diff --git a/ocaml/Block.ml b/ocaml/Block.ml
index a26c1f8..afb181c 100644
--- a/ocaml/Block.ml
+++ b/ocaml/Block.ml
@@ -68,7 +68,7 @@ let dir_name = lazy(
      Lazy.force Qputils.ezfio_filename
   in
   let md5 =
-     Md5.hash ()
+     QmcMd5.hash ()
   in
   List.fold_right ~init:"" ~f:Filename.concat 
     [ ezfio_filename ; "blocks" ; md5 ; Filename.dir_sep ]
@@ -142,7 +142,7 @@ let raw_data ?(locked=true) () =
 
 
 let properties = lazy (
-  let set = Set.empty ~comparator:Comparator.Poly.comparator in
+  let set = Set.Poly.empty in
   List.fold (raw_data ()) ~init:set ~f:(fun s x -> Set.add s x.property)
     |> Set.to_list
 )
diff --git a/ocaml/Launcher.ml b/ocaml/Launcher.ml
index 7b4066d..2c03b70 100644
--- a/ocaml/Launcher.ml
+++ b/ocaml/Launcher.ml
@@ -40,7 +40,7 @@ let create_nodefile () =
   in
 
   let h =
-    Hashtbl.create ~hashable:String.hashable ~size:1000 ()
+    String.Table.create ~size:1000 ()
   in
 
   let in_channel =
diff --git a/ocaml/Md5.ml b/ocaml/QmcMd5.ml
similarity index 100%
rename from ocaml/Md5.ml
rename to ocaml/QmcMd5.ml
diff --git a/ocaml/Qmcchem_dataserver.ml b/ocaml/Qmcchem_dataserver.ml
index 7a62954..1bad1f6 100644
--- a/ocaml/Qmcchem_dataserver.ml
+++ b/ocaml/Qmcchem_dataserver.ml
@@ -59,10 +59,12 @@ let run ?(daemon=true) ezfio_filename =
 
 
 
+(*
   (** Maximum size of the blocks file before compressing *)
   let max_file_size = ref (
     Byte_units.create `Kilobytes 64.)
   in
+*)
 
 
   let hostname =
@@ -781,6 +783,7 @@ let run ?(daemon=true) ezfio_filename =
             | _ -> 
             begin
               Out_channel.flush !block_channel ;
+            (*
               let file_size = 
                 (Unix.stat block_channel_filename_locked).Unix.st_size
                 |> Float.of_int64
@@ -791,6 +794,7 @@ let run ?(daemon=true) ezfio_filename =
                 compress_block_file ();
                 max_file_size := Byte_units.scale file_size 1.2;
               end
+            *)
             end
           end
       done;
diff --git a/ocaml/Qmcchem_debug.ml b/ocaml/Qmcchem_debug.ml
index 887d90d..e04f5f2 100644
--- a/ocaml/Qmcchem_debug.ml
+++ b/ocaml/Qmcchem_debug.ml
@@ -74,7 +74,7 @@ let spec =
 
 
 let command = 
-  Command.basic
+  Command.basic_spec
   ~summary: "Debug ZeroMQ communications"
   ~readme:(fun () -> "Gets debug information from the ZMQ debug sockets.")
   spec
diff --git a/ocaml/Qmcchem_edit.ml b/ocaml/Qmcchem_edit.ml
index 8a757f3..d3f9832 100644
--- a/ocaml/Qmcchem_edit.ml
+++ b/ocaml/Qmcchem_edit.ml
@@ -95,10 +95,10 @@ let create_temp_file ?temp_filename ezfio_filename fields =
 (** Write the input file corresponding to the MD5 key *)
 let write_input_in_ezfio  ezfio_filename  fields =
   let dirname = 
-    Lazy.force  Md5.input_directory
+    Lazy.force  QmcMd5.input_directory
   in
   let temp_filename = 
-    Md5.hash ()
+    QmcMd5.hash ()
     |> Filename.concat  dirname
   in
   let input_filename =
@@ -246,7 +246,7 @@ let run ~c ?f ?t ?l ?m ?e ?et ?s ?ts ?w ?wt ?n ?j ?p ?input ezfio_filename =
   if c then
       begin
         let dirname = 
-          Filename.concat (Filename.concat ezfio_filename "blocks") (Md5.hash ()) 
+          Filename.concat (Filename.concat ezfio_filename "blocks") (QmcMd5.hash ()) 
         in
         let rec clean_dir y =
           match Sys.is_directory y with
@@ -268,7 +268,7 @@ let run ~c ?f ?t ?l ?m ?e ?et ?s ?ts ?w ?wt ?n ?j ?p ?input ezfio_filename =
   ;
 
