diff --git a/ChangeLog b/ChangeLog
index 565ee05af..8f8b7268f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -47,6 +47,45 @@ Changelog
   #679
   (Cedric Cellier)
 
+## v2.11.0 (minor release)
+
+This minor release fixes a few bugs or interface mismatch with OCaml stdlib,
+and is compatible with BER MetaOCaml.
+
+This is the last planned release of the v2 series.
+Next planned release (v3.0.0) will introduce some API changes.
+
+Notable changes:
+
+- Add Unix.with_locked_file
+  #904
+  (Simon Cruanes, Cedric Cellier, review by Francois Berenger)
+
+- Build with -strict-sequence
+  #927
+  (Armaël Guéneau, review by Francois Berenger)
+
+- Add Legacy.Result for OCaml >= 4.8.0
+  #913
+  (Cedric Cellier, review by Francois Berenger)
+
+- Remove BatOo
+  #915
+  (Cedric Cellier, review by Francois Berenger)
+
+- Add BatFilename
+  #910
+  (Cedric Cellier, review by Francois Berenger)
+
+- Make batteries usable with BER MetaOCaml
+  #909
+  (Cedric Cellier, review by Francois Berenger and Gabriel Scherer)
+
+- Unix.sleepf is provided across all OCaml versions;
+  previously it was only for OCaml >= 4.03.0
+  #930
+  (Francois Berenger, review by Cedric Cellier)
+
 ## v2.10.0 (minor release)
 
 This minor release adds support for OCaml 4.08.0.
@@ -79,6 +118,10 @@ recommend trying the 'stdcompat' library.
   #891
   (Cedric Cellier, Francois Berenger, Gabriel Scherer)
 
+- added Unix.with_locked_file
+  #904
+  (Cedric Cellier, Francois Berenger)
+
 ## v2.9.0 (minor release)
 
 This minor release adds support for OCaml 4.07.0, as well as a certain
diff --git a/_tags b/_tags
index c74904414..2e8fc763f 100644
--- a/_tags
+++ b/_tags
@@ -12,4 +12,4 @@ true: package(bytes), warn_-3, bin_annot
 <src/batOpaqueInnerSys.*>: opaque
 true: safe_string
 true: no_alias_deps
-
+true: strict_sequence
diff --git a/opam b/opam
index f40435a67..3e0aa5f1f 100644
--- a/opam
+++ b/opam
@@ -9,7 +9,7 @@ authors: "OCaml batteries-included team"
 homepage: "http://batteries.forge.ocamlcore.org/"
 bug-reports: "https://github.com/ocaml-batteries-team/batteries-included/issues"
 dev-repo: "git://github.com/ocaml-batteries-team/batteries-included.git"
-license: "LGPL-2.1+ with OCaml linking exception"
+license: "LGPL-2.1-or-later with OCaml-LGPL-linking-exception"
 doc: "http://ocaml-batteries-team.github.io/batteries-included/hdoc2/"
 build: [
   ["ocaml" "setup.ml" "-configure" "--prefix" prefix]
@@ -18,7 +18,7 @@ build: [
 install: [make "install"]
 remove: ["ocamlfind" "remove" "batteries"]
 depends: [
-  "ocaml" {>= "3.12.1"}
+  "ocaml" {>= "4.00.0" & < "4.10.0"}
   "ocamlfind" {build & >= "1.5.3"}
   "ocamlbuild" {build}
   "qtest" {with-test & >= "2.5"}
diff --git a/setup.ml b/setup.ml
index 8df1e0dde..4dc94f0b1 100644
--- a/setup.ml
+++ b/setup.ml
@@ -1,7 +1,7 @@
 (* setup.ml generated for the first time by OASIS v0.2.0 *)
 
