\section[TcClassDcl]{Typechecking class declarations}
\begin{code}
-module TcClassDcl ( tcClassDecl1, checkValidClass, tcClassDecls2,
- tcMethodBind, badMethodErr
+module TcClassDcl ( tcClassDecl1, tcClassDecls2,
+ tcMethodBind, mkMethodBind, badMethodErr
) where
#include "HsVersions.h"
isClassOpSig, isPragSig,
getClassDeclSysNames, placeHolderType
)
-import BasicTypes ( TopLevelFlag(..), RecFlag(..), StrictnessMark(..) )
+import BasicTypes ( RecFlag(..), StrictnessMark(..) )
import RnHsSyn ( RenamedTyClDecl,
RenamedClassOpSig, RenamedMonoBinds,
- RenamedSig, maybeGenericMatch
+ maybeGenericMatch
)
import TcHsSyn ( TcMonoBinds )
import Inst ( Inst, InstOrigin(..), LIE, emptyLIE, plusLIE, plusLIEs,
instToId, newDicts, newMethod )
-import TcEnv ( TyThingDetails(..), tcExtendGlobalTyVars,
- tcLookupClass, tcExtendTyVarEnvForMeths,
- tcExtendLocalValEnv, tcExtendTyVarEnv
+import TcEnv ( TyThingDetails(..),
+ tcLookupClass, tcExtendTyVarEnv2,
+ tcExtendTyVarEnv
)
-import TcBinds ( tcBindWithSigs, tcSpecSigs )
-import TcMonoType ( tcHsType, tcHsTheta, mkTcSig )
-import TcSimplify ( tcSimplifyCheck, bindInstsOfLocalFuns )
+import TcBinds ( tcMonoBinds )
+import TcMonoType ( TcSigInfo(..), tcHsType, tcHsTheta, mkTcSig )
+import TcSimplify ( tcSimplifyCheck )
import TcUnify ( checkSigTyVars, sigCtxt )
-import TcMType ( tcInstSigTyVars, checkValidTheta, checkValidType, SourceTyCtxt(..), UserTypeCtxt(..) )
+import TcMType ( tcInstTyVars )
import TcType ( Type, TyVarDetails(..), TcType, TcThetaType, TcTyVar,
mkTyVarTys, mkPredTys, mkClassPred,
- tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitSigmaTy
+ tcIsTyVarTy, tcSplitTyConApp_maybe
)
import TcMonad
-import Generics ( mkGenericRhs, validGenericMethodType )
+import Generics ( mkGenericRhs )
import PrelInfo ( nO_METHOD_BINDING_ERROR_ID )
-import Class ( classTyVars, classBigSig, classTyCon, className,
+import Class ( classTyVars, classBigSig, classTyCon,
Class, ClassOpItem, DefMeth (..) )
+import TyCon ( tyConGenInfo )
import MkId ( mkDictSelId, mkDataConId, mkDataConWrapId, mkDefaultMethodId )
import DataCon ( mkDataCon )
import Id ( Id, idType, idName, setIdLocalExported )
import Outputable
import Var ( TyVar )
import CmdLineOpts
+import UnicodeUtil ( stringToUtf8 )
import ErrUtils ( dumpIfSet )
-import Util ( count, isSingleton, lengthIs, equalLength )
-import Maybes ( seqMaybe, maybeToBool )
+import Util ( count, lengthIs, equalLength )
+import Maybes ( seqMaybe )
+import Maybe ( isJust )
\end{code}
returnTc (unitNameEnv op all_generic)
where
- n_generic = count (maybeToBool . maybeGenericMatch) matches
+ n_generic = count (isJust . maybeGenericMatch) matches
none_generic = n_generic == 0
all_generic = matches `lengthIs` n_generic
\end{code}
returnTc (local_ty, (sel_id, dm_info))
\end{code}
-checkValidClass is called once the mutually-recursive knot has been
-tied, so we can look at things freely.
-
-\begin{code}
-checkValidClass :: Class -> TcM ()
-checkValidClass cls
- = -- CHECK ARITY 1 FOR HASKELL 1.4
- doptsTc Opt_GlasgowExts `thenTc` \ gla_exts ->
-
- -- Check that the class is unary, unless GlaExs
- checkTc (not (null tyvars)) (nullaryClassErr cls) `thenTc_`
- checkTc (gla_exts || unary) (classArityErr cls) `thenTc_`
-
- -- Check the super-classes
- checkValidTheta (ClassSCCtxt (className cls)) theta `thenTc_`
-
- -- Check the class operations
- mapTc_ check_op op_stuff `thenTc_`
-
- -- Check that if the class has generic methods, then the
- -- class has only one parameter. We can't do generic
- -- multi-parameter type classes!
