_names class_sigs def_methods pragmas
tycon_name datacon_name src_loc)
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (classDeclCtxt class_name) $
-
- -- CHECK ARITY 1 FOR HASKELL 1.4
+ = -- CHECK ARITY 1 FOR HASKELL 1.4
checkTc (opt_GlasgowExts || length tyvar_names == 1)
(classArityErr class_name) `thenTc_`
- -- LOOK THINGS UP IN THE ENVIRONMENT
- tcLookupClass class_name `thenTc` \ (class_kinds, rec_class) ->
- mapAndUnzipNF_Tc (tcLookupTyVar . getTyVarName) tyvar_names
- `thenNF_Tc` \ (tyvar_kinds, rec_tyvars) ->
+ -- Get the (mutable) class kind
+ tcLookupTy class_name `thenNF_Tc` \ (kind, _, _) ->
+
+ -- Make suitable tyvars and do kind checking
+ -- The net effect is to mutate the class kind
+ tcExtendTopTyVarScope kind tyvar_names $ \ _ _ ->
+ tcContext context `thenTc_`
+ mapTc kc_sig class_sigs `thenTc_`
+
+ returnTc ()
+ where
+ kc_sig (ClassOpSig _ _ op_ty loc) = tcAddSrcLoc loc (tcHsType op_ty)
+\end{code}
- -- FORCE THE CLASS AND ITS TYVAR TO HAVE SAME KIND
- unifyKinds class_kinds tyvar_kinds `thenTc_`
+%************************************************************************
+%* *
+\subsection{Type checking}
+%* *
+%************************************************************************
+
+\begin{code}
+tcClassDecl1 rec_env rec_inst_mapper
+ (ClassDecl context class_name
+ tyvar_names class_sigs def_methods pragmas
+ tycon_name datacon_name src_loc)
+ = -- LOOK THINGS UP IN THE ENVIRONMENT
+ tcLookupTy class_name `thenTc` \ (class_kind, _, AClass rec_class) ->
+ tcExtendTopTyVarScope class_kind tyvar_names $ \ tyvars _ ->
+ -- The class kind is by now immutable
+
-- CHECK THE CONTEXT
- tcClassContext class_name rec_class rec_tyvars context pragmas
+-- traceTc (text "tcClassCtxt" <+> ppr class_name) `thenTc_`
+ tcClassContext class_name rec_class tyvars context pragmas
`thenTc` \ (sc_theta, sc_tys, sc_sel_ids) ->
+-- traceTc (text "tcClassCtxt done" <+> ppr class_name) `thenTc_`
-- CHECK THE CLASS SIGNATURES,
- mapTc (tcClassSig rec_env rec_class rec_tyvars) class_sigs
+ mapTc (tcClassSig rec_env rec_class tyvars) class_sigs
`thenTc` \ sig_stuff ->
-- MAKE THE CLASS OBJECT ITSELF
let
(op_tys, op_sel_ids, defm_ids) = unzip3 sig_stuff
rec_class_inst_env = rec_inst_mapper rec_class
- clas = mkClass (getName class_name) rec_tyvars
+ clas = mkClass class_name tyvars
sc_theta sc_sel_ids op_sel_ids defm_ids
tycon
rec_class_inst_env
dict_con = mkDataCon datacon_name
[NotMarkedStrict | _ <- dict_component_tys]
[{- No labelled fields -}]
- rec_tyvars
+ tyvars
[{-No context-}]
[{-No existential tyvars-}] [{-Or context-}]
dict_component_tys
dict_con_id = mkDataConId dict_con
tycon = mkAlgTyCon tycon_name
- (foldr (mkArrowKind . tyVarKind) boxedTypeKind rec_tyvars)
- rec_tyvars
+ class_kind
+ tyvars
[] -- No context
[dict_con] -- Constructors
[] -- No derivings
is_tyvar other = False
-tcClassSig :: GlobalValueEnv -- Knot tying only!
+tcClassSig :: ValueEnv -- Knot tying only!
-> Class -- ...ditto...
