diff --git a/src/examples/downloader.ml b/src/examples/downloader.ml
index cc84058..fa9bf0e 100644
--- a/src/examples/downloader.ml
+++ b/src/examples/downloader.ml
@@ -101,7 +101,7 @@ let downloader () =
     let to_loop name_variable t_list =
       loop_while
         (string_matches_any name_variable#get
-           (List.map t_list (fun t -> sprintf "\\.%s$" t.extension)))
+           (List.map t_list ~f:(fun t -> sprintf "\\.%s$" t.extension)))
         ~body:(to_switch name_variable t_list)
 
     let all =
@@ -138,7 +138,7 @@ let downloader () =
         "Download archives and decrypt/unarchive them.\n\
          ./downloader -u URL [-c] [-f <file>] [-t <tmpdir>]"
   in
-  Command_line.parse cli_spec (fun ~anon url all_in_tmp filename_ov tmp_dir ->
+  Command_line.parse cli_spec (fun ~anon:_ url all_in_tmp filename_ov tmp_dir ->
       let current_name = tmp_file ~tmp_dir "current-name" in
       let set_output_of_download () =
         if_seq
diff --git a/src/examples/multigit.ml b/src/examples/multigit.ml
index 910657f..e2dc03b 100644
--- a/src/examples/multigit.ml
+++ b/src/examples/multigit.ml
@@ -282,7 +282,7 @@ Pretty cool, right:
           [ if_seq version
               ~t:[out (sprintf "%s: %s" name version_string) []]
               ~e:
-                [ setenv (str "PAGER") (str "cat")
+                [ setenv ~var:(str "PAGER") (str "cat")
                 ; Elist.iter anon ~f:(fun p -> do_section (p ()))
                 ; if_seq no_config ~t:[]
                     ~e:
@@ -593,7 +593,7 @@ module Meta_repository = struct
     in
     loop []
 
-  let readme_md ~path ~output =
+  let readme_md ~path:_ ~output =
     let o = open_out output in
     let open Format in
     let fmt = formatter_of_out_channel o in
diff --git a/src/examples/service_composer.ml b/src/examples/service_composer.ml
index b20775c..3409978 100644
--- a/src/examples/service_composer.ml
+++ b/src/examples/service_composer.ml
@@ -65,9 +65,7 @@ module Version = struct
                ; tm_mday
                ; tm_mon
                ; tm_year
-               ; tm_wday
-               ; tm_yday
-               ; tm_isdst } ->
+               ; _ } ->
         sprintf "%4d%02d%02d.%02d%02d%02d" (1900 + tm_year) (1 + tm_mon)
           tm_mday tm_hour tm_min tm_sec)
 
@@ -296,7 +294,7 @@ module Manual = struct
 
   let () =
     add
-    @@ from (fun ~root env ->
+    @@ from (fun ~root _ ->
            ksprintf title "%s: Compose Processes With Screen" (pre_title root)
        )
     @ from (fun ~root env ->
@@ -329,7 +327,7 @@ module Manual = struct
               root env.Environment.default_configuration_path )
     @ extended
         ( section "Installation"
-        @ from (fun ~root env ->
+        @ from (fun ~root _ ->
               ksprintf par
                 "Simply copy `%s*` to somewhere in your `$PATH`, the scripts \
                  depend on a reasonably valid version of `/bin/sh` and GNU \
@@ -339,7 +337,7 @@ module Manual = struct
                   "If you are using the code-generator, you can just point \
                    the `--output-path` option at the right directory." ) )
     @ section "Usage"
-    @ from (fun ~root env ->
+    @ from (fun ~root _ ->
           let intro fmt =
             ksprintf
               (ksprintf par
@@ -358,7 +356,7 @@ module Manual = struct
                `%s <command> --help`."
               root root )
     @ section "Screen Session Isolation"
-    @ from (fun ~root env ->
+    @ from (fun ~root _ ->
           ksprintf par
             "`%s` isolates Screen sessions by using their session name." root
           @ ksprintf par
@@ -379,7 +377,7 @@ module Manual = struct
               root )
     @ extended
         ( section "Docker Image For the Generator"
-        @ from (fun ~root env ->
+        @ from (fun ~root:_ _ ->
               let image = "smondet/genspio-doc-dockerfiles:apps406" in
               ksprintf par
                 "If you have [`opam`](https://opam.ocaml.org), setting up the \
@@ -578,7 +576,7 @@ module Manual_script = struct
           & flag ["--no-pager"] ~doc:"Do not use a pager."
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon extended no_pager describe ->
+        parse opts (fun ~anon:_ extended no_pager describe ->
             deal_with_describe describe
               [Manual.output ~root ~env extended ||> pager ~disable:no_pager ()]
         ) )
@@ -591,7 +589,7 @@ module Version_script = struct
     let description = "Show the version information."
   end)
 
-  let make ~env () =
+  let make ~env:_ () =
     Script.make [name] ~description (fun ~root ->
         let open Gedsl in
         let open Command_line in
@@ -600,7 +598,7 @@ module Version_script = struct
           flag ["--extended"; "-X"] ~doc:"Provide extra information"
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon extended describe ->
+        parse opts (fun ~anon:_ extended describe ->
             deal_with_describe describe
               [ if_seq extended
                   ~t:
@@ -617,7 +615,7 @@ module Init_script = struct
   end)
 
   let make ~env () =
-    Script.make ["configuration"; name] ~description (fun ~root ->
+    Script.make ["configuration"; name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -631,7 +629,7 @@ module Init_script = struct
             ~default:(Environment.make_default_screen_name env)
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon screen_name describe ->
+        parse opts (fun ~anon:_ screen_name describe ->
             deal_with_describe describe
               [Environment.init ~screen_name env; say "Done." []] ) )
 end
@@ -644,7 +642,7 @@ module Add_job_script = struct
   end)
 