 (* OASIS_START *)
-(* DO NOT EDIT (digest: 8eacb5fc3c01b3f2ec2fa94f8db2c52a) *)
+(* DO NOT EDIT (digest: c538dc9cea7562212bf9319fabb10941) *)
 (*
    Regenerated by OASIS v0.4.11
    Visit http://oasis.forge.ocamlcore.org for more information and
@@ -6742,7 +6742,7 @@ let setup_t =
        {
           oasis_version = "0.4";
           ocaml_version = Some (OASISVersion.VGreaterEqual "3.12.1");
-          version = "2.10.0";
+          version = "2.11.0";
           license =
             OASISLicense.DEP5License
               (OASISLicense.DEP5Unit
@@ -7019,7 +7019,7 @@ let setup_t =
        };
      oasis_fn = Some "_oasis";
      oasis_version = "0.4.11";
-     oasis_digest = Some "\031B\"\198\141\157`Yd\200\159F\169\162\127\022";
+     oasis_digest = Some "\197\026\147\198c\239\0223\026_)\201>2\152\150";
      oasis_exec = None;
      oasis_setup_args = [];
      setup_update = false
diff --git a/src/batBytes.mliv b/src/batBytes.mliv
index 386a7b72f..a5ebb8f9d 100644
--- a/src/batBytes.mliv
+++ b/src/batBytes.mliv
@@ -666,3 +666,5 @@ let s = Bytes.of_string "hello"
 
 ##V<4.4##external unsafe_fill : t -> int -> int -> char -> unit = "caml_fill_string" "noalloc"
 ##V>=4.4##external unsafe_fill:  t -> int -> int -> char -> unit = "caml_fill_bytes" "noalloc"
+
+##V>=4.09##external unsafe_blit_string : string -> int -> bytes -> int -> int -> unit = "caml_blit_string" "noalloc"
diff --git a/src/batFilename.mliv b/src/batFilename.mliv
index 0bcec2e32..8b274755f 100644
--- a/src/batFilename.mliv
+++ b/src/batFilename.mliv
@@ -30,7 +30,7 @@ val parent_dir_name : string
 
 val dir_sep : string
 (** The directory separator (e.g. [/] in Unix).
-   @since NEXT_RELEASE and OCaml 3.11.2 *)
+   @since 2.11.0 and OCaml 3.11.2 *)
 
 val concat : string -> string -> string
 (** [concat dir file] returns a file name that designates file
@@ -73,7 +73,7 @@ val chop_suffix : string -> string -> string
 ##V>=4.8##    this does not match exactly the interpretation of case-insensitive
 ##V>=4.8##    filename equivalence from Windows.
 ##V>=4.8##
-##V>=4.8##    @since NEXT_RELEASE and OCaml 4.08
+##V>=4.8##    @since 2.11.0 and OCaml 4.08
 ##V>=4.8##*)
 
 
@@ -89,7 +89,7 @@ val chop_suffix : string -> string -> string
 ##V>=4.4##    If such a suffix does not exist, [extension name] is the empty
 ##V>=4.4##    string.
 ##V>=4.4##
-##V>=4.4##    @since NEXT_RELEASE and OCaml 4.04
+##V>=4.4##    @since 2.11.0 and OCaml 4.04
 ##V>=4.4##*)
 
 ##V>=4.4##val remove_extension : string -> string
@@ -101,7 +101,7 @@ val chop_suffix : string -> string -> string
 ##V>=4.4##
 ##V>=4.4##    [remove_extension s ^ extension s = s]
 ##V>=4.4##
-##V>=4.4##    @since NEXT_RELEASE and OCaml 4.04
+##V>=4.4##    @since 2.11.0 and OCaml 4.04
 ##V>=4.4##*)
 
 val chop_extension : string -> string
@@ -141,8 +141,10 @@ val temp_file : ?temp_dir: string -> string -> string -> string
 *)
 
