diff --git a/lib/dot_of_tast.ml b/lib/dot_of_tast.ml
index ab0422b..a123df6 100644
--- a/lib/dot_of_tast.ml
+++ b/lib/dot_of_tast.ml
@@ -1,14 +1,111 @@
 open Merlin_kernel
 open Merlin_utils
+open Ocaml_parsing
+open Ocaml_typing
 
 let _ =
   Logs.set_reporter (Logs_fmt.reporter ());
   Logs.set_level (Some Debug)
 
+module F = Fmt
+
 module Log = (val Logs.src_log
                     (Logs.Src.create "dot_of_tast"
                        ~doc:"dot_of_tast.ml logger") : Logs.LOG)
 
+module L = struct
+  let stack = ref []
+  let push l = stack := l :: !stack
+  let peek () = match !stack with [] -> None | x :: _ -> Some x
+  let pop () = match !stack with [] -> () | _ :: xs -> stack := xs
+end
+
+let vertex_attributes = ref (fun _ -> [])
+let edge_attributes = ref (fun _ -> [])
+let graph_name = ref None
+
+module G = Graph.Imperative.Digraph.ConcreteBidirectional (struct
+  type t = string
+
+  let compare = String.compare
+  let equal = String.equal
+  let hash = Hashtbl.hash
+end)
+
+module Dot = Graph.Graphviz.Dot (struct
+  include G
+
+  let edge_attributes k = !edge_attributes k
+  let default_edge_attributes _ = []
+  let vertex_name k = k
+  let vertex_attributes k = !vertex_attributes k
+  let default_vertex_attributes _ = []
+  let get_subgraph _ = None
+
+  let graph_attributes _ =
+    match !graph_name with None -> [] | Some n -> [ `Label n ]
+end)
+
+let str_of_exp (exp : Typedtree.expression) =
+  Fmt.str "%a" Pprintast.expression (Untypeast.untype_expression exp)
+
+let str_of_ident (ident : Ident.t) = Ident.name ident
+
+let pp_value_binding_list ppf (vbl : Typedtree.value_binding list) =
+  Fmt.pf ppf "%a"
+    (Fmt.parens
+       (Fmt.list (fun ppf (ident, _loc, _ty) -> Ident.print ppf ident)))
+    (Typedtree.let_bound_idents_full vbl)
+
+let str_of_primary_value (exp : Typedtree.expression) =
+  match exp.exp_desc with
+  | Texp_ident _ | Texp_constant _ -> str_of_exp exp
+  | Texp_apply (exp, _) -> str_of_exp exp
+  | Texp_function { param; _ } ->
+      Fmt.str "fun %s" (str_of_ident param)
+  | Texp_let (_, vbl, _) -> Fmt.str "let %a" pp_value_binding_list vbl
+  | Texp_ifthenelse (_, _, Some _) -> Fmt.str "if/then/else"
+  | Texp_ifthenelse (_, _, None) -> Fmt.str "if/then"
+  | _ -> "????"
+
+let dot_of_impl (s : Typedtree.structure) : unit =
+  let g = G.create () in
+  let iterator =
+    {
+      Tast_iterator.default_iterator with
+      expr =
+        (fun iter exp ->
+          match exp.exp_desc with
+          | Texp_ident _ | Texp_constant _ | Texp_apply _
+          | Texp_function _ | Texp_let _ | Texp_ifthenelse _ -> (
+              let src = F.str "\"%s\"" (str_of_primary_value exp) in
+              Log.debug (fun m -> m "src: %s" src);
+              L.push (F.str "%s" src);
+              (match exp.exp_desc with
+              | Texp_apply (_exp, list) ->
+                  (* Tast_iterator.default_iterator.expr iter exp *)
+                  (* skip _exp *)
+                  List.iter
+                    (fun (_, o) -> Option.iter (iter.expr iter) o)
+                    list
+              | _ -> Tast_iterator.default_iterator.expr iter exp);
+              L.pop ();
+              match L.peek () with
+              | Some dst ->
+                  Log.debug (fun m -> m "G.add_edge %s %s" src dst);
+                  G.add_edge g src dst
+              | None -> ())
+          | _ ->
+              Tast_iterator.default_iterator.expr iter exp;
+              Log.info (fun m ->
+                  m "dot_of_impl unknown:@ %a" Pprintast.expression
+                    (Untypeast.untype_expression exp)));
+    }
+  in
+  iterator.structure iterator s;
+  Log.info (fun m ->
+      m "dot_of_impl fprint_graph:@ %a" Dot.fprint_graph g)
+
 let merlin_parse str : unit =
   let config, _command_args =
     Mconfig.parse_arguments ~wd:(Sys.getcwd ())
@@ -21,6 +118,14 @@ let merlin_parse str : unit =
   Mpipeline.with_pipeline pipeline @@ fun () ->
   Log.info (fun m -> m "merlin_parse...");
   let typer = Mpipeline.typer_result pipeline in
-  let structure = Mbrowse.of_typedtree (Mtyper.get_typedtree typer) in
-  Log.info (fun m ->
-      m "Mbrowse.print: %s" (Mbrowse.print () structure))
+  let typedtree = Mtyper.get_typedtree typer in
+  let _mbrowse = Mbrowse.of_typedtree typedtree in
+  match typedtree with
+  | `Implementation t ->
+      Log.info (fun m ->
+          m "Untyped:@ %a" Pprintast.structure
+            (Untypeast.untype_structure t));
+      Log.info (fun m ->
+          m "Printtyped:@ %a" Ocaml_typing.Printtyped.implementation t);
+      dot_of_impl t
+  | `Interface _ -> ()
diff --git a/lib/dune b/lib/dune
index 43f003d..088e10f 100644
--- a/lib/dune
+++ b/lib/dune
@@ -9,6 +9,8 @@
    merlin-lib.ocaml_utils
    merlin-lib.ocaml_preprocess
    merlin-lib.ocaml_parsing
-   merlin-lib.ocaml_typing))
+   merlin-lib.ocaml_typing
+   ocamlgraph
+))