   let make ~env () =
-    Script.make ["configuration"; name] ~description (fun ~root ->
+    Script.make ["configuration"; name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let default_none = str "--none--" in
@@ -660,7 +658,7 @@ module Add_job_script = struct
                  like `top`)"
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon name shell_command interpreter no_log describe ->
+        parse opts (fun ~anon:_ name shell_command interpreter no_log describe ->
             let jpath = Job.job_path env name in
             deal_with_describe describe
               [ if_then
@@ -689,13 +687,10 @@ module Remove_job_script = struct
   end)
 
   let make ~env () =
-    Script.make ["configuration"; name] ~description (fun ~root ->
+    Script.make ["configuration"; name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
-        let opts =
-          let open Arg in
-          describe_option_and_usage ()
-        in
+        let opts = describe_option_and_usage () in
         parse opts (fun ~anon describe ->
             deal_with_describe describe
               [ Elist.iter anon ~f:(fun name ->
@@ -718,7 +713,7 @@ module Start_script = struct
   end)
 
   let make ~env () =
-    Script.make [name] ~description (fun ~root ->
+    Script.make [name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -777,14 +772,11 @@ module Configuration_display_script = struct
   end)
 
   let make ~env () =
-    Script.make ["configuration"; name] ~description (fun ~root ->
+    Script.make ["configuration"; name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
-        let opts =
-          let open Arg in
-          describe_option_and_usage ()
-        in
-        parse opts (fun ~anon describe ->
+        let opts = describe_option_and_usage () in
+        parse opts (fun ~anon:_ describe ->
             let path = Environment.configuration_path env in
             deal_with_describe describe
               [ say "Configuration path: %s" [path]
@@ -815,14 +807,11 @@ module Configuration_destroy_script = struct
   end)
 
   let make ~env () =
-    Script.make ["configuration"; name] ~description (fun ~root ->
+    Script.make ["configuration"; name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
-        let opts =
-          let open Arg in
-          describe_option_and_usage ()
-        in
-        parse opts (fun ~anon describe ->
+        let opts = describe_option_and_usage () in
+        parse opts (fun ~anon:_ describe ->
             let path = Environment.configuration_path env in
             deal_with_describe describe
               [ say "Configuration path: %s" [path]
@@ -857,7 +846,7 @@ module Attach_script = struct
                   ; fail "STOPPING" ] ] ]
 
   let make ~env () =
-    Script.make [name] ~description (fun ~root ->
+    Script.make [name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -865,7 +854,7 @@ module Attach_script = struct
           flag ["--create"] ~doc:"Create if it doesn't exist."
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon create describe ->
+        parse opts (fun ~anon:_ create describe ->
             deal_with_describe describe [go env create] ) )
 end
 
@@ -877,7 +866,7 @@ module Kill_script = struct
   end)
 
   let make ~env () =
-    Script.make [name] ~description (fun ~root ->
+    Script.make [name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -927,7 +916,7 @@ module Logs_script = struct
   end)
 
   let make ~env () =
-    Script.make [name] ~description (fun ~root ->
+    Script.make [name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -986,7 +975,7 @@ module Status_script = struct
   end)
 
   let make ~env () =
-    Script.make [name] ~description (fun ~root ->
+    Script.make [name] ~description (fun ~root:_ ->
         let open Gedsl in
         let open Command_line in
         let opts =
@@ -994,7 +983,7 @@ module Status_script = struct
           flag ["--short"; "-s"] ~doc:"Don't output a ton of info"
           & describe_option_and_usage ()
         in
-        parse opts (fun ~anon short describe ->
+        parse opts (fun ~anon:_ short describe ->
             let prefix_output = exec ["sed"; "s/^/    |    /"] in
             deal_with_describe describe
               [ if_seq (Screen.is_on env)
@@ -1119,7 +1108,7 @@ module Example_script = struct
                   (List.map example ~f:(fun s ->
                        printf (str "    %s\\n") [str s] )) ]
         in
-        parse opts (fun ~anon run example describe ->
+        parse opts (fun ~anon:_ run example describe ->
             deal_with_describe describe
               [ switch
                   ( List.map [basic env root] ~f:(fun (n, cl) ->
diff --git a/src/examples/vm_tester.ml b/src/examples/vm_tester.ml
index 756229a..024dd05 100644
--- a/src/examples/vm_tester.ml
+++ b/src/examples/vm_tester.ml
@@ -14,11 +14,11 @@ module Shell_script = struct
     let m =
       String.map n ~f:(function
         | ('0' .. '9' | 'a' .. 'z' | 'A' .. 'Z' | '-') as c -> c
-        | other -> '_' )
+        | _ -> '_' )
     in
     String.sub ~index:0 ~length:40 m |> Option.value ~default:m
 
-  let path {name; content} =
+  let path {name; content; _} =
     let hash =
       Marshal.to_string content [] |> Digest.string |> Digest.to_hex
     in
@@ -65,7 +65,6 @@ module Run_environment = struct
       List.map files ~f:(function Http (url, act) as t ->
           let base = local_file_name t in
           let wget =
-            let open Shell_script in
             let open Genspio.EDSL in
             check_sequence
               [ ("mkdir", exec ["mkdir"; "-p"; "_cache"])
@@ -161,7 +160,8 @@ module Run_environment = struct
 
   let start_qemu_vm : t -> Shell_script.t = function
     | { ssh_port
-      ; vm= Qemu_arm {kernel; machine; sd_card; root_device; initrd; _} } ->
+      ; vm= Qemu_arm {kernel; machine; sd_card; root_device; initrd; _}
+      ; _ } ->
         let open Shell_script in
         let open Genspio.EDSL in
         make "Start-qemu-arm"
@@ -187,7 +187,7 @@ module Run_environment = struct
                ; "-append"
                ; sprintf "console=ttyAMA0 verbose debug root=%s" root_device ]
              ))
-    | {ssh_port; vm= Qemu_amd46 {hda; ui}} ->
+    | {ssh_port; vm= Qemu_amd46 {hda; ui}; _} ->
         (* See https://wiki.qemu.org/Hosts/BSD
          qemu-system-x86_64 -m 2048 \
           -hda FreeBSD-11.0-RELEASE-amd64.qcow2 -enable-kvm \
@@ -214,8 +214,7 @@ module Run_environment = struct
                ; "e1000,netdev=mynet0" ] ))
 
