diff --git a/ocaml/Block.ml b/ocaml/Block.ml
index 36cb482..1d969aa 100644
--- a/ocaml/Block.ml
+++ b/ocaml/Block.ml
@@ -127,12 +127,11 @@ let update_raw_data ?(locked=true) () =
       with
       | End_of_file -> List.rev accu
     in
-    List.map (fun filename ->
+    List.concat_map (fun filename ->
       let ic = open_in filename in
       let result = aux ic [] in
       close_in ic;
       result ) files
-    |> List.concat
     |> transform [] 
   in
   result
diff --git a/ocaml/Input.ml b/ocaml/Input.ml
index 16c7d94..efd9292 100644
--- a/ocaml/Input.ml
+++ b/ocaml/Input.ml
@@ -840,7 +840,8 @@ end = struct
 
 
   let read () =
-    List.map (fun x -> (x, Property.calc x)) Property.all 
+    List.rev_map (fun x -> (x, Property.calc x)) Property.all 
+    |> List.rev
 
 
   let write l =
@@ -848,17 +849,18 @@ end = struct
 
 
   let to_string l =
-    List.map (fun (x,b) -> 
+    List.rev_map (fun (x,b) -> 
       let ch =
          if b then "X" else " "
       in
       Printf.sprintf "(%s) %s" ch (Property.to_string x)) l
+    |> List.rev
     |> String.concat "\n"
 
 
   let of_string s =
     String.split_on_char '\n' s 
-    |> List.map (fun x ->
+    |> List.rev_map (fun x ->
        let (calc,prop) = 
          String.trim x
          |> String_ext.rsplit2_exn ~on:' '
@@ -874,6 +876,7 @@ end = struct
        in
        (prop, calc)
     )
+    |> List.rev
 
 end
 
diff --git a/ocaml/Message.ml b/ocaml/Message.ml
index a6601ba..1c34cea 100644
--- a/ocaml/Message.ml
+++ b/ocaml/Message.ml
@@ -56,7 +56,8 @@ let create m =
         | (0,tail) -> 
             let result = 
               List.rev accu 
-              |> List.map float_of_string
+              |> List.rev_map float_of_string
+              |> List.rev
               |> Array.of_list
             in
             (result, tail)
diff --git a/ocaml/QmcMd5.ml b/ocaml/QmcMd5.ml
index ee09049..ef70acf 100644
--- a/ocaml/QmcMd5.ml
+++ b/ocaml/QmcMd5.ml
@@ -111,8 +111,8 @@ let hash () =
     in
     let md5_string = 
       files_to_track
-      |> List.map (fun x -> Printf.sprintf "%s/%s" ezfio_filename x)
-      |> List.map hash_file
+      |> List.rev_map (fun x -> Printf.sprintf "%s/%s" ezfio_filename x)
+      |> List.rev_map hash_file
       |> String.concat ""
     in
 
