diff --git a/lib/slot_machine/slot.rb b/lib/slot_machine/slot.rb
index 07d57593..d0a905c7 100644
--- a/lib/slot_machine/slot.rb
+++ b/lib/slot_machine/slot.rb
@@ -18,11 +18,13 @@ module SlotMachine
 
     attr_reader :name , :next_slot
 
+    # initialize with just the name of the slot. Add more to the chain with set_next
     def initialize( name )
       raise "No name" unless name
-      @name =  name
+      @name = name
     end
 
+    #set the next_slot , but always at the end of the chain
     def set_next(slot)
       if(@next_slot)
         @next_slot.set_next(slot)
@@ -31,12 +33,18 @@ module SlotMachine
       end
     end
 
+    # return the length of chain, ie 1 plus however many more next_slots there are
+    def length
+      return 1 unless @next_slot
+      1 + @next_slot.length
+    end
+
+    # name of all the slots, with dot syntax
     def to_s
       names = name.to_s
       names += ".#{@next_slot}" if @next_slot
       names
     end
 
-
   end
 end
diff --git a/lib/slot_machine/slotted.rb b/lib/slot_machine/slotted.rb
index ab309001..fb59b06f 100644
--- a/lib/slot_machine/slotted.rb
+++ b/lib/slot_machine/slotted.rb
@@ -11,27 +11,41 @@ module SlotMachine
       when Parfait::Object , Risc::Label
         SlottedObject.new(object , slots)
       else
-        raise "not supported type #{object}"
+        raise "not supported type #{object}:#{object.class}"
       end
     end
 
     # The first in a possible chain of slots, that name instance variables in the
     # previous object
-    attr_reader :slot
+    attr_reader :slots
 
     def initialize( slots )
       raise "No slots #{object}" unless slots
       slots = [slots] unless slots.is_a?(Array)
       first = slots.shift
-      @slot = Slot.new(first)
+      return unless first
+      @slots = Slot.new(first)
       until(slots.empty?)
-        @slot.set_next( Slot.new( slots.shift ))
+        @slots.set_next( Slot.new( slots.shift ))
+      end
+    end
+
+    def slots_length
+      return 0 unless @slots
+      1 + @slots.length
+    end
+
+    def set_next(slot)
+      if(@slots)
+        @slots.set_next(slot)
+      else
+        @slots = slot
       end
     end
 
     def to_s
       names = known_name.to_s
-      names += ".#{@slot}" if @slot
+      names += ".#{@slots}" if @slots
       names
     end
 
diff --git a/lib/slot_machine/slotted_constant.rb b/lib/slot_machine/slotted_constant.rb
index 9542337a..b8ee9e65 100644
--- a/lib/slot_machine/slotted_constant.rb
+++ b/lib/slot_machine/slotted_constant.rb
@@ -1,7 +1,6 @@
 module SlotMachine
   class SlottedConstant < Slotted
 
-
     attr_reader :known_object
 
     def initialize( object , slots)
@@ -27,11 +26,11 @@ module SlotMachine
       parfait = known_object.to_parfait(compiler)
       const = Risc.load_constant(source, parfait , right)
       compiler.add_code const
-      if slots.length == 1
-        raise "only type allowed for constants, not #{slots[0]}" unless slots[0] == :type
+      if slots_length == 2
+        raise "only type allowed for constants, not #{slots}" unless slots.name == :type
         compiler.add_code Risc::SlotToReg.new( source , right , Parfait::TYPE_INDEX, right)
       end
-      raise "Can't have slots into Constants #{slots}" if slots.length > 1
+      raise "Can't have slots into Constants #{slots}" if slots_length > 2
       return const.register
     end
 
diff --git a/lib/slot_machine/slotted_message.rb b/lib/slot_machine/slotted_message.rb
index 4986bff4..1407635d 100644
--- a/lib/slot_machine/slotted_message.rb
+++ b/lib/slot_machine/slotted_message.rb
@@ -1,7 +1,6 @@
 module SlotMachine
   class SlottedMessage < Slotted
 
