\section[TcClassDcl]{Typechecking class declarations}
\begin{code}
-module TcClassDcl ( tcClassDecl1, checkValidClass, tcClassDecls2,
+module TcClassDcl ( tcClassDecl1, tcClassDecls2,
tcMethodBind, mkMethodBind, badMethodErr
) where
tcIsTyVarTy, tcSplitTyConApp_maybe, tcSplitSigmaTy
)
import TcMonad
-import Generics ( mkGenericRhs, validGenericMethodType )
+import Generics ( mkGenericRhs )
import PrelInfo ( nO_METHOD_BINDING_ERROR_ID )
import Class ( classTyVars, classBigSig, classTyCon, className,
Class, ClassOpItem, DefMeth (..) )
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}
-
%************************************************************************
%* *
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
= 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)"),
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}
-> TcM (TcExpr, LIE) -- Generalised expr with expected type, and LIE
tcExpr expr expected_ty
+ = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenNF_Tc_`
+ tc_expr' expr expected_ty
+
+tc_expr' expr expected_ty
| not (isSigmaTy expected_ty) -- Monomorphic case
= tcMonoExpr expr expected_ty
-- Checking type validity
Rank, UserTypeCtxt(..), checkValidType, pprUserTypeCtxt,
SourceTyCtxt(..), checkValidTheta,
+ checkValidTyCon, checkValidClass,
checkValidInstHead, instTypeErr, checkAmbiguity,
--------------------------------
)
import qualified Type ( splitFunTys )
import Subst ( Subst, mkTopTyVarSubst, substTy )
-import Class ( Class, classArity, className )
+import Class ( Class, DefMeth(..), classArity, className, classBigSig )
import TyCon ( TyCon, mkPrimTyCon, isSynTyCon, isUnboxedTupleTyCon,
- tyConArity, tyConName, tyConKind )
+ tyConArity, tyConName, tyConKind, tyConTheta,
+ getSynTyConDefn, tyConDataCons )
+import DataCon ( DataCon, dataConWrapId, dataConName, dataConSig, dataConFieldLabels )
+import FieldLabel ( fieldLabelName, fieldLabelType )
import PrimRep ( PrimRep(VoidRep) )
-import Var ( TyVar, tyVarKind, tyVarName, isTyVar, mkTyVar, isMutTyVar )
+import Var ( TyVar, idType, idName, tyVarKind, tyVarName, isTyVar, mkTyVar, isMutTyVar )
-- others:
+import Generics ( validGenericMethodType )
import TcMonad -- TcType, amongst others
import TysWiredIn ( voidTy, listTyCon, tupleTyCon )
import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
import Unique ( Uniquable(..) )
import SrcLoc ( noSrcLoc )
import Util ( nOfThem, isSingleton, equalLength )
-import ListSetOps ( removeDups )
+import ListSetOps ( equivClasses, removeDups )
import Outputable
\end{code}
%************************************************************************
%* *
+\subsection{Validity check for TyCons}
+%* *
+%************************************************************************
+
+checkValidTyCon is called once the mutually-recursive knot has been
+tied, so we can look at things freely.
+
+\begin{code}
+checkValidTyCon :: TyCon -> TcM ()
+checkValidTyCon tc
+ | isSynTyCon tc = checkValidType (TySynCtxt name) syn_rhs
+ | otherwise
+ = -- Check the context on the data decl
+ checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenTc_`
+
+ -- Check arg types of data constructors
+ mapTc_ checkValidDataCon data_cons `thenTc_`
+
+ -- Check that fields with the same name share a type
+ mapTc_ check_fields groups
+
+ where
+ name = tyConName tc
+ (_, syn_rhs) = getSynTyConDefn tc
+ data_cons = tyConDataCons tc
+
+ fields = [field | con <- data_cons, field <- dataConFieldLabels con]
+ groups = equivClasses cmp_name fields
+ cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2
+
+ check_fields fields@(first_field_label : other_fields)
+ -- These fields all have the same name, but are from
+ -- different constructors in the data type
+ = -- Check that all the fields in the group have the same type
+ -- NB: this check assumes that all the constructors of a given
+ -- data type use the same type variables
+ checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name)
+ where
+ field_ty = fieldLabelType first_field_label
+ field_name = fieldLabelName first_field_label
+ other_tys = map fieldLabelType other_fields
+
+checkValidDataCon :: DataCon -> TcM ()
+checkValidDataCon con
+ = checkValidType ctxt (idType (dataConWrapId con)) `thenTc_`
+ -- This checks the argument types and
+ -- ambiguity of the existential context (if any)
+ tcAddErrCtxt (existentialCtxt con)
+ (checkFreeness ex_tvs ex_theta)
+ where
+ ctxt = ConArgCtxt (dataConName con)
+ (_, _, ex_tvs, ex_theta, _, _) = dataConSig con
+
+
+fieldTypeMisMatch field_name
+ = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
+
+existentialCtxt con = ptext SLIT("When checking the existential context of constructor")
+ <+> ppr con
+\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
