diff --git a/.gitignore b/.gitignore
index f1914d18..800ae845 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,10 +4,11 @@ _build
 *.native
 *.byte
 .session
-TAGS
 *.docdir
 setup.*
 *.html
 .merlin
 *.install
 .ignore
+_opam
+*.exe
diff --git a/Makefile b/Makefile
index 8e57f6bf..9071a626 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,7 @@ BENCH_TARGETS=run_benchs.exe run_bench_hash.exe
 
 benchs:
 	dune build $(PROMOTE) $(addprefix benchs/, $(BENCH_TARGETS))
+	@for i in $(BENCH_TARGETS) ; do ln -sf _build/default/benchs/$$i ; done
 
 examples:
 	dune build examples/id_sexp.exe
diff --git a/benchs/dune b/benchs/dune
index 374bd297..962fc524 100644
--- a/benchs/dune
+++ b/benchs/dune
@@ -1,9 +1,8 @@
  (executables
   (names run_benchs run_bench_hash run_objsize)
-  (libraries containers containers.data containers.iter
-             containers.thread benchmark gen iter qcheck oseq
+  (libraries containers containers-data
+             containers-thread benchmark gen iter qcheck oseq
              batteries base sek)
   (flags :standard -warn-error -3 -safe-string -color always -open CCShims_)
   (ocamlopt_flags :standard -O3 -color always
-                   -unbox-closures -unbox-closures-factor 20)
-  )
+                   -unbox-closures -unbox-closures-factor 20))
diff --git a/examples/dune b/examples/dune
index 53b04e82..33361d56 100644
--- a/examples/dune
+++ b/examples/dune
@@ -1,9 +1,8 @@
 
 (executable
   (name id_sexp)
-  (libraries containers.sexp)
+  (libraries containers)
   (modules id_sexp)
-  (flags :standard -w +a-4-42-44-48-50-58-32-60@8 -safe-string -color always)
+  (flags :standard -warn-error -a+8 -safe-string -color always)
   (ocamlopt_flags :standard -O3 -color always
-                   -unbox-closures -unbox-closures-factor 20)
-  )
+                   -unbox-closures -unbox-closures-factor 20))
diff --git a/qtest/dune b/qtest/dune
index 163f1066..b3ef0799 100644
--- a/qtest/dune
+++ b/qtest/dune
@@ -14,11 +14,12 @@
   (modes native)
   (modules run_qtest)
   ; disable some warnings in qtests
-  (flags :standard -warn-error -a -w -3-33-35-27-39 -nolabels)
-  (libraries iter gen qcheck containers containers.unix unix uutf))
+  (flags :standard -warn-error -a -w -3-33-35-27-39-50 -nolabels)
+  (libraries iter gen qcheck containers containers.unix unix uutf threads))
 
 (alias
   (name    runtest)
+  (locks ctest)
   (package containers)
   (action  (run ./run_qtest.exe)))
 
@@ -32,12 +33,13 @@
   (modes native)
   (modules run_qtest_data)
   ; disable some warnings in qtests
-  (flags :standard -warn-error -a -w -3-33-35-27-39)
+  (flags :standard -warn-error -a -w -3-33-35-27-39-50)
   (libraries iter gen qcheck containers containers-data))
 
 (alias
   (name    runtest)
   (package containers-data)
+  (locks ctest)
   (action  (run ./run_qtest_data.exe)))
 
 (rule
@@ -50,10 +52,11 @@
   (modes native)
   (modules run_qtest_thread)
   ; disable some warnings in qtests
-  (flags :standard -warn-error -a -w -3-33-35-27-39)
+  (flags :standard -warn-error -a -w -3-33-35-27-39-50)
   (libraries qcheck containers containers-thread iter threads))
 
 (alias
   (name    runtest)
+  (locks ctest)
   (package containers-thread)
   (action  (run ./run_qtest_thread.exe)))
diff --git a/qtest/make.ml b/qtest/make.ml
index 6a5d0c68..edc22068 100644
--- a/qtest/make.ml
+++ b/qtest/make.ml
@@ -18,7 +18,7 @@ let do_not_test file =
   assert (not (is_suffix ~sub:"make.ml" file));
   str_sub ~sub:"Labels.ml" file ||
   is_suffix ~sub:"containers.ml" file ||
-  is_suffix ~sub:"containers_top.ml" file ||
+  is_suffix ~sub:"_top.ml" file ||
   is_suffix ~sub:"mkflags.ml" file ||
   is_suffix ~sub:"mkshims.ml" file ||
   is_suffix ~sub:"unlabel.ml" file ||
diff --git a/src/core/CCArray.ml b/src/core/CCArray.ml
index 2c62aae7..2d593617 100644
--- a/src/core/CCArray.ml
+++ b/src/core/CCArray.ml
@@ -3,8 +3,6 @@
 (** {1 Array utils} *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
-type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a gen = unit -> 'a option
 type 'a equal = 'a -> 'a -> bool
 type 'a ord = 'a -> 'a -> int
@@ -549,7 +547,6 @@ let to_std_seq a =
 *)
 
 let to_iter a k = iter k a
-let to_seq = to_iter
 
 let to_gen a =
   let k = ref 0 in
@@ -561,8 +558,6 @@ let to_gen a =
       Some x
     ) else None
 
-let to_klist a = _to_klist a 0 (Array.length a)
-
 (** {2 Generic Functions} *)
 
 module type MONO_ARRAY = sig
diff --git a/src/core/CCArray.mli b/src/core/CCArray.mli
index bdbb842c..cb6d4bb0 100644
--- a/src/core/CCArray.mli
+++ b/src/core/CCArray.mli
@@ -3,15 +3,10 @@
 
 (** {1 Array utils} *)
 
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
 
-type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a gen = unit -> 'a option
 type 'a equal = 'a -> 'a -> bool
 type 'a ord = 'a -> 'a -> int
@@ -143,27 +138,12 @@ val find_map : ('a -> 'b option) -> 'a t -> 'b option
     @since 1.3, but only
     @since 2.1 with labels *)
 
-val find : ('a -> 'b option) -> 'a t -> 'b option
-(** [find f a] is an alias to {!find_map}.
-    @deprecated since 1.3, use {!find_map} instead.
-    The version with labels is
-    @deprecated since 2.1, use {!find_map} instead. *)
-[@@ocaml.deprecated "use find_map instead"]
-
 val find_map_i : (int -> 'a -> 'b option) -> 'a t -> 'b option
 (** [find_map_i f a] is like {!find_map}, but the index of the element is also passed
     to the predicate function [f].
     @since 1.3, but only
     @since 2.1 with labels *)
 
-val findi : (int -> 'a -> 'b option) -> 'a t -> 'b option
-(** [findi f a] is an alias to {!find_map_i}.
-    @since 0.3.4
-    @deprecated since 1.3, use {!find_map_i} instead.
-    The version with labels is
-    @deprecated since 2.1, use {!find_map_i} instead. *)
-[@@ocaml.deprecated "use find_map_i instead"]
-
 val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx f a] returns [Some (i,x)] where [x] is the [i]-th element of [a],
     and [f x] holds. Otherwise returns [None].
@@ -253,19 +233,9 @@ val to_std_seq : 'a t -> 'a Seq.t
     @since 2.8
 *)
 
-val to_seq : 'a t -> 'a sequence
-(** Same as {!to_iter}.
-    @deprecated use {!to_iter} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
 val to_gen : 'a t -> 'a gen
 (** [to_gen a] returns a [gen] of the elements of an array [a]. *)
 
-val to_klist : 'a t -> 'a klist
-(** [to_klist] returns a [klist] of the elements of an array [a].
-    @deprecated use {!to_std_seq} *)
-[@@ocaml.deprecated "use to_std_seq"]
-
 (** {2 IO} *)
 
 val pp: ?sep:string -> 'a printer -> 'a t printer
diff --git a/src/core/CCArrayLabels.mli b/src/core/CCArrayLabels.mli
index c880fd3c..af596800 100644
--- a/src/core/CCArrayLabels.mli
+++ b/src/core/CCArrayLabels.mli
@@ -2,16 +2,10 @@
 
 (** {1 Array utils} *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
 
-type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a gen = unit -> 'a option
 type 'a equal = 'a -> 'a -> bool
 type 'a ord = 'a -> 'a -> int
@@ -143,27 +137,12 @@ val find_map : f:('a -> 'b option) -> 'a t -> 'b option
     @since 1.3, but only
     @since 2.1 with labels *)
 
-val find : f:('a -> 'b option) -> 'a t -> 'b option
-(** [find ~f a] is an alias to {!find_map}.
-    @deprecated since 1.3, use {!find_map} instead.
-    The version with labels is
-    @deprecated since 2.1, use {!find_map} instead. *)
-[@@ocaml.deprecated "use find_map instead"]
-
 val find_map_i : f:(int -> 'a -> 'b option) -> 'a t -> 'b option
 (** [find_map_i ~f a] is like {!find_map}, but the index of the element is also passed
     to the predicate function [~f].
     @since 1.3, but only
     @since 2.1 with labels *)
 
-val findi : f:(int -> 'a -> 'b option) -> 'a t -> 'b option
-(** [findi ~f a] is an alias to {!find_map_i}.
-    @since 0.3.4
-    @deprecated since 1.3, use {!find_map_i} instead.
-    The version with labels is
-    @deprecated since 2.1, use {!find_map_i} instead. *)
-[@@ocaml.deprecated "use find_map_i instead"]
-
 val find_idx : f:('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx ~f a] returns [Some (i,x)] where [x] is the [i]-th element of [a],
     and [~f x] holds. Otherwise returns [None].
@@ -260,19 +239,9 @@ val to_std_seq : 'a t -> 'a Seq.t
     @since 2.8
 *)
 
-val to_seq : 'a t -> 'a sequence
-(** Same as {!to_iter}.
-    @deprecated use {!to_iter} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
 val to_gen : 'a t -> 'a gen
 (** [to_gen a] returns a [gen] of the elements of an array [a]. *)
 
-val to_klist : 'a t -> 'a klist
-(** [to_klist] returns a [klist] of the elements of an array [a].
-    @deprecated use {!to_std_seq} *)
-[@@ocaml.deprecated "use to_std_seq"]
-
 (** {2 IO} *)
 
 val pp: ?sep:string -> 'a printer -> 'a t printer
diff --git a/src/core/CCBool.ml b/src/core/CCBool.ml
index 227bc3b2..cc2187f9 100644
--- a/src/core/CCBool.ml
+++ b/src/core/CCBool.ml
@@ -25,8 +25,6 @@ let of_int x : t = x<>0
   true (of_int min_int)
 *)
 
-let negate = not
-
 type 'a printer = Format.formatter -> 'a -> unit
 
 let pp = Format.pp_print_bool
diff --git a/src/core/CCBool.mli b/src/core/CCBool.mli
index 078627c8..1208d76d 100644
--- a/src/core/CCBool.mli
+++ b/src/core/CCBool.mli
@@ -18,11 +18,6 @@ val of_int : int -> t
 (** [of_int i] is the same as [i <> 0]
     @since 2.7 *)
 
-val negate : t -> t
-(** Negation on booleans (functional version of [not]).
-    @deprecated since 1.3, simply use {!not} instead. *)
-[@@ocaml.deprecated "use `not` instead"]
-
 type 'a printer = Format.formatter -> 'a -> unit
 
 val pp : t printer
diff --git a/src/core/CCFloat.ml b/src/core/CCFloat.ml
index 3543308f..deb41796 100644
--- a/src/core/CCFloat.ml
+++ b/src/core/CCFloat.ml
@@ -111,7 +111,6 @@ let of_int (a:int) = Stdlib.float_of_int a
 
 let to_string (a:float) = Stdlib.string_of_float a
 let of_string_exn (a:string) = Stdlib.float_of_string a
-let of_string (a:string) = Stdlib.float_of_string a
 let of_string_opt (a:string) =
   try Some (Stdlib.float_of_string a)
   with Failure _ -> None
diff --git a/src/core/CCFloat.mli b/src/core/CCFloat.mli
index 7556a579..cd9503ee 100644
--- a/src/core/CCFloat.mli
+++ b/src/core/CCFloat.mli
@@ -103,12 +103,6 @@ val of_string_exn : string -> t
     @raise Failure in case of failure.
     @since 1.2 *)
 
-val of_string : string -> t
-(** Alias to {!float_of_string}.
-    @deprecated since 1.2, use {!of_string_exn} instead.
-    @raise Failure in case of failure. *)
-[@@ocaml.deprecated "use of_string_exn instead"]
-
 val of_string_opt : string -> t option
 (** @since NEXT_RELEASE *)
 
diff --git a/src/core/CCHashtbl.ml b/src/core/CCHashtbl.ml
index 82669bf0..8b3144bf 100644
--- a/src/core/CCHashtbl.ml
+++ b/src/core/CCHashtbl.ml
@@ -4,7 +4,6 @@
 (** {1 Extension to the standard Hashtbl}  *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 type 'a eq = 'a -> 'a -> bool
 type 'a hash = 'a -> int
 type 'a printer = Format.formatter -> 'a -> unit
@@ -90,12 +89,6 @@ module Poly = struct
     add_std_seq_count tbl i;
     tbl
 
-  let to_seq = to_iter
-  let add_seq = add_iter
-  let of_seq = of_iter
-  let add_seq_count = add_iter_count
-  let of_seq_count = of_iter_count
-
   let to_list tbl =
     Hashtbl.fold
       (fun k v l -> (k,v) :: l)
@@ -213,11 +206,6 @@ module type S = sig
   (** Iterate on bindings in the table.
       @since 2.8 *)
 
-  val to_seq : 'a t -> (key * 'a) sequence
-  (** Iterate on values in the table.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter"]
-
   val add_iter : 'a t -> (key * 'a) iter -> unit
   (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
       @since 2.8 *)
@@ -226,12 +214,6 @@ module type S = sig
   (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
       @since 2.8 *)
 
-  val add_seq : 'a t -> (key * 'a) sequence -> unit
-  (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
-      @since 0.16
-      @deprecated use {!add_iter} or {!add_std_seq} *)
-  [@@ocaml.deprecated "use add_iter or add_std_seq"]
-
   val of_iter : (key * 'a) iter -> 'a t
   (** From the given bindings, added in order.
       @since 2.8 *)
@@ -240,11 +222,6 @@ module type S = sig
   (** From the given bindings, added in order.
       @since 2.8 *)
 
