with graph;--allows me access to the spec and body of graph
procedure Graph_Driver0 is

Max_Cities : constant := 20;  -- since cities are my vertices, this refers to the
										-- maximum number of vertices I can have in my graph
type City is (atlanta, boston, cleveland, dallas, great_falls, houston, ithaca, jacksonville,
              kansas_city, lexington, minneapolis, new_york, oswego, princeton, quogue,
				  talahassee, utica, venice, washington, yonkers);  -- enumerated type declaration
				  
subtype Distance is natural;

function cityName(location : in city) return City is
begin
   return location;
end cityName;
				  
package Routes is new graph( vertex_type => city,
									  key_type => city,
									  weight_type => distance,
									  key_of => cityName,
									  "=" => "=");
									  				  	  
myGraph : Routes.Graph_Type(Max_Cities);
leg : Routes.Edge_Type;

begin
Routes.Clear(Graph => myGraph); -- initialize graph to have no nodes and no edges in it
Routes.Add_Vertex (Graph => myGraph, Vertex => new_york);
Routes.Add_Vertex (Graph => myGraph, Vertex => boston);
--leg.from := new_york;
--leg.to := boston;
leg := (from => new_york, to => boston);
Routes.Add_Edge (Graph => myGraph, Edge => leg, weight => 188);

end Graph_Driver0;