diff --git a/Makefile b/Makefile
index 1528836e..85893647 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,10 @@
+PROMOTE=$(if $(shell ocamlc -version |grep '4\.0[012]\.[0-9][0-9]*'), \
+	      --ignore-promoted-rules, )
 
 all: build test
 
 build:
-	dune build @install
+	dune build $(PROMOTE) @install
 
 test: build
 	dune runtest --no-buffer --force
@@ -11,12 +13,12 @@ clean:
 	dune clean
 
 doc:
-	dune build @doc
+	dune build $(PROMOTE) @doc
 
 BENCH_TARGETS=run_benchs.exe run_bench_hash.exe
 
 benchs:
-	dune build $(addprefix benchs/, $(BENCH_TARGETS))
+	dune build $(PROMOTE) $(addprefix benchs/, $(BENCH_TARGETS))
 
 examples:
 	dune build examples/id_sexp.exe
diff --git a/qtest/make.ml b/qtest/make.ml
index 42b1bfd4..c8c7c3d6 100644
--- a/qtest/make.ml
+++ b/qtest/make.ml
@@ -20,6 +20,7 @@ let do_not_test file =
   is_suffix ~sub:"containers.ml" file ||
   is_suffix ~sub:"containers_top.ml" file ||
   is_suffix ~sub:"mkflags.ml" file ||
+  is_suffix ~sub:"unlabel.ml" file ||
   is_suffix ~sub:"utop.ml" file
 
 let prefix = "src"
diff --git a/src/core/CCArray.mli b/src/core/CCArray.mli
index e7d1260b..0b138167 100644
--- a/src/core/CCArray.mli
+++ b/src/core/CCArray.mli
@@ -1,3 +1,4 @@
+(*  AUTOGENERATED FROM CCArrayLabels.mli  *)
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
@@ -13,6 +14,10 @@ type 'a printer = Format.formatter -> 'a -> unit
 
 (** {2 Arrays} *)
 
+(**/**)
+external make_float : int -> float array = "caml_make_float_vect" (* compat *)
+(**/**)
+
 include module type of Array
 
 type 'a t = 'a array
@@ -57,28 +62,30 @@ val length : _ t -> int
 (** [length a] returns the length (number of elements) of the given array [a]. *)
 
 val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
-(** [fold f acc a] computes [f (... (f (f acc a.(0)) a.(1)) ...) a.(n-1)],
+(** [fold f init a] computes [f (... (f (f init a.(0)) a.(1)) ...) a.(n-1)],
     where [n] is the length of the array [a]. *)
 
 val foldi : ('a -> int -> 'b -> 'a) -> 'a -> 'b t -> 'a
-(** [foldi f acc a] is just like {!fold}, but it also passes in the index
+(** [foldi f init a] is just like {!fold}, but it also passes in the index
     of each element as the second argument to the folded function [f]. *)
 
 val fold_while : ('a -> 'b -> 'a * [`Stop | `Continue]) -> 'a -> 'b t -> 'a
-(** [fold_while f acc a] folds left on array [a] until a stop condition via [('a, `Stop)]
+(** [fold_while f init a] folds left on array [a] until a stop condition via [('a, `Stop)]
     is indicated by the accumulator.
     @since 0.8 *)
 
 val fold_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a t -> 'acc * 'b t
-(** [fold_map f acc a] is a [fold_left]-like function, but it also maps the
+(** [fold_map f init a] is a [fold_left]-like function, but it also maps the
     array to another array.
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.1 with labels *)
 
 val scan_left : ('acc -> 'a -> 'acc) -> 'acc -> 'a t -> 'acc t
-(** [scan_left f acc a] returns the array
-    [ [|acc; f acc x0; f (f acc a.(0)) a.(1); …|] ].
+(** [scan_left f init a] returns the array
+    [ [|init; f init x0; f (f init a.(0)) a.(1); …|] ].
 
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.1 with labels *)
 
 val iter : ('a -> unit) -> 'a t -> unit
 (** [iter f a] applies function [f] in turn to all elements of [a].
@@ -103,24 +110,27 @@ val reverse_in_place : 'a t -> unit
 (** [reverse_in_place a] reverses the array [a] in place. *)
 
 val sorted : ('a -> 'a -> int) -> 'a t -> 'a array
-(** [sorted cmp a] makes a copy of [a] and sorts it with [cmp].
+    (* FIXME: better label this ~cmp ?? *)
+(** [sorted f a] makes a copy of [a] and sorts it with [f].
     @since 1.0 *)
 
 val sort_indices : ('a -> 'a -> int) -> 'a t -> int array
-(** [sort_indices cmp a] returns a new array [b], with the same length as [a],
-    such that [b.(i)] is the index at which the [i]-th element of [sorted cmp a]
+    (* FIXME: better label this ~cmp ?? *)
+(** [sort_indices f a] returns a new array [b], with the same length as [a],
+    such that [b.(i)] is the index at which the [i]-th element of [sorted f a]
     appears in [a]. [a] is not modified.
 
-    In other words, [map (fun i -> a.(i)) (sort_indices cmp a) = sorted cmp a].
+    In other words, [map (fun i -> a.(i)) (sort_indices f a) = sorted f a].
     [sort_indices] yields the inverse permutation of {!sort_ranking}.
     @since 1.0 *)
 
 val sort_ranking : ('a -> 'a -> int) -> 'a t -> int array
-(** [sort_ranking cmp a] returns a new array [b], with the same length as [a],
+    (* FIXME: better label this ~cmp ?? *)
+(** [sort_ranking f a] returns a new array [b], with the same length as [a],
     such that [b.(i)] is the index at which the [i]-th element of [a] appears
-    in [sorted cmp a]. [a] is not modified.
+    in [sorted f a]. [a] is not modified.
 