   let kill_qemu_vm : t -> Shell_script.t = function
-    | {name} ->
-        let open Shell_script in
+    | {name; _} ->
         let open Genspio.EDSL in
         let pid = get_stdout (exec ["cat"; "qemu.pid"]) in
         Shell_script.(make (sprintf "kill-qemu-%s" name))
@@ -240,8 +239,7 @@ module Run_environment = struct
                    ~e:[printf (string "No PID file") []; exec ["false"]] ) ]
 
   let configure : t -> Shell_script.t = function
-    | {name; local_dependencies} ->
-        let open Shell_script in
+    | {name; local_dependencies; _} ->
         let open Genspio.EDSL in
         let report = tmp_file "configure-report.md" in
         let there_was_a_failure = tmp_file "bool-failure" in
@@ -268,14 +266,14 @@ module Run_environment = struct
              (List.mapi cmds ~f:(fun i c -> (sprintf "config-%s-%d" name i, c)))
 
   let make_dependencies = function
-    | {vm= Qemu_amd46 {hda}} -> File.make_files [hda]
-    | {vm= Qemu_arm {kernel; sd_card; initrd}} ->
+    | {vm= Qemu_amd46 {hda; _}; _} -> File.make_files [hda]
+    | {vm= Qemu_arm {kernel; sd_card; initrd; _}; _} ->
         File.make_files
           ( [kernel; sd_card]
           @ Option.value_map initrd ~default:[] ~f:(fun x -> [x]) )
 
   let setup_dir_content tvm =
-    let {name; root_password; setup; ssh_port; vm} = tvm in
+    let {root_password; setup; ssh_port; _} = tvm in
     let other_files = ref [] in
     let dependencies = make_dependencies tvm in
     let start_deps = List.map dependencies ~f:(fun (base, _, _) -> base) in
@@ -361,7 +359,7 @@ module Run_environment = struct
                 ; List.map
                     ( ("help", Some "Display this help message")
                     :: !help_entries ) ~f:(function
-                    | target, None -> ""
+                    | _, None -> ""
                     | target, Some doc ->
                         sprintf "* `make %s`: %s\n" target doc )
                   |> String.concat ~sep:""
@@ -491,7 +489,7 @@ let () =
   in
   let set_example arg =
     match !example with
-    | Some s -> fail "Too many arguments (%S)!" arg
+    | Some _ -> fail "Too many arguments (%S)!" arg
     | None ->
         example :=
           Some
@@ -535,7 +533,7 @@ let () =
   let usage = sprintf "vm-tester --vm <vm-name> <path>" in
   let anon arg =
     match !path with
-    | Some s -> fail "Too many arguments (%S)!" arg
+    | Some _ -> fail "Too many arguments (%S)!" arg
     | None -> path := Some arg
   in
   Arg.parse args anon usage ;
diff --git a/src/lib/EDSL.ml b/src/lib/EDSL.ml
index 5fbaa9f..49453d8 100644
--- a/src/lib/EDSL.ml
+++ b/src/lib/EDSL.ml
@@ -82,7 +82,7 @@ let switch l =
   let default = ref None in
   let cases =
     List.filter_map l ~f:(function
-      | `Default d when !default <> None ->
+      | `Default _ when !default <> None ->
           failwith "Cannot build switch with >1 defaults"
       | `Default d ->
           default := Some d ;
@@ -122,7 +122,7 @@ let tmp_file ?tmp_dir name : file =
     let clean =
       String.map name ~f:(function
         | ('a' .. 'z' | 'A' .. 'Z' | '0' .. '9' | '_' | '-') as c -> c
-        | other -> '_' )
+        | _ -> '_' )
     in
     Str.concat_list
       [ get_tmp_dir
@@ -132,7 +132,7 @@ let tmp_file ?tmp_dir name : file =
              Digest.(string name |> to_hex)) ]
   in
   let tmp = Str.concat_list [path; string "-tmp"] in
-  object (self)
+  object (_self)
     method get = get_stdout (call [string "cat"; path])
 
     method path = path
@@ -192,7 +192,7 @@ module Command_line = struct
   let parse (options : ('a, unit t) cli_options)
       (action : anon:str list t -> 'a) : unit t =
     let prefix = Common.Unique_name.variable "getopts" in
-    let variable {switches; doc} =
+    let variable {switches; _} =
       sprintf "%s_%s" prefix
         (String.concat ~sep:"" switches |> Digest.string |> Digest.to_hex)
     in
@@ -233,7 +233,7 @@ module Command_line = struct
             f
         | Opt_cons (Opt_string x, more) ->
             let var = variable x in
-            to_init (setenv (string var) x.default) ;
+            to_init (setenv ~var:(string var) x.default) ;
             to_case
               (case
                  (List.fold ~init:(bool false) x.switches ~f:(fun p s ->
@@ -245,7 +245,7 @@ module Command_line = struct
                            (string "ERROR option '%s' requires an argument\\n")
                            [getenv (string "1")]
                        ; fail "Wrong command line" ]
-                     ~e:[setenv (string var) (getenv (string "2"))]
+                     ~e:[setenv ~var:(string var) (getenv (string "2"))]
                  ; exec ["shift"]
                  ; exec ["shift"] ]) ;
             ksprintf to_help "* `%s <string>`: %s"
@@ -254,12 +254,12 @@ module Command_line = struct
             loop (f (string_of_var var)) more
         | Opt_cons (Opt_flag x, more) ->
             let var = variable x in
-            to_init (setenv (string var) (Bool.to_string x.default)) ;
+            to_init (setenv ~var:(string var) (Bool.to_string x.default)) ;
             to_case
               (case
                  (List.fold ~init:(bool false) x.switches ~f:(fun p s ->
                       p ||| Str.equals (string s) (getenv (string "1")) ))
-                 [ setenv (string var) (Bool.to_string (bool true))
+                 [ setenv ~var:(string var) (Bool.to_string (bool true))
                  ; exec ["shift"] ]) ;
             ksprintf to_help "* `%s`: %s"
               (String.concat ~sep:"," x.switches)
@@ -276,7 +276,7 @@ module Command_line = struct
     let while_loop =
       let body =
         let append_anon_arg_to_list =
-          setenv anon_var
+          setenv ~var:anon_var
             ( Elist.append anon (Elist.make [getenv (string "1")])
             |> Elist.serialize_str_list )
         in
@@ -285,7 +285,7 @@ module Command_line = struct
           case
             (List.fold ~init:(bool false) help_switches ~f:(fun p s ->
                  p ||| Str.(str s =$= getenv (str "1")) ))
-            [ setenv help_flag_var (Bool.to_string (bool true))
+            [ setenv ~var:help_flag_var (Bool.to_string (bool true))
             ; byte_array help_msg >> exec ["cat"]
             ; exec ["break"] ]
         in
@@ -313,8 +313,8 @@ module Command_line = struct
       loop_while (bool true) ~body
     in
     seq
-      [ setenv help_flag_var (Bool.to_string (bool false))
-      ; setenv anon_var (Elist.serialize_byte_array_list (Elist.make []))
+      [ setenv ~var:help_flag_var (Bool.to_string (bool false))
+      ; setenv ~var:anon_var (Elist.serialize_byte_array_list (Elist.make []))
       ; seq (List.rev !inits)
       ; while_loop
       ; if_then_else
@@ -380,9 +380,9 @@ let fresh_name suf =
 let sanitize_name n =
   String.map n ~f:(function
     | ('0' .. '9' | 'a' .. 'z' | 'A' .. 'Z' | '-') as c -> c
-    | other -> '_' )
+    | _ -> '_' )
 