 val open_temp_file :
-      ?mode: open_flag list -> ?perms: int -> ?temp_dir: string -> string ->
-      string -> string * out_channel
+          ?mode: open_flag list ->
+##V>4.2## ?perms: int ->
+          ?temp_dir: string -> string ->
+          string -> string * out_channel
 (** Same as {!Filename.temp_file}, but returns both the name of a fresh
    temporary file, and an output channel opened (atomically) on
    this file.  This function is more secure than [temp_file]: there
@@ -150,13 +152,11 @@ val open_temp_file :
    by a symbolic link) before the program opens it.  The optional argument
    [mode] is a list of additional flags to control the opening of the file.
    It can contain one or several of [Open_append], [Open_binary],
-   and [Open_text].  The default is [[Open_text]] (open in text mode). The
-   file is created with permissions [perms] (defaults to readable and
-   writable only by the file owner, [0o600]).
+   and [Open_text].  The default is [[Open_text]] (open in text mode).
+##V>4.2## The file is created with permissions [perms] (defaults to readable and
+##V>4.2## writable only by the file owner, [0o600]).
 
    @raise Sys_error if the file could not be opened.
-   @before 4.03.0 no ?perms optional argument
-   @before 3.11.2 no ?temp_dir optional argument
 *)
 
 ##V>=4.0##val get_temp_dir_name : unit -> string
@@ -166,24 +166,24 @@ val open_temp_file :
 ##V>=4.0##    Under Windows, the value of the [TEMP] environment variable, or "."
 ##V>=4.0##    if the variable is not set.
 ##V>=4.0##    The temporary directory can be changed with {!Filename.set_temp_dir_name}.
-##V>=4.0##    @since NEXT_RELEASE and OCaml 4.00.0
+##V>=4.0##    @since 2.11.0 and OCaml 4.00.0
 ##V>=4.0##*)
 
 ##V>=4.0##val set_temp_dir_name : string -> unit
 ##V>=4.0##(** Change the temporary directory returned by {!Filename.get_temp_dir_name}
 ##V>=4.0##    and used by {!Filename.temp_file} and {!Filename.open_temp_file}.
-##V>=4.0##    @since NEXT_RELEASE and OCaml 4.00.0
+##V>=4.0##    @since 2.11.0 and OCaml 4.00.0
 ##V>=4.0##*)
 
 val temp_dir_name : string
-  [@@ocaml.deprecated "Use Filename.get_temp_dir_name instead"]
+##V>=4.2##  [@@ocaml.deprecated "Use Filename.get_temp_dir_name instead"]
 (** The name of the initial temporary directory:
     Under Unix, the value of the [TMPDIR] environment variable, or "/tmp"
     if the variable is not set.
     Under Windows, the value of the [TEMP] environment variable, or "."
     if the variable is not set.
     @deprecated You should use {!Filename.get_temp_dir_name} instead.
-    @since NEXT_RELEASE and OCaml 3.09.1
+    @since 2.11.0 and OCaml 3.09.1
 *)
 
 val quote : string -> string
@@ -226,9 +226,26 @@ val quote : string -> string
 ##V>4.9##    Raise [Failure] if the command cannot be escaped on the current platform.
 ##V>4.9##*)
 
+##V<4.4## val extension : string -> string
+##V<4.4##(* extension name is the shortest suffix ext of name0 where:
+##V<4.4##
+##V<4.4## - name0 is the longest suffix of name that does not contain a directory separator;
+##V<4.4## - ext starts with a period;
+##V<4.4## - ext is preceded by at least one non-period character in name0.
+##V<4.4## If such a suffix does not exist, extension name is the empty string.
+##V<4.4##
+##V<4.4##   @since 2.11.0 *)
+
+##V<4.4## val remove_extension : string -> string
+##V<4.4##(* Return the given file name without its extension, as defined in
+##V<4.4##   Filename.extension. If the extension is empty, the function returns
+##V<4.4##   the given file name.
+##V<4.4##
+##V<4.4##   @since 2.11.0 *)
+
 val split_extension : string -> string * string
 (** [split_extension s] returns both the filename [s] without its extension
     and its extension in two distinct strings.
     For instance, [split_extension "foo.bar"] returns the pair ["foo",".bar"].
 