   Input.validate ();
-  Md5.reset_hash ();
+  QmcMd5.reset_hash ();
   write_input_in_ezfio ezfio_filename fields
 
 
@@ -308,7 +308,7 @@ let spec =
 ;;
 
 let command =
-    Command.basic
+    Command.basic_spec
     ~summary: "Edit input data"
     ~readme:(fun () ->
       "
diff --git a/ocaml/Qmcchem_forwarder.ml b/ocaml/Qmcchem_forwarder.ml
index b5807d3..7e1dd5c 100644
--- a/ocaml/Qmcchem_forwarder.ml
+++ b/ocaml/Qmcchem_forwarder.ml
@@ -20,7 +20,7 @@ let bind_socket ~socket_type ~socket ~address =
 let run ezfio_filename dataserver =
 
   let dataserver_address, dataserver_port =
-    Substring.create ~pos:6 dataserver
+    Substring.create ~pos:6 (Bytes.of_string dataserver)
     |> Substring.to_string
     |> String.lsplit2_exn ~on:':' 
   and qmc = 
diff --git a/ocaml/Qmcchem_info.ml b/ocaml/Qmcchem_info.ml
index a293791..6360c4e 100644
--- a/ocaml/Qmcchem_info.ml
+++ b/ocaml/Qmcchem_info.ml
@@ -20,7 +20,7 @@ let spec =
   +> anon ("ezfio_file" %: string)
 
 let command = 
-    Command.basic
+    Command.basic_spec
     ~summary: "Display info on an EZFIO database"
     ~readme:(fun () ->
       "
diff --git a/ocaml/Qmcchem_md5.ml b/ocaml/Qmcchem_md5.ml
index 2f728cd..4287af9 100644
--- a/ocaml/Qmcchem_md5.ml
+++ b/ocaml/Qmcchem_md5.ml
@@ -5,13 +5,13 @@ let run ?c ?d ~l ~update ezfio_filename =
   Qputils.set_ezfio_filename ezfio_filename;
 
   let input_directory =
-    Lazy.force Md5.input_directory
+    Lazy.force QmcMd5.input_directory
   in
 
   let handle_options () =
 
     let current_md5 = 
-      Md5.hash ()
+      QmcMd5.hash ()
     in
 
     let filename_of_key key = 
@@ -30,9 +30,9 @@ let run ?c ?d ~l ~update ezfio_filename =
           Printf.printf "Updating\n%!" ;
           let update_one old_key =
             Qmcchem_edit.run ~c:false ~input:(filename_of_key old_key) ezfio_filename;
-            Md5.reset_hash ();
+            QmcMd5.reset_hash ();
             let new_key =
-              Md5.hash ()
+              QmcMd5.hash ()
             in
 
             if (old_key <> new_key) then
@@ -118,7 +118,7 @@ let run ?c ?d ~l ~update ezfio_filename =
 
   match (c,d,l,update) with
   | (None,None,false,false) -> 
-      Printf.printf "Current key :\n%s\n" (Md5.hash ())
+      Printf.printf "Current key :\n%s\n" (QmcMd5.hash ())
   | _ -> handle_options ()
 
 
@@ -138,7 +138,7 @@ let spec =
 
 
 let command =
-    Command.basic
+    Command.basic_spec
     ~summary: "Manipulate input MD5 keys"
     ~readme:(fun () ->
       "
diff --git a/ocaml/Qmcchem_result.ml b/ocaml/Qmcchem_result.ml
index ebbb149..3cf9e34 100644
--- a/ocaml/Qmcchem_result.ml
+++ b/ocaml/Qmcchem_result.ml
@@ -258,7 +258,7 @@ let spec =
 ;;
 
 let command =
-    Command.basic
+    Command.basic_spec
     ~summary: "Displays the results computed in an EZFIO directory."
     ~readme:(fun () -> "Displays the results computed in an EZFIO directory.")
     spec
diff --git a/ocaml/Qmcchem_run.ml b/ocaml/Qmcchem_run.ml
index 368695c..fd22d38 100644
--- a/ocaml/Qmcchem_run.ml
+++ b/ocaml/Qmcchem_run.ml
@@ -204,7 +204,7 @@ let spec =
 