+
+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"))]
+
+genericMultiParamErr clas
+ = ptext SLIT("The multi-parameter class") <+> quotes (ppr clas) <+>
+ ptext SLIT("cannot have generic methods")
+
+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")])
+\end{code}
+
+
+%************************************************************************
+%* *
\subsection{Checking for a decent instance head type}
%* *
%************************************************************************
import TcEnv ( TcEnv, RecTcEnv, TcTyThing(..), TyThing(..), TyThingDetails(..),
tcExtendKindEnv, tcLookup, tcExtendGlobalEnv,
isLocalThing )
-import TcTyDecls ( tcTyDecl, kcConDetails, checkValidTyCon )
-import TcClassDcl ( tcClassDecl1, checkValidClass )
+import TcTyDecls ( tcTyDecl, kcConDetails )
+import TcClassDcl ( tcClassDecl1 )
import TcInstDcls ( tcAddDeclCtxt )
import TcMonoType ( kcHsTyVars, kcHsType, kcHsLiftedSigType, kcHsContext, mkTyClTyVars )
-import TcMType ( newKindVar, zonkKindEnv )
+import TcMType ( newKindVar, zonkKindEnv, checkValidTyCon, checkValidClass )
import TcUnify ( unifyKind )
import TcType ( Type, Kind, TcKind, mkArrowKind, liftedTypeKind, zipFunTys )
import Type ( splitTyConApp_maybe )
\section[TcTyDecls]{Typecheck type declarations}
\begin{code}
-module TcTyDecls ( tcTyDecl, checkValidTyCon, kcConDetails ) where
+module TcTyDecls ( tcTyDecl, kcConDetails ) where
#include "HsVersions.h"
TyThingDetails(..), RecTcEnv
)
import TcType ( tcEqType, tyVarsOfTypes, tyVarsOfPred, ThetaType )
-import TcMType ( checkValidType, UserTypeCtxt(..), checkValidTheta, SourceTyCtxt(..) )
import TcMonad
-import DataCon ( DataCon, mkDataCon, dataConFieldLabels, dataConWrapId, dataConName )
+import DataCon ( DataCon, mkDataCon, dataConFieldLabels )
+import FieldLabel ( fieldLabelName, fieldLabelType, allFieldLabelTags, mkFieldLabel )
import MkId ( mkDataConId, mkDataConWrapId, mkRecordSelId )
-import FieldLabel
-import Var ( TyVar, idType )
+import Var ( TyVar )
import Name ( Name, NamedThing(..) )
import Outputable
import TyCon ( TyCon, DataConDetails(..), visibleDataCons,
- tyConName, tyConTheta, getSynTyConDefn,
- tyConTyVars, tyConDataCons, isSynTyCon )
+ tyConName, tyConTheta,
+ tyConTyVars, isSynTyCon )
import VarSet ( intersectVarSet, isEmptyVarSet )
import PrelNames ( unpackCStringName, unpackCStringUtf8Name )
-import ListSetOps ( equivClasses )
import List ( nubBy )
\end{code}
%************************************************************************
%* *
-\subsection{Validity check}
-%* *
-%************************************************************************
-
-checkValidTyCon is called once the mutually-recursive knot has been
-tied, so we can look at things freely.
-
-\begin{code}
-checkValidTyCon :: TyCon -> TcM ()
-checkValidTyCon tc
- | isSynTyCon tc = checkValidType (TySynCtxt name) syn_rhs
- | otherwise
- = -- Check the context on the data decl
- checkValidTheta (DataTyCtxt name) (tyConTheta tc) `thenTc_`
-
- -- Check arg types of data constructors
- mapTc_ check_data_con data_cons `thenTc_`
-
- -- Check that fields with the same name share a type
- mapTc_ check_fields groups
-
- where
- name = tyConName tc
- (_, syn_rhs) = getSynTyConDefn tc
- data_cons = tyConDataCons tc
-
- fields = [field | con <- data_cons, field <- dataConFieldLabels con]
- groups = equivClasses cmp_name fields
- cmp_name field1 field2 = fieldLabelName field1 `compare` fieldLabelName field2
-
- check_data_con con = checkValidType (ConArgCtxt (dataConName con))
- (idType (dataConWrapId con))
- -- This checks the argument types and
- -- the existential context (if any)
-
- check_fields fields@(first_field_label : other_fields)
- -- These fields all have the same name, but are from
- -- different constructors in the data type
- = -- Check that all the fields in the group have the same type
- -- NB: this check assumes that all the constructors of a given
- -- data type use the same type variables
- checkTc (all (tcEqType field_ty) other_tys) (fieldTypeMisMatch field_name)
- where
- field_ty = fieldLabelType first_field_label
- field_name = fieldLabelName first_field_label
- other_tys = map fieldLabelType other_fields
-\end{code}
-
-
-
-%************************************************************************
-%* *
\subsection{Kind and type check constructors}
%* *
%************************************************************************
\begin{code}
-fieldTypeMisMatch field_name
- = sep [ptext SLIT("Different constructors give different types for field"), quotes (ppr field_name)]
-
exRecConErr name
= ptext SLIT("Can't combine named fields with locally-quantified type variables")
$$
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