-  val of_seq : (key * 'a) sequence -> 'a t
-  (** From the given bindings, added in order.
-      @deprecated use {!of_iter} or {!of_std_seq} *)
-  [@@ocaml.deprecated "use of_iter or of_std_seq"]
-
   val add_iter_count : int t -> key iter -> unit
   (** [add_iter_count tbl i] increments the count of each element of [i]
       by calling {!incr}. This is useful for counting how many times each
@@ -257,14 +234,6 @@ module type S = sig
       element of [seq] occurs.
       @since 2.8 *)
 
-  val add_seq_count : int t -> key sequence -> unit
-  (** [add_seq_count tbl seq] increments the count of each element of [seq]
-      by calling {!incr}. This is useful for counting how many times each
-      element of [seq] occurs.
-      @since 0.16
-      @deprecated use {!add_iter_count} or {!add_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val of_iter_count : key iter -> int t
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
@@ -273,12 +242,6 @@ module type S = sig
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
 
-  val of_seq_count : key sequence -> int t
-  (** Like {!add_seq_count}, but allocates a new table and returns it.
-      @since 0.16
-      @deprecated use {!of_iter_count} or {!of_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val to_list : 'a t -> (key * 'a) list
   (** List of bindings (order unspecified). *)
 
@@ -420,12 +383,6 @@ module Make(X : Hashtbl.HashedType)
     add_std_seq_count tbl i;
     tbl
 
-  let to_seq = to_iter
-  let add_seq = add_iter
-  let of_seq = of_iter
-  let add_seq_count = add_iter_count
-  let of_seq_count = of_iter_count
-
   let to_list tbl =
     fold
       (fun k v l -> (k,v) :: l)
diff --git a/src/core/CCHashtbl.mli b/src/core/CCHashtbl.mli
index a3f092d8..0f85045c 100644
--- a/src/core/CCHashtbl.mli
+++ b/src/core/CCHashtbl.mli
@@ -5,11 +5,6 @@
 
     @since 0.4 *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -66,11 +61,6 @@ module Poly : sig
   (** Iterate on bindings in the table.
       @since 2.8 *)
 
-  val to_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence
-  (** Iterate on bindings in the table.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter"]
-
   val add_list : ('a, 'b list) Hashtbl.t -> 'a -> 'b -> unit
   (** [add_list tbl x y] adds [y] to the list [x] is bound to. If [x] is
       not bound, it becomes bound to [y].
@@ -84,12 +74,6 @@ module Poly : sig
   (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
       @since 2.8 *)
 
-  val add_seq : ('a,'b) Hashtbl.t -> ('a * 'b) sequence -> unit
-  (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
-      @since 0.16
-      @deprecated use {!add_iter} or {!add_std_seq} *)
-  [@@ocaml.deprecated "use add_iter or add_std_seq"]
-
   val of_iter : ('a * 'b) iter -> ('a,'b) Hashtbl.t
   (** From the given bindings, added in order.
       @since 2.8 *)
@@ -98,11 +82,6 @@ module Poly : sig
   (** From the given bindings, added in order.
       @since 2.8 *)
 
-  val of_seq : ('a * 'b) sequence -> ('a,'b) Hashtbl.t
-  (** From the given bindings, added in order.
-      @deprecated use {!of_iter} or {!of_std_seq} *)
-  [@@ocaml.deprecated "use of_iter or of_std_seq"]
-
   val add_iter_count : ('a, int) Hashtbl.t -> 'a iter -> unit
   (** [add_iter_count tbl i] increments the count of each element of [i]
       by calling {!incr}. This is useful for counting how many times each
@@ -115,14 +94,6 @@ module Poly : sig
       element of [seq] occurs.
       @since 2.8 *)
 
-  val add_seq_count : ('a, int) Hashtbl.t -> 'a sequence -> unit
-  (** [add_seq_count tbl seq] increments the count of each element of [seq]
-      by calling {!incr}. This is useful for counting how many times each
-      element of [seq] occurs.
-      @since 0.16 
-      @deprecated use {!add_iter_count} or {!add_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val of_iter_count : 'a iter -> ('a, int) Hashtbl.t
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
@@ -131,12 +102,6 @@ module Poly : sig
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
 
-  val of_seq_count : 'a sequence -> ('a, int) Hashtbl.t
-  (** Like {!add_seq_count}, but allocates a new table and returns it.
-      @since 0.16
-      @deprecated use {!of_iter_count} or {!of_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val to_list : ('a,'b) Hashtbl.t -> ('a * 'b) list
   (** List of bindings (order unspecified). *)
 
@@ -222,11 +187,6 @@ module type S = sig
   (** Iterate on bindings in the table.
       @since 2.8 *)
 
-  val to_seq : 'a t -> (key * 'a) sequence
-  (** Iterate on values in the table.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter"]
-
   val add_iter : 'a t -> (key * 'a) iter -> unit
   (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
       @since 2.8 *)
@@ -235,12 +195,6 @@ module type S = sig
   (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
       @since 2.8 *)
 
-  val add_seq : 'a t -> (key * 'a) sequence -> unit
-  (** Add the corresponding pairs to the table, using {!Hashtbl.add}.
-      @since 0.16
-      @deprecated use {!add_iter} or {!add_std_seq} *)
-  [@@ocaml.deprecated "use add_iter or add_std_seq"]
-
   val of_iter : (key * 'a) iter -> 'a t
   (** From the given bindings, added in order.
       @since 2.8 *)
@@ -249,11 +203,6 @@ module type S = sig
   (** From the given bindings, added in order.
       @since 2.8 *)
 
-  val of_seq : (key * 'a) sequence -> 'a t
-  (** From the given bindings, added in order.
-      @deprecated use {!of_iter} or {!of_std_seq} *)
-  [@@ocaml.deprecated "use of_iter or of_std_seq"]
-
   val add_iter_count : int t -> key iter -> unit
   (** [add_iter_count tbl i] increments the count of each element of [i]
       by calling {!incr}. This is useful for counting how many times each
@@ -266,14 +215,6 @@ module type S = sig
       element of [seq] occurs.
       @since 2.8 *)
 
-  val add_seq_count : int t -> key sequence -> unit
-  (** [add_seq_count tbl seq] increments the count of each element of [seq]
-      by calling {!incr}. This is useful for counting how many times each
-      element of [seq] occurs.
-      @since 0.16
-      @deprecated use {!add_iter_count} or {!add_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val of_iter_count : key iter -> int t
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
@@ -282,12 +223,6 @@ module type S = sig
   (** Like {!add_seq_count}, but allocates a new table and returns it.
       @since 2.8 *)
 
-  val of_seq_count : key sequence -> int t
-  (** Like {!add_seq_count}, but allocates a new table and returns it.
-      @since 0.16
-      @deprecated use {!of_iter_count} or {!of_std_seq_count} *)
-  [@@ocaml.deprecated "use add_iter_count or add_std_seq_count"]
-
   val to_list : 'a t -> (key * 'a) list
   (** List of bindings (order unspecified). *)
 
diff --git a/src/core/CCHeap.ml b/src/core/CCHeap.ml
index 10bbfcb6..c6a0bfc7 100644
--- a/src/core/CCHeap.ml
+++ b/src/core/CCHeap.ml
@@ -59,7 +59,7 @@ end
 (*$QR & ~count:30
   Q.(list_of_size Gen.(return 1_000) int) (fun l ->
     (* put elements into a heap *)
-    let h = H.of_seq (Iter.of_list l) in
+    let h = H.of_iter (Iter.of_list l) in
     OUnit.assert_equal 1_000 (H.size h);
     let l' = extract_list h in
     is_sorted l'
@@ -70,10 +70,10 @@ end
 (*$QR & ~count:30
   Q.(list_of_size Gen.(return 1_000) int) (fun l ->
     (* put elements into a heap *)
-    let h = H.of_seq (Iter.of_list l) in
+    let h = H.of_iter (Iter.of_list l) in
     let h = H.filter (fun x->x mod 2=0) h in
     OUnit.assert_bool "all odd"
-      (H.to_seq h |> Iter.for_all (fun x -> x mod 2 = 0));
+      (H.to_iter h |> Iter.for_all (fun x -> x mod 2 = 0));
     let l' = extract_list h in
     is_sorted l'
   )
@@ -82,8 +82,8 @@ end
 (*$QR
   Q.(list_of_size Gen.(return 1_000) int) (fun l ->
     (* put elements into a heap *)
-    let h = H.of_seq (Iter.of_list l) in
-    let l' = H.to_seq_sorted h |> Iter.to_list in
+    let h = H.of_iter (Iter.of_list l) in
+    let l' = H.to_iter_sorted h |> Iter.to_list in
     is_sorted l'
   )
 *)
@@ -153,7 +153,7 @@ module type S = sig
 
   (** {2 Conversions}
 
-      The interface of [of_gen], [of_seq], [of_klist]
+      The interface of [of_gen], [of_iter], [of_klist]
       has changed since 0.16 (the old signatures
       are now [add_seq], [add_gen], [add_klist]). *)
 
@@ -180,11 +180,6 @@ module type S = sig
   (** Like {!add_list}.
       @since 2.8 *)
 
-  val add_seq : t -> elt sequence -> t (** @since 0.16 *)
-  (** Like {!add_list}.
-      @deprecated use {!add_iter} or {!add_std_seq} instead *)
-  [@@ocaml.deprecated "use add_iter. For the standard Seq, see {!add_std_seq}"]
-
   val of_iter : elt iter -> t
   (** Build a heap from a given [iter]. Complexity: [O(n log n)].
       @since 2.8 *)
@@ -193,11 +188,6 @@ module type S = sig
   (** Build a heap from a given [Seq.t]. Complexity: [O(n log n)].
       @since 2.8 *)
 
-  val of_seq : elt sequence -> t
-  (** Build a heap from a given [sequence]. Complexity: [O(n log n)].
-      @deprecated use {!of_iter} or {!of_std_seq} instead *)
-  [@@ocaml.deprecated "use of_iter. For the standard Seq, see {!of_std_seq}"]
-
   val to_iter : t -> elt iter
   (** Return a [iter] of the elements of the heap.
       @since 2.8 *)
@@ -206,11 +196,6 @@ module type S = sig
   (** Return a [Seq.t] of the elements of the heap.
       @since 2.8 *)
 
-  val to_seq : t -> elt sequence
-  (** Return a [sequence] of the elements of the heap.
-      @deprecated use {!to_iter} or {!to_std_seq} instead *)
-  [@@ocaml.deprecated "use to_iter. For the standard Seq, see {!to_std_seq}"]
-
   val to_iter_sorted : t -> elt iter
   (** Iterate on the elements, in increasing order.
       @since 2.8 *)
@@ -219,12 +204,6 @@ module type S = sig
   (** Iterate on the elements, in increasing order.
       @since 2.8 *)
 
-  val to_seq_sorted : t -> elt sequence
-  (** Iterate on the elements, in increasing order.
-      @since 1.1
-      @deprecated use {!to_iter_sorted} or {!to_std_seq_sorted} instead *)
-  [@@ocaml.deprecated "use to_iter_sorted or to_std_seq_sorted"]
-
   val add_klist : t -> elt klist -> t (** @since 0.16 *)
 
   val of_klist : elt klist -> t
@@ -418,11 +397,6 @@ module Make(E : PARTIAL_ORD) : S with type elt = E.t = struct
     | None -> Seq.Nil
     | Some (h', x) -> Seq.Cons (x, to_std_seq_sorted h')
 
-  let add_seq = add_iter
-  let of_seq = of_iter
-  let to_seq = to_iter
-  let to_seq_sorted = to_iter_sorted
-
   let rec add_klist h l = match l() with
     | `Nil -> h
     | `Cons (x, l') ->
diff --git a/src/core/CCHeap.mli b/src/core/CCHeap.mli
index e5440ef8..c5a189f5 100644
--- a/src/core/CCHeap.mli
+++ b/src/core/CCHeap.mli
@@ -2,7 +2,7 @@
 (* This file is free software, part of containers. See file "license" for more details. *)
 
 (** {1 Leftist Heaps}
-    
+
     Implementation following Okasaki's book. *)
 
 
@@ -126,11 +126,6 @@ module type S = sig
   (** Like {!add_list}.
       @since 2.8 *)
 
-  val add_seq : t -> elt sequence -> t (** @since 0.16 *)
-  (** Like {!add_list}.
-      @deprecated use {!add_iter} or {!add_std_seq} instead *)
-  [@@ocaml.deprecated "use add_iter. For the standard Seq, see {!add_std_seq}"]
-
   val of_iter : elt iter -> t
   (** Build a heap from a given [iter]. Complexity: [O(n log n)].
       @since 2.8 *)
@@ -139,11 +134,6 @@ module type S = sig
   (** Build a heap from a given [Seq.t]. Complexity: [O(n log n)].
       @since 2.8 *)
 
-  val of_seq : elt sequence -> t
-  (** Build a heap from a given [sequence]. Complexity: [O(n log n)].
-      @deprecated use {!of_iter} or {!of_std_seq} instead *)
-  [@@ocaml.deprecated "use of_iter. For the standard Seq, see {!of_std_seq}"]
-
   val to_iter : t -> elt iter
   (** Return a [iter] of the elements of the heap.
       @since 2.8 *)
@@ -152,11 +142,6 @@ module type S = sig
   (** Return a [Seq.t] of the elements of the heap.
       @since 2.8 *)
 
-  val to_seq : t -> elt sequence
-  (** Return a [sequence] of the elements of the heap.
-      @deprecated use {!to_iter} or {!to_std_seq} instead *)
-  [@@ocaml.deprecated "use to_iter. For the standard Seq, see {!to_std_seq}"]
-
   val to_iter_sorted : t -> elt iter
   (** Iterate on the elements, in increasing order.
       @since 2.8 *)
@@ -165,12 +150,6 @@ module type S = sig
   (** Iterate on the elements, in increasing order.
       @since 2.8 *)
 
-  val to_seq_sorted : t -> elt sequence
-  (** Iterate on the elements, in increasing order.
-      @since 1.1
-      @deprecated use {!to_iter_sorted} or {!to_std_seq_sorted} instead *)
-  [@@ocaml.deprecated "use to_iter_sorted or to_std_seq_sorted"]
-
   val add_klist : t -> elt klist -> t (** @since 0.16 *)
 
   val of_klist : elt klist -> t
diff --git a/src/core/CCIO.ml b/src/core/CCIO.ml
index b13f68b7..54292dd7 100644
--- a/src/core/CCIO.ml
+++ b/src/core/CCIO.ml
@@ -75,8 +75,6 @@ let read_chunks_gen ?(size=1024) ic =
   in
   next
 
