use existing constant

lib/mom/instruction/slot_definition.rb

@@ -72,7 +72,7 @@ module Mom
         const << Risc::SlotToReg.new( instruction , right ,index, right)
         if slots.length > 2
           raise "3 slots only for type #{slots}" unless slots[2] == :type
-          const << Risc::SlotToReg.new( instruction , right , 0, right)
+          const << Risc::SlotToReg.new( instruction , right , Parfait::TYPE_INDEX, right)
         end
       end
       const

lib/parfait/object.rb

@@ -39,7 +39,7 @@ module Parfait
 
     # 0 -based index
     def set_internal_word(index , value)
-      return set_type(value) if( index == 0)
+      return set_type(value) if( index == TYPE_INDEX)
       raise "not type #{@type.class}" unless @type.is_a?(Type)
       name = @type.name_at(index)
       #return value unless name