-    In other words, [map (fun i -> (sorted cmp a).(i)) (sort_ranking cmp a) = a].
+    In other words, [map (fun i -> (sorted f a).(i)) (sort_ranking f a) = a].
     [sort_ranking] yields the inverse permutation of {!sort_indices}.
 
     In the absence of duplicate elements in [a], we also have
@@ -130,97 +140,103 @@ val sort_ranking : ('a -> 'a -> int) -> 'a t -> int array
 val find_map : ('a -> 'b option) -> 'a t -> 'b option
 (** [find_map f a] returns [Some y] if there is an element [x] such
     that [f x = Some y]. Otherwise returns [None].
-    @since 1.3 *)
+    @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. *)
+    @deprecated since 1.3, use {!find_map} instead.
+    The version with labels is
+    @deprecated since 2.1, 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 *)
+    @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. *)
+    @deprecated since 1.3, use {!find_map} instead.
+    The version with labels is
+    @deprecated since 2.1, use {!find_map} instead. *)
 
 val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
-(** [find_idx p a] returns [Some (i,x)] where [x] is the [i]-th element of [a],
-    and [p x] holds. Otherwise returns [None].
+(** [find_idx f a] returns [Some (i,x)] where [x] is the [i]-th element of [a],
+    and [f x] holds. Otherwise returns [None].
     @since 0.3.4 *)
 
 val lookup : cmp:'a ord -> 'a -> 'a t -> int option
-(** [lookup cmp x a] lookups the index of some key [x] in a sorted array [a].
-    Undefined behavior if the array [a] is not sorted wrt [cmp].
+(** [lookup ~cmp key a] lookups the index of some key [key] in a sorted array [a].
+    Undefined behavior if the array [a] is not sorted wrt [~cmp].
     Complexity: [O(log (n))] (dichotomic search).
-    @return [None] if the key [x] is not present, or
+    @return [None] if the key [key] is not present, or
       [Some i] ([i] the index of the key) otherwise. *)
 
 val lookup_exn : cmp:'a ord -> 'a -> 'a t -> int
-(** [lookup_exn cmp x a] is like {!lookup}, but
-    @raise Not_found if the key [x] is not present. *)
+(** [lookup_exn ~cmp key a] is like {!lookup}, but
+    @raise Not_found if the key [key] is not present. *)
 
 val bsearch : cmp:('a -> 'a -> int) -> 'a -> 'a t ->
   [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
-(** [bsearch ~cmp x a] finds the index of the object [x] in the array [a],
-    provided [a] is {b sorted} using [cmp]. If the array is not sorted,
+(** [bsearch ~cmp key a] finds the index of the object [key] in the array [a],
+    provided [a] is {b sorted} using [~cmp]. If the array is not sorted,
     the result is not specified (may raise Invalid_argument).
 
     Complexity: [O(log n)] where n is the length of the array [a]
     (dichotomic search).
 
     @return
-    - [`At i] if [cmp a.(i) x = 0] (for some i).
-    - [`All_lower] if all elements of [a] are lower than [x].
-    - [`All_bigger] if all elements of [a] are bigger than [x].
-    - [`Just_after i] if [a.(i) < x < a.(i+1)].
+    - [`At i] if [cmp a.(i) key = 0] (for some i).
+    - [`All_lower] if all elements of [a] are lower than [key].
+    - [`All_bigger] if all elements of [a] are bigger than [key].
+    - [`Just_after i] if [a.(i) < key < a.(i+1)].
     - [`Empty] if the array [a] is empty.
 
     @raise Invalid_argument if the array is found to be unsorted w.r.t [cmp].
     @since 0.13 *)
 
 val for_all : ('a -> bool) -> 'a t -> bool
-(** [for_all p [|a1; ...; an|]] is [true] if all elements of the array
-    satisfy the predicate [p]. That is, it returns
-    [(p a1) && (p a2) && ... && (p an)]. *)
+(** [for_all f [|a1; ...; an|]] is [true] if all elements of the array
+    satisfy the predicate [f]. That is, it returns
+    [(f a1) && (f a2) && ... && (f an)]. *)
 
 val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
-(** [for_all2 p [|a1; ...; an|] [|b1; ...; bn|]] is [true] if each pair of elements [ai bi]
-    satisfies the predicate [p].
-    That is, it returns [(p a1 b1) && (p a2 b2) && ... && (p an bn)].
+(** [for_all2 f [|a1; ...; an|] [|b1; ...; bn|]] is [true] if each pair of elements [ai bi]
+    satisfies the predicate [f].
+    That is, it returns [(f a1 b1) && (f a2 b2) && ... && (f an bn)].
 
     @raise Invalid_argument if arrays have distinct lengths.
     Allow different types.
     @since 0.20 *)
 
 val exists : ('a -> bool) -> 'a t -> bool
-(** [exists p [|a1; ...; an|]] is [true] if at least one element of
-    the array satisfies the predicate [p]. That is, it returns
-    [(p a1) || (p a2) || ... || (p an)]. *)
+(** [exists f [|a1; ...; an|]] is [true] if at least one element of
+    the array satisfies the predicate [f]. That is, it returns
+    [(f a1) || (f a2) || ... || (f an)]. *)
 
 val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
-(** [exists2 p [|a1; ...; an|] [|b1; ...; bn|]] is [true] if any pair of elements [ai bi]
-    satisfies the predicate [p].
-    That is, it returns [(p a1 b1) || (p a2 b2) || ... || (p an bn)].
+(** [exists2 f [|a1; ...; an|] [|b1; ...; bn|]] is [true] if any pair of elements [ai bi]
+    satisfies the predicate [f].
+    That is, it returns [(f a1 b1) || (f a2 b2) || ... || (f an bn)].
 