-let read_chunks = read_chunks_gen
-
 let read_line ic =
   try Some (input_line ic)
   with End_of_file -> None
@@ -88,8 +86,6 @@ let read_lines_gen ic =
     else try Some (input_line ic)
       with End_of_file -> (stop:=true; None)
 
-let read_lines = read_lines_gen
-
 let read_lines_l ic =
   let l = ref [] in
   try
@@ -200,7 +196,7 @@ let write_lines_l oc l =
       (fun (name, oc) ->
         write_lines oc (Gen.of_list l);
         flush oc;
-        l' := with_in name (fun ic -> read_lines ic |> Gen.to_list);
+        l' := with_in name (fun ic -> read_lines_gen ic |> Gen.to_list);
       ) ();
      String.concat "\n" l = String.concat "\n" !l'
     )
diff --git a/src/core/CCIO.mli b/src/core/CCIO.mli
index f7ec3a3b..e19e1db6 100644
--- a/src/core/CCIO.mli
+++ b/src/core/CCIO.mli
@@ -66,11 +66,6 @@ val with_in : ?mode:int -> ?flags:open_flag list ->
     @raise Sys_error in case of error (same as {!open_in} and {!close_in}).
     @param flags opening flags (default [[Open_text]]). [Open_rdonly] is used in any cases. *)
 
-val read_chunks : ?size:int -> in_channel -> string gen
-(** Read the channel's content into chunks of size [size].
-    @deprecated use {!read_chunks_gen} instead. *)
-[@@ocaml.deprecated "use read_chunks_gen"]
-
 val read_chunks_gen : ?size:int -> in_channel -> string gen
 (** Read the channel's content into chunks of size [size].
     {b NOTE} the generator must be used within the lifetime of the channel,
@@ -80,11 +75,6 @@ val read_line : in_channel -> string option
 (** Read a line from the channel. Returns [None] if the input is terminated.
     The "\n" is removed from the line. *)
 
-val read_lines : in_channel -> string gen
-(** Read all lines. The generator should be traversed only once.
-    @deprecated use {!read_lines_gen} instead. *)
-[@@ocaml.deprecated "use read_lines_gen"]
-
 val read_lines_gen : in_channel -> string gen
 (** Read all lines. The generator should be traversed only once.
     {b NOTE} the generator must be used within the lifetime of the channel,
diff --git a/src/core/CCInt64.ml b/src/core/CCInt64.ml
index 4387dc97..1a769c94 100644
--- a/src/core/CCInt64.ml
+++ b/src/core/CCInt64.ml
@@ -45,11 +45,6 @@ let hash x = Stdlib.abs (to_int x)
 
 (** {2 Conversion} *)
 
-let of_int_exn = of_int
-let of_nativeint_exn = of_nativeint
-let of_int32_exn = of_int32
-let of_float_exn = of_float
-
 let of_string_exn = of_string
 
 let of_string x = try Some (of_string_exn x) with Failure _ -> None
diff --git a/src/core/CCInt64.mli b/src/core/CCInt64.mli
index db2fee87..3cedcc79 100644
--- a/src/core/CCInt64.mli
+++ b/src/core/CCInt64.mli
@@ -115,11 +115,6 @@ val of_int : int -> t
 (** Alias to {!Int64.of_int}.
     NOTE: used to return an option, but the function actually never fails. *)
 
-val of_int_exn : int -> t
-(** Alias to {!Int64.of_int}.
-    @deprecated since 2.1, use {!Int64.of_int} instead. *)
-[@@ocaml.deprecated "use Int64.of_int instead"]
-
 val to_int32 : t -> int32
 (** Convert the given 64-bit integer (type [int64]) to a
     32-bit integer (type [int32]). The 64-bit integer
@@ -130,11 +125,6 @@ val of_int32 : int32 -> t
 (** Alias to {!Int64.of_int32}.
     NOTE: use to return an option, but the function actually never fails. *)
 
-val of_int32_exn : int32 -> t
-(** Alias to {!Int64.of_int32}.
-    @deprecated since 2.1, use {!Int64.of_int32} instead. *)
-[@@ocaml.deprecated "use Int64.of_int32 instead"]
-
 val to_nativeint : t -> nativeint
 (** Convert the given 64-bit integer (type [int64]) to a
     native integer.  On 32-bit platforms, the 64-bit integer
@@ -145,11 +135,6 @@ val of_nativeint : nativeint -> t
 (** Alias to {!Int64.of_nativeint}.
     NOTE: use to return an option, but the function actually never fails. *)
 
-val of_nativeint_exn : nativeint -> t
-(** Alias to {!Int64.of_nativeint}.
-    @deprecated since 2.1, use {!Int64.of_nativeint} instead. *)
-[@@ocaml.deprecated "use Int64.of_nativeint instead"]
-
 val to_float : t -> float
 (** Convert the given 64-bit integer to a floating-point number. *)
 
@@ -161,11 +146,6 @@ val of_float : float -> t
     the number is outside the range \[{!CCInt64.min_int}, {!CCInt64.max_int}\].
     NOTE: used to return an option, but the function never fails. *)
 
-val of_float_exn : float -> t
-(** Alias to {!Int64.of_float}.
-    @deprecated since 2.1, use {!Int64.of_float} instead. *)
-[@@ocaml.deprecated "use Int64.of_float instead"]
-
 val to_string : t -> string
 (** Return the string representation of its argument, in decimal. *)
 
diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index de825357..9d2672dc 100644
--- a/src/core/CCList.ml
+++ b/src/core/CCList.ml
@@ -1666,7 +1666,6 @@ end
 (** {2 Conversions} *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a printer = Format.formatter -> 'a -> unit
@@ -1739,12 +1738,9 @@ let of_std_seq l =
   direct direct_depth_default_ l
 
 (*$Q
-  Q.(list int) (fun l -> of_seq (to_seq l) = l)
+  Q.(list int) (fun l -> of_iter (to_iter l) = l)
 *)
 
-let to_seq = to_iter
-let of_seq = of_iter
-
 let to_gen l =
   let l = ref l in
   fun () ->
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index 1760e678..6f18433d 100644
--- a/src/core/CCList.mli
+++ b/src/core/CCList.mli
@@ -3,11 +3,6 @@
 
 (** {1 Complements to list} *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -727,11 +722,6 @@ val to_std_seq : 'a t -> 'a Seq.t
 (** Return a [Seq.t] of the elements of the list.
     @since 2.8 *)
 
-val to_seq : 'a t -> 'a sequence
-(** Return a [sequence] of the elements of the list.
-    @deprecated use {!to_iter} or {!to_std_seq} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
 val of_iter : 'a iter -> 'a t
 (** Build a list from a given [iter].
     In the result, elements appear in the same order as they did in the source [iter].
@@ -746,12 +736,6 @@ val of_std_seq : 'a Seq.t -> 'a t
     In the result, elements appear in the same order as they did in the source [seq].
     @since 2.8 *)
 
-val of_seq : 'a sequence -> 'a t
-(** Build a list from a given [sequence].
-    In the result, elements appear in the same order as they did in the source [sequence].
-    @deprecated use {!of_iter} or {!of_std_seq} instead *)
-[@@ocaml.deprecated "use of_iter or of_std_seq"]
-
 val to_gen : 'a t -> 'a gen
 (** Return a [gen] of the elements of the list. *)
 
diff --git a/src/core/CCListLabels.mli b/src/core/CCListLabels.mli
index 63a6874d..b9371d7d 100644
--- a/src/core/CCListLabels.mli
+++ b/src/core/CCListLabels.mli
@@ -3,11 +3,6 @@
 
 (** {1 Complements to list} *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -731,11 +726,6 @@ val to_std_seq : 'a t -> 'a Seq.t
 (** Return a [Seq.t] of the elements of the list.
     @since 2.8 *)
 
-val to_seq : 'a t -> 'a sequence
-(** Return a [sequence] of the elements of the list.
-    @deprecated use {!to_iter} or {!to_std_seq} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
 val of_iter : 'a iter -> 'a t
 (** Build a list from a given [iter].
     In the result, elements appear in the same order as they did in the source [iter].
@@ -750,12 +740,6 @@ val of_std_seq : 'a Seq.t -> 'a t
     In the result, elements appear in the same order as they did in the source [seq].
     @since 2.8 *)
 
-val of_seq : 'a sequence -> 'a t
-(** Build a list from a given [sequence].
-    In the result, elements appear in the same order as they did in the source [sequence].
-    @deprecated use {!of_iter} or {!of_std_seq} instead *)
-[@@ocaml.deprecated "use of_iter or of_std_seq"]
-
 val to_gen : 'a t -> 'a gen
 (** Return a [gen] of the elements of the list. *)
 
diff --git a/src/core/CCMap.ml b/src/core/CCMap.ml
index d58bc078..31b0260e 100644
--- a/src/core/CCMap.ml
+++ b/src/core/CCMap.ml
@@ -4,7 +4,6 @@
 (** {1 Extensions of Standard Map} *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 type 'a printer = Format.formatter -> 'a -> unit
 
 module type OrderedType = Map.OrderedType
@@ -81,20 +80,6 @@ module type S = sig
   (** Like {!to_list}.
       @since 2.8 *)
 
-  val of_seq : (key * 'a) sequence -> 'a t
-  (** Like {!of_list}.
-      @deprecated use {!of_iter} instead. *)
-  [@@ocaml.deprecated "use of_iter instead"]
-
-  val add_seq : 'a t -> (key * 'a) sequence -> 'a t
-  (** @since 0.14
-      @deprecated use {!add_iter} instead. *)
-  [@@ocaml.deprecated "use add_iter instead"]
-
-  val to_seq : 'a t -> (key * 'a) sequence
-  (** @deprecated use {!to_iter} instead. *)
-  [@@ocaml.deprecated "use to_iter instead"]
-
   val of_list : (key * 'a) list -> 'a t
   (** Build a map from the given list of bindings [k_i -> v_i],
       added in order using {!add}.
@@ -225,10 +210,6 @@ module Make(O : Map.OrderedType) = struct
   let to_iter m yield =
     iter (fun k v -> yield (k,v)) m
 
-  let add_seq = add_iter
-  let of_seq = of_iter
-  let to_seq = to_iter
-
   let keys m yield =
     iter (fun k _ -> yield k) m
 
diff --git a/src/core/CCMap.mli b/src/core/CCMap.mli
index 5a8f8418..10cefc13 100644
--- a/src/core/CCMap.mli
+++ b/src/core/CCMap.mli
@@ -6,11 +6,6 @@
     Provide useful functions and iterators on [Map.S]
     @since 0.5 *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -92,20 +87,6 @@ module type S = sig
   (** Like {!to_list}.
       @since 2.8 *)
 
-  val of_seq : (key * 'a) sequence -> 'a t
-  (** Like {!of_list}.
-      @deprecated use {!of_iter} instead. *)
-  [@@ocaml.deprecated "use of_iter instead"]
-
-  val add_seq : 'a t -> (key * 'a) sequence -> 'a t
-  (** @since 0.14
-      @deprecated use {!add_iter} instead. *)
-  [@@ocaml.deprecated "use add_iter instead"]
-
-  val to_seq : 'a t -> (key * 'a) sequence
-  (** @deprecated use {!to_iter} instead. *)
-  [@@ocaml.deprecated "use to_iter instead"]
-
   val of_list : (key * 'a) list -> 'a t
   (** Build a map from the given list of bindings [k_i -> v_i],
       added in order using {!add}.
diff --git a/src/core/CCOpt.ml b/src/core/CCOpt.ml
index c6f5ea8c..18a6607b 100644
--- a/src/core/CCOpt.ml
+++ b/src/core/CCOpt.ml
@@ -177,7 +177,7 @@ end
 
 include Infix
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Format.formatter -> 'a -> unit
 type 'a random_gen = Random.State.t -> 'a
@@ -187,7 +187,7 @@ let random g st =
 
 exception ExitChoice
 
-let choice_seq s =
+let choice_iter s =
   let r = ref None in
   begin try
       s (function
@@ -199,9 +199,20 @@ let choice_seq s =
   !r
 
 (*$T
-  choice_seq (Iter.of_list [None; Some 1; Some 2]) = Some 1
-  choice_seq Iter.empty = None
-  choice_seq (Iter.repeat None |> Iter.take 100) = None
+  choice_iter (Iter.of_list [None; Some 1; Some 2]) = Some 1
+  choice_iter Iter.empty = None
+  choice_iter (Iter.repeat None |> Iter.take 100) = None
+*)
+
+let rec choice_seq s = match s() with
+  | Seq.Nil -> None
+  | Seq.Cons (Some x, _) -> Some x
+  | Seq.Cons (None, tl) -> choice_seq tl
+
+(*$T
+  choice_seq (CCSeq.of_list [None; Some 1; Some 2]) = Some 1
+  choice_seq CCSeq.empty = None
+  choice_seq (CCSeq.repeat None |> CCSeq.take 100) = None
 *)
 
 let to_gen o =
diff --git a/src/core/CCOpt.mli b/src/core/CCOpt.mli
index 5b806c54..c84d410e 100644
--- a/src/core/CCOpt.mli
+++ b/src/core/CCOpt.mli
@@ -186,17 +186,20 @@ val to_result_lazy : (unit -> 'e) -> 'a t -> ('a, 'e) result
 val of_result : ('a, _) result -> 'a t
 (** @since 1.2 *)
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Format.formatter -> 'a -> unit
 type 'a random_gen = Random.State.t -> 'a
 
 val random : 'a random_gen -> 'a t random_gen
 
-val choice_seq : 'a t sequence -> 'a t
+val choice_iter : 'a t iter -> 'a t
 (** [choice_seq s] is similar to {!choice}, but works on sequences.
     It returns the first [Some x] occurring in [s], or [None] otherwise.
-    @since 0.13 *)
+    @since 3.0 *)
+
+val choice_seq : 'a t Seq.t -> 'a t
+(** @since 3.0 *)
 
 val to_gen : 'a t -> 'a gen
 
@@ -204,14 +207,8 @@ val to_std_seq : 'a t -> 'a Seq.t
 (** Same as {!Stdlib.Option.to_seq}
     @since 2.8 *)
 
-val to_iter : 'a t -> 'a sequence
+val to_iter : 'a t -> 'a iter
 (** Returns an internal iterator, like in the library [Iter].
     @since 2.8 *)
 