- checkTc (unary || no_generics) (genericMultiParamErr cls)
-
- where
- (tyvars, theta, _, op_stuff) = classBigSig cls
- unary = isSingleton tyvars
- no_generics = null [() | (_, GenDefMeth) <- op_stuff]
-
- check_op (sel_id, dm)
- = checkValidTheta SigmaCtxt (tail theta) `thenTc_`
- -- The 'tail' removes the initial (C a) from the
- -- class itself, leaving just the method type
-
- checkValidType (FunSigCtxt op_name) tau `thenTc_`
-
- -- Check that for a generic method, the type of
- -- the method is sufficiently simple
- checkTc (dm /= GenDefMeth || validGenericMethodType op_ty)
- (badGenericMethodType op_name op_ty)
- where
- op_name = idName sel_id
- op_ty = idType sel_id
- (_,theta,tau) = tcSplitSigmaTy op_ty
-\end{code}
-
%************************************************************************
%* *
-- (If necessary we can fix that, but we don't have a convenient Id to hand.)
tcDefMeth clas tyvars binds_in prags op_item@(sel_id, DefMeth dm_name)
- = tcInstSigTyVars ClsTv tyvars `thenNF_Tc` \ clas_tyvars ->
+ = tcInstTyVars ClsTv tyvars `thenNF_Tc` \ (clas_tyvars, inst_tys, _) ->
let
dm_ty = idType sel_id -- Same as dict selector!
-- The default method's type should really come from the
-- of types of default methods (and dict funs) by annotating them
-- TyGenNever (in MkId). Ugh! KSW 1999-09.
- inst_tys = mkTyVarTys clas_tyvars
theta = [mkClassPred clas inst_tys]
dm_id = mkDefaultMethodId dm_name dm_ty
local_dm_id = setIdLocalExported dm_id
-- Reason for setIdLocalExported: see notes with MkId.mkDictFunId
+ xtve = tyvars `zip` clas_tyvars
in
- newDicts origin theta `thenNF_Tc` \ [this_dict] ->
+ newDicts origin theta `thenNF_Tc` \ [this_dict] ->
- tcExtendTyVarEnvForMeths tyvars clas_tyvars (
- tcMethodBind clas origin clas_tyvars inst_tys theta
- binds_in prags False op_item
- ) `thenTc` \ (defm_bind, insts_needed, local_dm_inst) ->
+ mkMethodBind origin clas inst_tys binds_in op_item `thenTc` \ (dm_inst, meth_info) ->
+ tcMethodBind xtve clas_tyvars theta
+ [this_dict] meth_info `thenTc` \ (defm_bind, insts_needed) ->
tcAddErrCtxt (defltMethCtxt clas) $
full_bind = AbsBinds
clas_tyvars'
[instToId this_dict]
- [(clas_tyvars', local_dm_id, instToId local_dm_inst)]
+ [(clas_tyvars', local_dm_id, instToId dm_inst)]
emptyNameSet -- No inlines (yet)
(dict_binds `andMonoBinds` defm_bind)
in
\begin{code}
tcMethodBind
- :: Class
- -> InstOrigin
+ :: [(TyVar,TcTyVar)] -- Bindings for type environment
-> [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 <=> This method is from an instance declaration
- -> ClassOpItem -- The method selector and default-method Id
- -> TcM (TcMonoBinds, LIE, Inst)
-
-tcMethodBind clas origin inst_tyvars inst_tys inst_theta
- meth_binds prags is_inst_decl (sel_id, dm_info)
+ -- enclosing class/instance decl.