diff --git a/ocaml/Qmcchem_dataserver.ml b/ocaml/Qmcchem_dataserver.ml
index 2d79c3e..0b3fe53 100644
--- a/ocaml/Qmcchem_dataserver.ml
+++ b/ocaml/Qmcchem_dataserver.ml
@@ -231,7 +231,8 @@ let run ?(daemon=true) ezfio_filename =
           Array.map Array.to_list walkers_array
           |> Array.to_list
           |> List.concat
-          |> List.map float_of_string
+          |> List.rev_map float_of_string
+          |> List.rev
         in
         Ezfio.set_electrons_elec_coord_pool (Ezfio.ezfio_array_of_list
           ~rank:3 ~dim:[| elec_num+1 ; 3 ; walk_num_tot |] ~data:walkers_list);
@@ -631,7 +632,8 @@ let run ?(daemon=true) ezfio_filename =
           Unix.gettimeofday ()
         in
         let msg =
-          List.map String.trim raw_msg
+          List.rev_map String.trim raw_msg
+          |> List.rev
           |> Message.create 
         and msg_size =
           List.fold_left (fun accu x -> accu + (String.length x)) 0 raw_msg
@@ -716,7 +718,8 @@ let run ?(daemon=true) ezfio_filename =
           Unix.gettimeofday ()
         in
         let msg =
-          List.map String.trim raw_msg
+          List.rev_map String.trim raw_msg
+          |> List.rev
           |> Message.create 
         and msg_size =
           List.fold_left (fun accu x -> accu + (String.length x)) 0 raw_msg
diff --git a/ocaml/Qmcchem_edit.ml b/ocaml/Qmcchem_edit.ml
index 0258f87..dc700b3 100644
--- a/ocaml/Qmcchem_edit.ml
+++ b/ocaml/Qmcchem_edit.ml
@@ -83,7 +83,7 @@ let create_temp_file ?temp_filename ezfio_filename fields =
     | Some name -> name
   in
   let out_channel = open_out filename in
-  (file_header ezfio_filename) :: (List.map get fields)
+  (file_header ezfio_filename) :: (List.rev @@ List.rev_map get fields)
   |> String.concat "\n"
   |> output_string out_channel
   ; close_out out_channel
@@ -210,10 +210,11 @@ let run ~c ?f ?t ?l ?m ?e ?et ?s ?ts ?w ?wt ?n ?j ?p ?input ezfio_filename =
       in
       let data = 
         ( List.filter (fun x -> Str.string_match re_data x 0) raw_data
-          |> List.map String.trim ) @
+          |> List.rev_map String.trim |> List.rev ) @
         [
         List.filter (fun x -> Str.string_match re_prop x 0) raw_data 
-        |> List.map String.trim
+        |> List.rev_map String.trim
+        |> List.rev
         |> String.concat "\n" ]
       in
       let open Input in
diff --git a/ocaml/Qmcchem_forwarder.ml b/ocaml/Qmcchem_forwarder.ml
index 929356b..acca486 100644
--- a/ocaml/Qmcchem_forwarder.ml
+++ b/ocaml/Qmcchem_forwarder.ml
@@ -309,7 +309,7 @@ let run ezfio_filename dataserver =
                 | head :: tail -> aux (head::header) tail
                 | _            -> failwith "Too many routers in the middle"
               in
-              aux [] (List.map String.trim raw_msg)
+              aux [] (List.rev @@ List.rev_map String.trim raw_msg)
             in
             let handle message =
               match message with
@@ -401,7 +401,7 @@ let run ezfio_filename dataserver =
             | head :: tail -> aux (head::header) tail
             | _            -> failwith "Too many routers in the middle"
           in
-          aux [] (List.map String.trim raw_msg)
+          aux [] (List.rev @@ List.rev_map String.trim raw_msg)
         in
         let handle message =
           match message with
diff --git a/ocaml/Qmcchem_result.ml b/ocaml/Qmcchem_result.ml
index d1abdb0..12aa15d 100644
--- a/ocaml/Qmcchem_result.ml
+++ b/ocaml/Qmcchem_result.ml
@@ -11,7 +11,8 @@ let display_table ~range property =
   and data  = p.Random_variable.data
   in
   let results = 
-  List.map2 (fun (val1, err1) (val2,err2) -> (val1, err1, val2, err2)) conv rconv 
+    List.rev_map2 (fun (val1, err1) (val2,err2) -> (val1, err1, val2, err2)) conv rconv 
+    |> List.rev
   in
   List.iter2 (fun (val1, err1, val2, err2) block ->
      Printf.printf "%10.6f  %10.6f    %10.6f  %10.6f   %10.6f\n"
@@ -116,14 +117,15 @@ let display_histogram ~range property =
   and norm =
     1. /. (sqrt(sigma2 *. 2.*.pi))
   in
-  List.map histo ~f:(fun (x,y) -> 
+  List.rev_map histo ~f:(fun (x,y) -> 
     let g =
       norm *. exp(-.((x-.mu)*.(x-.mu)*.one_over_2sigma2))
     in
     (x,y,g)
   )
-  |>  List.iter ~f:(fun (x,y,g) ->
-      Printf.printf "%16.10f  %16.10f  %16.10f\n" x y g)
+  |> List.rev
+  |> List.iter ~f:(fun (x,y,g) ->
+     Printf.printf "%16.10f  %16.10f  %16.10f\n" x y g)
       *)
 
