Merged the auxiliary class [scope] into [free].

src/KitFa.ml

@@ -14,23 +14,16 @@
 
 (* -------------------------------------------------------------------------- *)
 
-(* The auxiliary class [scope] defines the environment to be a set of atoms
+(* The auxiliary class [free] defines the environment to be a set of atoms
    (the atoms that are currently in scope). It defines the method [extend]
    so as to update this set. *)
 
-class ['self] scope = object (_ : 'self)
-  method private extend = Atom.Set.add
-end
-
-(* -------------------------------------------------------------------------- *)
-
-(* The auxiliary class [free] inherits [scope] and further defines the method
-   [visit_'fn] so that, at a free name occurrence: -1. if the name is local,
-   nothing happens; -2. if the name is free, then the method [visit_free] is
-   invoked. *)
+(* Furthermore, this class defines the method [visit_'fn] so that, at a free
+   name occurrence: -1. if the name is local, nothing happens; -2. if the name
+   is free, then the method [visit_free] is invoked. *)
 
 class virtual ['self] free = object (self : 'self)
-  inherit [_] scope
+  method private extend = Atom.Set.add
   method private visit_'fn env x =
     if not (Atom.Set.mem x env) then
       self#visit_free x