-
     def known_name
       :message
     end
@@ -13,13 +12,13 @@ module SlotMachine
     def to_register(compiler, source)
       type = :Message
       right = compiler.use_reg( type )
-      slots = @slot
+      slots = @slots
       left = Risc.message_reg
       left = left.resolve_and_add( slots.name , compiler)
       reg = compiler.current.register
       slots = slots.next_slot
       while( slots )
-        left = left.resolve_and_add( slots , compiler)
+        left = left.resolve_and_add( slots.name , compiler)
         slots = slots.next_slot
       end
       return reg
@@ -32,15 +31,14 @@ module SlotMachine
     #       They are very similar (apart from the final reg_to_slot here) and should
     #       most likely be united
     def reduce_and_load(const_reg , compiler , original_source )
-      left_slots = slots.dup
       raise "Not Message #{object}" unless known_object == :message
       left = Risc.message_reg
-      slot = left_slots.shift
-      while( !left_slots.empty? )
-        left = left.resolve_and_add( slot , compiler)
-        slot = left_slots.shift
+      slot = slots
+      while( slot.next_slot )
+        left = left.resolve_and_add( slot.name , compiler)
+        slot = slot.next_slot
       end
-      compiler.add_code Risc.reg_to_slot(original_source, const_reg , left, slot)
+      compiler.add_code Risc.reg_to_slot(original_source, const_reg , left, slot.name)
     end
 
   end
diff --git a/lib/slot_machine/slotted_object.rb b/lib/slot_machine/slotted_object.rb
index 41b291ef..3ef99b20 100644
--- a/lib/slot_machine/slotted_object.rb
+++ b/lib/slot_machine/slotted_object.rb
@@ -21,16 +21,16 @@ module SlotMachine
       right = compiler.use_reg( type )
       const = Risc.load_constant(source, known_object , right)
       compiler.add_code const
-      if slots.length > 0
+      if slots_length > 1
         # desctructively replace the existing value to be loaded if more slots
-        compiler.add_code Risc.slot_to_reg( source , right ,slots[0], right)
+        compiler.add_code Risc.slot_to_reg( source , right ,slots.name, right)
       end
-      if slots.length > 1
+      if slots_length > 2
         # desctructively replace the existing value to be loaded if more slots
-        index = Risc.resolve_to_index(slots[0] , slots[1] ,compiler)
+        index = Risc.resolve_to_index(slots.name , slots.next_slot.name ,compiler)
         compiler.add_code Risc::SlotToReg.new( source , right ,index, right)
-        if slots.length > 2
-          raise "3 slots only for type #{slots}" unless slots[2] == :type
+        if slots_length > 3
+          raise "3 slots only for type #{slots}" unless slots.next_slot.next_slot.name == :type
           compiler.add_code Risc::SlotToReg.new( source , right , Parfait::TYPE_INDEX, right)
         end
       end
@@ -44,7 +44,7 @@ module SlotMachine
       raise "only cache" unless known_object.is_a?( Parfait::CacheEntry)
       left = compiler.use_reg( :CacheEntry )
       compiler.add_code Risc.load_constant(original_source, known_object , left)
-      compiler.add_code Risc.reg_to_slot(original_source, const_reg , left, slots.first)
+      compiler.add_code Risc.reg_to_slot(original_source, const_reg , left, slots.name)
     end
   end
 end
diff --git a/lib/sol/assignment.rb b/lib/sol/assignment.rb
index 6ae9c70b..7713ffc6 100644
--- a/lib/sol/assignment.rb
+++ b/lib/sol/assignment.rb
@@ -33,7 +33,7 @@ module Sol
     # Derived classes do not implement to_slot, only slot_position
     def to_slot(compiler)
       to = SlotMachine::Slotted.for(:message , self.slot_position(compiler))
-      from = @value.to_slot_definition(compiler)
+      from = @value.to_slotted(compiler)
       assign = SlotMachine::SlotLoad.new(self,to,from)
       return assign unless @value.is_a?(CallStatement)
       @value.to_slot(compiler) << assign
diff --git a/lib/sol/basic_values.rb b/lib/sol/basic_values.rb
index f4eb7025..0f710eb3 100644
--- a/lib/sol/basic_values.rb
+++ b/lib/sol/basic_values.rb
@@ -9,7 +9,7 @@ module Sol
     def initialize(value)
       @value = value
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for(SlotMachine::IntegerConstant.new(@value) , [])
     end
     def ct_type
@@ -37,7 +37,7 @@ module Sol
     def ct_type
       Parfait.object_space.get_type_by_class_name(:True)
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for(Parfait.object_space.true_object , [])
     end
     def to_s(depth = 0)
@@ -49,7 +49,7 @@ module Sol
     def ct_type
       Parfait.object_space.get_type_by_class_name(:False)
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for(Parfait.object_space.false_object , [])
     end
     def to_s(depth = 0)
@@ -61,7 +61,7 @@ module Sol
     def ct_type
       Parfait.object_space.get_type_by_class_name(:Nil)
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for(Parfait.object_space.nil_object , [])
     end
     def to_s(depth = 0)
@@ -75,7 +75,7 @@ module Sol
     def initialize(type = nil)
       @my_type = type
     end
-    def to_slot_definition(compiler)
+    def to_slotted(compiler)
       @my_type = compiler.receiver_type
       SlotMachine::Slotted.for(:message , [:receiver])
     end
@@ -91,7 +91,7 @@ module Sol
     def initialize(value)
       @value = value
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for(SlotMachine::StringConstant.new(@value),[])
     end
     def ct_type
diff --git a/lib/sol/call_statement.rb b/lib/sol/call_statement.rb
index 0f1dfdfc..62109bc0 100644
--- a/lib/sol/call_statement.rb
+++ b/lib/sol/call_statement.rb
@@ -10,7 +10,7 @@ module Sol
 