 
diff --git a/ocaml/Qmcchem_run.ml b/ocaml/Qmcchem_run.ml
index f2201f9..cb0dcf7 100644
--- a/ocaml/Qmcchem_run.ml
+++ b/ocaml/Qmcchem_run.ml
@@ -103,7 +103,8 @@ let full_run ?(start_dataserver=true) ezfio_filename  =
     in
     match launcher
     |> String.split_on_char ' '
-    |> List.map String.trim
+    |> List.rev_map String.trim
+    |> List.rev
     |> List.filter (fun x -> x <> "")
     with
     | launcher_exe::launcher_flags -> 
diff --git a/ocaml/Random_variable.ml b/ocaml/Random_variable.ml
index fb0985a..a4632e1 100644
--- a/ocaml/Random_variable.ml
+++ b/ocaml/Random_variable.ml
@@ -232,7 +232,7 @@ let ave_error { property ; data } =
   in
 
   if (Property.is_scalar property) then
-    List.map (fun x ->
+    List.rev_map (fun x ->
       (Sample.to_float  x.Block.value,
        Weight.to_float  x.Block.weight)
     ) data
@@ -247,7 +247,7 @@ let ave_error { property ; data } =
       in
       let result = 
         Array.init dim (fun idx ->
-          List.map (fun x ->
+          List.rev_map (fun x ->
             (Sample.to_float  ~idx  x.Block.value,
              Weight.to_float        x.Block.weight)
           ) list_of_samples
@@ -429,7 +429,8 @@ let merge ~create_key ?update_block_id ?update_value ?update_weight t =
         if (x>y) then 1
         else if (x<y) then -1
         else 0)
-    |>  List.map (fun (x,y) -> y)
+    |>  List.rev_map (fun (x,y) -> y)
+    |>  List.rev
   }
 
 
@@ -505,7 +506,7 @@ let error_x_over_y = function
 (** Create float, variable operators *)
 let one_variable_operator ~update_value p f = 
     { p with 
-      data = List.map (fun b -> { b with 
+      data = List.rev @@ List.rev_map (fun b -> { b with 
         Block.value = Sample.of_float (update_value (Sample.to_float b.Block.value) ) }
       ) p.data }
 
@@ -594,7 +595,8 @@ let max_value_per_compute_node t =
         if (x>y) then 1
         else if (x<y) then -1
         else 0)
-    |>  List.map (fun (x,y) -> y)
+    |>  List.rev_map (fun (x,y) -> y)
+    |>  List.rev
   }
 
 
@@ -675,7 +677,8 @@ let compress_files () =
          with
          | Not_found -> true
        )
-    |> List.map (fun x -> dir_name^x)
+    |> List.rev_map (fun x -> dir_name^x)
+    |> List.rev
   in
 
   let out_channel_dir = 
@@ -774,11 +777,11 @@ let centered_cumulants { property ; data } =
     |> Average.to_float
   in
   let centered_data =
-     List.map (fun x -> 
+     List.rev_map (fun x -> 
       ( (Weight.to_float x.Block.weight), 
         (Sample.to_float x.Block.value) -. ave )
-      ) 
-     data
+      ) data
+     |> List.rev
   in
   let var  = 
      let (num, denom) = 
@@ -795,11 +798,11 @@ let centered_cumulants { property ; data } =
      let sigma_inv =
        1. /. (sqrt var)
      in
-     List.map (fun x -> 
+     List.rev_map (fun x -> 
       ( (Weight.to_float x.Block.weight), 
         ( (Sample.to_float x.Block.value) -. ave ) *. sigma_inv )
-      ) 
-     data
+      ) data
+     |> List.rev
   in
   let (cum3,cum4) = 
      let (cum3, cum4, denom) =