     @raise Invalid_argument if arrays have distinct lengths.
     Allow different types.
     @since 0.20 *)
 
 val fold2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc
-(** [fold2 f acc a b] fold on two arrays [a] and [b] stepwise.
-    It computes [f (... (f acc a1 b1)...) an bn].
+(** [fold2 f init a b] fold on two arrays [a] and [b] stepwise.
+    It computes [f (... (f init a1 b1)...) an bn].
 
-    @raise Invalid_argument if arrays have distinct lengths.
+    @raise Invalid_argument if [a] and [b] have distinct lengths.
     @since 0.20 *)
 
 val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit
 (** [iter2 f a b] iterates on the two arrays [a] and [b] stepwise.
     It is equivalent to  [f a0 b0; ...; f a.(length a - 1) b.(length b - 1); ()].
 
-    @raise Invalid_argument if arrays have distinct lengths.
+    @raise Invalid_argument if [a] and [b] have distinct lengths.
     @since 0.20 *)
 
 val shuffle : 'a t -> unit
@@ -275,8 +291,8 @@ val rev : 'a t -> 'a t
     @since 0.20 *)
 
 val filter : ('a -> bool) -> 'a t -> 'a t
-(** [filter p a] filters elements out of the array [a]. Only the elements satisfying
-    the given predicate [p] will be kept. *)
+(** [filter f a] filters elements out of the array [a]. Only the elements satisfying
+    the given predicate [f] will be kept. *)
 
 val filter_map : ('a -> 'b option) -> 'a t -> 'b t
 (** [filter_map f [|a1; ...; an|]] calls [(f a1) ... (f an)] and returns an array [b] consisting
@@ -328,6 +344,6 @@ end
 val sort_generic :
   (module MONO_ARRAY with type t = 'arr and type elt = 'elt) ->
   cmp:('elt -> 'elt -> int) -> 'arr -> unit
-(** [sort_generic (module M) cmp a] sorts the array [a], without allocating (eats stack space though).
+(** [sort_generic (module M) ~cmp a] sorts the array [a], without allocating (eats stack space though).
     Performance might be lower than {!Array.sort}.
     @since 0.14 *)
diff --git a/src/core/CCArrayLabels.ml b/src/core/CCArrayLabels.ml
index f100fe0e..fdf51544 100644
--- a/src/core/CCArrayLabels.ml
+++ b/src/core/CCArrayLabels.ml
@@ -1,21 +1,4 @@
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
-(* fallback function *)
-external make_float : int -> float array = "caml_make_float_vect"
-
 include CCArray
-
-(*$inject
-  module type A = module type of CCArray
-  module type AL = module type of CCArrayLabels
-*)
-
-(*$R
-  ignore (module CCArrayLabels : A)
-*)
-
-(*$R
-  ignore (module CCArray : AL)
-*)
-
diff --git a/src/core/CCArrayLabels.mli b/src/core/CCArrayLabels.mli
index 074965ef..c53ae79b 100644
--- a/src/core/CCArrayLabels.mli
+++ b/src/core/CCArrayLabels.mli
@@ -75,22 +75,24 @@ val fold_while : f:('a -> 'b -> 'a * [`Stop | `Continue]) -> init:'a -> 'b t ->
 val fold_map : f:('acc -> 'a -> 'acc * 'b) -> init:'acc -> 'a t -> 'acc * 'b t
 (** [fold_map ~f ~init a] is a [fold_left]-like function, but it also maps the
     array to another array.
-    @since 2.1 *)
+    @since 1.2, but only
+    @since 2.1 with labels *)
 
 val scan_left : f:('acc -> 'a -> 'acc) -> init:'acc -> 'a t -> 'acc t
 (** [scan_left ~f ~init a] returns the array
     [ [|~init; ~f ~init x0; ~f (~f ~init a.(0)) a.(1); …|] ].
 
-    @since 2.1 *)
-    
+    @since 1.2, but only
+    @since 2.1 with labels *)
+
 val iter : f:('a -> unit) -> 'a t -> unit
-(** [iter ~f a] applies function [~f] in turn to all elements of [a].  
+(** [iter ~f a] applies function [~f] in turn to all elements of [a].
     It is equivalent to [~f a.(0); ~f a.(1); ...; ~f a.(length a - 1); ()]. *)
 
 val iteri : f:(int -> 'a -> unit) -> 'a t -> unit
 (** [iteri ~f a] is like {!iter}, but the function [~f] is applied with the index of the
     element as first argument, and the element itself as second argument. *)
-  
+
 val blit : 'a t -> int -> 'a t -> int -> int -> unit
 (** [blit a1 o1 a2 o2 len] copies [len] elements
     from array [a1], starting at element number [o1], to array [a2],
@@ -106,10 +108,12 @@ val reverse_in_place : 'a t -> unit
 (** [reverse_in_place a] reverses the array [a] in place. *)
 
 val sorted : f:('a -> 'a -> int) -> 'a t -> 'a array
+    (* FIXME: better label this ~cmp ?? *)
 (** [sorted ~f a] makes a copy of [a] and sorts it with [~f].
     @since 1.0 *)
 
 val sort_indices : f:('a -> 'a -> int) -> 'a t -> int array
+    (* FIXME: better label this ~cmp ?? *)
 (** [sort_indices ~f a] returns a new array [b], with the same length as [a],
     such that [b.(i)] is the index at which the [i]-th element of [sorted ~f a]
     appears in [a]. [a] is not modified.
@@ -119,6 +123,7 @@ val sort_indices : f:('a -> 'a -> int) -> 'a t -> int array
     @since 1.0 *)
 
 val sort_ranking : f:('a -> 'a -> int) -> 'a t -> int array
+    (* FIXME: better label this ~cmp ?? *)
 (** [sort_ranking ~f a] returns a new array [b], with the same length as [a],
     such that [b.(i)] is the index at which the [i]-th element of [a] appears
     in [sorted ~f a]. [a] is not modified.
@@ -133,39 +138,45 @@ val sort_ranking : f:('a -> 'a -> int) -> 'a t -> int array
 val find_map : f:('a -> 'b option) -> 'a t -> 'b option
 (** [find_map ~f a] returns [Some y] if there is an element [x] such
     that [~f x = Some y]. Otherwise returns [None].
-    @since 2.1 *)
+    @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. *)
 