     # When used as right hand side, this tells what data to move to get the result into
     # a varaible. It is (off course) the return value of the message
-    def to_slot_definition(_)
+    def to_slotted(_)
       SlotMachine::Slotted.for(:message ,[ :return_value])
     end
 
diff --git a/lib/sol/if_statement.rb b/lib/sol/if_statement.rb
index 840b5da2..e2674e0a 100644
--- a/lib/sol/if_statement.rb
+++ b/lib/sol/if_statement.rb
@@ -32,7 +32,7 @@ module Sol
 
     # create the slot lazily, so to_slot gets called first
     def check_slot(compiler , false_label)
-      SlotMachine::TruthCheck.new(@condition.to_slot_definition(compiler) , false_label)
+      SlotMachine::TruthCheck.new(@condition.to_slotted(compiler) , false_label)
     end
 
     def each(&block)
diff --git a/lib/sol/lambda_expression.rb b/lib/sol/lambda_expression.rb
index 4bfef395..de57a9de 100644
--- a/lib/sol/lambda_expression.rb
+++ b/lib/sol/lambda_expression.rb
@@ -13,7 +13,7 @@ module Sol
     #
     # This means we do the compiler here (rather than to_slot, which is in
     # fact never called)
-    def to_slot_definition(compiler)
+    def to_slotted(compiler)
       compile(compiler) unless @parfait_block
       return SlotMachine::Slotted.for(SlotMachine::LambdaConstant.new(parfait_block(compiler)) , [])
     end
diff --git a/lib/sol/macro_expression.rb b/lib/sol/macro_expression.rb
index 1320f683..63968319 100644
--- a/lib/sol/macro_expression.rb
+++ b/lib/sol/macro_expression.rb
@@ -14,7 +14,7 @@ module Sol
 
     # When used as right hand side, this tells what data to move to get the result into
     # a varaible. It is (off course) the return value of the message
-    def to_slot_definition(_)
+    def to_slotted(_)
       SlotMachine::Slotted.for(:message ,[ :return_value])
     end
 
diff --git a/lib/sol/return_statement.rb b/lib/sol/return_statement.rb
index af06e269..ac1dc5a8 100644
--- a/lib/sol/return_statement.rb
+++ b/lib/sol/return_statement.rb
@@ -32,7 +32,7 @@ module Sol
 
     def slot_load(compiler)
       SlotMachine::SlotLoad.new( self , [:message , :return_value] ,
-                        @return_value.to_slot_definition(compiler) )
+                        @return_value.to_slotted(compiler) )
     end
   end
 end
diff --git a/lib/sol/send_statement.rb b/lib/sol/send_statement.rb
index 2630745f..a0cd9221 100644
--- a/lib/sol/send_statement.rb
+++ b/lib/sol/send_statement.rb
@@ -67,11 +67,11 @@ module Sol
 