-    @since NEXT_RELEASE *)
+    @since 2.11.0 *)
diff --git a/src/batFilename.ml b/src/batFilename.mlv
similarity index 55%
rename from src/batFilename.ml
rename to src/batFilename.mlv
index 82c2e1b12..258808f53 100644
--- a/src/batFilename.ml
+++ b/src/batFilename.mlv
@@ -21,6 +21,37 @@
 
 include Filename
 
+##V<4.4## let is_dir_sep name i =
+##V<4.4##   try
+##V<4.4##     for j = 0 to String.length dir_sep - 1 do
+##V<4.4##       if i + j >= String.length name ||
+##V<4.4##          name.[i + j] != dir_sep.[j] then raise Exit
+##V<4.4##     done;
+##V<4.4##     true
+##V<4.4##   with Exit ->
+##V<4.4##     false
+##V<4.4##
+##V<4.4## let extension_len name =
+##V<4.4##   let rec check i0 i =
+##V<4.4##     if i < 0 || is_dir_sep name i then 0
+##V<4.4##     else if name.[i] = '.' then check i0 (i - 1)
+##V<4.4##     else String.length name - i0
+##V<4.4##   in
+##V<4.4##   let rec search_dot i =
+##V<4.4##     if i < 0 || is_dir_sep name i then 0
+##V<4.4##     else if name.[i] = '.' then check i (i - 1)
+##V<4.4##     else search_dot (i - 1)
+##V<4.4##   in
+##V<4.4##   search_dot (String.length name - 1)
+##V<4.4##
+##V<4.4## let remove_extension name =
+##V<4.4##   let l = extension_len name in
+##V<4.4##   if l = 0 then name else String.sub name 0 (String.length name - l)
+##V<4.4##
+##V<4.4## let extension name =
+##V<4.4##   let l = extension_len name in
+##V<4.4##   if l = 0 then "" else String.sub name (String.length name - l) l
+
 let split_extension s =
   remove_extension s, extension s
 
diff --git a/src/batGc.mliv b/src/batGc.mliv
index de5554e90..3b452135e 100644
--- a/src/batGc.mliv
+++ b/src/batGc.mliv
@@ -356,7 +356,7 @@ val finalise : ('a -> unit) -> 'a -> unit
 ##V>=4.4##    finalisation function attached with `GC.finalise` are always
 ##V>=4.4##    called before the finalisation function attached with `GC.finalise_last`.
 ##V>=4.4##
-##V>=4.4##    @since NEXT_RELEASE and OCaml 4.04
+##V>=4.4##    @since 2.11.0 and OCaml 4.04
 ##V>=4.4##*)
 
 val finalise_release : unit -> unit;;
diff --git a/src/batIO.mli b/src/batIO.mli
index 7a9d3561c..02dd94db3 100644
--- a/src/batIO.mli
+++ b/src/batIO.mli
@@ -951,7 +951,7 @@ module Incubator : sig
       ?last:string ->
       ?sep:string ->
       ?indent:int ->
-      (Format.formatter -> 'a -> 'b) -> Format.formatter -> 'a array -> unit
+      (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a array -> unit
       (** Print the contents of an array, with [first] preceding the first item
           (default: ["\[|"]), [last] following the last item (default: ["|\]"])
           and [sep] separating items (default: ["; "]). A printing function must
@@ -972,7 +972,7 @@ module Incubator : sig
       ?last:string ->
       ?sep:string ->
       ?indent:int ->
-      (Format.formatter -> 'a -> 'b) -> Format.formatter -> 'a BatEnum.t -> unit
+      (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a BatEnum.t -> unit
       (** Print the contents of an enum, with [first] preceding the first item
           (default: [""]), [last] following the last item (default: [""])
           and [sep] separating items (default: [" "]). A printing function must
@@ -992,7 +992,7 @@ module Incubator : sig
       ?last:string ->
       ?sep:string ->
       ?indent:int ->
-      (Format.formatter -> 'a -> 'b) -> Format.formatter -> 'a list -> unit
+      (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a list -> unit
       (** Print the contents of a list, with [first] preceding the first item
           (default: ["\["]), [last] following the last item (default: ["\]"])
           and [sep] separating items (default: ["; "]). A printing function must
diff --git a/src/batInnerPervasives.mlv b/src/batInnerPervasives.mlv
index 7394c6792..088c104a7 100644
--- a/src/batInnerPervasives.mlv
+++ b/src/batInnerPervasives.mlv
@@ -58,7 +58,7 @@ let ok = function
 