 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 2.1 *)
+    @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 2.1, use {!find_map_i} instead. *)
+    @deprecated since 1.3, use {!find_map} instead.
+    The version with labels is
+    @deprecated since 2.1, use {!find_map} 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].
     @since 0.3.4 *)
 
-val lookup : cmp:'a ord -> key:'a -> 'a t -> int option
+val lookup : cmp:('a ord [@keep_label]) -> key:'a -> 'a t -> int option
 (** [lookup ~cmp ~key a] lookups the index of some key [~key] in a sorted array [a].
     Undefined behavior if the array [a] is not sorted wrt [~cmp].
     Complexity: [O(log (n))] (dichotomic search).
     @return [None] if the key [~key] is not present, or
       [Some i] ([i] the index of the key) otherwise. *)
 
-val lookup_exn : cmp:'a ord -> key:'a -> 'a t -> int
+val lookup_exn : cmp:('a ord [@keep_label]) -> key:'a -> 'a t -> int
 (** [lookup_exn ~cmp ~key a] is like {!lookup}, but
     @raise Not_found if the key [~key] is not present. *)
 
-val bsearch : cmp:('a -> 'a -> int) -> key:'a -> 'a t ->
+val bsearch : cmp:(('a -> 'a -> int) [@keep_label]) -> key:'a -> 'a t ->
   [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
 (** [bsearch ~cmp ~key a] finds the index of the object [~key] in the array [a],
     provided [a] is {b sorted} using [~cmp]. If the array is not sorted,
@@ -270,8 +281,8 @@ val map2 : f:('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
     and builds an array with the results returned by [~f]:
     [[| ~f a.(0) b.(0); ...; ~f a.(length a - 1) b.(length b - 1)|]].
 
-      @raise Invalid_argument if [a] and [b] have distinct lengths.
-      @since 0.20 *)
+    @raise Invalid_argument if [a] and [b] have distinct lengths.
+    @since 0.20 *)
 
 val rev : 'a t -> 'a t
 (** [rev a] copies the array [a] and reverses it in place.
@@ -330,8 +341,7 @@ end
 
 val sort_generic :
   (module MONO_ARRAY with type t = 'arr and type elt = 'elt) ->
-  cmp:('elt -> 'elt -> int) -> 'arr -> unit
+  cmp:(('elt -> 'elt -> int) [@keep_label]) -> 'arr -> unit
 (** [sort_generic (module M) ~cmp a] sorts the array [a], without allocating (eats stack space though).
     Performance might be lower than {!Array.sort}.
     @since 0.14 *)
-
diff --git a/src/core/CCArray_slice.mli b/src/core/CCArray_slice.mli
index 6f2bd4da..f79fcb78 100644
--- a/src/core/CCArray_slice.mli
+++ b/src/core/CCArray_slice.mli
@@ -1,3 +1,5 @@
+(*  AUTOGENERATED FROM CCArray_sliceLabels.mli  *)
+
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
@@ -153,13 +155,13 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
     and [p x] holds. Otherwise returns [None].
     @since 0.3.4 *)
 
-val lookup : cmp:'a ord -> 'a -> 'a t -> int option
+val lookup : cmp:('a ord) -> 'a -> 'a t -> int option
 (** [lookup ~cmp x as] lookups the index [i] of some key [x] in the slice [as], provided [as] is
     sorted using [cmp].
     @return [None] if the key [x] is not present, or
       [Some i] ([i] the index of the key) otherwise. *)
 
-val lookup_exn : cmp:'a ord -> 'a -> 'a t -> int
+val lookup_exn : cmp:('a ord) -> 'a -> 'a t -> int
 (** [lookup_exn ~cmp x as] is like {!lookup}, but
     @raise Not_found if the key [x] is not present. *)
 