-let default_on_failure ~step:(i, u) ~stdout ~stderr =
+let default_on_failure ~step:(i, _) ~stdout ~stderr =
   seq
     [ printf (ksprintf str "Step '%s' FAILED:\\n" i) []
     ; cat_markdown "stdout" stdout
@@ -391,7 +391,7 @@ let default_on_failure ~step:(i, u) ~stdout ~stderr =
 
 let check_sequence ?(verbosity = `Announce ">> ")
     ?(on_failure = default_on_failure)
-    ?(on_success = fun ~step ~stdout ~stderr -> nop) ?(tmpdir = "/tmp") cmds =
+    ?(on_success = fun ~step:_ ~stdout:_ ~stderr:_ -> nop) ?(tmpdir = "/tmp") cmds =
   let tmp_prefix = fresh_name "-cmd" in
   let tmpout which id =
     str
diff --git a/src/lib/EDSL.mli b/src/lib/EDSL.mli
index 9a6f21a..9602f16 100644
--- a/src/lib/EDSL.mli
+++ b/src/lib/EDSL.mli
@@ -15,10 +15,13 @@ type 'a t = 'a Language.t
     to a C-string. *)
 type str = Language.byte_array
 
+type byte_array = Language.byte_array
+type c_string = Language.c_string
+
 (** {3 Literals } *)
 
 val str : string -> str t
-(** Create a {!type:c_string} literal. *)
+(** Create a {!type:byte_array} literal. *)
 
 val string : string -> str t
 (** [string] is an alias for {!function:str}. *)
@@ -60,7 +63,7 @@ val setenv : var:str t -> str t -> unit t
 
     If the [~var] argument is not a valid variable name or if the value does
     not fit in a shell variable (e.g. newlines), behavior is undefined.
-    
+
     Also, the total environment of a UNIX process counts towards the
     total size of the arguments passed on to a sub-process (see
     usually the result of ["getconf ARG_MAX"]). Genspio does not check
@@ -254,7 +257,7 @@ val to_file : int t -> str t -> fd_redirection
 (** Create a file-descriptor to file redirection. *)
 
 val with_redirections : unit t -> fd_redirection list -> unit t
-(** 
+(**
    Run a [unit t] expression after applying a list of file-descriptor
    redirections.
 
@@ -323,7 +326,7 @@ type file =
 val tmp_file : ?tmp_dir:str t -> string -> file
 (** Create a temporary file that may contain arbitrary strings (can be
     used as variable containing [string t] values).
-    
+
     [tmp_file "foo"] points to a path that is a {b function}
     of the string ["foo"]; it does not try to make temporary-files
     unique, on the contrary: two calls to [tmp_file "foo"] ensure that
@@ -334,7 +337,7 @@ val tmp_file : ?tmp_dir:str t -> string -> file
 
 (** Typed command-line parsing for your shell scripts, à la {!Printf.scanf}. *)
 module Command_line : sig
-  (** 
+  (**
 
      Use this module like OCaml's {!Printf.scanf} function.
 
@@ -369,7 +372,7 @@ module Command_line : sig
             string Genspio.EDSL.t -> string Genspio.EDSL.t -> unit Genspio.EDSL.t,
             unit Genspio.EDSL.t)
            Genspio.EDSL.Command_line.cli_options
-          
+
            so the action function (the second argument to parse) must have type:
 
            anon:string list Genspio.EDSL.t ->
@@ -565,7 +568,7 @@ val ensure : string -> condition:bool t -> how:(string * unit t) list -> unit t
 - If [true] do nothing, succeed
 - If [false], run [~how] with {!check_sequence}.
 - Test the condition again, if [true] succeed, if [false] fail.
-    
+
 Failures happen thanks to the !{fail} call.
  *)
 