 let wrap f x = try Ok (f x) with ex -> Error ex
 
-let forever f x = ignore (while true do f x done)
+let forever f x = ignore (while true do ignore (f x) done)
 
 let ignore_exceptions f x = try ignore (f x) with _ -> ()
 
diff --git a/src/batLazyList.ml b/src/batLazyList.ml
index 6c4fe715e..c5c48e7ac 100644
--- a/src/batLazyList.ml
+++ b/src/batLazyList.ml
@@ -106,7 +106,7 @@ let make n x =
 
 let iter f l =
   let rec aux l = match next l with
-    | Cons (x, t) -> (f x; aux t)
+    | Cons (x, t) -> (ignore (f x); aux t)
     | Nil -> ()
   in aux l
 
diff --git a/src/batList.mliv b/src/batList.mliv
index 560b4db63..1fb2534aa 100644
--- a/src/batList.mliv
+++ b/src/batList.mliv
@@ -299,13 +299,13 @@ val min : 'a list -> 'a
 val sum : int list -> int
 (** [sum l] returns the sum of the integers of [l].
     Returns [0] on the empty list.
-    Note: prior to NEXT_RELEASE, used to raise Invalid_argument on the empty list.
+    Note: prior to 2.11.0, used to raise Invalid_argument on the empty list.
  *)
 
 val fsum : float list -> float
 (** [fsum l] returns the sum of the floats of [l].
     Returns [0.] on the empty list.
-    Note: prior to NEXT_RELEASE, used to raise Invalid_argument on the empty list.
+    Note: prior to 2.11.0, used to raise Invalid_argument on the empty list.
  *)
 
 val favg : float list -> float
diff --git a/src/batPrintexc.mliv b/src/batPrintexc.mliv
index 2ea7f3bf8..0f3e20b91 100644
--- a/src/batPrintexc.mliv
+++ b/src/batPrintexc.mliv
@@ -325,7 +325,7 @@ val print : _ BatInnerIO.output -> exn -> unit
 ##V>=4.4##    raw_backtrace_slot -> raw_backtrace_slot option
 ##V>=4.4##(** [get_raw_backtrace_next_slot slot] returns the next slot inlined, if any.
 ##V>=4.4##
-##V>=4.4##    @since NEXT_RELEASE and OCaml 4.04
+##V>=4.4##    @since 2.11.0 and OCaml 4.04
 ##V>=4.4##*)
 
 
@@ -348,3 +348,17 @@ val print : _ BatInnerIO.output -> exn -> unit
 
 ##V>=4.08##type t = exn = ..
 ##V>=4.08##(** The type of exception values. *)
+
+##V>=4.09##val use_printers: exn -> string option
+##V>=4.09##(** [Printexc.use_printers e] returns [None] if there are no registered
+##V>=4.09##    printers and [Some s] with else as the resulting string otherwise.
+##V>=4.09##
+##V>=4.09##    @since 2.11.0 and OCaml 4.09
+##V>=4.09##*)
+
+##V>=4.09##val to_string_default: exn -> string
+##V>=4.09##(** [Printexc.to_string_default e] returns a string representation of the
+##V>=4.09##    exception [e], ignoring all registered exception printers.
+##V>=4.09##
+##V>=4.09##    @since 2.11.0 and OCaml 4.09
+##V>=4.09##*)
diff --git a/src/batRefList.ml b/src/batRefList.ml
index 36bb5446e..84150b9a4 100644
--- a/src/batRefList.ml
+++ b/src/batRefList.ml
@@ -121,12 +121,12 @@ module Index = struct
 
   let index pred rl =
     let index = ref (-1) in
-    List.find (fun it -> incr index; pred it; ) !rl;
+    ignore (List.find (fun it -> incr index; pred it; ) !rl);
     !index
 
   let index_of rl item =
     let index = ref (-1) in
-    List.find (fun it -> incr index; it = item; ) !rl;
+    ignore (List.find (fun it -> incr index; it = item; ) !rl);
     !index
 
   let at_index rl pos = List.nth !rl pos
diff --git a/src/batString.mliv b/src/batString.mliv
index 70c32e54c..9a79d7293 100644
--- a/src/batString.mliv
+++ b/src/batString.mliv
@@ -745,7 +745,7 @@ val split_on_char: char -> string -> string list
       (String.split_on_char sep s) = s]).
     - No string in the result contains the [sep] character.
 