-> [TyVar] -- The class type variable, used for error check only
-> RenamedClassOpSig
-- NB: Renamer checks that the class type variable is mentioned in local_ty,
-- and that it is not constrained by theta
- tcHsType op_ty `thenTc` \ local_ty ->
+-- traceTc (text "tcClassSig" <+> ppr op_name) `thenTc_`
+ tcHsTopType op_ty `thenTc` \ local_ty ->
let
global_ty = mkSigmaTy rec_clas_tyvars
[(rec_clas, mkTyVarTys rec_clas_tyvars)]
local_ty
- in
-- Build the selector id and default method id
- let
sel_id = mkMethodSelId op_name rec_clas global_ty
maybe_dm_id = case maybe_dm_name of
Nothing -> Nothing
in
Just (tcAddImportedIdInfo rec_env dm_id)
in
+-- traceTc (text "tcClassSig done" <+> ppr op_name) `thenTc_`
returnTc (local_ty, sel_id, maybe_dm_id)
\end{code}
\begin{code}
tcClassDecls2 :: [RenamedHsDecl]
- -> NF_TcM s (LIE s, TcMonoBinds s)
+ -> NF_TcM s (LIE, TcMonoBinds)
tcClassDecls2 decls
= foldr combine
(returnNF_Tc (emptyLIE, EmptyMonoBinds))
- [tcClassDecl2 cls_decl | ClD cls_decl <- decls]
+ [tcClassDecl2 cls_decl | TyClD cls_decl <- decls, isClassDecl cls_decl]
where
combine tc1 tc2 = tc1 `thenNF_Tc` \ (lie1, binds1) ->
tc2 `thenNF_Tc` \ (lie2, binds2) ->
@tcClassDecl2@ is the business end of things.
\begin{code}
-tcClassDecl2 :: RenamedClassDecl -- The class declaration
- -> NF_TcM s (LIE s, TcMonoBinds s)
+tcClassDecl2 :: RenamedTyClDecl -- The class declaration
+ -> NF_TcM s (LIE, TcMonoBinds)
tcClassDecl2 (ClassDecl context class_name
tyvar_names class_sigs default_binds pragmas _ _ src_loc)
tcAddSrcLoc src_loc $
-- Get the relevant class
- tcLookupClass class_name `thenTc` \ (_, clas) ->
+ tcLookupClass class_name `thenNF_Tc` \ clas ->
let
(tyvars, sc_theta, sc_sel_ids, op_sel_ids, defm_ids) = classBigSig clas
-- The selector binds are already in the selector Id's unfoldings
--- sel_binds = [ CoreMonoBind (RealId sel_id) (getUnfoldingTemplate (getIdUnfolding sel_id))
+-- sel_binds = [ CoreMonoBind sel_id (getUnfoldingTemplate (getIdUnfolding sel_id))
-- | sel_id <- sc_sel_ids ++ op_sel_ids,
-- isLocallyDefined sel_id
-- ]
tcDefaultMethodBinds
:: Class
-> RenamedMonoBinds
- -> TcM s (LIE s, TcMonoBinds s)
+ -> TcM s (LIE, TcMonoBinds)
tcDefaultMethodBinds clas default_binds
= -- Construct suitable signatures
-- Typecheck the default bindings
let
+ theta = [(clas,inst_tys)]
tc_dm sel_id_w_dm@(_, Just dm_id)
- = tcMethodBind clas origin inst_tys clas_tyvars
+ = tcMethodBind clas origin clas_tyvars inst_tys theta
default_binds [{-no prags-}] False
sel_id_w_dm `thenTc` \ (bind, insts, (_, local_dm_id)) ->
- returnTc (bind, insts, (clas_tyvars, RealId dm_id, local_dm_id))
- in
- mapAndUnzip3Tc tc_dm sel_ids_w_dms `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) ->
+ returnTc (bind, insts, (clas_tyvars, dm_id, local_dm_id))
+ in
+ tcExtendTyVarEnvForMeths tyvars clas_tyvars (
+ mapAndUnzip3Tc tc_dm sel_ids_w_dms
+ ) `thenTc` \ (defm_binds, insts_needed, abs_bind_stuff) ->
+
-- Check the context
- newDicts origin [(clas,inst_tys)] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newDicts origin theta `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
let
avail_insts = this_dict
in
- tcAddErrCtxt (classDeclCtxt clas) $
+ tcAddErrCtxt (defltMethCtxt clas) $
-- tcMethodBind has checked that the class_tyvars havn't
-- been unified with each other or another type, but we must
- -- still zonk them
+ -- still zonk them before passing them to tcSimplifyAndCheck
mapNF_Tc zonkTcTyVarBndr clas_tyvars `thenNF_Tc` \ clas_tyvars' ->
tcSimplifyAndCheck
\begin{code}
tcMethodBind
:: Class
- -> InstOrigin s
- -> [TcType s] -- Instance types
- -> [TcTyVar s] -- Free variables of those instance types
- -- they'll be signature tyvars, and we
- -- want to check that they don't bound
+ -> InstOrigin
+ -> [TcTyVar] -- Instantiated type variables for the
+ -- enclosing class/instance decl.