@@ -641,18 +644,18 @@ module Dispatcher_script : sig
     -> description:string
     -> unit
     -> unit Genspio__Language.t
-  (** 
+  (**
      Make a “toplevel” script that behaves a bit like ["git"] by
      calling [name ^ "-${1}"]. The search for the argument can be
      “hijacked” with the list of [~aliases]; with [~name:"hello"] and
      [~aliases:[str "W", str "wolrd"]], when ["hello W"] is called,
      the generated script with lool for ["hello-world"] in the
      ["$PATH"].
-     
+
      Just like scripts made with {!Script_with_describe}, the
      [~description] argument is used to answer the ["--describe"]
      command line option.
-     
+
      When called without arguments, with ["-h"], ["-help"], or with
      ["--help"], the script lists all the commands it can find and the
      aliases. E.g.:
diff --git a/src/lib/EDSL_v0.ml b/src/lib/EDSL_v0.ml
index ba922a0..d71afa5 100644
--- a/src/lib/EDSL_v0.ml
+++ b/src/lib/EDSL_v0.ml
@@ -20,7 +20,7 @@ let switch l =
   let default = ref None in
   let cases =
     List.filter_map l ~f:(function
-      | `Default d when !default <> None ->
+      | `Default _ when !default <> None ->
           failwith "Cannot build switch with >1 defaults"
       | `Default d ->
           default := Some d ;
@@ -64,7 +64,7 @@ let tmp_file ?tmp_dir name : file =
     let clean =
       String.map name ~f:(function
         | ('a' .. 'z' | 'A' .. 'Z' | '0' .. '9' | '_' | '-') as c -> c
-        | other -> '_' )
+        | _ -> '_' )
     in
     C_string.concat_list
       [ get_tmp_dir
@@ -137,7 +137,7 @@ module Command_line = struct
   let parse (options : ('a, unit t) cli_options)
       (action : anon:c_string list t -> 'a) : unit t =
     let prefix = Common.Unique_name.variable "getopts" in
-    let variable {switches; doc} =
+    let variable {switches; _} =
       sprintf "%s_%s" prefix
         (String.concat ~sep:"" switches |> Digest.string |> Digest.to_hex)
     in
@@ -181,7 +181,7 @@ module Command_line = struct
             f
         | Opt_cons (Opt_string x, more) ->
             let var = variable x in
-            to_init (setenv (string var) x.default) ;
+            to_init (setenv ~var:(string var) x.default) ;
             to_case
               (case
                  (List.fold ~init:(bool false) x.switches ~f:(fun p s ->
@@ -193,7 +193,7 @@ module Command_line = struct
                            (string "ERROR option '%s' requires an argument\\n")
                            [getenv (string "1")]
                        ; fail "Wrong command line" ]
-                     ~e:[setenv (string var) (getenv (string "2"))]
+                     ~e:[setenv ~var:(string var) (getenv (string "2"))]
                  ; exec ["shift"]
                  ; exec ["shift"] ]) ;
             ksprintf to_help "* `%s <string>`: %s"
@@ -202,12 +202,12 @@ module Command_line = struct
             loop (f (string_of_var var)) more
         | Opt_cons (Opt_flag x, more) ->
             let var = variable x in
-            to_init (setenv (string var) (Bool.to_string x.default)) ;
+            to_init (setenv ~var:(string var) (Bool.to_string x.default)) ;
             to_case
               (case
                  (List.fold ~init:(bool false) x.switches ~f:(fun p s ->
                       p ||| C_string.equals (string s) (getenv (string "1")) ))
-                 [ setenv (string var) (Bool.to_string (bool true))
+                 [ setenv ~var:(string var) (Bool.to_string (bool true))
                  ; exec ["shift"] ]) ;
             ksprintf to_help "* `%s`: %s"
               (String.concat ~sep:"," x.switches)
@@ -236,7 +236,7 @@ module Command_line = struct
           case
             (List.fold ~init:(bool false) help_switches ~f:(fun p s ->
                  p ||| C_string.(c_string s =$= getenv (c_string "1")) ))
-            [ setenv help_flag_var (Bool.to_string (bool true))
+            [ setenv ~var:help_flag_var (Bool.to_string (bool true))
             ; byte_array help_msg >> exec ["cat"]
             ; exec ["break"] ]
         in
@@ -264,7 +264,7 @@ module Command_line = struct
       loop_while (bool true) ~body
     in
     seq
-      [ setenv help_flag_var (Bool.to_string (bool false))
+      [ setenv ~var:help_flag_var (Bool.to_string (bool false))
       ; anon_tmp#set (Elist.serialize_byte_array_list (Elist.make []))
       ; seq (List.rev !inits)
       ; while_loop
@@ -331,9 +331,9 @@ let fresh_name suf =
 let sanitize_name n =
   String.map n ~f:(function
     | ('0' .. '9' | 'a' .. 'z' | 'A' .. 'Z' | '-') as c -> c
-    | other -> '_' )
+    | _ -> '_' )
 
-let default_on_failure ~step:(i, u) ~stdout ~stderr =
+let default_on_failure ~step:(i, _) ~stdout ~stderr =
   seq
     [ printf (ksprintf c_string "Step '%s' FAILED:\\n" i) []
     ; cat_markdown "stdout" stdout
@@ -342,7 +342,7 @@ let default_on_failure ~step:(i, u) ~stdout ~stderr =
 
 let check_sequence ?(verbosity = `Announce ">> ")
     ?(on_failure = default_on_failure)
-    ?(on_success = fun ~step ~stdout ~stderr -> nop) ?(tmpdir = "/tmp") cmds =
+    ?(on_success = fun ~step:_ ~stdout:_ ~stderr:_ -> nop) ?(tmpdir = "/tmp") cmds =
   let tmp_prefix = fresh_name "-cmd" in
   let tmpout which id =
     c_string
diff --git a/src/lib/compile.ml b/src/lib/compile.ml
index 3024541..8ddf970 100644
--- a/src/lib/compile.ml
+++ b/src/lib/compile.ml
@@ -1,7 +1,5 @@
 open Common
 