-    Note: prior to NEXT_RELEASE [split_on_char _ ""] used to return an empty list.
+    Note: prior to 2.11.0 [split_on_char _ ""] used to return an empty list.
     @since 2.5.3
 *)
 
@@ -790,7 +790,8 @@ val nsplit : string -> by:string -> string list
 ##V>=4.2##  [@@ocaml.deprecated "Use split_on_string instead."]
 (** [nsplit s sep] splits the string [s] into a list of strings
     which are separated by [sep] (excluded).
-    [nsplit "" _] returns an empty string.
+    [nsplit "" _] returns a single empty string.
+    Note: prior to 2.11.0 [nsplit "" _] used to return an empty list.
 
     Example: [String.nsplit "abcabcabc" "bc" = ["a"; "a"; "a"; ""]]
 
@@ -829,6 +830,29 @@ val cut_on_char : char -> int -> string -> string
    @since 2.9.0
 *)
 
+val cut_on_char : char -> int -> string -> string
+(**
+   Similar to Unix [cut]. [cut_on_char chr n str] returns the substring of
+   [str] located strictly between the [n]-th occurrence of [chr] and
+   the [n+1]-th one.
+
+   - {b Occurrences of [chr] are numbered from 1}.
+   - If [n = 0], returns the substring from the beginning of
+     [str] to the first occurrence of [chr].
+   - If there are exactly [n] occurrences of [chr] in [str], returns the
+     substring between the last occurrence of [chr] and the end of [str].
+   - These behaviours cumulate: if [n] equals [0] and [chr] is
+     absent from [str], returns the full string [str].
+
+   {b Remark:} [cut_on_char] can return the empty string. Examples of this
+   behaviour are [cut_on_char ',' 1 "foo,,bar"] and [cut_on_char ',' 0 ",foo"].
+
+   @raise Not_found if there are strictly less than [n] occurrences of [chr] in str.
+   @raise Invalid_argument if [n < 0].
+
+   @since 2.9.0
+*)
+
 val join : string -> string list -> string
 (** Same as {!concat} *)
 
diff --git a/src/batSys.mliv b/src/batSys.mliv
index b7a4f9333..7df166a78 100644
--- a/src/batSys.mliv
+++ b/src/batSys.mliv
@@ -29,7 +29,8 @@
     @author David Teller
 *)
 
-val argv : string array
+##V>=4.09##external argv : string array = "%sys_argv"
+##V<4.09##val argv : string array
 (** The command line arguments given to the process.
     The first element is the command name used to invoke the program.
     The following elements are the command-line arguments
diff --git a/src/batUnix.mliv b/src/batUnix.mliv
index 4e7dd990e..017cade4b 100644
--- a/src/batUnix.mliv
+++ b/src/batUnix.mliv
@@ -1041,6 +1041,16 @@ val lockf : file_descr -> lock_command -> int -> unit
     acquired on the specified region, without actually putting a lock.
     It returns immediately if successful, or fails otherwise. *)
 
+val with_locked_file : kind:[`Read|`Write] -> string -> (file_descr -> 'a) -> 'a
+(** [with_locked_file ~kind filename f] puts a lock (using lockf) on the whole
+    file named [filename], calls [f] with the file descriptor, and returns
+    its result after the file is unlocked.
+    The file is opened with permissions matching [kind], and created if it
+    does not exist yet.
+    If [f ()] raises an exception the exception is re-raised after the file
+    is unlocked.
+
+    @param kind specifies whether the lock is read-only or read-write. *)
 
