error message

File "sreedhar.ml", line 30, characters 62-63:
Error: This expression has type G.V.t but an expression was expected of type
         DJG.V.t
make: *** [sreedhar.cmx] Error 2

ocaml.ml

exception NotComparable                                                            
                                                                                   
module DJEdge =  struct                                                            
  type t = D | J                                                                   
  (* TODO(awreece) Can we avoid needing a comparison function? *)                  
  let compare l r = raise NotComparable                                            
  let default = D                                                                  
end                                                                                
                                                                                   
(* TODO(awreece) Accept a builder parameter? *)                                    
module Make(G : Dominator.G) = struct                                              
  module UF = Graph.Unionfind.Make(G.V)                                            
  module Dom = Dominator.Make(G)
  (*
   * http://ocamlgraph.lri.fr/doc/Imperative.S.AbstractLabeled.html 
   * 
   * module AbstractLabeled: 
   *  functor (V : Sig.ANY_TYPE) -> 
   *    functor (E : Sig.ORDERED_TYPE_DFT) -> Sig.IM  with type V.label = V.t and type E.label = E.t
   *)
  module DJG = Graph.Imperative.Digraph.AbstractLabeled(struct type t = G.V.t end)(DJEdge)
                                                                                   
  let dj_graph cfg s0 =                                                            
    let idom = Dom.compute_idom cfg s0 in                                          
    (* TODO(awreece) I feel like this should ask for s0. *)                        
    let dom_tree:(G.V.t -> G.V.t list) = Dom.idom_to_dom_tree cfg idom in                                
    let graph:(DJG.t) = DJG.create ~size:(G.nb_vertex cfg) () in                           
    let add_d_edge (g:DJG.t) (v:DJG.V.t) (w:DJG.V.t) = DJG.add_edge_e g (DJG.E.create v DJEdge.D w) in 
    let add_d_edges (g:DJG.t) (v:DJG.V.t) (idoms:DJG.V.t list) = List.iter (add_d_edge g v) idoms in
    let () = G.iter_vertex (fun (v:G.V.t) -> add_d_edge graph v (dom_tree v)) cfg in 
    "Let the games begin"                                                          
end