-type 'a t = 'a Language.t
-
 let default_max_argument_length = Some 100_000
 
 module To_posix = struct
@@ -38,7 +36,7 @@ module To_posix = struct
   let failure_to_stderr : death_function =
    fun ~comment_stack msg ->
     let summary s =
-      match String.sub s 0 65 with Some s -> s ^ " …" | None -> s
+      match String.sub s ~index:0 ~length:65 with Some s -> s ^ " …" | None -> s
     in
     let open Format in
     let big_string fmt s = Format.fprintf fmt "@[%s@]" (summary s) in
@@ -74,8 +72,7 @@ module To_posix = struct
     let statement_separator =
       match options.style with `Multi_line -> "\n" | `One_liner -> " ; "
     in
-    let {max_argument_length; print_failure} = options in
-    let open Language in
+    let {max_argument_length; print_failure;_} = options in
     match options.fail_with with
     | `Nothing ->
         to_shell
diff --git a/src/lib/language.ml b/src/lib/language.ml
index 7bd3ee9..76348e5 100644
--- a/src/lib/language.ml
+++ b/src/lib/language.ml
@@ -27,7 +27,7 @@ module Literal = struct
          |'/' | '#' | '@' | '!' | ' ' | '~' | '`' | '\\' | '|' | '?' | '>'
          |'<' | '.' | ',' | ':' | ';' | '{' | '}' | '(' | ')' | '[' | ']' ->
             true
-        | other -> false )
+        | _ -> false )
 
     let impossible_to_escape_for_variable = String.exists ~f:(( = ) '\x00')
   end
@@ -181,9 +181,9 @@ let rec pp : type a. Format.formatter -> a t -> unit =
     | String_to_int i -> pp_fun_call fmt "string-to-int" pp [i]
     | Bool_to_string b -> pp_fun_call fmt "bool-to-string" pp [b]
     | String_to_bool b -> pp_fun_call fmt "string-to-bool" pp [b]
-    | List_to_string (l, f) -> pp_fun_call fmt "list-to-string" pp [l]
+    | List_to_string (l, _) -> pp_fun_call fmt "list-to-string" pp [l]
     (* : 'a list t * ('a t -> byte_array t) -> byte_array t *)
-    | String_to_list (s, f) -> pp_fun_call fmt "string-to-list" pp [s]
+    | String_to_list (s, _) -> pp_fun_call fmt "string-to-list" pp [s]
     | List l -> pp_fun_call fmt "list" pp l
     | C_string_concat t -> pp_fun_call fmt "c-string-concat" pp [t]
     | Byte_array_concat t -> pp_fun_call fmt "byte-array-concat" pp [t]
@@ -277,7 +277,7 @@ module Construct = struct
 
     let ( %%% ) s u = comment s u
 
-    let make_switch : type a.
+    let make_switch :
         (bool t * unit t) list -> default:unit t -> unit t =
      fun conds ~default ->
       List.fold_right conds ~init:default ~f:(fun (x, body) prev ->
diff --git a/src/lib/standard_compiler.ml b/src/lib/standard_compiler.ml
index 99ad815..b37b694 100644
--- a/src/lib/standard_compiler.ml
+++ b/src/lib/standard_compiler.ml
@@ -90,7 +90,7 @@ let error ?code ~comment_backtrace error =
 let pp_error fmt {code; comment_backtrace; error} =
   let open Format in
   let summary s =
-    match String.sub s 0 70 with Some s -> s ^ " …" | None -> s
+    match String.sub s ~index:0 ~length:70 with Some s -> s ^ " …" | None -> s
   in
   let big_string fmt s = fprintf fmt "@[%s@]" (summary s) in
   fprintf fmt "@[<hov 2>" ;
@@ -391,9 +391,9 @@ let rec to_ir : type a. _ -> _ -> a Language.t -> internal_representation =
         | one :: two :: t -> one :: "printf -- ' '" :: build (two :: t)
       in
       seq (build outputs) |> ir_list
-  | List_to_string (l, f) ->
+  | List_to_string (l, _) ->
       continue (Output_as_string (Raw_cmd (None, continue l))) |> ir_octostring
-  | String_to_list (s, f) ->
+  | String_to_list (s, _) ->
       continue s |> expand_octal
       |> sprintf "printf -- '%%s' \"$(%s)\""
       |> ir_list
diff --git a/src/lib/to_slow_flow.ml b/src/lib/to_slow_flow.ml
index 5cc58d9..f4c6f9c 100644
--- a/src/lib/to_slow_flow.ml
+++ b/src/lib/to_slow_flow.ml
@@ -168,12 +168,12 @@ In that case, we compare the octal representations.
   let to_path_argument = function
     | Unit -> assert false
     | Raw_inline s -> s
-    | Literal_value s -> assert false
+    | Literal_value _ -> assert false
     | File f -> Filename.quote f
     | Tmp_file_in_variable f ->
         (* Parameters.(tmp_file_db := f :: !tmp_file_db) ; *)
         sprintf "\"${%s}\"" f
-    | Octal_value_in_variable var -> assert false
+    | Octal_value_in_variable _ -> assert false
 
   (*md
 
@@ -297,7 +297,7 @@ In that case, we compare the octal representations.
     in
     {commands= commands @ morecmds; result= r}
 
