; stupid_theta <- tcHsKindedContext ctxt
; want_generic <- doptM Opt_Generics
; unbox_strict <- doptM Opt_UnboxStrictFields
- ; gla_exts <- doptM Opt_GlasgowExts
; empty_data_decls <- doptM Opt_EmptyDataDecls
; kind_signatures <- doptM Opt_KindSignatures
; gadt_ok <- doptM Opt_GADTs
= do { -- CHECK ARITY 1 FOR HASKELL 1.4
gla_exts <- doptM Opt_GlasgowExts
; multi_param_type_classes <- doptM Opt_MultiParamTypeClasses
+ ; fundep_classes <- doptM Opt_FunctionalDependencies
-- Check that the class is unary, unless GlaExs
; checkTc (notNull tyvars) (nullaryClassErr cls)
; checkTc (multi_param_type_classes || unary) (classArityErr cls)
+ ; checkTc (fundep_classes || null fundeps) (classFunDepsErr cls)
-- Check the super-classes
; checkValidTheta (ClassSCCtxt (className cls)) theta
; checkTc (unary || no_generics) (genericMultiParamErr cls)
}
where
- (tyvars, theta, _, op_stuff) = classBigSig cls
+ (tyvars, fundeps, theta, _, _, op_stuff) = classExtraBigSig cls
unary = isSingleton tyvars
no_generics = null [() | (_, GenDefMeth) <- op_stuff]
= vcat [ptext SLIT("Too many parameters for class") <+> quotes (ppr cls),
parens (ptext SLIT("Use -XMultiParamTypeClasses to allow multi-parameter classes"))]
+classFunDepsErr cls
+ = vcat [ptext SLIT("Fundeps in class") <+> quotes (ppr cls),
+ parens (ptext SLIT("Use -XFunctionalDependencies to allow fundeps"))]
+
noClassTyVarErr clas op
= sep [ptext SLIT("The class method") <+> quotes (ppr op),
ptext SLIT("mentions none of the type variables of the class") <+>