+ -- They'll be signature tyvars, and we
+ -- want to check that they don't get bound
+ -- Always equal the range of the type envt
+ -> TcThetaType -- Available theta; it's just used for the error message
+ -> [Inst] -- Available from context, used to simplify constraints
+ -- from the method body
+ -> (Id, TcSigInfo, RenamedMonoBinds) -- Details of this method
+ -> TcM (TcMonoBinds, LIE)
+
+tcMethodBind xtve inst_tyvars inst_theta avail_insts
+ (sel_id, meth_sig, meth_bind)
+ =
+ -- Check the bindings; first adding inst_tyvars to the envt
+ -- so that we don't quantify over them in nested places
+ tcExtendTyVarEnv2 xtve (
+ tcAddErrCtxt (methodCtxt sel_id) $
+ tcMonoBinds meth_bind [meth_sig] NonRecursive
+ ) `thenTc` \ (meth_bind, meth_lie, _, _) ->
+
+ -- Now do context reduction. We simplify wrt both the local tyvars
+ -- and the ones of the class/instance decl, so that there is
+ -- no problem with
+ -- class C a where
+ -- op :: Eq a => a -> b -> a
+ --
+ -- We do this for each method independently to localise error messages
+
+ let
+ TySigInfo meth_id meth_tvs meth_theta _ local_meth_id _ _ = meth_sig
+ in
+ tcAddErrCtxtM (sigCtxt sel_id inst_tyvars inst_theta (idType meth_id)) $
+ newDicts SignatureOrigin meth_theta `thenNF_Tc` \ meth_dicts ->
+ let
+ all_tyvars = meth_tvs ++ inst_tyvars
+ all_insts = avail_insts ++ meth_dicts
+ in
+ tcSimplifyCheck
+ (ptext SLIT("class or instance method") <+> quotes (ppr sel_id))
+ all_tyvars all_insts meth_lie `thenTc` \ (lie, lie_binds) ->
+
+ checkSigTyVars all_tyvars `thenTc` \ all_tyvars' ->
+
+ let
+ meth_tvs' = take (length meth_tvs) all_tyvars'
+ poly_meth_bind = AbsBinds meth_tvs'
+ (map instToId meth_dicts)
+ [(meth_tvs', meth_id, local_meth_id)]
+ emptyNameSet -- Inlines?
+ (lie_binds `andMonoBinds` meth_bind)
+ in
+ returnTc (poly_meth_bind, lie)
+
+
+mkMethodBind :: InstOrigin
+ -> Class -> [TcType] -- Class and instance types
+ -> RenamedMonoBinds -- Method binding (pick the right one from in here)
+ -> ClassOpItem
+ -> TcM (Inst, -- Method inst
+ (Id, -- Global selector Id
+ TcSigInfo, -- Signature
+ RenamedMonoBinds)) -- Binding for the method
+
+mkMethodBind origin clas inst_tys meth_binds (sel_id, dm_info)
= tcGetSrcLoc `thenNF_Tc` \ loc ->
- newMethod origin sel_id inst_tys `thenNF_Tc` \ meth ->
+ newMethod origin sel_id inst_tys `thenNF_Tc` \ meth_inst ->
let
- meth_id = instToId meth
+ meth_id = instToId meth_inst
meth_name = idName meth_id
- meth_prags = find_prags (idName sel_id) meth_name prags
in
- mkTcSig meth_id loc `thenNF_Tc` \ sig_info ->
-
-- Figure out what method binding to use
-- If the user suppplied one, use it, else construct a default one
(case find_bind (idName sel_id) meth_name meth_binds of
Just user_bind -> returnTc user_bind
- Nothing -> mkDefMethRhs is_inst_decl clas inst_tys sel_id loc dm_info `thenTc` \ rhs ->
+ Nothing -> mkDefMethRhs origin clas inst_tys sel_id loc dm_info `thenTc` \ rhs ->
returnTc (FunMonoBind meth_name False -- Not infix decl
[mkSimpleMatch [] rhs placeHolderType loc] loc)
) `thenTc` \ meth_bind ->
- -- 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 tyvar envt,
- -- but not into the global tyvars, so that the call to checkSigTyVars below works ok
- tcExtendGlobalTyVars inst_tyvars
- (tcAddErrCtxt (methodCtxt sel_id) $
- tcBindWithSigs NotTopLevel meth_bind
- [sig_info] meth_prags NonRecursive
- ) `thenTc` \ (binds, insts, _) ->
-
- tcExtendLocalValEnv [(meth_name, meth_id)]
- (tcSpecSigs meth_prags) `thenTc` \ (prag_binds1, prag_lie) ->
-
- -- The prag_lie for a SPECIALISE pragma will mention the function
- -- itself, so we have to simplify them away right now lest they float
- -- outwards!