-  let return_value_to_bool ~tmp {commands; result} v =
+  let return_value_to_bool ~tmp {commands; _} v =
     { tmp with
       commands=
         tmp.commands @ commands
@@ -391,7 +391,7 @@ let rec to_ir : type a. fail_commands:_ -> tmpdb:_ -> a t -> Script.t =
         | Unit -> assert false
         | Literal_value li when String.exists li ~f:(( = ) '\x00') ->
             fail_commands "Cannot convert literal %S to C-String"
-        | Literal_value li -> []
+        | Literal_value _ -> []
         | File f ->
             [ If_then_else
                 { condition=
@@ -410,7 +410,7 @@ let rec to_ir : type a. fail_commands:_ -> tmpdb:_ -> a t -> Script.t =
                     ksprintf fail_commands
                       "Byte array in $%s cannot be converted to a C-String" v
                 ; block_else= [] } ]
-        | Raw_inline ri -> []
+        | Raw_inline _ -> []
         | Octal_value_in_variable v ->
             [ If_then_else
                 { condition=
@@ -468,7 +468,7 @@ let rec to_ir : type a. fail_commands:_ -> tmpdb:_ -> a t -> Script.t =
             match s.result with
             | Unit -> Script.commands s
             | Raw_inline cmd -> Script.(Raw cmd :: commands s)
-            | other -> assert false )
+            | _ -> assert false )
       in
       Script.unit cmds
   | Not t ->
@@ -610,8 +610,8 @@ let rec to_ir : type a. fail_commands:_ -> tmpdb:_ -> a t -> Script.t =
                           as_arg tmparg ] ) )
           in
           List.concat_map scripts ~f:(fun c -> c.commands) @ echos )
-  | List_to_string (l, f) -> continue l
-  | String_to_list (s, f) -> continue s
+  | List_to_string (l, _) -> continue l
+  | String_to_list (s, _) -> continue s
   | C_string_concat sl ->
       let sl_script = continue sl in
       concat_string_list sl_script
@@ -883,7 +883,7 @@ let test () =
         ]
     ; seq
         [ setenv
-            (C_string.concat_list [c_string "A"; c_string "A"; c_string "A"])
+            ~var:(C_string.concat_list [c_string "A"; c_string "A"; c_string "A"])
             (get_stdout (exec ["echo"; "HELLO WORLD"]) |> Byte_array.to_c)
         ; "Calling a sub-shell with `sh`,\nit should display HELLO WORLD"
           %%% exec ["sh"; "-c"; "echo \"$AAA\""] ]
@@ -896,10 +896,10 @@ let test () =
        let v1 = c_string "V1" in
        let v2 = c_string "V2" in
        seq
-         [ setenv var v1
+         [ setenv ~var v1
          ; loop_seq_while
              C_string.(getenv var =$= v1)
-             [printf (c_string "Iteration\\n") []; setenv var v2] ]) ]
+             [printf (c_string "Iteration\\n") []; setenv ~var v2] ]) ]
   in
   List.iteri exprs ~f:(fun idx expr ->
       let ir = compile expr in
diff --git a/src/lib/transform.ml b/src/lib/transform.ml
index 7ab0747..7331609 100644
--- a/src/lib/transform.ml
+++ b/src/lib/transform.ml
@@ -199,13 +199,13 @@ The `propagator` class inherits from `Visitor.nothing_doer` and overwrites only
  *)
   class propagator ?trace () =
     object (self)
-      inherit Visitor.nothing_doer ?trace () as super
+      inherit Visitor.nothing_doer ?trace () as _super
 
       (*md
 Boolean operators are not commutative, the left side has to be
 evaluated first and may break the execution flow (e.g. with `fail`).
 *)
-      method bool_operator (a, op, b) =
+      method! bool_operator (a, op, b) =
         let ga = self#expression a in
         let gb = self#expression b in
         match (ga, op, gb) with
@@ -219,7 +219,7 @@ literals (all non-literals can be non-deterministic and
 side-effectful).
 
  *)
-      method string_operator (a, op, b) =
+      method! string_operator (a, op, b) =
         let ga = self#expression a in
         let gb = self#expression b in
         match (ga, op, gb) with
@@ -230,7 +230,7 @@ side-effectful).
               | `Eq -> Literal.Bool (sa = sb) )
         | _ -> String_operator (ga, op, gb)
 
-      method returns : type a. expr:a t -> _ =
+      method! returns : type a. expr:a t -> _ =
         fun ~expr ~value ->
           let e = self#expression expr in
           match (e, value) with
@@ -238,7 +238,7 @@ side-effectful).
           | No_op, _ -> Construct.bool false
           | _ -> Returns {expr; value}
 
-      method if_ (c, t, e) =
+      method! if_ (c, t, e) =
         let gc = self#expression c in
         let gt = self#expression t in
         let ge = self#expression e in
@@ -247,28 +247,28 @@ side-effectful).
         | Literal (Literal.Bool false) -> ge
         | _ -> If (gc, gt, ge)
 
-      method while_ ~condition ~body =
+      method! while_ ~condition ~body =
         match self#expression condition with
         | Literal (Literal.Bool false) -> No_op
         | cond -> While {condition= cond; body= self#expression body}
 
-      method not b =
+      method! not b =
         let gb = self#expression b in
         match gb with
         | Literal (Literal.Bool b) -> Literal (Literal.Bool (not b))
         | other -> Not other
 
-      method seq l =
+      method! seq l =
         let transformed =
           List.map ~f:self#expression l |> List.filter ~f:(( <> ) No_op)
         in
         match transformed with [] -> No_op | [one] -> one | l -> Seq l
 
-      method pipe l =
+      method! pipe l =
         let tr = List.map ~f:self#expression l in
         match tr with Pipe l :: more -> Pipe (l @ more) | other -> Pipe other
 
-      method c_string_concat l =
+      method! c_string_concat l =
         let gl = self#expression l in
         match gl with
         | List [] -> Construct.c_string ""
@@ -294,7 +294,7 @@ side-effectful).
             | more -> C_string_concat (List more) )
         | default -> C_string_concat default
 
-      method byte_array_concat l =
+      method! byte_array_concat l =
         let gl = self#expression l in
         match gl with
         | List [] -> Construct.byte_array ""
@@ -315,7 +315,7 @@ side-effectful).
             | more -> Byte_array_concat (List more) )
         | default -> Byte_array_concat default
 
-      method list_append (a, b) =
+      method! list_append (a, b) =
         let la = self#expression a in
         let lb = self#expression b in
         match (la, lb) with
@@ -324,11 +324,11 @@ side-effectful).
         | List lla, List llb -> List (lla @ llb)
         | _, _ -> List_append (la, lb)
 
-      method list_iter (l, f) =
+      method! list_iter (l, f) =
         let gl = self#expression l in
         match gl with List [] -> No_op | _ -> List_iter (gl, f)
 
-      method int_bin_op (a, op, b) =
+      method! int_bin_op (a, op, b) =
         let ga = self#expression a in
         let gb = self#expression b in
         let default = Int_bin_op (ga, op, gb) in
@@ -347,7 +347,7 @@ side-effectful).
           | _ -> default )
         | _ -> default
 