diff --git a/src/core/CCArray_sliceLabels.ml b/src/core/CCArray_sliceLabels.ml
new file mode 100644
index 00000000..97fcfb10
--- /dev/null
+++ b/src/core/CCArray_sliceLabels.ml
@@ -0,0 +1,4 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+include CCArray_slice
diff --git a/src/core/CCArray_sliceLabels.mli b/src/core/CCArray_sliceLabels.mli
new file mode 100644
index 00000000..41b59667
--- /dev/null
+++ b/src/core/CCArray_sliceLabels.mli
@@ -0,0 +1,259 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Array Slice} *)
+
+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
+type 'a random_gen = Random.State.t -> 'a
+type 'a printer = Format.formatter -> 'a -> unit
+
+type 'a t
+(** The type for an array slice, containing elements of type ['a] *)
+
+val empty : 'a t
+(** [empty] is the empty array slice. *)
+
+val equal : 'a equal -> 'a t equal
+(** [equal eq as1 as2] is [true] if the lengths of [as1] and [as2] are the same
+    and if the corresponding elements test equal using [eq]. *)
+
+val compare : 'a ord -> 'a t ord
+(** [compare cmp as1 as2] compares the two slices [as1] and [as2] using 
+    the comparison function [cmp], element by element. *)
+
+val get : 'a t -> int -> 'a
+(** [get as n] returns the element number [n] of slice [as].
+    The first element has number 0.
+    The last element has number [length as - 1].
+    You can also write [as.(n)] instead of [get as n].
+
+    Raise [Invalid_argument "index out of bounds"]
+    if [n] is outside the range 0 to [(length as - 1)]. *)
+
+val get_safe : 'a t -> int -> 'a option
+(** [get_safe as i] returns [Some as.(i)] if [i] is a valid index.
+    @since 0.18 *)
+
+val make : 'a array -> int -> len:(int [@keep_label]) -> 'a t
+(** [make a i ~len] creates a slice from given offset [i] and length [len] of the given array [a].
+    @raise Invalid_argument if the slice isn't valid. *)
+
+val of_slice : ('a array * int * int) -> 'a t
+(** [of_slice (a, i, len)] makes a slice from a triple [(a, i, len)] where [a] is the array,
+    [i] the offset in [a], and [len] the number of elements of the slice.
+    @raise Invalid_argument if the slice isn't valid (See {!make}). *)
+
+val to_slice : 'a t -> ('a array * int * int)
+(** [to_slice as] converts the slice [as] into a triple [(a, i, len)] where [len] is the length of
+    the sub-array of [a] starting at offset [i]. *)
+
+val to_list : 'a t -> 'a list
+(** [to_list as] converts the slice [as] directly to a list.
+    @since 1.0 *)
+
+val full : 'a array -> 'a t
+(** [full a] creates a slice that covers the full array [a]. *)
+
+val underlying : 'a t -> 'a array
+(** [underlying as] returns the underlying array (shared). Modifying this array will modify
+    the slice [as]. *)
+
+val copy : 'a t -> 'a array
+(** [copy as] copies the slice [as] into a new array. *)
+
+val sub : 'a t -> int -> int -> 'a t
+(** [sub as i len] builds a new sub-slice that contains the given subrange specified
+    by the index [i] and the length [len]. *)
+
+val set : 'a t -> int -> 'a -> unit
+(** [set as n x] modifies the slice [as] in place, replacing
+    element number [n] with [x].
+    You can also write [as.(n) <- x] instead of [set as n x].
+
+    Raise [Invalid_argument "index out of bounds"]
+    if [n] is outside the range 0 to [length as - 1]. *)
+
+val length : _ t -> int
+(** [length as] returns the length (number of elements) of the given slice [as]. *)
+
+val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** [fold f acc as] computes [f (... (f (f acc as.(0)) as.(1)) ...) as.(length as - 1)]. *)
+
+val foldi : ('a -> int -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** [foldi f acc as] is just like {!fold} but it also passes in the index of each element
+    as the second argument to the folded function [f]. *)
+
+val fold_while : ('a -> 'b -> 'a * [`Stop | `Continue]) -> 'a -> 'b t -> 'a
+(** [fold_while f acc as] folds left on slice [as] until a stop condition via [('a, `Stop)]
+    is indicated by the accumulator.
+    @since 0.8 *)
+
+val iter : ('a -> unit) -> 'a t -> unit
+(** [iter f as] applies function [f] in turn to all elements of [as].
+    It is equivalent to [f as.(0); f as.(1); ...; f as.(length as - 1); ()]. *)
+
+val iteri : (int -> 'a -> unit) -> 'a t -> unit
+(** [iteri f as] is like {!iter}, but the function [f] is applied with the index of the element
+    as first argument, and the element itself as second argument. *)
+
+val blit : 'a t -> int -> 'a t -> int -> int -> unit
+(** [blit as1 o1 as2 o2 len] copies [len] elements
+    from slice [as1], starting at element number [o1], to slice [as2],
+    starting at element number [o2]. It works correctly even if
+    [as1] and [as2] are the same slice, and the source and
+    destination chunks overlap.
+
+    Raise [Invalid_argument "CCArray_slice.blit"] if [o1] and [len] do not
+    designate a valid subarray of [as1], or if [o2] and [len] do not
+    designate a valid subarray of [as2]. *)
+
+val reverse_in_place : 'a t -> unit
+(** [reverse_in_place as] reverses the slice [as] in place. *)
+
+val sorted : ('a -> 'a -> int) -> 'a t -> 'a array
+(** [sorted cmp as] makes a copy of [as] and sorts it with [cmp].
+    @since 1.0 *)
+
+val sort_indices : ('a -> 'a -> int) -> 'a t -> int array
+(** [sort_indices cmp as] returns a new array [b], with the same length as [as],
+    such that [b.(i)] is the index at which the [i]-th element of [sorted cmp as]
+    appears in [as]. [as] is not modified.
+
+    In other words, [map (fun i -> as.(i)) (sort_indices cmp as) = sorted cmp as].
+    [sort_indices] yields the inverse permutation of {!sort_ranking}.
+    @since 1.0 *)
+
+val sort_ranking : ('a -> 'a -> int) -> 'a t -> int array
+(** [sort_ranking cmp as] returns a new array [b], with the same length as [as],
+    such that [b.(i)] is the index at which the [i]-th element of [as] appears
+    in [sorted cmp as]. [as] is not modified.
+
+    In other words, [map (fun i -> (sorted cmp as).(i)) (sort_ranking cmp as) = as].
+    [sort_ranking] yields the inverse permutation of {!sort_indices}.
+
+    In the absence of duplicate elements in [as], we also have
+    [lookup_exn as.(i) (sorted as) = (sorted_ranking as).(i)].
+    @since 1.0 *)
+
+val find : ('a -> 'b option) -> 'a t -> 'b option
+(** [find f as] returns [Some y] if there is an element [x] such
+    that [f x = Some y]. Otherwise returns [None]. *)
+
+val findi : (int -> 'a -> 'b option) -> 'a t -> 'b option
+(** [findi f as] is like {!find}, but the index of the element is also passed 
+    to the predicate function [f].
+    @since 0.3.4 *)
+
+val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
+(** [find_idx p as] returns [Some (i,x)] where [x] is the [i]-th element of [as],