 (** {6 Signals}
     Note: installation of signal handlers is performed via
@@ -1134,10 +1144,10 @@ val alarm : int -> int
 val sleep : int -> unit
 (** Stop execution for the given number of seconds. *)
 
-##V>=4.3##val sleepf : float -> unit
-##V>=4.3##(** Stop execution for the given number of seconds.  Like [sleep],
-##V>=4.3##    but fractions of seconds are supported.
-##V>=4.3##    @since 2.5.0 and OCaml 4.03 *)
+val sleepf : float -> unit
+(** Stop execution for the given number of seconds.  Like [sleep],
+    but fractions of seconds are supported.
+    @since 2.5.0 *)
 
 val times : unit -> process_times
 (** Return the execution times of the process. *)
diff --git a/src/batUnix.mlv b/src/batUnix.mlv
index 19ac50dc4..c17b630d5 100644
--- a/src/batUnix.mlv
+++ b/src/batUnix.mlv
@@ -30,6 +30,37 @@ include Unix
 ##V<4.2##let send_substring = send
 ##V<4.2##let sendto_substring = sendto
 
+##V<4.3##let sleepf (timeout: float): unit =
+##V<4.3##  let elapsed = ref 0.0 in
+##V<4.3##  while !elapsed < timeout do
+##V<4.3##    let start = gettimeofday () in
+##V<4.3##    begin
+##V<4.3##      try ignore(select [] [] [] (timeout -. !elapsed))
+##V<4.3##      with Unix_error(EINTR, _, _) -> ()
+##V<4.3##    end;
+##V<4.3##    let stop = gettimeofday () in
+##V<4.3##    let dt = stop -. start in
+##V<4.3##    elapsed := !elapsed +. dt
+##V<4.3##  done;
+##V<4.3##  ()
+
+(* chronometer is useful to test sleepf *)
+(*$inject
+let chronometer f =
+  let start = gettimeofday () in
+  let res = f () in
+  let stop = gettimeofday () in
+  let dt = stop -. start in
+  (dt, res) ;;
+*)
+
+(* do not underestimate the imprecission of sleepf
+   and so don't be too harsh when testing it *)
+(*$T sleepf
+let dt, _ = chronometer (fun () -> sleepf 0.002) in \
+0.001 <= dt && dt <= 0.003
+*)
+
 let run_and_read cmd =
   (* This code is before the open of BatInnerIO
      to avoid using batteries' wrapped IOs *)
@@ -215,3 +246,26 @@ let is_directory fn = (lstat fn).st_kind = S_DIR
 let rec restart_on_EINTR f x =
   try f x
   with Unix_error(EINTR, _, _) -> restart_on_EINTR f x
+
+(**
+   {6 Locking}
+*)
+
+let with_locked_file ~kind filename f =
+  let perms =
+    [O_CREAT ; match kind with `Read -> O_RDONLY | `Write -> O_RDWR] in
+  let lock_file = openfile filename perms 0o644 in
+  let lock_action = match kind with
+    | `Read -> F_RLOCK
+    | `Write -> F_LOCK
+  in
+  lockf lock_file lock_action 0;
+  BatInnerPervasives.finally
+    (fun () ->
+      (* Although the user might expect EINTR to interrupt locking, we must
+       * not allow such interrupt here since there is no way to restart the
+       * unlock: *)
+      ignore (restart_on_EINTR (lseek lock_file 0) SEEK_SET);
+      restart_on_EINTR (lockf lock_file F_ULOCK) 0;
+      restart_on_EINTR close lock_file)
+    f lock_file
diff --git a/src/batteries.mlv b/src/batteries.mlv
index 37e804185..ecbb5801d 100644
--- a/src/batteries.mlv
+++ b/src/batteries.mlv
@@ -34,7 +34,7 @@ module Legacy = struct
   module Random = Random
   module Scanf = Scanf
   module Set = Set
-  module Sort = Sort
+##V<4.8## module Sort = Sort
   module Stack = Stack
   module StdLabels = StdLabels
   module Stream = Stream