+ -- They'll be signature tyvars, and we
+ -- want to check that they don't get bound
+ -> [TcType] -- Instance types
+ -> TcThetaType -- Available theta; this could be used to check
+ -- the method signature, but actually that's done by
+ -- the caller; here, it's just used for the error message
-> RenamedMonoBinds -- Method binding (pick the right one from in here)
-> [RenamedSig] -- Pramgas (just for this one)
-> Bool -- True <=> supply default decl if no explicit decl
-- This is true for instance decls,
-- false for class decls
-> (Id, Maybe Id) -- The method selector and default-method Id
- -> TcM s (TcMonoBinds s, LIE s, (LIE s, TcIdOcc s))
+ -> TcM s (TcMonoBinds, LIE, (LIE, TcId))
-tcMethodBind clas origin inst_tys inst_tyvars
+tcMethodBind clas origin inst_tyvars inst_tys inst_theta
meth_binds prags supply_default_bind
(sel_id, maybe_dm_id)
= tcGetSrcLoc `thenNF_Tc` \ loc ->
- newMethod origin (RealId sel_id) inst_tys `thenNF_Tc` \ meth@(_, TcId meth_id) ->
- mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
+ newMethod origin sel_id inst_tys `thenNF_Tc` \ meth@(_, meth_id) ->
+ mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
let
meth_name = idName meth_id
(omittedMethodWarn sel_id clas) `thenNF_Tc_`
-- Check the pragmas
- tcExtendLocalValEnv [meth_name] [meth_id] (
+ tcExtendLocalValEnv [(meth_name, meth_id)] (
tcPragmaSigs meth_prags
) `thenTc` \ (prag_info_fn, prag_binds1, prag_lie) ->
- -- Check the bindings
+ -- Check the bindings; first add inst_tyvars to the envt
+ -- so that we don't quantify over them in nested places
+ -- The *caller* put the class/inst decl tyvars into the envt
tcExtendGlobalTyVars (mkVarSet inst_tyvars) (
tcAddErrCtxt (methodCtxt sel_id) $
tcBindWithSigs NotTopLevel meth_bind [sig_info]
NonRecursive prag_info_fn
- ) `thenTc` \ (binds, insts, _) ->
+ ) `thenTc` \ (binds, insts, _) ->
-- The prag_lie for a SPECIALISE pragma will mention the function
-- Now check that the instance type variables
-- (or, in the case of a class decl, the class tyvars)
-- have not been unified with anything in the environment
- tcAddErrCtxtM (sigCtxt (quotes (ppr sel_id)) (idType meth_id)) (
+ tcAddErrCtxtM (sigCtxt sig_msg (mkSigmaTy inst_tyvars inst_theta (idType meth_id))) $
checkSigTyVars inst_tyvars `thenTc_`
returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2,
insts `plusLIE` prag_lie',
- meth))
-
+ meth)
where
+ sig_msg ty = sep [ptext SLIT("When checking the expected type for"),
+ nest 4 (ppr sel_name <+> dcolon <+> ppr ty)]
+
sel_name = idName sel_id
-- The renamer just puts the selector ID as the binder in the method binding
-- but we must use the method name; so we substitute it here. Crude but simple.
find_bind meth_name (FunMonoBind op_name fix matches loc)
| op_name == sel_name = Just (FunMonoBind meth_name fix matches loc)
- find_bind meth_name (PatMonoBind (VarPatIn op_name) rhs loc)
- | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) rhs loc)
+ find_bind meth_name (PatMonoBind (VarPatIn op_name) grhss loc)
+ | op_name == sel_name = Just (PatMonoBind (VarPatIn meth_name) grhss loc)
find_bind meth_name (AndMonoBinds b1 b2)
= find_bind meth_name b1 `seqMaybe` find_bind meth_name b2
find_bind meth_name other = Nothing -- Default case
mk_default_bind local_meth_name loc
= PatMonoBind (VarPatIn local_meth_name)
- (GRHSsAndBindsIn (unguardedRHS (default_expr loc) loc) EmptyBinds)
+ (GRHSs (unguardedRHS (default_expr loc) loc) EmptyBinds Nothing)
loc
default_expr loc
classArityErr class_name
= ptext SLIT("Too many parameters for class") <+> quotes (ppr class_name)
-classDeclCtxt class_name
- = ptext SLIT("In the class declaration for") <+> quotes (ppr class_name)
-
superClassErr class_name sc
= ptext SLIT("Illegal superclass constraint") <+> quotes (pprClassAssertion sc)
<+> ptext SLIT("in declaration for class") <+> quotes (ppr class_name)
+defltMethCtxt class_name
+ = ptext SLIT("When checking the default methods for class") <+> quotes (ppr class_name)
+
methodCtxt sel_id
= ptext SLIT("In the definition for method") <+> quotes (ppr sel_id)
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