+    and [p x] holds. Otherwise returns [None].
+    @since 0.3.4 *)
+
+val lookup : cmp:(('a ord) [@keep_label]) -> 'a -> 'a t -> int option
+(** [lookup ~cmp x as] lookups the index [i] of some key [x] in the slice [as], provided [as] is
+    sorted using [cmp].
+    @return [None] if the key [x] is not present, or
+      [Some i] ([i] the index of the key) otherwise. *)
+
+val lookup_exn : cmp:(('a ord) [@keep_label]) -> 'a -> 'a t -> int
+(** [lookup_exn ~cmp x as] is like {!lookup}, but
+    @raise Not_found if the key [x] is not present. *)
+
+val bsearch : cmp:(('a -> 'a -> int) [@keep_label]) -> 'a -> 'a t ->
+  [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
+(** [bsearch ~cmp x as] finds the index of the object [x] in the slice [as],
+    provided [as] is {b sorted} using [cmp]. If the slice is not sorted,
+    the result is not specified (may raise Invalid_argument).
+
+    Complexity: [O(log n)] where n is the length of the slice [as]
+    (dichotomic search).
+
+    @return
+    - [`At i] if [cmp as.(i) x = 0] (for some i).
+    - [`All_lower] if all elements of [as] are lower than [x].
+    - [`All_bigger] if all elements of [as] are bigger than [x].
+    - [`Just_after i] if [as.(i) < x < as.(i+1)].
+    - [`Empty] if the slice [as] is empty.
+
+    @raise Invalid_argument if the slice is found to be unsorted w.r.t [cmp].
+    @since 0.13 *)
+
+val for_all : ('a -> bool) -> 'a t -> bool
+(** [for_all p [|as1; ...; asn|]] checks if all elements of the slice
+    satisfy the predicate [p]. That is, it returns
+    [(p as1) && (p as2) && ... && (p asn)]. *)
+
+val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
+(** [for_all2 p [|as1; ...; asn|] [|bs1; ...; bsn|]] is [true] if each pair of elements [asi bsi]
+    satisfies the predicate [p].
+    That is, it returns [(p as1 bs1) && (p as2 bs2) && ... && (p asn bsn)].
+
+    @raise Invalid_argument if slices have distinct lengths.
+    Allow different types.
+    @since 0.20 *)
+
+val exists : ('a -> bool) -> 'a t -> bool
+(** [exists p [|as1; ...; asn|]] is [true] if at least one element of
+    the slice satisfies the predicate [p]. That is, it returns
+    [(p as1) || (p as2) || ... || (p asn)]. *)
+
+val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
+(** [exists2 p [|as1; ...; asn|] [|bs1; ...; bsn|]] is [true] if any pair of elements [asi bsi]
+    satisfies the predicate [p].
+    That is, it returns [(p as1 bs1) || (p as2 bs2) || ... || (p asn bsn)].
+
+    @raise Invalid_argument if slices have distinct lengths.
+    Allow different types.
+    @since 0.20 *)
+
+val fold2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc
+(** [fold2 f acc as bs] fold on two slices [as] and [bs] stepwise.
+    It computes [f (... (f acc as1 bs1)...) asn bsn].
+
+    @raise Invalid_argument if slices have distinct lengths.
+    @since 0.20 *)
+
+val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit
+(** [iter2 f as bs] iterates on the two slices [as] and [bs] stepwise.
+    It is equivalent to  [f as0 bs0; ...; f as.(length as - 1) bs.(length bs - 1); ()].
+
+    @raise Invalid_argument if slices have distinct lengths.
+    @since 0.20 *)
+
+val shuffle : 'a t -> unit
+(** [shuffle as] randomly shuffles the slice [as], in place. *)
+
+val shuffle_with : Random.State.t -> 'a t -> unit
+(** [shuffle_with rs as] randomly shuffles the slice [as] (like {!shuffle}) but a specialized random
+    state [rs] is used to control the random numbers being produced during shuffling (for reproducibility). *)
+
+val random_choose : 'a t -> 'a random_gen
+(** [random_choose as rs] randomly chooses an element of [as].
+    @raise Not_found if the array/slice is empty. *)
+
+val to_seq : 'a t -> 'a sequence
+(** [to_seq as] returns a [sequence] of the elements of a slice [as].
+    The input slice [as] is shared with the sequence and modification of it will result
+    in modification of the sequence. *)
+
+val to_gen : 'a t -> 'a gen
+(** [to_gen as] returns a [gen] of the elements of a slice [as]. *)
+
+val to_klist : 'a t -> 'a klist
+(** [to_klist as] returns a [klist] of the elements of a slice [as]. *)
+
+(** {2 IO} *)
+
+val pp: ?sep:string -> 'a printer -> 'a t printer
+(** [pp ~sep pp_item ppf as] formats the slice [as] on [ppf].
+    Each element is formatted with [pp_item] and elements are separated
+    by [sep] (defaults to ", "). *)
+
+val pp_i: ?sep:string -> (int -> 'a printer) -> 'a t printer
+(** [pp_i ~sep pp_item ppf as] prints the slice [as] on [ppf].
+    The printing function [pp_item] is giving both index and element.
+    Elements are separated by [sep] (defaults to ", "). *)
diff --git a/src/core/CCEqual.mli b/src/core/CCEqual.mli
index f940a56c..0ebc13c4 100644
--- a/src/core/CCEqual.mli
+++ b/src/core/CCEqual.mli
@@ -1,3 +1,5 @@
+(*  AUTOGENERATED FROM CCEqualLabels.mli  *)
+
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
diff --git a/src/core/CCEqualLabels.ml b/src/core/CCEqualLabels.ml
new file mode 100644
index 00000000..63c6f1f8
--- /dev/null
+++ b/src/core/CCEqualLabels.ml
@@ -0,0 +1,4 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+include CCEqual
diff --git a/src/core/CCEqualLabels.mli b/src/core/CCEqualLabels.mli
new file mode 100644
index 00000000..52b91f9e
--- /dev/null
+++ b/src/core/CCEqualLabels.mli
@@ -0,0 +1,44 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Equality Combinators} *)
+
+(** @since 1.2 *)
+
+type 'a t = 'a -> 'a -> bool
+(** Equality function. Must be transitive, symmetric, and reflexive. *)
+
+val poly : 'a t
+(** Standard polymorphic equality. *)
+
+val physical : 'a t
+(** Standard physical equality.
+    @since 2.0 *)
+
+val int : int t
+val string : string t
+val bool : bool t
+val float : float t
+val unit : unit t
+
+val list : 'a t -> 'a list t
+val array : 'a t -> 'a array t
+
+val option : 'a t -> 'a option t
+val pair : 'a t -> 'b t -> ('a * 'b) t
+val triple : 'a t -> 'b t -> 'c t -> ('a * 'b * 'c) t
+
+val map : f:('a -> 'b) -> 'b t -> 'a t
+(** [map f eq] is the equality function that, given objects [x] and [y],
+    projects [x] and [y] using [f] (e.g. using a record field) and then
+    compares those projections with [eq].
+    Example:
+    [map fst int] compares values of type [(int * 'a)]  by their
+      first component. *)
+
+module Infix : sig
+  val (>|=) : 'b t -> ('a -> 'b) -> 'a t
+  (** Infix equivalent of {!map}. *)
+end
+
+include module type of Infix
diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index af60128c..395e9df7 100644
--- a/src/core/CCList.ml
+++ b/src/core/CCList.ml
@@ -968,7 +968,7 @@ let find_idx p l = find_mapi (fun i x -> if p x then Some (i, x) else None) l
   find_map (fun x -> if x=3 then Some "a" else None) [1;2;4;5] = None
 *)
 