-val to_seq : 'a t -> 'a sequence
-(** Previous name for {!to_iter}
-    @deprecated use {!to_iter} or {!to_std_seq} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
-
 val pp : 'a printer -> 'a t printer
diff --git a/src/core/CCRandom.ml b/src/core/CCRandom.ml
index b655bb62..4eaf694d 100644
--- a/src/core/CCRandom.ml
+++ b/src/core/CCRandom.ml
@@ -93,10 +93,6 @@ let sample_without_duplicates (type elt) ~cmp k (rng:elt t) st=
   if k<=0 then invalid_arg "sample_without_duplicates";
   aux S.empty k
 
-(* deprecated *)
-let sample_without_replacement ~compare k rng =
-  sample_without_duplicates ~cmp:compare k rng
-
 let list_seq l st = List.map (fun f -> f st) l
 
 let split i st =
@@ -123,7 +119,7 @@ let _diff_list ~last l =
 let split_list i ~len st =
   if len <= 1 then invalid_arg "Random.split_list";
   if i >= len then (
-    let xs = sample_without_replacement ~compare (len-1) (int_range 1 (i-1)) st in
+    let xs = sample_without_duplicates ~cmp:compare (len-1) (int_range 1 (i-1)) st in
     _diff_list ~last:i (0::xs)
   ) else
     None
diff --git a/src/core/CCRandom.mli b/src/core/CCRandom.mli
index 3d353fb3..1c8ffed5 100644
--- a/src/core/CCRandom.mli
+++ b/src/core/CCRandom.mli
@@ -59,16 +59,6 @@ val replicate : int -> 'a t -> 'a list t
 (** [replicate n g] makes a list of [n] elements which are all generated
     randomly using [g]. *)
 
-val sample_without_replacement:
-  compare:('a -> 'a -> int) -> int -> 'a t -> 'a list t
-(** [sample_without_replacement n g] makes a list of [n] elements which are all
-    generated randomly using [g] with the added constraint that none of the generated
-    random values are equal.
-    @deprecated use sample_without_duplicates instead
-    @raise Invalid_argument if [n <= 0].
-    @since 0.15 *)
-[@@ocaml.deprecated "use sample_without_duplicates instead"]
-
 val sample_without_duplicates:
   cmp:('a -> 'a -> int) -> int -> 'a t -> 'a list t
 (** [sample_without_replacement n g] makes a list of [n] elements which are all
diff --git a/src/core/CCRef.ml b/src/core/CCRef.ml
index 44eab344..b1dee371 100644
--- a/src/core/CCRef.ml
+++ b/src/core/CCRef.ml
@@ -8,7 +8,7 @@
 type 'a printer = Format.formatter -> 'a -> unit
 type 'a ord = 'a -> 'a -> int
 type 'a eq = 'a -> 'a -> bool
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 
 type 'a t = 'a ref
 
@@ -38,6 +38,6 @@ let swap a b =
   b := x
 
 let to_list r = [!r]
-let to_seq r yield = yield !r
+let to_iter r yield = yield !r
 
 let pp pp_x out r = pp_x out !r
diff --git a/src/core/CCRef.mli b/src/core/CCRef.mli
index e108316d..672bba80 100644
--- a/src/core/CCRef.mli
+++ b/src/core/CCRef.mli
@@ -7,7 +7,7 @@
 type 'a printer = Format.formatter -> 'a -> unit
 type 'a ord = 'a -> 'a -> int
 type 'a eq = 'a -> 'a -> bool
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 
 type 'a t = 'a ref
 
@@ -41,6 +41,7 @@ val equal : 'a eq -> 'a t eq
 
 val to_list : 'a t -> 'a list
 
-val to_seq : 'a t -> 'a sequence
+val to_iter : 'a t -> 'a iter
+(** @since 3.0 *)
 
 val pp : 'a printer -> 'a t printer
diff --git a/src/core/CCResult.ml b/src/core/CCResult.ml
index b30659b0..50d02716 100644
--- a/src/core/CCResult.ml
+++ b/src/core/CCResult.ml
@@ -3,7 +3,6 @@
 (** {1 Error Monad} *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 type 'a equal = 'a -> 'a -> bool
 type 'a ord = 'a -> 'a -> int
 type 'a printer = Format.formatter -> 'a -> unit
@@ -240,7 +239,7 @@ let flatten_l l =
 
 exception LocalExit
 
-let fold_seq f acc seq =
+let fold_iter f acc seq =
   let err = ref None in
   try
     let acc = ref acc in
@@ -252,7 +251,7 @@ let fold_seq f acc seq =
   with LocalExit ->
   match !err with None -> assert false | Some s -> Error s
 
-let fold_l f acc l = fold_seq f acc (fun k -> List.iter k l)
+let fold_l f acc l = fold_iter f acc (fun k -> List.iter k l)
 
 (** {2 Misc} *)
 
@@ -345,8 +344,6 @@ let to_iter e k = match e with
   | Ok x -> k x
   | Error _ -> ()
 
-let to_seq = to_iter
-
 type ('a, 'b) error = [`Ok of 'a | `Error of 'b]
 
 let of_err = function
diff --git a/src/core/CCResult.mli b/src/core/CCResult.mli
index e6b2cb30..0201f263 100644
--- a/src/core/CCResult.mli
+++ b/src/core/CCResult.mli
@@ -6,11 +6,6 @@
 
     @since 0.16 *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -221,7 +216,8 @@ val map_l : ('a -> ('b, 'err) t) -> 'a list -> ('b list, 'err) t
 
 val fold_l : ('b -> 'a -> ('b, 'err) t) -> 'b -> 'a list -> ('b, 'err) t
 
-val fold_seq : ('b -> 'a -> ('b, 'err) t) -> 'b -> 'a sequence -> ('b, 'err) t
+val fold_iter : ('b -> 'a -> ('b, 'err) t) -> 'b -> 'a iter -> ('b, 'err) t
+(** @since 3.0 *)
 
 (** {2 Misc} *)
 
@@ -268,10 +264,6 @@ val to_iter : ('a, _) t -> 'a iter
 val to_std_seq : ('a, _) t -> 'a Seq.t
 (** @since 2.8 *)
 
-val to_seq : ('a, _) t -> 'a sequence
-(** @deprecated use {!to_iter} or {!to_std_seq} *)
-[@@ocaml.deprecated "use to_iter or to_std_seq"]
-
 type ('a, 'b) error = [`Ok of 'a | `Error of 'b]
 
