Implement -XFunctionalDependencies

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index b033bf3..4bdfc65 100644 (file)
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -184,6 +184,7 @@ data DynFlag
    | Opt_GADTs
    | Opt_RelaxedPolyRec                        -- -X=RelaxedPolyRec
    | Opt_MultiParamTypeClasses
+   | Opt_FunctionalDependencies
    | Opt_MagicHash
    | Opt_EmptyDataDecls
    | Opt_KindSignatures
@@ -1133,6 +1134,7 @@ xFlags = [
   ( "ImplicitParams",                  Opt_ImplicitParams ),
   ( "ScopedTypeVariables",             Opt_ScopedTypeVariables ),
   ( "MultiParamTypeClasses",        Opt_MultiParamTypeClasses ),
+  ( "FunctionalDependencies",        Opt_FunctionalDependencies ),
   ( "GeneralizedNewtypeDeriving",   Opt_GeneralizedNewtypeDeriving ),
   ( "AllowOverlappingInstances",       Opt_AllowOverlappingInstances ),
   ( "AllowUndecidableInstances",       Opt_AllowUndecidableInstances ),
@@ -1150,6 +1152,7 @@ glasgowExtsFlags = [ Opt_GlasgowExts
                   , Opt_ImplicitParams 
                   , Opt_ScopedTypeVariables
            , Opt_MultiParamTypeClasses
+           , Opt_FunctionalDependencies
                   , Opt_MagicHash
            , Opt_RecursiveDo
            , Opt_ParallelListComp

diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs
index 7623b19..8a4e05b 100644 (file)
--- a/compiler/typecheck/TcTyClsDecls.lhs
+++ b/compiler/typecheck/TcTyClsDecls.lhs
@@ -1061,10 +1061,12 @@ checkValidClass cls
   = 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
@@ -1078,7 +1080,7 @@ checkValidClass cls
        ; 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]
 
@@ -1141,6 +1143,10 @@ classArityErr cls
   = 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") <+>