 
 let command =
-    Command.basic
+    Command.basic_spec
     ~summary: "Run a calculation"
     ~readme:(fun () ->
       "
diff --git a/ocaml/Qmcchem_stop.ml b/ocaml/Qmcchem_stop.ml
index 2607eac..595084e 100644
--- a/ocaml/Qmcchem_stop.ml
+++ b/ocaml/Qmcchem_stop.ml
@@ -12,7 +12,7 @@ let spec =
   +> anon ("ezfio_file" %: string)
 
 let command = 
-    Command.basic
+    Command.basic_spec
     ~summary: "Stop a running calculation"
     ~readme:(fun () ->
       "
diff --git a/ocaml/Random_variable.ml b/ocaml/Random_variable.ml
index 904caf2..69d39f1 100644
--- a/ocaml/Random_variable.ml
+++ b/ocaml/Random_variable.ml
@@ -344,10 +344,10 @@ let max_block =
 
 
 (** Create a hash table for merging *)
-let create_hash ~hashable ~create_key ?(update_block_id=(fun x->x)) 
+let create_hash ~create_key ?(update_block_id=(fun x->x)) 
     ?(update_value=(fun wc vc wb vb sw -> (wc *. vc +. wb *. vb) /. sw) )
     ?(update_weight=(fun wc wb -> wc +. wb) ) t =
-  let table = Hashtbl.create ~hashable:hashable ()
+  let table = String.Table.create ()
   in
   List.iter t.data ~f:(fun block ->
     let key = create_key block
@@ -405,8 +405,8 @@ let create_hash ~hashable ~create_key ?(update_block_id=(fun x->x))
 
 
 (** Genergic merge function *)
-let merge ~hashable ~create_key ?update_block_id ?update_value ?update_weight t =
-  let table = create_hash ~hashable ~create_key ?update_block_id ?update_value ?update_weight t
+let merge ~create_key ?update_block_id ?update_value ?update_weight t =
+  let table = create_hash ~create_key ?update_block_id ?update_value ?update_weight t
   in
   { property = t.property ;
     data = Hashtbl.to_alist table
@@ -422,14 +422,12 @@ let merge ~hashable ~create_key ?update_block_id ?update_value ?update_weight t
 (** Merge per block id *)
 let merge_per_block_id =
   merge 
-   ~hashable:Int.hashable
-   ~create_key:(fun block -> Block_id.to_int block.Block.block_id)
+   ~create_key:(fun block -> Block_id.to_string block.Block.block_id)
 
 
 (** Merge per compute_node *)
 let merge_per_compute_node =
   merge
-   ~hashable:String.hashable
    ~create_key:(fun block -> 
       Printf.sprintf "%s" 
        (Compute_node.to_string block.Block.compute_node) )
@@ -439,7 +437,6 @@ let merge_per_compute_node =
 (** Merge per Compute_node and PID *)
 let merge_per_compute_node_and_pid =
   merge
-   ~hashable:String.hashable
    ~create_key:(fun block -> 
       Printf.sprintf "%s %10.10d" 
        (Compute_node.to_string block.Block.compute_node)
@@ -450,7 +447,6 @@ let merge_per_compute_node_and_pid =
 (** Merge per Compute_node and BlockId *)
 let merge_per_compute_node_and_block_id =
   merge
-   ~hashable:String.hashable
    ~create_key:(fun block -> 
       Printf.sprintf "%s %10.10d" 
        (Compute_node.to_string block.Block.compute_node)
@@ -481,7 +477,6 @@ let ( /@ ) p f = one_variable_operator p f
 let two_variable_operator ~update_value p1 p2 = 
   merge
   ~update_value
-  ~hashable:String.hashable
   ~create_key:(fun block ->
       Printf.sprintf "%s %10.10d %10.10d" 
        (Compute_node.to_string block.Block.compute_node)
@@ -509,7 +504,6 @@ let ( /! ) = two_variable_operator
 (** Merge two consecutive blocks *)
 let compress =
   merge
-   ~hashable:String.hashable
    ~create_key:(fun block -> 
       Printf.sprintf "%s %10.10d" (Compute_node.to_string block.Block.compute_node)
       (((Block_id.to_int block.Block.block_id)+1)/2))
@@ -522,7 +516,7 @@ let compress =
 
 (** Last value on each compute node (for wall_time) *)
 let max_value_per_compute_node t =
-  let table = Hashtbl.create ~hashable:String.hashable ()
+  let table = String.Table.create ()
   in
   let create_key block =
       Printf.sprintf "%s %10.10d"