 val of_err : ('a, 'b) error -> ('a, 'b) t
diff --git a/src/core/CCSeq.ml b/src/core/CCSeq.ml
new file mode 100644
index 00000000..69221e47
--- /dev/null
+++ b/src/core/CCSeq.ml
@@ -0,0 +1,541 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+type 'a iter = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+type 'a equal = 'a -> 'a -> bool
+type 'a ord = 'a -> 'a -> int
+type 'a printer = Format.formatter -> 'a -> unit
+
+type + 'a t = unit -> 'a node
+and +'a node = 'a Seq.node =
+  | Nil
+  | Cons of 'a * 'a t
+
+let nil () = Nil
+let cons a b () = Cons (a,b)
+let empty = nil
+
+let singleton x () = Cons (x, nil)
+
+let rec _forever x () = Cons (x, _forever x)
+
+let rec _repeat n x () =
+  if n<=0 then Nil else Cons (x, _repeat (n-1) x)
+
+let repeat ?n x = match n with
+  | None -> _forever x
+  | Some n -> _repeat n x
+
+(*$T
+  repeat ~n:4 0 |> to_list = [0;0;0;0]
+  repeat ~n:0 1 |> to_list = []
+  repeat 1 |> take 20 |> to_list = (repeat ~n:20 1 |> to_list)
+*)
+
+let is_empty l = match l () with
+  | Nil -> true
+  | Cons _ -> false
+
+let head_exn l = match l() with | Nil -> raise Not_found | Cons (x, _) -> x
+let head l = match l() with Nil -> None | Cons (x, _) -> Some x
+let tail_exn l = match l() with | Nil -> raise Not_found | Cons (_, l) -> l
+let tail l = match l() with | Nil -> None | Cons (_, l) -> Some l
+
+let rec equal eq l1 l2 = match l1(), l2() with
+  | Nil, Nil -> true
+  | Nil, _
+  | _, Nil -> false
+  | Cons (x1,l1'), Cons (x2,l2') ->
+    eq x1 x2 && equal eq l1' l2'
+
+let rec compare cmp l1 l2 = match l1(), l2() with
+  | Nil, Nil -> 0
+  | Nil, _ -> -1
+  | _, Nil -> 1
+  | Cons (x1,l1'), Cons (x2,l2') ->
+    let c = cmp x1 x2 in
+    if c = 0 then compare cmp l1' l2' else c
+
+let rec fold f acc res = match res () with
+  | Nil -> acc
+  | Cons (s, cont) -> fold f (f acc s) cont
+
+let fold_left = fold
+
+let rec iter f l = match l () with
+  | Nil -> ()
+  | Cons (x, l') -> f x; iter f l'
+
+let iteri f l =
+  let rec aux f l i = match l() with
+    | Nil -> ()
+    | Cons (x, l') ->
+      f i x;
+      aux f l' (i+1)
+  in
+  aux f l 0
+
+let length l = fold (fun acc _ -> acc+1) 0 l
+
+let rec take n (l:'a t) () =
+  if n=0 then Nil
+  else match l () with
+    | Nil -> Nil
+    | Cons (x,l') -> Cons (x, take (n-1) l')
+
+let rec take_while p l () = match l () with
+  | Nil -> Nil
+  | Cons (x,l') ->
+    if p x then Cons (x, take_while p l') else Nil
+
+(*$T
+  of_list [1;2;3;4] |> take_while (fun x->x < 4) |> to_list = [1;2;3]
+*)
+
+let rec drop n (l:'a t) () = match l () with
+  | l' when n=0 -> l'
+  | Nil -> Nil
+  | Cons (_,l') -> drop (n-1) l' ()
+
+let rec drop_while p l () = match l() with
+  | Nil -> Nil
+  | Cons (x,l') when p x -> drop_while p l' ()
+  | Cons _ as res -> res
+
+(*$Q
+  (Q.pair (Q.list Q.small_int) Q.small_int) (fun (l,n) -> \
+    let s = of_list l in let s1, s2 = take n s, drop n s in \
+    append s1 s2 |> to_list = l  )
+*)
+
+let rec map f l () = match l () with
+  | Nil -> Nil
+  | Cons (x, l') -> Cons (f x, map f l')
+
+(*$T
+  (map ((+) 1) (1 -- 5) |> to_list) = (2 -- 6 |> to_list)
+*)
+
+let mapi f l =
+  let rec aux f l i () = match l() with
+    | Nil -> Nil
+    | Cons (x, tl) ->
+      Cons (f i x, aux f tl (i+1))
+  in
+  aux f l 0
+
+(*$T
+  mapi (fun i x -> i,x) (1 -- 3) |> to_list = [0, 1; 1, 2; 2, 3]
+*)
+
+let rec fmap f (l:'a t) () = match l() with
+  | Nil -> Nil
+  | Cons (x, l') ->
+    begin match f x with
+      | None -> fmap f l' ()
+      | Some y -> Cons (y, fmap f l')
+    end
+
+(*$T
+  fmap (fun x -> if x mod 2=0 then Some (x*3) else None) (1--10) |> to_list \
+    = [6;12;18;24;30]
+*)
+
+let rec filter p l () = match l () with
+  | Nil -> Nil
+  | Cons (x, l') ->
+    if p x
+    then Cons (x, filter p l')
+    else filter p l' ()
+
+let rec append l1 l2 () = match l1 () with
+  | Nil -> l2 ()
+  | Cons (x, l1') -> Cons (x, append l1' l2)
+
+let rec cycle l () = append l (cycle l) ()
+
+(*$T
+  cycle (of_list [1;2]) |> take 5 |> to_list = [1;2;1;2;1]
+  cycle (of_list [1; ~-1]) |> take 100_000 |> fold (+) 0 = 0
+*)
+
+let rec unfold f acc () = match f acc with
+  | None -> Nil
+  | Some (x, acc') -> Cons (x, unfold f acc')
+
+(*$T
+  let f = function  10 -> None | x -> Some (x, x+1) in \
+  unfold f 0 |> to_list = [0;1;2;3;4;5;6;7;8;9]
+*)
+
+let rec flat_map f l () = match l () with
+  | Nil -> Nil
+  | Cons (x, l') ->
+    _flat_map_app f (f x) l' ()
+and _flat_map_app f l l' () = match l () with
+  | Nil -> flat_map f l' ()
+  | Cons (x, tl) ->
+    Cons (x, _flat_map_app f tl l')
+
+let product_with f l1 l2 =
+  let rec _next_left h1 tl1 h2 tl2 () =
+    match tl1() with
+      | Nil -> _next_right ~die:true h1 tl1 h2 tl2 ()
+      | Cons (x, tl1') ->
+        _map_list_left x h2
+          (_next_right ~die:false (x::h1) tl1' h2 tl2)
+          ()
+  and _next_right ~die h1 tl1 h2 tl2 () =
+    match tl2() with
+      | Nil when die -> Nil
+      | Nil -> _next_left h1 tl1 h2 tl2 ()
+      | Cons (y, tl2') ->
+        _map_list_right h1 y
+          (_next_left h1 tl1 (y::h2) tl2')
+          ()
+  and _map_list_left x l kont () = match l with
+    | [] -> kont()
+    | y::l' -> Cons (f x y, _map_list_left x l' kont)
+  and _map_list_right l y kont () = match l with
+    | [] -> kont()
+    | x::l' -> Cons (f x y, _map_list_right l' y kont)
+  in
+  _next_left [] l1 [] l2
+
+let product l1 l2 =
+  product_with (fun x y -> x,y) l1 l2
+
+let rec group eq l () = match l() with
+  | Nil -> Nil
+  | Cons (x, l') ->
+    Cons (cons x (take_while (eq x) l'), group eq (drop_while (eq x) l'))
+
+(*$T
+  of_list [1;1;1;2;2;3;3;1] |> group (=) |> map to_list |> to_list = \
+    [[1;1;1]; [2;2]; [3;3]; [1]]
+*)
+
+let rec _uniq eq prev l () = match prev, l() with
+  | _, Nil -> Nil
+  | None, Cons (x, l') ->
+    Cons (x, _uniq eq (Some x) l')
+  | Some y, Cons (x, l') ->
+    if eq x y
+    then _uniq eq prev l' ()
+    else Cons (x, _uniq eq (Some x) l')
+
+let uniq eq l = _uniq eq None l
+
+let rec filter_map f l () = match l() with
+  | Nil -> Nil
+  | Cons (x, l') ->
+    begin match f x with
+      | None -> filter_map f l' ()
+      | Some y -> Cons (y, filter_map f l')
+    end
+
+let flatten l = flat_map (fun x->x) l
+
+let range i j =
+  let rec aux i j () =
+    if i=j then Cons(i, nil)
+    else if i<j then Cons (i, aux (i+1) j)
+    else Cons (i, aux (i-1) j)
+  in aux i j
+
+(*$T
+  range 0 5 |> to_list = [0;1;2;3;4;5]
+  range 0 0 |> to_list = [0]
+  range 5 2 |> to_list = [5;4;3;2]
+*)
+
+let (--) = range
+
+let (--^) i j =
+  if i=j then empty
+  else if i<j then range i (j-1)
+  else range i (j+1)
+
+(*$T
+  1 --^ 5 |> to_list = [1;2;3;4]
+  5 --^ 1 |> to_list = [5;4;3;2]
+  1 --^ 2 |> to_list = [1]
+  0 --^ 0 |> to_list = []
+*)
+
+let rec fold2 f acc l1 l2 = match l1(), l2() with
+  | Nil, _
+  | _, Nil -> acc
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    fold2 f (f acc x1 x2) l1' l2'
+
+let rec map2 f l1 l2 () = match l1(), l2() with
+  | Nil, _
+  | _, Nil -> Nil
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    Cons (f x1 x2, map2 f l1' l2')
+
+let rec iter2 f l1 l2 = match l1(), l2() with
+  | Nil, _
+  | _, Nil -> ()
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    f x1 x2; iter2 f l1' l2'
+
+let rec for_all2 f l1 l2 = match l1(), l2() with
+  | Nil, _
+  | _, Nil -> true
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    f x1 x2 && for_all2 f l1' l2'
+
+let rec exists2 f l1 l2 = match l1(), l2() with
+  | Nil, _
+  | _, Nil -> false
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    f x1 x2 || exists2 f l1' l2'
+
+let rec merge cmp l1 l2 () = match l1(), l2() with
+  | Nil, tl2 -> tl2
+  | tl1, Nil -> tl1
+  | Cons(x1,l1'), Cons(x2,l2') ->
+    if cmp x1 x2 < 0
+    then Cons (x1, merge cmp l1' l2)
+    else Cons (x2, merge cmp l1 l2')
+
+let rec zip a b () = match a(), b() with
+  | Nil, _
+  | _, Nil -> Nil
+  | Cons (x, a'), Cons (y, b') -> Cons ((x,y), zip a' b')
+
+let unzip l =
+  let rec first l () = match l() with
+    | Nil -> Nil
+    | Cons ((x,_), tl) -> Cons (x, first tl)
+  and second l () = match l() with
+    | Nil -> Nil
+    | Cons ((_, y), tl) -> Cons (y, second tl)
+  in
+  first l, second l
+
+(*$Q
+  Q.(list (pair int int)) (fun l -> \
+    let l = of_list l in let a, b = unzip l in equal (=) l (zip a b))
+*)
+
+(** {2 Implementations} *)
+
+let return x () = Cons (x, nil)
+let pure = return
+let (>>=) xs f = flat_map f xs
+let (>|=) xs f = map f xs
+
+let (<*>) fs xs = product_with (fun f x -> f x) fs xs
+
+(** {2 Conversions} *)
+
+let rec _to_rev_list acc l = match l() with
+  | Nil -> acc
+  | Cons (x,l') -> _to_rev_list (x::acc) l'
+
+let to_rev_list l = _to_rev_list [] l
+
+let to_list l =
+  let rec direct i (l:'a t) = match l () with
+    | Nil -> []
+    | _ when i=0 -> List.rev (_to_rev_list [] l)
+    | Cons (x, f) -> x :: direct (i-1) f
+  in
+  direct 200 l
+
+let of_list l =
+  let rec aux l () = match l with
+    | [] -> Nil
+    | x::l' -> Cons (x, aux l')
+  in aux l
+
+let of_array a =
+  let rec aux a i () =
+    if i=Array.length a then Nil
+    else Cons (a.(i), aux a (i+1))
+  in
+  aux a 0
+
+let to_array l =
+  match l() with
+    | Nil -> [| |]
+    | Cons (x, _) ->
+      let n = length l in
+      let a = Array.make n x in (* need first elem to create [a] *)
+      iteri
+        (fun i x -> a.(i) <- x)
+        l;
+      a
+
+(*$Q
+   Q.(array int) (fun a -> of_array a |> to_array = a)
+*)
+
+(*$T
+  of_array [| 1; 2; 3 |] |> to_list = [1;2;3]
+  of_list [1;2;3] |> to_array = [| 1; 2; 3; |]
+*)
+
+let rec to_iter res k = match res () with
+  | Nil -> ()
+  | Cons (s, f) -> k s; to_iter f k
+
+let to_gen l =
+  let l = ref l in
+  fun () ->
+    match !l () with
+      | Nil -> None
+      | Cons (x,l') ->
+        l := l';
+        Some x
+
+type 'a of_gen_state =
+  | Of_gen_thunk of 'a gen
+  | Of_gen_saved of 'a node
+
+let of_gen g =
+  let rec consume r () = match !r with
+    | Of_gen_saved cons -> cons
+    | Of_gen_thunk g ->
+      begin match g() with
+        | None ->
+          r := Of_gen_saved Nil;
+          Nil
+        | Some x ->
+          let tl = consume (ref (Of_gen_thunk g)) in
+          let l = Cons (x, tl) in
+          r := Of_gen_saved l;
+          l
+      end
+  in
+  consume (ref (Of_gen_thunk g))
+
+(*$R
+  let g = let n = ref 0 in fun () -> Some (incr n; !n) in
+  let l = of_gen g in
+  assert_equal [1;2;3;4;5;6;7;8;9;10] (take 10 l |> to_list);
+  assert_equal [1;2;3;4;5;6;7;8;9;10] (take 10 l |> to_list);
+  assert_equal [11;12] (drop 10 l |> take 2 |> to_list);
+*)
+
+let sort ~cmp l =
+  let l = to_list l in
+  of_list (List.sort cmp l)
+
+let sort_uniq ~cmp l =
+  let l = to_list l in
+  uniq (fun x y -> cmp x y = 0) (of_list (List.sort cmp l))
+
+type 'a memoize =
+  | MemoThunk
+  | MemoSave of 'a node
+
+let rec memoize f =
+  let r = ref MemoThunk in
+  fun () -> match !r with
+    | MemoSave l -> l
+    | MemoThunk ->
+      let l = match f() with
+        | Nil -> Nil
+        | Cons (x, tail) -> Cons (x, memoize tail)
+      in
+      r := MemoSave l;
+      l
+
+(*$R
+  let printer = Q.Print.(list int) in
+  let gen () =
+    let rec l = let r = ref 0 in fun () -> incr r; Cons (!r, l) in l
+  in
+  let l1 = gen () in
+  assert_equal ~printer [1;2;3;4] (take 4 l1 |> to_list);
+  assert_equal ~printer [5;6;7;8] (take 4 l1 |> to_list);
+  let l2 = gen () |> memoize in
+  assert_equal ~printer [1;2;3;4] (take 4 l2 |> to_list);
+  assert_equal ~printer [1;2;3;4] (take 4 l2 |> to_list);
+*)
+
+
+(** {2 Fair Combinations} *)
+
+let rec interleave a b () = match a() with
+  | Nil -> b ()
+  | Cons (x, tail) -> Cons (x, interleave b tail)
+
+let rec fair_flat_map f a () = match a() with
+  | Nil -> Nil
+  | Cons (x, tail) ->
+    let y = f x in
+    interleave y (fair_flat_map f tail) ()
+
+let rec fair_app f a () = match f() with
+  | Nil -> Nil
+  | Cons (f1, fs) ->
+    interleave (map f1 a) (fair_app fs a) ()
+
+let (>>-) a f = fair_flat_map f a
+let (<.>) f a = fair_app f a
+
+(*$T
+  interleave (of_list [1;3;5]) (of_list [2;4;6]) |> to_list = [1;2;3;4;5;6]
+  fair_app (of_list [(+)1; ( * ) 3]) (of_list [1; 10]) \
+    |> to_list |> List.sort Stdlib.compare = [2; 3; 11; 30]
+*)
+
+(** {2 Infix} *)
+
+module Infix = struct
+  let (>>=) = (>>=)
+  let (>|=) = (>|=)
+  let (<*>) = (<*>)
+  let (>>-) = (>>-)
+  let (<.>) = (<.>)
+  let (--) = (--)
+  let (--^) = (--^)
+end
+
+(** {2 Monadic Operations} *)
+module type MONAD = sig
+  type 'a t
+  val return : 'a -> 'a t
+  val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
+end
+
+module Traverse(M : MONAD) = struct
+  open M
+
+  let map_m f l =
+    let rec aux acc l = match l () with
+      | Nil -> return (of_list (List.rev acc))
+      | Cons (x,l') ->
+        f x >>= fun x' ->
+        aux (x' :: acc) l'
+    in
+    aux [] l
+
+  let sequence_m l = map_m (fun x->x) l
+
+  let rec fold_m f acc l = match l() with
+    | Nil -> return acc
+    | Cons (x,l') ->
+      f acc x >>= fun acc' -> fold_m f acc' l'
+end
+
+(** {2 IO} *)
+
+let pp ?(sep=",") pp_item fmt l =
+  let rec pp fmt l = match l() with
+    | Nil -> ()
+    | Cons (x,l') ->
+      Format.pp_print_string fmt sep;
+      Format.pp_print_cut fmt ();
+      pp_item fmt x;
+      pp fmt l'
+  in
+  match l() with
+    | Nil -> ()
+    | Cons (x,l') -> pp_item fmt x; pp fmt l'
diff --git a/src/core/CCSeq.mli b/src/core/CCSeq.mli
new file mode 100644
index 00000000..7fda8dee
--- /dev/null
+++ b/src/core/CCSeq.mli
@@ -0,0 +1,277 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Helpers for the standard {b Seq} type}
+
+    See {{: https://github.com/c-cube/oseq/} oseq} for a richer API.
+*)
+
+type 'a iter = ('a -> unit) -> unit
+type 'a gen = unit -> 'a option
+type 'a equal = 'a -> 'a -> bool
+type 'a ord = 'a -> 'a -> int
+type 'a printer = Format.formatter -> 'a -> unit
+
+(** {2 Basics} *)
+
+type + 'a t = unit -> 'a node
+and +'a node = 'a Seq.node =
+  | Nil
+  | Cons of 'a * 'a t
+
+val nil : 'a t
+
+val empty : 'a t
+
+val cons : 'a -> 'a t -> 'a t
+
+val singleton : 'a -> 'a t
+
+val repeat : ?n:int -> 'a -> 'a t
+(** [repeat ~n x] repeats [x] [n] times then stops. If [n] is omitted,
+    then [x] is repeated forever.
+    @since 0.3.3 *)
+
+val cycle : 'a t -> 'a t
+(** Cycle through the iterator infinitely. The iterator shouldn't be empty.
+    @since 0.3.3 *)
+
+val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t
+(** [unfold f acc] calls [f acc] and:
+    - if [f acc = Some (x, acc')], yield [x], continue with [unfold f acc'].
+    - if [f acc = None], stops.
+    @since 0.13 *)
+
+val is_empty : 'a t -> bool
+
+val head : 'a t -> 'a option
+(** Head of the list.
+    @since 0.13 *)
+
+val head_exn : 'a t -> 'a
+(** Unsafe version of {!head}.
+    @raise Not_found if the list is empty.
+    @since 0.13 *)
+
+val tail : 'a t -> 'a t option
+(** Tail of the list.
+    @since 0.13 *)
+
+val tail_exn : 'a t -> 'a t
+(** Unsafe version of {!tail}.
+    @raise Not_found if the list is empty.
+    @since 0.13 *)
+
+val equal : 'a equal -> 'a t equal
+(** Equality step by step. Eager. *)
+
+val compare : 'a ord -> 'a t ord
+(** Lexicographic comparison. Eager. *)
+
+val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** Fold on values. *)
+
+val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** Alias for {!fold} *)
+
+val iter : ('a -> unit) -> 'a t -> unit
+
+val iteri : (int -> 'a -> unit) -> 'a t -> unit
+(** Iterate with index (starts at 0).
+    @since 0.13 *)
+
+val length : _ t -> int
+(** Number of elements in the list.
+    Will not terminate if the list if infinite:
+    use (for instance) {!take} to make the list finite if necessary. *)
+
+val take : int -> 'a t -> 'a t
+
+val take_while : ('a -> bool) -> 'a t -> 'a t
+
+val drop : int -> 'a t -> 'a t
+
+val drop_while : ('a -> bool) -> 'a t -> 'a t
+
+val map : ('a -> 'b) -> 'a t -> 'b t
+
+val mapi : (int -> 'a -> 'b) -> 'a t -> 'b t
+(** Map with index (starts at 0).
+    @since 0.13 *)
+
+val fmap : ('a -> 'b option) -> 'a t -> 'b t
+
+val filter : ('a -> bool) -> 'a t -> 'a t
+
+val append : 'a t -> 'a t -> 'a t
+
+val product_with : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
+(** Fair product of two (possibly infinite) lists into a new list. Lazy.
+    The first parameter is used to combine each pair of elements.
+    @since 0.3.3 *)
+
+val product : 'a t -> 'b t -> ('a * 'b) t
+(** Specialization of {!product_with} producing tuples.
+    @since 0.3.3 *)
+
+val group : 'a equal -> 'a t -> 'a t t
+(** [group eq l] groups together consecutive elements that satisfy [eq]. Lazy.
+    For instance [group (=) [1;1;1;2;2;3;3;1]] yields
+      [[1;1;1]; [2;2]; [3;3]; [1]].
+    @since 0.3.3 *)
+
+val uniq : 'a equal -> 'a t -> 'a t
+(** [uniq eq l] returns [l] but removes consecutive duplicates. Lazy.
+    In other words, if several values that are equal follow one another,
+    only the first of them is kept.
+    @since 0.3.3 *)
+
+val flat_map : ('a -> 'b t) -> 'a t -> 'b t
+
+val filter_map : ('a -> 'b option) -> 'a t -> 'b t
+
+val flatten : 'a t t -> 'a t
+
+val range : int -> int -> int t
+
+val (--) : int -> int -> int t
+(** [a -- b] is the range of integers containing
+    [a] and [b] (therefore, never empty). *)
+
+val (--^) : int -> int -> int t
+(** [a -- b] is the integer range from [a] to [b], where [b] is excluded.
+    @since 0.17 *)
+
+(** {2 Operations on two Collections} *)
+
+val fold2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc
+(** Fold on two collections at once. Stop at soon as one of them ends. *)
+
+val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
+(** Map on two collections at once. Stop as soon as one of the
+    arguments is exhausted. *)
+
+val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit
+(** Iterate on two collections at once. Stop as soon as one of them ends. *)
+
+val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
+val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
+
+val merge : 'a ord -> 'a t -> 'a t -> 'a t
+(** Merge two sorted iterators into a sorted iterator. *)
+
+val zip : 'a t -> 'b t -> ('a * 'b) t
+(** Combine elements pairwise. Stop as soon as one of the lists stops.
+    @since 0.13 *)
+
+val unzip : ('a * 'b) t -> 'a t * 'b t
+(** Split each tuple in the list.
+    @since 0.13 *)
+
+(** {2 Misc} *)
+
+val sort : cmp:'a ord -> 'a t -> 'a t
+(** Eager sort. Require the iterator to be finite. [O(n ln(n))] time
+    and space.
+    @since 0.3.3 *)
+
+val sort_uniq : cmp:'a ord -> 'a t -> 'a t
+(** Eager sort that removes duplicate values. Require the iterator to be
+    finite. [O(n ln(n))] time and space.
+    @since 0.3.3 *)
+
+val memoize : 'a t -> 'a t
+(** Avoid recomputations by caching intermediate results.
+    @since 0.14 *)
+
+(** {2 Fair Combinations} *)
+
+val interleave : 'a t -> 'a t -> 'a t
+(** Fair interleaving of both streams.
+    @since 0.13 *)
+
+val fair_flat_map : ('a -> 'b t) -> 'a t -> 'b t
+(** Fair version of {!flat_map}.
+    @since 0.13 *)
+
+val fair_app : ('a -> 'b) t -> 'a t -> 'b t
+(** Fair version of {!(<*>)}.
+    @since 0.13 *)
+
+(** {2 Implementations}
+    @since 0.3.3 *)
+
+val return : 'a -> 'a t
+val pure : 'a -> 'a t
+val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
+val (>|=) : 'a t -> ('a -> 'b) -> 'b t
+val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
+
+val (>>-) : 'a t -> ('a -> 'b t) -> 'b t
+(** Infix version of {! fair_flat_map}.
+    @since 0.13 *)
+
+val (<.>) : ('a -> 'b) t -> 'a t -> 'b t
+(** Infix version of {!fair_app}.
+    @since 0.13 *)
+
+(** {2 Infix operators}
+
+    @since 0.17 *)
+
+module Infix : sig
+  val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
+  val (>|=) : 'a t -> ('a -> 'b) -> 'b t
+  val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
+  val (>>-) : 'a t -> ('a -> 'b t) -> 'b t
+  val (<.>) : ('a -> 'b) t -> 'a t -> 'b t
+  val (--) : int -> int -> int t
+  val (--^) : int -> int -> int t
+end
+
+(** {2 Monadic Operations} *)
+module type MONAD = sig
+  type 'a t
+  val return : 'a -> 'a t
+  val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
+end
+
+module Traverse(M : MONAD) : sig
+  val sequence_m : 'a M.t t -> 'a t M.t
+
+  val fold_m : ('b -> 'a -> 'b M.t) -> 'b -> 'a t -> 'b M.t
+
+  val map_m : ('a -> 'b M.t) -> 'a t -> 'b t M.t
+end
+
+(** {2 Conversions} *)
+
+val of_list : 'a list -> 'a t
+
+val to_list : 'a t -> 'a list
+(** Gather all values into a list. *)
+
+val of_array : 'a array -> 'a t
+(** Iterate on the array.
+    @since 0.13 *)
+
+val to_array : 'a t -> 'a array
+(** Convert into array. Iterate twice.
+    @since 0.13 *)
+
+val to_rev_list : 'a t -> 'a list
+(** Convert to a list, in reverse order. More efficient than {!to_list}. *)
+
+val to_iter : 'a t -> 'a iter
+
+val to_gen : 'a t -> 'a gen
+
+val of_gen : 'a gen -> 'a t
+(** [of_gen g] consumes the generator and caches intermediate results.
+    @since 0.13 *)
+
+(** {2 IO} *)
+
+val pp : ?sep:string -> 'a printer -> 'a t printer
+(** Print the list with the given separator (default ",").
+    Do not print opening/closing delimiters. *)
diff --git a/src/core/CCSet.ml b/src/core/CCSet.ml
index ce62d920..29cdeebf 100644
--- a/src/core/CCSet.ml
+++ b/src/core/CCSet.ml
@@ -4,7 +4,6 @@
 (** {1 Wrapper around Set} *)
 