- bindInstsOfLocalFuns prag_lie [meth_id] `thenTc` \ (prag_lie', prag_binds2) ->
-
- -- 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
- --
- -- We do this for each method independently to localise error messages
- -- ...and this is why the call to tcExtendGlobalTyVars must be here
- -- rather than in the caller
- tcAddErrCtxt (ptext SLIT("When checking the type of class method")
- <+> quotes (ppr sel_id)) $
- tcAddErrCtxtM (sigCtxt inst_tyvars inst_theta (idType meth_id)) $
- checkSigTyVars inst_tyvars `thenTc_`
-
- returnTc (binds `AndMonoBinds` prag_binds1 `AndMonoBinds` prag_binds2,
- insts `plusLIE` prag_lie',
- meth)
+
+ mkTcSig meth_id loc `thenNF_Tc` \ meth_sig ->
+
+ returnTc (meth_inst, (sel_id, meth_sig, meth_bind))
+
-- The user didn't supply a method binding,
-- so we have to make up a default binding
-- The RHS of a default method depends on the default-method info
-mkDefMethRhs is_inst_decl clas inst_tys sel_id loc (DefMeth dm_name)
+mkDefMethRhs origin clas inst_tys sel_id loc (DefMeth dm_name)
= -- An polymorphic default method
returnTc (HsVar dm_name)
-mkDefMethRhs is_inst_decl clas inst_tys sel_id loc NoDefMeth
+mkDefMethRhs origin clas inst_tys sel_id loc NoDefMeth
= -- No default method
-- Warn only if -fwarn-missing-methods
doptsTc Opt_WarnMissingMethods `thenNF_Tc` \ warn ->
- warnTc (is_inst_decl && warn)
+ warnTc (isInstDecl origin && warn)
(omittedMethodWarn sel_id) `thenNF_Tc_`
returnTc error_rhs
where
error_rhs = HsApp (HsVar (getName nO_METHOD_BINDING_ERROR_ID))
- (HsLit (HsString (_PK_ error_msg)))
+ (HsLit (HsStringPrim (_PK_ (stringToUtf8 error_msg))))
error_msg = showSDoc (hcat [ppr loc, text "|", ppr sel_id ])
-mkDefMethRhs is_inst_decl clas inst_tys sel_id loc GenDefMeth
+mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth
= -- A generic default method
-- If the method is defined generically, we can only do the job if the
-- instance declaration is for a single-parameter type class with
-- a type constructor applied to type arguments in the instance decl
-- (checkTc, so False provokes the error)
- checkTc (not is_inst_decl || simple_inst)
- (badGenericInstance sel_id) `thenTc_`
+ ASSERT( isInstDecl origin ) -- We never get here from a class decl
+
+ checkTc (isJust maybe_tycon)
+ (badGenericInstance sel_id (notSimple inst_tys)) `thenTc_`
+ checkTc (isJust (tyConGenInfo tycon))
+ (badGenericInstance sel_id (notGeneric tycon)) `thenTc_`
ioToTc (dumpIfSet opt_PprStyle_Debug "Generic RHS" stuff) `thenNF_Tc_`
returnTc rhs
-- case we require that the instance decl is for a single-parameter
-- type class with type variable arguments:
-- instance (...) => C (T a b)
- simple_inst = maybeToBool maybe_tycon
clas_tyvar = head (classTyVars clas)
Just tycon = maybe_tycon
maybe_tycon = case inst_tys of
Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon
other -> Nothing
other -> Nothing
+
+isInstDecl InstanceDeclOrigin = True
+isInstDecl ClassDeclOrigin = False
\end{code}
Contexts and errors
~~~~~~~~~~~~~~~~~~~
\begin{code}
-nullaryClassErr cls
- = ptext SLIT("No parameters for class") <+> quotes (ppr cls)
-
-classArityErr cls
- = vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
- parens (ptext SLIT("Use -fglasgow-exts to allow multi-parameter classes"))]
-
defltMethCtxt clas
= ptext SLIT("When checking the default methods for class") <+> quotes (ppr clas)
omittedMethodWarn sel_id
= ptext SLIT("No explicit method nor default method for") <+> quotes (ppr sel_id)
-badGenericMethodType op op_ty
- = hang (ptext SLIT("Generic method type is too complex"))
- 4 (vcat [ppr op <+> dcolon <+> ppr op_ty,
- ptext SLIT("You can only use type variables, arrows, and tuples")])
-
-badGenericInstance sel_id
+badGenericInstance sel_id because
= sep [ptext SLIT("Can't derive generic code for") <+> quotes (ppr sel_id),
- ptext SLIT("because the instance declaration is not for a simple type (T a b c)"),
- ptext SLIT("(where T is a derivable type constructor)")]
+ because]
+
+notSimple inst_tys
+ = vcat [ptext SLIT("because the instance type(s)"),
+ nest 2 (ppr inst_tys),
+ ptext SLIT("is not a simple type of form (T a b c)")]
+
+notGeneric tycon
+ = vcat [ptext SLIT("because the instance type constructor") <+> quotes (ppr tycon) <+>
+ ptext SLIT("was not compiled with -fgenerics")]
mixedGenericErr op
= ptext SLIT("Can't mix generic and non-generic equations for class method") <+> quotes (ppr op)
-
-genericMultiParamErr clas
- = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
- ptext SLIT("cannot have generic methods")
\end{code}
projects / ghc-hetmet.git / blobdiff