Here are all of the testAccess procedures in one file.  
You need to separate them into separate .adb files to play with them
procedure testAccess0 is

type  nodepointer is access onewaylistnode;  
type onewaylistnode is
   record
	   info : integer;  -- could be any type
		next : nodepointer;
   end record;
		
begin
  null;
end;		
      

      **************************

procedure testAccess1 is

type onewaylistnode;   -- incomplete type definition
                       -- required for recursive type
type  nodepointer is access onewaylistnode;  
type onewaylistnode is
   record
	   info : integer;  -- could be any type
		next : nodepointer;
   end record;
		
begin
  null;
end;		


      **************************

-- won't compile
with ada.text_io;
with ada.integer_text_io;
procedure testAccess2 is

type onewaylistnode;   -- incomplete type definition
                       -- required for recursive type
type  nodepointer is access onewaylistnode;  
type onewaylistnode is
   record
	   info : integer;  -- could be any type
		next : nodepointer;
   end record;

  head, tail : onewaylistnode; -- this declares 2 records
begin
  head := new OneWayListNode; -- trying to point to a record
  tail := head;
  head.info := 25;
  ada.integer_text_io.put (head.info);
  ada.integer_text_io.put (tail.info);
  ada.text_io.put (head.next);  -- believe head.next is null & can't print it this way
end;		


      **************************
with ada.text_io;
with ada.integer_text_io;
procedure testAccess3 is

type onewaylistnode;   -- incomplete type definition
                       -- required for recursive type
type  nodepointer is access onewaylistnode;  
type onewaylistnode is
   record
	   info : integer;  -- could be any type
		next : nodepointer;
   end record;

--  head, tail : onewaylistnode;
	 head, tail : nodePointer;	
begin
  head := new OneWayListNode;
  tail := head;
  head.info := 25;
  ada.integer_text_io.put (head.info);
  ada.integer_text_io.put (tail.info);
--  ada.text_io.put (head.next);
  if (head.next = null) then
     ada.text_io.put (" head.next isn't pointing anywhere ");
  end if;
end;		


      **************************
with ada.text_io;
with ada.integer_text_io;
procedure testAccess5 is

type onewaylistnode;   -- incomplete type definition
                       -- required for recursive type
type  nodepointer is access onewaylistnode;  
type onewaylistnode is
   record
	   info : integer;  -- could be any type
		next : nodepointer := null;
   end record;

--  head, tail : onewaylistnode;
	 head, tail, temp, walker : nodePointer;	
begin
  head := new OneWayListNode;
  tail := head;
  head.info := 25;
  ada.integer_text_io.put (head.info);
  ada.integer_text_io.put (tail.info);
   -- getting a new node, inserting a value into it, connecting it to the end of the list
	-- and making the end_of_list_pointer point to that newest node
  temp := new OneWayListNode;
  temp.info := 4;
  tail.next := temp;
  tail := temp;
  
  -- showing the list after two nodes
  ada.text_io.put_line (" here's the list after a second node is inserted ");
  ada.integer_text_io.put (head.info);
  ada.integer_text_io.put (tail.info);

 -- getting a new node, inserting a value into it, connecting it to the end of the list
	-- and making the end_of_list_pointer point to that newest node  
  temp := new OneWayListNode;
  temp.info := 6;
  tail.next := temp;
  tail := temp; 

  -- want to walk through the whole list and print the walues stored
  walker := head; 
  ada.integer_text_io.put( walker.info);
  walker := walker.next;
  ada.integer_text_io.put( walker.info);
  walker := walker.next; 
  ada.integer_text_io.put( walker.info);
  
  
end testAccess5;