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 type 'a printer = Format.formatter -> 'a -> unit
 
 module type OrderedType = Set.OrderedType
@@ -62,21 +61,6 @@ module type S = sig
   (** [to_iter t] converts the set [t] to a [iter] of the elements.
       @since 2.8 *)
 
-  val of_seq : elt sequence -> t
-  (** Build a set from the given [sequence] of elements.
-      @deprecated use {!of_iter} instead. *)
-  [@@ocaml.deprecated "use of_iter instead"]
-
-  val add_seq : t -> elt sequence -> t
-  (** @since 0.14
-      @deprecated use {!add_iter} instead. *)
-  [@@ocaml.deprecated "use add_iter instead"]
-
-  val to_seq : t -> elt sequence
-  (** [to_seq t] converts the set [t] to a [sequence] of the elements.
-      @deprecated use {!to_iter} instead. *)
-  [@@ocaml.deprecated "use to_iter instead"]
-
   val add_list : t -> elt list -> t
   (** @since 0.14 *)
 
@@ -166,10 +150,6 @@ module Make(O : Map.OrderedType) = struct
   let of_iter s = add_iter empty s
   let to_iter s yield = iter yield s
 
-  let add_seq = add_iter
-  let of_seq = of_iter
-  let to_seq = to_iter
-
   let add_list = List.fold_left (fun set x -> add x set)
 
   let to_list = elements
diff --git a/src/core/CCSet.mli b/src/core/CCSet.mli
index 16e202e1..e4a568e5 100644
--- a/src/core/CCSet.mli
+++ b/src/core/CCSet.mli
@@ -5,11 +5,6 @@
 
     @since 0.9 *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -65,21 +60,6 @@ module type S = sig
   (** [to_iter t] converts the set [t] to a [iter] of the elements.
       @since 2.8 *)
 
-  val of_seq : elt sequence -> t
-  (** Build a set from the given [sequence] of elements.
-      @deprecated use {!of_iter} instead. *)
-  [@@ocaml.deprecated "use of_iter instead"]
-
-  val add_seq : t -> elt sequence -> t
-  (** @since 0.14
-      @deprecated use {!add_iter} instead. *)
-  [@@ocaml.deprecated "use add_iter instead"]
-
-  val to_seq : t -> elt sequence
-  (** [to_seq t] converts the set [t] to a [sequence] of the elements.
-      @deprecated use {!to_iter} instead. *)
-  [@@ocaml.deprecated "use to_iter instead"]
-
   val add_list : t -> elt list -> t
   (** @since 0.14 *)
 
diff --git a/src/core/CCString.ml b/src/core/CCString.ml
index a0f6ba89..a278f91a 100644
--- a/src/core/CCString.ml
+++ b/src/core/CCString.ml
@@ -7,7 +7,6 @@ open CCShims_
 
 type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
-type 'a sequence = ('a -> unit) -> unit
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 
 (* standard implementations *)
@@ -51,16 +50,6 @@ module type S = sig
       @since 2.8
   *)
 
-  val to_seq : t -> char sequence
-  (** Return the [sequence] of characters contained in the string.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter or to_std_seq"]
-
-  val to_klist : t -> char klist
-  (** Return the [klist] of characters contained in the string.
-      @deprecated use {!to_std_seq} instead *)
-  [@@ocaml.deprecated "use to_std_seq"]
-
   val to_list : t -> char list
   (** Return the list of characters contained in the string. *)
 
@@ -848,8 +837,6 @@ let of_gen g =
 
 let to_iter s k = String.iter k s
 
-let to_seq = to_iter
-
 let rec _to_std_seq s i len () =
   if len=0 then Seq.Nil
   else Seq.Cons (s.[i], _to_std_seq s (i+1)(len-1))
@@ -866,8 +853,6 @@ let of_std_seq seq =
   Seq.iter (Buffer.add_char b) seq;
   Buffer.contents b
 
-let of_seq = of_iter
-
 let rec _to_klist s i len () =
   if len=0 then `Nil
   else `Cons (s.[i], _to_klist s (i+1)(len-1))
diff --git a/src/core/CCString.mli b/src/core/CCString.mli
index 5a5baa97..3536d2bd 100644
--- a/src/core/CCString.mli
+++ b/src/core/CCString.mli
@@ -5,11 +5,6 @@
 
 (** {1 Basic String Utils} *)
 
-
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -56,16 +51,6 @@ module type S = sig
       @since 2.8
   *)
 
-  val to_seq : t -> char sequence
-  (** Return the [sequence] of characters contained in the string.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter or to_std_seq"]
-
-  val to_klist : t -> char klist
-  (** Return the [klist] of characters contained in the string.
-      @deprecated use {!to_std_seq} instead *)
-  [@@ocaml.deprecated "use to_std_seq"]
-
   val to_list : t -> char list
   (** Return the list of characters contained in the string. *)
 
@@ -116,16 +101,6 @@ val of_std_seq : char Seq.t -> string
 (** Convert a [sequence] of characters to a string.
     @since 2.8 *)
 
-val of_seq : char sequence -> string
-(** Convert a [sequence] of characters to a string.
-    @deprecated use {!of_iter} instead *)
-[@@ocaml.deprecated "use of_iter"]
-
-val of_klist : char klist -> string
-(** Convert a [klist] of characters to a string.
-    @deprecated use {!of_std_seq} instead *)
-[@@ocaml.deprecated "use of_std_seq"]
-
 val of_list : char list -> string
 (** Convert a list of characters to a string. *)
 
@@ -377,20 +352,12 @@ module Split : sig
 
   val gen : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) gen
 
-  val iter : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) sequence
+  val iter : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) iter
   (** @since 2.8 *)
 
   val std_seq : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) Seq.t
   (** @since 2.8 *)
 
-  val seq : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) sequence
-  (** deprecated, use {!iter} instead *)
-  [@@ocaml.deprecated "use iter"]
-
-  val klist : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) klist
-  (** deprecated, use {!std_seq} instead *)
-  [@@ocaml.deprecated "use std_seq"]
-
   (** {4 Copying functions}
 
       Those split functions actually copy the substrings, which can be
@@ -400,20 +367,12 @@ module Split : sig
 
   val gen_cpy : ?drop:drop_if_empty -> by:string -> string -> string gen
 
-  val iter_cpy : ?drop:drop_if_empty -> by:string -> string -> string sequence
+  val iter_cpy : ?drop:drop_if_empty -> by:string -> string -> string iter 
   (** @since 2.8 *)
 
   val std_seq_cpy : ?drop:drop_if_empty -> by:string -> string -> string Seq.t
   (** @since 2.8 *)
 
-  val seq_cpy : ?drop:drop_if_empty -> by:string -> string -> string sequence
-  (** deprecated, use {!iter_cpy} instead *)
-  [@@ocaml.deprecated "use iter_cpy"]
-
-  val klist_cpy : ?drop:drop_if_empty -> by:string -> string -> string klist
-  (** deprecated, use {!std_seq_cpy} instead *)
-  [@@ocaml.deprecated "use std_seq_cpy"]
-
   val left : by:string -> string -> (string * string) option
   (** Split on the first occurrence of [by] from the leftmost part of
       the string.
diff --git a/src/core/CCStringLabels.mli b/src/core/CCStringLabels.mli
index 993aafd3..d362d86a 100644
--- a/src/core/CCStringLabels.mli
+++ b/src/core/CCStringLabels.mli
@@ -3,10 +3,6 @@
 
 (** {1 Basic String Utils} *)
 
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -53,16 +49,6 @@ module type S = sig
       @since 2.8
   *)
 
-  val to_seq : t -> char sequence
-  (** Return the [sequence] of characters contained in the string.
-      @deprecated use {!to_iter} instead *)
-  [@@ocaml.deprecated "use to_iter or to_std_seq"]
-
-  val to_klist : t -> char klist
-  (** Return the [klist] of characters contained in the string.
-      @deprecated use {!to_std_seq} instead *)
-  [@@ocaml.deprecated "use to_std_seq"]
-
   val to_list : t -> char list
   (** Return the list of characters contained in the string. *)
 
@@ -116,16 +102,6 @@ val of_std_seq : char Seq.t -> string
 (** Convert a [sequence] of characters to a string.
     @since 2.8 *)
 
-val of_seq : char sequence -> string
-(** Convert a [sequence] of characters to a string.
-    @deprecated use {!of_iter} instead *)
-[@@ocaml.deprecated "use of_iter"]
-
-val of_klist : char klist -> string
-(** Convert a [klist] of characters to a string.
-    @deprecated use {!of_std_seq} instead *)
-[@@ocaml.deprecated "use of_std_seq"]
-
 val of_list : char list -> string
 (** Convert a list of characters to a string. *)
 
@@ -393,20 +369,12 @@ module Split : sig
 
   val gen : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) gen
 
-  val iter : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) sequence
+  val iter : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) iter
   (** @since 2.8 *)
 
   val std_seq : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) Seq.t
   (** @since 2.8 *)
 
-  val seq : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) sequence
-  (** deprecated, use {!iter} instead *)
-  [@@ocaml.deprecated "use iter"]
-
-  val klist : ?drop:drop_if_empty -> by:string -> string -> (string*int*int) klist
-  (** deprecated, use {!std_seq} instead *)
-  [@@ocaml.deprecated "use std_seq"]
-
   (** {4 Copying functions}
 
       Those split functions actually copy the substrings, which can be
@@ -416,20 +384,12 @@ module Split : sig
 
   val gen_cpy : ?drop:drop_if_empty -> by:string -> string -> string gen
 
-  val iter_cpy : ?drop:drop_if_empty -> by:string -> string -> string sequence
+  val iter_cpy : ?drop:drop_if_empty -> by:string -> string -> string iter
   (** @since 2.8 *)
 
   val std_seq_cpy : ?drop:drop_if_empty -> by:string -> string -> string Seq.t
   (** @since 2.8 *)
 