-let remove ~eq ~x l =
+let remove ~eq x l =
   let rec remove' eq x acc l = match l with
     | [] -> List.rev acc
     | y :: tail when eq x y -> remove' eq x acc tail
@@ -977,8 +977,8 @@ let remove ~eq ~x l =
   remove' eq x [] l
 
 (*$T
-  remove ~eq:CCInt.equal ~x:1 [2;1;3;3;2;1] = [2;3;3;2]
-  remove ~eq:CCInt.equal ~x:10 [1;2;3] = [1;2;3]
+  remove ~eq:CCInt.equal 1 [2;1;3;3;2;1] = [2;3;3;2]
+  remove ~eq:CCInt.equal 10 [1;2;3] = [1;2;3]
 *)
 
 let filter_map f l =
@@ -1483,7 +1483,7 @@ module Assoc = struct
     not (Assoc.mem ~eq:CCInt.equal 4 [1,"1"; 2,"2"; 3, "3"])
   *)
 
-  let update ~eq ~f x l =
+  let update ~eq f x l =
     search_set eq [] l x
       ~f:(fun x opt_y rest ->
         match f opt_y with
@@ -1492,13 +1492,13 @@ module Assoc = struct
   (*$=
     [1,"1"; 2,"22"] \
       (Assoc.update ~eq:CCInt.equal \
-        ~f:(function Some "2" -> Some "22" | _ -> assert false) 2 [1,"1"; 2,"2"] |> lsort)
+        (function Some "2" -> Some "22" | _ -> assert false) 2 [1,"1"; 2,"2"] |> lsort)
     [1,"1"; 3,"3"] \
       (Assoc.update ~eq:CCInt.equal \
-        ~f:(function Some "2" -> None | _ -> assert false) 2 [1,"1"; 2,"2"; 3,"3"] |> lsort)
+        (function Some "2" -> None | _ -> assert false) 2 [1,"1"; 2,"2"; 3,"3"] |> lsort)
     [1,"1"; 2,"2"; 3,"3"] \
       (Assoc.update ~eq:CCInt.equal \
-        ~f:(function None -> Some "3" | _ -> assert false) 3 [1,"1"; 2,"2"] |> lsort)
+        (function None -> Some "3" | _ -> assert false) 3 [1,"1"; 2,"2"] |> lsort)
   *)
 
   let remove ~eq x l =
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index b8277b92..b0146c5a 100644
--- a/src/core/CCList.mli
+++ b/src/core/CCList.mli
@@ -1,3 +1,5 @@
+(*  AUTOGENERATED FROM CCListLabels.mli  *)
+
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
@@ -61,14 +63,15 @@ val fold_while : ('a -> 'b -> 'a * [`Stop | `Continue]) -> 'a -> 'b t -> 'a
     @since 0.8 *)
 
 val fold_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a list -> 'acc * 'b list
-(** [fold_map f acc l] is a [fold_left]-like function, but it also maps the
+(** [fold_map f init l] is a [fold_left]-like function, but it also maps the
     list to another list.
     @since 0.14 *)
 
 val scan_left : ('acc -> 'a -> 'acc) -> 'acc -> 'a list -> 'acc list
-(** [scan_left f acc l] returns the list [[acc; f acc x0; f (f acc x0) x1; ...]]
+(** [scan_left f init l] returns the list [[init; f init x0; f (f init x0) x1; ...]]
     where [x0], [x1], etc. are the elements of [l].
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val fold_map2 : ('acc -> 'a -> 'b -> 'acc * 'c) -> 'acc -> 'a list -> 'b list -> 'acc * 'c list
 (** [fold_map2] is to [fold_map] what [List.map2] is to [List.map].
@@ -76,7 +79,7 @@ val fold_map2 : ('acc -> 'a -> 'b -> 'acc * 'c) -> 'acc -> 'a list -> 'b list ->
     @since 0.16 *)
 
 val fold_filter_map : ('acc -> 'a -> 'acc * 'b option) -> 'acc -> 'a list -> 'acc * 'b list
-(** [fold_filter_map f acc l] is a [fold_left]-like function, but also
+(** [fold_filter_map f init l] is a [fold_left]-like function, but also
     generates a list of output in a way similar to {!filter_map}.
     @since 0.17 *)
 