-      method int_bin_comparison (a, op, b) =
+      method! int_bin_comparison (a, op, b) =
         let ga = self#expression a in
         let gb = self#expression b in
         let default = Int_bin_comparison (ga, op, gb) in
@@ -438,7 +438,7 @@ side-effectful).
           [ e 42
           ; loop_seq_while
               ("Comment on the success" %%% succeeds (s 0))
-              [e 1; "Comment on the `setenv`" %%% setenv (string "bouh") expr]
+              [e 1; "Comment on the `setenv`" %%% setenv ~var:(string "bouh") expr]
           ])
     in
     check "deep1"
diff --git a/src/test-lib/test_lib.ml b/src/test-lib/test_lib.ml
index bee7cda..a643849 100644
--- a/src/test-lib/test_lib.ml
+++ b/src/test-lib/test_lib.ml
@@ -118,12 +118,12 @@ let optimize : type a. _ -> a Genspio.Language.t -> _ =
 
   let stderr_path test = sprintf "_log/%s/stderr.txt" @@ unique_name test
 
-  let display_script t = function
-    | Exits {no_trap; name; args; returns; script} ->
+  let display_script _t = function
+    | Exits {script; _} ->
         Genspio.Compile.to_string_hum script
 
   let display_opti_script t = function
-    | Exits {no_trap; name; args; returns; script} ->
+    | Exits {script; _} ->
         List.fold t.optimization_passes ~init:script ~f:(fun prev -> function
           | `Cst_prop -> Genspio.Transform.Constant_propagation.process prev )
         |> Genspio.Compile.to_string_hum
@@ -131,7 +131,7 @@ let optimize : type a. _ -> a Genspio.Language.t -> _ =
   let run_test_script t =
     let test_name = name t in
     function
-    | Exits {no_trap; name; args; returns; script} as test ->
+    | Exits {name; args; returns; _} as test ->
         let fill_result_file which =
           let echos =
             [ sprintf "- Returns $RRR (expected: %d)." returns
@@ -183,7 +183,7 @@ let optimize : type a. _ -> a Genspio.Language.t -> _ =
           else "" )
 
   let script_content t = function
-    | Exits {no_trap; name; args; returns; script} -> (
+    | Exits {no_trap; script; _} -> (
         let script =
           List.fold t.optimization_passes ~init:script ~f:(fun prev -> function
             | `Cst_prop -> Genspio.Transform.Constant_propagation.process prev
@@ -198,7 +198,7 @@ let optimize : type a. _ -> a Genspio.Language.t -> _ =
             |> Format.asprintf "%a\n"
                  Genspio.Compile.To_slow_flow.Script.pp_posix )
 
-  let make_report_path t = "script" // "make_report.sh"
+  let make_report_path _ = "script" // "make_report.sh"
 
   let make_report_content t testlist =
     (let open Genspio.EDSL_v0 in
@@ -369,7 +369,7 @@ module Example = struct
           let fence = String.make 50 '`' in
           ff fmt "%s%s@\n%s@\n%s@\n@\n" fence lang (String.strip code) fence
         in
-        let if_show s f = if List.mem s show then f () else () in
+        let if_show s f = if List.mem s ~set:show then f () else () in
         let try_url =
           let base =
             try Sys.getenv "genspio_demo_url" with _ -> default_demo_url
diff --git a/src/test/main.ml b/src/test/main.ml
index 5f52bb4..dc9e635 100644
--- a/src/test/main.ml
+++ b/src/test/main.ml
@@ -424,7 +424,7 @@ let () =
     exits
       ~name:(sprintf "parse-cli-only-anon-%s" name)
       ~args 0
-      (Command_line.parse spec (fun ~anon one two bone ->
+      (Command_line.parse spec (fun ~anon  _ _ _  ->
            assert_or_fail
              (sprintf "anon-is-anon-%s" name)
              (check_anon anon args) ))
@@ -807,7 +807,7 @@ let () =
 let () =
   add_tests
   @@ List.concat
-       [ exits 2 ~name:"no-trap" Genspio.EDSL.(return 2)
+       [ exits 2 ~name:"no-trap" (return 2)
        (* Dying with error messages does not work without `trap` any more
        (string-schism): *)
        (* exits 2 ~no_trap:true ~name:"no-trap-but-failwith" Genspio.EDSL.( *)
@@ -1101,7 +1101,7 @@ let () =
         ; return 5 ])
   in
   List.concat_mapi ~f:make_int_test
-    [[]; [1]; [3]; [1; 2; 3]; [1; 2; 3; 0]; List.init 42 (fun i -> i)]
+    [[]; [1]; [3]; [1; 2; 3]; [1; 2; 3; 0]; List.init 42 ~f:(fun i -> i)]
 
 let () =
   add_tests
@@ -1299,7 +1299,8 @@ let compilation_error_tests () =
       in
       printf "* %s: %s\n%s\n%!%!"
         (if succ then "SUCCESS" else "FAILURE")
-        (String.sub expr_str 0 60 |> Option.value ~default:expr_str)
+        (String.sub expr_str ~index:0 ~length:60
+         |> Option.value ~default:expr_str)
         res_str ) ;
   List.exists !results ~f:(fun (_, res, _) -> res = false)
 
@@ -1353,7 +1354,6 @@ let () =
     | moar -> failf "Too many arguments: %s" (String.concat ~sep:", " moar)
   in
   Option.iter path_opt ~f:(fun path ->
-      let open Test in
       let testlist =
         List.concat !tests
         |>
@@ -1363,11 +1363,9 @@ let () =
             let matches name = String.index_of_string name ~sub:s <> None in
             fun tests ->
               List.filter tests ~f:(function
-                | Tests.Test_lib.Test.Exits
-                    {no_trap; name; args; returns; script}
-                  when matches name ->
+                | Tests.Test_lib.Test.Exits { name; _} when matches name ->
                     true
-                | other -> false )
+                | _ -> false )
       in
       printf "Testlist: %d\n%!" (List.length testlist) ;
       let testdir =