[project @ 2000-05-25 12:41:14 by simonpj]

[ghc-hetmet.git] / ghc / compiler / types / Class.lhs

diff --git a/ghc/compiler/types/Class.lhs b/ghc/compiler/types/Class.lhs
index 035a12c..781e342 100644 (file)
--- a/ghc/compiler/types/Class.lhs
+++ b/ghc/compiler/types/Class.lhs
@@ -5,7 +5,7 @@
 
 \begin{code}
 module Class (
-       Class, ClassOpItem,
+       Class, ClassOpItem, ClassPred, ClassContext, FunDep,
 
        mkClass, classTyVars,
        classKey, className, classSelIds, classTyCon,
@@ -40,7 +40,7 @@ data Class
        className :: Name,
        
        classTyVars  :: [TyVar],                -- The class type variables
-       classFunDeps :: [([TyVar], [TyVar])],   -- The functional dependencies
+       classFunDeps :: [FunDep TyVar],         -- The functional dependencies
 
        classSCTheta :: [(Class,[Type])],       -- Immediate superclasses, and the
        classSCSels  :: [Id],                   -- corresponding selector functions to
@@ -54,6 +54,12 @@ data Class
        classTyCon :: TyCon             -- The data type constructor for dictionaries
   }                                    -- of this class
 
+type ClassPred           = (Class, [Type])
+type ClassContext = [ClassPred]
+
+type FunDep a    = ([a],[a])   --  e.g. class C a b c |  a b -> c, a c -> b  where ...
+                               --  Here fun-deps are [([a,b],[c]), ([a,c],[b])]
+
 type ClassOpItem = (Id,        --   Selector function; contains unfolding
                    Id,         --   Default methods
                    Bool)       --   True <=> an explicit default method was