     def message_setup(compiler,called_method)
       setup  = SlotMachine::MessageSetup.new( called_method )
-      slot_receive = @receiver.to_slot_definition(compiler)
+      slot_receive = @receiver.to_slotted(compiler)
       arg_target = [:message , :next_message ]
       args = []
       @arguments.each_with_index do |arg , index| # +1 because of type
-        args << SlotMachine::SlotLoad.new(self, arg_target + ["arg#{index+1}".to_sym] , arg.to_slot_definition(compiler))
+        args << SlotMachine::SlotLoad.new(self, arg_target + ["arg#{index+1}".to_sym] , arg.to_slotted(compiler))
       end
       setup << SlotMachine::ArgumentTransfer.new(self, slot_receive , args )
     end
@@ -111,10 +111,11 @@ module Sol
 
     private
     def receiver_type_definition(compiler)
-      defi = @receiver.to_slot_definition(compiler)
-      defi.slots << :type
+      defi = @receiver.to_slotted(compiler)
+      defi.set_next( SlotMachine::Slot.new(:type) )
       defi
     end
+
     def build_condition(ok_label, compiler)
       cached_type = SlotMachine::Slotted.for(dynamic_call.cache_entry , [:cached_type])
       current_type = receiver_type_definition(compiler)
diff --git a/lib/sol/variables.rb b/lib/sol/variables.rb
index f2d1efd5..351271a7 100644
--- a/lib/sol/variables.rb
+++ b/lib/sol/variables.rb
@@ -10,7 +10,7 @@ module Sol
 
   class LocalVariable < Expression
     include Named
-    def to_slot_definition(compiler)
+    def to_slotted(compiler)
       slot_def = compiler.slot_type_for(@name)
       SlotMachine::Slotted.for(:message , slot_def)
     end
@@ -24,7 +24,7 @@ module Sol
 
   class InstanceVariable < Expression
     include Named
-    def to_slot_definition(_)
+    def to_slotted(_)
       SlotMachine::Slotted.for(:message , [ :receiver , @name] )
     end
     # used to collect type information
@@ -51,7 +51,7 @@ module Sol
     def ct_type
       get_named_class.single_class.instance_type
     end
-    def to_slot_definition(_)
+    def to_slotted(_)
       return SlotMachine::Slotted.for( get_named_class, [])
     end
     def get_named_class
diff --git a/lib/sol/while_statement.rb b/lib/sol/while_statement.rb
index dbd5123f..59063b21 100644
--- a/lib/sol/while_statement.rb
+++ b/lib/sol/while_statement.rb
@@ -15,7 +15,7 @@ module Sol
       codes = cond_label
       codes << @hoisted.to_slot(compiler) if @hoisted
       codes << @condition.to_slot(compiler) if @condition.is_a?(SendStatement)
-      codes << SlotMachine::TruthCheck.new(condition.to_slot_definition(compiler) , merge_label)
+      codes << SlotMachine::TruthCheck.new(condition.to_slotted(compiler) , merge_label)
       codes << @body.to_slot(compiler)
       codes << SlotMachine::Jump.new(cond_label)
       codes << merge_label
diff --git a/lib/sol/yield_statement.rb b/lib/sol/yield_statement.rb
index be67e0e0..23b6fae9 100644
--- a/lib/sol/yield_statement.rb
+++ b/lib/sol/yield_statement.rb
@@ -49,11 +49,11 @@ module Sol
     def yield_arg_block(compiler)
       arg_index = compiler.get_method.arguments_type.get_length - 1
       setup  = SlotMachine::MessageSetup.new( arg_index )
-      slot_receive = @receiver.to_slot_definition(compiler)
+      slot_receive = @receiver.to_slotted(compiler)
       arg_target = [:message , :next_message ]
       args = []
       @arguments.each_with_index do |arg , index| # +1 because of type
-        args << SlotMachine::SlotLoad.new(self, arg_target + ["arg#{index+1}".to_sym] , arg.to_slot_definition(compiler))
+        args << SlotMachine::SlotLoad.new(self, arg_target + ["arg#{index+1}".to_sym] , arg.to_slotted(compiler))
       end
       setup << SlotMachine::ArgumentTransfer.new( self , slot_receive , args )
       setup << SlotMachine::BlockYield.new( self , arg_index )