-  val seq_cpy : ?drop:drop_if_empty -> by:string -> string -> string sequence
-  (** deprecated, use {!iter_cpy} instead *)
-  [@@ocaml.deprecated "use iter_cpy"]
-
-  val klist_cpy : ?drop:drop_if_empty -> by:string -> string -> string klist
-  (** deprecated, use {!std_seq_cpy} instead *)
-  [@@ocaml.deprecated "use std_seq_cpy"]
-
   val left : by:(string [@keep_label]) -> string -> (string * string) option
   (** Split on the first occurrence of [by] from the leftmost part of
       the string.
diff --git a/src/core/CCUtf8_string.ml b/src/core/CCUtf8_string.ml
index 71a0c422..003784c4 100644
--- a/src/core/CCUtf8_string.ml
+++ b/src/core/CCUtf8_string.ml
@@ -10,7 +10,6 @@ open CCShims_
 type uchar = Uchar.t
 type 'a gen = unit -> 'a option
 type 'a iter = ('a -> unit) -> unit
-type 'a sequence = ('a -> unit) -> unit
 
 let equal (a:string) b = Stdlib.(=) a b
 let hash : string -> int = Hashtbl.hash
@@ -125,8 +124,6 @@ let to_iter ?(idx=0) s : uchar iter =
       done
     with Stop -> ()
 
-let to_seq = to_iter
-
 let to_std_seq ?(idx=0) s : uchar Seq.t =
   let rec loop st =
     let r = ref None in
@@ -226,8 +223,6 @@ let of_iter i : t =
   i (code_to_string buf);
   Buffer.contents buf
 
-let of_seq = of_iter
-
 let of_list l : t =
   let buf = Buffer.create 32 in
   List.iter (code_to_string buf) l;
@@ -292,7 +287,7 @@ let of_string s = if is_valid s then Some s else None
   with Exit ->
     false
 
-  let uutf_to_seq s f =
+  let uutf_to_iter s f =
   Uutf.String.fold_utf_8
     (fun () _ -> function
        | `Malformed _ -> f (Uchar.of_int 0xfffd)
@@ -302,7 +297,7 @@ let of_string s = if is_valid s then Some s else None
 
 (*$R
   let s = of_string_exn "このため、" in
-  let s' = to_seq s |> of_seq in
+  let s' = to_iter s |> of_iter in
   assert_equal ~cmp:equal ~printer s s'
 *)
 
@@ -315,7 +310,7 @@ let of_string s = if is_valid s then Some s else None
 (*$QR & ~long_factor:10
   Q.small_string (fun s ->
     Q.assume (CCString.for_all (fun c -> Char.code c < 128) s);
-    s = (of_string_exn s |> to_seq |> of_seq |> to_string)
+    s = (of_string_exn s |> to_iter|> of_iter|> to_string)
   )
 *)
 
@@ -338,7 +333,7 @@ let of_string s = if is_valid s then Some s else None
   Q.string (fun s ->
     Q.assume (is_valid s);
     let s = of_string_exn s in
-    let s2 = s |> to_seq |> of_seq in
+    let s2 = s |> to_iter|> of_iter in
     if s=s2 then true
     else Q.Test.fail_reportf "s=%S, s2=%S" (to_string s)(to_string s2)
   )
@@ -369,8 +364,8 @@ let of_string s = if is_valid s then Some s else None
   Q.small_string (fun s ->
     Q.assume (is_valid s && uutf_is_valid s);
     let pp s = Q.Print.(list pp_uchar) s in
-    let l_uutf = uutf_to_seq s |> Iter.to_list in
-    let l_co = of_string_exn s |> to_seq |> Iter.to_list in
+    let l_uutf = uutf_to_iter s |> Iter.to_list in
+    let l_co = of_string_exn s |> to_iter |> Iter.to_list in
     if l_uutf = l_co then true
     else Q.Test.fail_reportf "uutf: '%s', containers: '%s', is_valid %B, uutf_is_valid %B"
       (pp l_uutf) (pp l_co) (is_valid s) (uutf_is_valid s)
diff --git a/src/core/CCUtf8_string.mli b/src/core/CCUtf8_string.mli
index 33f2e5f3..147d1e99 100644
--- a/src/core/CCUtf8_string.mli
+++ b/src/core/CCUtf8_string.mli
@@ -19,10 +19,6 @@
 type uchar = Uchar.t
 type 'a gen = unit -> 'a option
 
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -54,12 +50,6 @@ val to_iter : ?idx:int -> t -> uchar iter
     @param idx offset where to start the decoding.
     @since 2.8 *)
 
-val to_seq : ?idx:int -> t -> uchar sequence
-(** Iter of unicode codepoints.
-    @param idx offset where to start the decoding.
-    @deprecated use {!to_iter} or {!to_std_seq} instead *)
-[@@ocaml.deprecated "use to_iter or to_std_seq instead"]
-
 val to_std_seq : ?idx:int -> t -> uchar Seq.t
 (** Iter of unicode codepoints.
     @param idx offset where to start the decoding.
@@ -94,14 +84,10 @@ val of_std_seq : uchar Seq.t -> t
 (** Build a string from unicode codepoints
     @since 2.8 *)
 
-val of_iter : uchar sequence -> t
+val of_iter : uchar iter -> t
 (** Build a string from unicode codepoints
     @since 2.8 *)
 
-val of_seq : uchar sequence -> t
-(** @deprecated use {!of_seq} or {!of_std_seq} instead *)
-[@@ocaml.deprecated "use of_iter or of_std_seq instead"]
-
 val of_gen : uchar gen -> t
 
 val of_list : uchar list -> t
diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 42e69a98..d7d4c26a 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -5,7 +5,6 @@
 type rw = [`RW]
 type ro = [`RO]
 
-type 'a sequence = ('a -> unit) -> unit
 type 'a iter = ('a -> unit) -> unit
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 type 'a gen = unit -> 'a option
@@ -165,11 +164,11 @@ let clear v =
   v.size <- 0
 
 (*$R
-  let v = of_seq Iter.(1 -- 10) in
+  let v = of_iter Iter.(1 -- 10) in
   OUnit.assert_equal 10 (size v);
   clear v;
   OUnit.assert_equal 0 (size v);
-  OUnit.assert_bool "empty_after_clear" (Iter.is_empty (to_seq v));
+  OUnit.assert_bool "empty_after_clear" (Iter.is_empty (to_iter v));
 *)
 
 let clear_and_reset v =
@@ -177,7 +176,7 @@ let clear_and_reset v =
   v.vec <- [||]
 
 (* TODO*)
-(*    
+(*
   let v = create() in
   let a = Weak.create 1 in
   push v ("hello"^"world");
@@ -232,8 +231,8 @@ let append a b =
 *)
 
 (*$R
-  let a = of_seq Iter.(1 -- 5) in
-  let b = of_seq Iter.(6 -- 10) in
+  let a = of_iter Iter.(1 -- 5) in
+  let b = of_iter Iter.(6 -- 10) in
   append a b;
   OUnit.assert_equal 10 (size a);
   OUnit.assert_equal (Iter.to_array Iter.(1 -- 10)) (to_array a);
@@ -327,8 +326,8 @@ let rec append_gen a b = match b() with
   (Q.pair (gen Q.int) (gen Q.int)) (fun (v1,v2) ->
     let l1 = to_list v1 in
     append v1 v2;
-    Iter.to_list (to_seq v1) =
-      Iter.(to_list (append (of_list l1) (to_seq v2)))
+    Iter.to_list (to_iter v1) =
+      Iter.(to_list (append (of_list l1) (to_iter v2)))
   )
 *)
 
@@ -418,7 +417,7 @@ let copy v = {
 *)
 
 (*$R
-  let v = of_seq Iter.(1 -- 100) in
+  let v = of_iter Iter.(1 -- 100) in
   OUnit.assert_equal 100 (size v);
   let v' = copy v in
   OUnit.assert_equal 100 (size v');
@@ -443,7 +442,7 @@ let shrink v n =
   )
 
 (*$R
-  let v = of_seq Iter.(1 -- 10) in
+  let v = of_iter Iter.(1 -- 10) in
   shrink v 5;
   OUnit.assert_equal [1;2;3;4;5] (to_list v);
 *)
@@ -620,8 +619,6 @@ let filter_in_place p v =
   fill_with_junk_ v.vec !j (v.size - !j);
   v.size <- !j
 
-let filter' = filter_in_place
-
 (*$T
   let v = 1 -- 10 in filter_in_place (fun x->x<4) v; \
     to_list v = [1;2;3]
@@ -921,7 +918,7 @@ let of_std_seq ?(init=create ()) seq =
   init
 
 (*$T
-  of_seq Iter.(1 -- 10) |> to_list = CCList.(1 -- 10)
+  of_iter Iter.(1 -- 10) |> to_list = CCList.(1 -- 10)
 *)
 
 let to_iter v k = iter k v
@@ -946,18 +943,12 @@ let to_std_seq_rev v =
   in
   aux (size v-1)
 
-let of_seq = of_iter
-let to_seq = to_iter
-let to_seq_rev = to_iter_rev
-let append_seq = append_iter
-let flat_map_seq = flat_map_iter
-
 (*$Q
   Q.(list int) (fun l -> \
-    let v= of_list l in v |> to_seq_rev |> Iter.to_rev_list = l)
+    let v= of_list l in v |> to_iter_rev |> Iter.to_rev_list = l)
 *)
 
-let slice_seq v start len =
+let slice_iter v start len =
   assert (start >= 0 && len >= 0);
   fun k ->
     assert (start+len <= v.size);
@@ -967,32 +958,13 @@ let slice_seq v start len =
     done
 
 (*$T
-  slice_seq (of_list [0;1;2;3;4]) 1 3 |> CCList.of_seq = [1;2;3]
-  slice_seq (of_list [0;1;2;3;4]) 1 4 |> CCList.of_seq = [1;2;3;4]
-  slice_seq (of_list [0;1;2;3;4]) 0 5 |> CCList.of_seq = [0;1;2;3;4]
+  slice_iter (of_list [0;1;2;3;4]) 1 3 |> CCList.of_iter = [1;2;3]
+  slice_iter (of_list [0;1;2;3;4]) 1 4 |> CCList.of_iter = [1;2;3;4]
+  slice_iter (of_list [0;1;2;3;4]) 0 5 |> CCList.of_iter = [0;1;2;3;4]
 *)
 
 let slice v = (v.vec, 0, v.size)
 
-let fill_empty_slots_with v x : unit =
-  if capacity v > length v then (
-    Array.fill v.vec (length v) (capacity v - length v) x;
-  )
-
-(* check it frees memory properly *)
-(*$R
-  let s = "coucou" ^ "lol" in
-  let w = Weak.create 1 in
-  Weak.set w 0 (Some s);
-  let v = of_list ["a"; s] in
-  ignore (pop_exn v :string);
-  assert_equal ~printer:string_of_int 1 (length v);
-  assert_equal ~printer:CCFun.id      "a" (get v 0);
-  fill_empty_slots_with v "";
-  Gc.major();
-  assert_equal None (Weak.get w 0);
-*)
-
 let (--) i j =
   if i>j
   then init (i-j+1) (fun k -> i-k)
diff --git a/src/core/CCVector.mli b/src/core/CCVector.mli
index b7d9682d..bee621a0 100644
--- a/src/core/CCVector.mli
+++ b/src/core/CCVector.mli
@@ -18,10 +18,6 @@ type 'a ro_vector = ('a, ro) t
 (** Alias for immutable vectors.
     @since 0.15 *)
 
-(* TODO: remove for 3.0 *)
-type 'a sequence = ('a -> unit) -> unit
-(** @deprecated use ['a iter] instead *)
-
 type 'a iter = ('a -> unit) -> unit
 (** Fast internal iterator.
     @since 2.8 *)
@@ -94,9 +90,6 @@ val append_std_seq : ('a, rw) t -> 'a Seq.t -> unit
 (** Append content of iterator.
     @since 2.8 *)
 
-val append_seq : ('a, rw) t -> 'a sequence -> unit
-(** Append content of sequence. *)
-
 val append_list : ('a, rw) t -> 'a list -> unit
 (** Append content of list.
     @since 0.14 *)
@@ -183,11 +176,6 @@ val filter_in_place : ('a -> bool) -> ('a, rw) t -> unit
 (** Filter elements from the vector in place.
     @since NEXT_RELEASE *)
 
-val filter' : ('a -> bool) -> ('a, rw) t -> unit
-(** Alias of {!filter_in_place}
-    @deprecated since NEXT_RELEASE, use {!filter_in_place} instead. *)
-[@@ocaml.deprecated "use filter_in_place instead"]
-
 val fold : ('b -> 'a -> 'b) -> 'b -> ('a,_) t -> 'b
 (** Fold on elements of the vector *)
 
@@ -219,21 +207,10 @@ val filter_map_in_place : ('a -> 'a option) -> ('a,_) t -> unit
 val flat_map : ('a -> ('b,_) t) -> ('a,_) t -> ('b, 'mut) t
 (** Map each element to a sub-vector. *)
 
-val flat_map_iter : ('a -> 'b sequence) -> ('a,_) t -> ('b, 'mut) t
-(** Like {!flat_map}, but using {!iter} for intermediate collections.
-    @since 2.8 *)
-
 val flat_map_std_seq : ('a -> 'b Seq.t) -> ('a,_) t -> ('b, 'mut) t
 (** Like {!flat_map}, but using [Seq] for intermediate collections.
     @since 2.8 *)
 
-val flat_map_seq : ('a -> 'b sequence) -> ('a,_) t -> ('b, 'mut) t
-(** Like {!flat_map}, but using {!sequence} for
-    intermediate collections.
-    @deprecated use {!flat_map_iter} or {!flat_map_std_seq}
-    @since 0.14 *)
-[@@ocaml.deprecated "use flat_map_iter or flat_map_std_seq"]
-
 val flat_map_list : ('a -> 'b list) -> ('a,_) t -> ('b, 'mut) t
 (** Like {!flat_map}, but using {!list} for
     intermediate collections.
@@ -311,15 +288,9 @@ val of_iter : ?init:('a,rw) t -> 'a iter -> ('a, rw) t
 (** Convert an Iterator to a vector.
     @since 2.8.1 *)
 
-val of_seq : ?init:('a,rw) t -> 'a sequence -> ('a, rw) t
-(** Convert an Iterator to a vector.
-    @deprecated use of_iter *)
-[@@ocaml.deprecated "use of_iter. For the standard Seq, see {!of_std_seq}"]
-
 val of_std_seq : ?init:('a,rw) t -> 'a Seq.t -> ('a, rw) t
 (** Convert an Iterator to a vector.
-    @deprecated use of_iter *)
-[@@ocaml.deprecated "use of_iter. For the standard Seq, see {!of_std_seq}"]
+    @since 2.8.1 *)
 
 val to_iter : ('a,_) t -> 'a iter
 (** Return a [iter] with the elements contained in the vector.
@@ -343,32 +314,15 @@ val to_std_seq_rev : ('a,_) t -> 'a Seq.t
     @since 2.8
 *)
 
-val to_seq : ('a,_) t -> 'a sequence
-(** @deprecated use to_iter *)
-[@@ocaml.deprecated "use to_iter. For the standard Seq, see {!to_std_seq}"]
-
-val to_seq_rev : ('a, _) t -> 'a sequence
-(** [to_seq_rev v] returns the sequence of elements of [v] in reverse order,
-    that is, the last elements of [v] are iterated on first.
-    @since 0.14
-    @deprecated use {!to_iter_rev} *)
-[@@ocaml.deprecated "use to_iter_rev. For the standard Seq, see {!to_std_seq_rev}"]
-
 val slice : ('a,rw) t -> ('a array * int * int)
 (** Vector as an array slice. By doing it we expose the internal array, so
     be careful!. *)
 
-val slice_seq : ('a,_) t -> int -> int -> 'a sequence
+val slice_iter : ('a,_) t -> int -> int -> 'a iter
 (** [slice_seq v start len] is the sequence of elements from [v.(start)]
-    to [v.(start+len-1)]. *)
-
-val fill_empty_slots_with : ('a, _) t -> 'a -> unit
-(** [fill_empty_slots_with v x] puts [x] in the slots of [v]'s underlying
-    array that are not used (ie in the last [capacity v - length v] slots).
-    This is useful if you removed some elements from the vector and
-    @deprecated after 2.8, as the vector doesn't keep values alive anymore (see #279, #282, #283)
-    @since 2.4 *)
-[@@ocaml.deprecated "not needed anymore, see #279,#282,#283"]
+    to [v.(start+len-1)].
+    @since NEXT_RELEASE
+*)
 
 val of_klist : ?init:('a, rw) t -> 'a klist -> ('a, rw) t
 val to_klist : ('a,_) t -> 'a klist
diff --git a/src/core/containers.ml b/src/core/containers.ml
index 16d94403..8417af22 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -39,6 +39,7 @@ module Parse = CCParse
 module Random = CCRandom
 module Ref = CCRef
 module Result = CCResult
+module Seq = CCSeq
 module Set = CCSet
 module String = CCString
 module Vector = CCVector
diff --git a/src/core/dune b/src/core/dune
index 3d316b80..0b99c77d 100644
--- a/src/core/dune
+++ b/src/core/dune
@@ -16,7 +16,7 @@
  (public_name containers)
  (wrapped false)
  (modules :standard \ mkshims)
- (flags :standard :standard -warn-error -a+8 -safe-string -nolabels -open
+ (flags :standard :standard -warn-error -a+8 -w -32-67 -safe-string -nolabels -open
    CCMonomorphic)
  (ocamlopt_flags (:include ../flambda.flags))
  (libraries seq containers.monomorphic))
diff --git a/src/data/CCBV.ml b/src/data/CCBV.ml
index 08fbb0c2..7c3aa884 100644
--- a/src/data/CCBV.ml
+++ b/src/data/CCBV.ml
@@ -549,8 +549,8 @@ let of_seq seq =
   bv
 
 (*$T
-  CCList.range 0 10 |> CCList.to_seq |> of_seq |> to_seq \
-    |> CCList.of_seq |> List.sort CCOrd.compare = CCList.range 0 10
+  CCList.range 0 10 |> CCList.to_iter |> of_seq |> to_seq \
+    |> CCList.of_iter |> List.sort CCOrd.compare = CCList.range 0 10
 *)
 
 let pp out bv =
diff --git a/src/data/CCHashTrie.ml b/src/data/CCHashTrie.ml
index 85f8f726..dc34ed04 100644
--- a/src/data/CCHashTrie.ml
+++ b/src/data/CCHashTrie.ml
@@ -603,7 +603,7 @@ module Make(Key : KEY)
   (*$R
     let m = M.of_list [1, 1; 2, 2; 5, 5] in
     let m' = M.update 4
-      (function
+      ~f:(function
       | None -> Some 4
       | Some _ -> Some 0
       ) m
diff --git a/src/data/CCIntMap.ml b/src/data/CCIntMap.ml
index 14faf74f..5707b20a 100644
--- a/src/data/CCIntMap.ml
+++ b/src/data/CCIntMap.ml
@@ -562,7 +562,7 @@ let rec merge ~f t1 t2 : _ t =
 (*$QR
   Q.(let p = small_list (pair small_int unit) in pair p p) (fun (l1,l2) ->
     let l1 = _list_uniq l1 and l2 = _list_uniq l2 in
-    equal Stdlib.(=)
+    equal ~eq:Stdlib.(=)
       (union (fun _ v1 _ -> v1) (of_list l1) (of_list l2))
       (merge ~f:merge_union (of_list l1) (of_list l2)))
   *)
@@ -570,14 +570,14 @@ let rec merge ~f t1 t2 : _ t =
 (*$QR
   Q.(let p = small_list (pair small_int unit) in pair p p) (fun (l1,l2) ->
     let l1 = _list_uniq l1 and l2 = _list_uniq l2 in
-    equal Stdlib.(=)
+    equal ~eq:Stdlib.(=)
       (inter (fun _ v1 _ -> v1) (of_list l1) (of_list l2))
       (merge ~f:merge_inter (of_list l1) (of_list l2)))
   *)
 
 (** {2 Conversions} *)
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 
@@ -600,14 +600,14 @@ let to_list t = fold (fun k v l -> (k,v) :: l) t []
     of_list l |> cardinal = List.length l)
 *)
 
-let add_seq t seq =
+let add_iter t iter =
   let t = ref t in
-  seq (fun (k,v) -> t := add k v !t);
+  iter (fun (k,v) -> t := add k v !t);
   !t
 
-let of_seq seq = add_seq empty seq
+let of_iter iter = add_iter empty iter
 
-let to_seq t yield = iter (fun k v -> yield (k,v)) t
+let to_iter t yield = iter (fun k v -> yield (k,v)) t
 
 let keys t yield = iter (fun k _ -> yield k) t
 
diff --git a/src/data/CCIntMap.mli b/src/data/CCIntMap.mli
index b684e380..4173493b 100644
--- a/src/data/CCIntMap.mli
+++ b/src/data/CCIntMap.mli
@@ -82,7 +82,7 @@ val merge :
 
 (** {2 Whole-collection operations} *)
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
 
@@ -92,15 +92,15 @@ val of_list : (int * 'a) list -> 'a t
 
 val to_list : 'a t -> (int * 'a) list
 
-val add_seq : 'a t -> (int * 'a) sequence -> 'a t
+val add_iter : 'a t -> (int * 'a) iter -> 'a t
 
-val of_seq : (int * 'a) sequence -> 'a t
+val of_iter : (int * 'a) iter -> 'a t
 
-val to_seq : 'a t -> (int * 'a) sequence
+val to_iter : 'a t -> (int * 'a) iter
 
-val keys : _ t -> int sequence
+val keys : _ t -> int iter
 
-val values : 'a t -> 'a sequence
+val values : 'a t -> 'a iter
 
 val add_gen : 'a t -> (int * 'a) gen -> 'a t
 (** @since 0.13 *)
diff --git a/src/data/CCLazy_list.ml b/src/data/CCLazy_list.ml
index 16c4e10f..5c6ec50c 100644
--- a/src/data/CCLazy_list.ml
+++ b/src/data/CCLazy_list.ml
@@ -90,7 +90,7 @@ let default ~default l =
   )
 
 (*$=
-  [1] (default (return 1) empty |> to_list)
+  [1] (default ~default:(return 1) empty |> to_list)
 *)
 
 module Infix = struct
diff --git a/src/data/CCRingBuffer.ml b/src/data/CCRingBuffer.ml
index 808f1c95..523f8895 100644
--- a/src/data/CCRingBuffer.ml
+++ b/src/data/CCRingBuffer.ml
@@ -284,7 +284,7 @@ module MakeFromArray(A:Array.S) : S with module Array = A = struct
     let b = Byte.create (max s_len 64) in \
     Byte.blit_from b s 0 s_len; \
     let b' = Byte.copy b in \
-    try Byte.iteri b (fun i c -> if Byte.get_front b' i <> c then raise Exit); true with Exit -> false)
+    try Byte.iteri b ~f:(fun i c -> if Byte.get_front b' i <> c then raise Exit); true with Exit -> false)
   *)
 
   (*$Q
@@ -481,7 +481,7 @@ module MakeFromArray(A:Array.S) : S with module Array = A = struct
     let s_len = Bytes.length s in \
     let b = Byte.create (max s_len 64) in \
     Byte.blit_from b s 0 s_len; \
-    try Byte.iteri b (fun i c -> if Byte.get_front b i <> c then raise Exit); \
+    try Byte.iteri b ~f:(fun i c -> if Byte.get_front b i <> c then raise Exit); \
       true with Exit -> false)
   *)
 
diff --git a/src/data/CCWBTree.ml b/src/data/CCWBTree.ml
index 8363d93f..39aa4f6a 100644
--- a/src/data/CCWBTree.ml
+++ b/src/data/CCWBTree.ml
@@ -41,7 +41,7 @@
   Q.(list op) (fun l -> let m = apply_ops l M.empty in M.balanced m)
 *)
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Format.formatter -> 'a -> unit
 
@@ -149,11 +149,11 @@ module type S = sig
 
   val to_list : 'a t -> (key * 'a) list
 
-  val add_seq : 'a t -> (key * 'a) sequence -> 'a t
+  val add_iter : 'a t -> (key * 'a) iter -> 'a t
 
-  val of_seq : (key * 'a) sequence -> 'a t
+  val of_iter : (key * 'a) iter -> 'a t
 
-  val to_seq : 'a t -> (key * 'a) sequence
+  val to_iter : 'a t -> (key * 'a) iter
 
   val add_gen : 'a t -> (key * 'a) gen -> 'a t
 
@@ -500,8 +500,8 @@ module MakeFull(K : KEY) : S with type key = K.t = struct
       List.for_all (fun (k,v) ->
         let l, v', r = M.split k m in
         v' = Some v
-        && (M.to_seq l |> Iter.for_all (fun (k',_) -> k' < k))
-        && (M.to_seq r |> Iter.for_all (fun (k',_) -> k' > k))
+        && (M.to_iter l |> Iter.for_all (fun (k',_) -> k' < k))
+        && (M.to_iter r |> Iter.for_all (fun (k',_) -> k' > k))
         && M.balanced m
         && M.cardinal l + M.cardinal r + 1 = List.length lst
       ) lst)
@@ -533,7 +533,7 @@ module MakeFull(K : KEY) : S with type key = K.t = struct
   (*$R
     let m1 = M.of_list [1, 1; 2, 2; 4, 4] in
     let m2 = M.of_list [1, 1; 3, 3; 4, 4; 7, 7] in
-    let m = M.merge (fun k -> CCOpt.map2 (+)) m1 m2 in
+    let m = M.merge ~f:(fun k -> CCOpt.map2 (+)) m1 m2 in
     assert_bool "balanced" (M.balanced m);
     assert_equal
       ~cmp:(CCList.equal (CCPair.equal CCInt.equal CCInt.equal))
@@ -546,7 +546,7 @@ module MakeFull(K : KEY) : S with type key = K.t = struct
     Q.(let p = list (pair small_int small_int) in pair p p) (fun (l1, l2) ->
         let l1 = _list_uniq l1 and l2 = _list_uniq l2 in
         let m1 = M.of_list l1 and m2 = M.of_list l2  in
-        let m = M.merge (fun _ v1 v2 -> match v1 with
+        let m = M.merge ~f:(fun _ v1 v2 -> match v1 with
           | None -> v2 | Some _ as r -> r) m1 m2 in
         List.for_all (fun (k,v) -> M.get_exn k m = v) l1  &&
         List.for_all (fun (k,v) -> M.mem k m1 || M.get_exn k m = v) l2)
@@ -560,14 +560,14 @@ module MakeFull(K : KEY) : S with type key = K.t = struct
 
   let to_list m = fold ~f:(fun acc k v -> (k,v) :: acc) ~x:[] m
 
-  let add_seq m seq =
+  let add_iter m seq =
     let m = ref m in
     seq (fun (k,v) -> m := add k v !m);
     !m
 
-  let of_seq s = add_seq empty s
+  let of_iter s = add_iter empty s
 
-  let to_seq m yield = iter ~f:(fun k v -> yield (k,v)) m
+  let to_iter m yield = iter ~f:(fun k v -> yield (k,v)) m
 
   let rec add_gen m g = match g() with
     | None -> m
diff --git a/src/data/CCWBTree.mli b/src/data/CCWBTree.mli
index c62ce15e..71e0a719 100644
--- a/src/data/CCWBTree.mli
+++ b/src/data/CCWBTree.mli
@@ -6,7 +6,7 @@
 
     @since 0.13 *)
 
-type 'a sequence = ('a -> unit) -> unit
+type 'a iter = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Format.formatter -> 'a -> unit
 
@@ -114,11 +114,11 @@ module type S = sig
 
   val to_list : 'a t -> (key * 'a) list
 
-  val add_seq : 'a t -> (key * 'a) sequence -> 'a t
+  val add_iter : 'a t -> (key * 'a) iter -> 'a t
 
-  val of_seq : (key * 'a) sequence -> 'a t
+  val of_iter : (key * 'a) iter -> 'a t
 
-  val to_seq : 'a t -> (key * 'a) sequence
+  val to_iter : 'a t -> (key * 'a) iter
 
   val add_gen : 'a t -> (key * 'a) gen -> 'a t
 
diff --git a/src/threads/dune b/src/threads/dune
index 34ac97f9..55ce29ea 100644
--- a/src/threads/dune
+++ b/src/threads/dune
@@ -4,7 +4,7 @@
   (public_name containers-thread)
   (wrapped false)
   (optional)
-  (flags :standard -warn-error -a+8 -safe-string -open CCShims_)
+  (flags :standard -warn-error -a+8 -w -32 -safe-string -open CCShims_)
   (ocamlopt_flags :standard (:include ../flambda.flags))
   (libraries containers threads))