@@ -87,12 +90,11 @@ val fold_flat_map : ('acc -> 'a -> 'acc * 'b list) -> 'acc -> 'a list -> 'acc *
 
 val count : ('a -> bool) -> 'a list -> int
 (** [count p l] counts how many elements of [l] satisfy predicate [p].
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val count_true_false : ('a -> bool) -> 'a list -> int * int
-(** [let ok_count, ko_count = count_true_false p l in ...]
-    count_true_false how many elements of [l] satisfy (resp. violate) predicate [p].
-    @since NEXT_RELEASE *)
+(** @since NEXT_RELEASE *)
 
 val init : int -> (int -> 'a) -> 'a t
 (** [init len f] is [f 0; f 1; ...; f (len-1)].
@@ -105,31 +107,37 @@ val combine : 'a list -> 'b list -> ('a * 'b) list
     [combine [a1; ...; an] [b1; ...; bn]] is
     [[(a1,b1); ...; (an,bn)]].
     @raise Invalid_argument if the lists have distinct lengths.
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val combine_gen : 'a list -> 'b list -> ('a * 'b) gen
 (** Lazy version of {!combine}.
     Unlike {!combine}, it does not fail if the lists have different
     lengths;
     instead, the output has as many pairs as the smallest input list.
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val split : ('a * 'b) t -> 'a t * 'b t
 (** A tail-recursive version of {!List.split}.
     Transform a list of pairs into a pair of lists:
-    [split [(a1,b1); ...; (an,bn)]] is [([a1; ...; an], [b1; ...; bn])]. *)
+    [split [(a1,b1); ...; (an,bn)]] is [([a1; ...; an], [b1; ...; bn])].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
 
 val compare_lengths : 'a t -> 'b t -> int
 (** Equivalent to [compare (length l1) (length l2)] but more efficient.
     Compare the lengths of two lists.
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val compare_length_with : 'a t -> int -> int
 (** Equivalent to [compare (length l) x] but more efficient.
     Compare the length of a list to an integer.
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 
@@ -158,14 +166,16 @@ val cartesian_product : 'a t t -> 'a t t
       [[1;3;4;5;6];[2;3;4;5;6]];;
     ]}
     invariant: [cartesian_product l = map_product id l].
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val map_product_l : ('a -> 'b list) -> 'a list -> 'b list list
 (** [map_product_l f l] maps each element of [l] to a list of
     objects of type ['b] using [f].
     We obtain [[l1;l2;...;ln]] where [length l=n] and [li : 'b list].
     Then, it returns all the ways of picking exactly one element per [li].
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val diagonal : 'a t -> ('a * 'a) t
 (** All pairs of distinct positions of the list. [list_diagonal l] will
@@ -263,16 +273,21 @@ val sublists_of_len :
       If [last = CCOpt.return], it will simply keep the last group.
       By default, [last = fun _ -> None], i.e. the last group is dropped if shorter than [n].
     @raise Invalid_argument if [offset <= 0] or [n <= 0].
-    @since 1.0 *)
+    See {!CCList.sublists_of_len} for more details.
+
+    @since 1.0, but only
+    @since 1.5 with labels *)
 
 val intersperse : 'a -> 'a list -> 'a list
 (** Insert the first argument between every element of the list.
-    @since 2.1 *)
+    @since 2.1, but only
+    @since 2.2 with labels *)
 
 val interleave : 'a list -> 'a list -> 'a list
 (** [interleave [x1…xn] [y1…ym]] is [x1,y1,x2,y2,…] and finishes with
     the suffix of the longest list.
-    @since 2.1 *)
+    @since 2.1, but only
+    @since 2.2 with labels *)
 
 val pure : 'a -> 'a t
 (** [pure] is [return]. *)
@@ -281,7 +296,7 @@ val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
 (** [funs <*> l] is [product (fun f x -> f x) funs l]. *)
 
 val (<$>) : ('a -> 'b) -> 'a t -> 'b t
-(** [(<$>)] = [map]. *)
+(** [(<$>)] is [map]. *)
 
 val return : 'a -> 'a t
 (** [return x] is [x]. *)
@@ -314,7 +329,8 @@ val drop_while : ('a -> bool) -> 'a t -> 'a t
 
 val take_drop_while : ('a -> bool) -> 'a t -> 'a t * 'a t
 (** [take_drop_while p l] = [take_while p l, drop_while p l].
-    @since 1.2 *)
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val last : int -> 'a t -> 'a t
 (** [last n l] takes the last [n] elements of [l] (or less if
@@ -339,7 +355,8 @@ val find_pred : ('a -> bool) -> 'a t -> 'a option
 
 val find_opt : ('a -> bool) -> 'a t -> 'a option
 (** Safe version of {!find}.
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val find_pred_exn : ('a -> bool) -> 'a t -> 'a
 (** Unsafe version of {!find_pred}.
@@ -360,8 +377,9 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx p x] returns [Some (i,x)] where [x] is the [i]-th element of [l],
     and [p x] holds. Otherwise returns [None]. *)
 
-val remove : eq:('a -> 'a -> bool) -> x:'a -> 'a t -> 'a t
-(** [remove ~x l] removes every instance of [x] from [l]. Tail-recursive.
+val remove : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+    (* FIXME: the original CCList.mli uses ~x instead of ~key !! *)
+(** [remove key l] removes every instance of [key] from [l]. Tail-recursive.
     @param eq equality function.
     @since 0.11 *)
 
@@ -373,21 +391,25 @@ val filter_map : ('a -> 'b option) -> 'a t -> 'b t
 val keep_some : 'a option t -> 'a t
 (** [keep_some l] retains only elements of the form [Some x].
     Like [filter_map CCFun.id].
-    @since 1.3 *)
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val keep_ok : ('a, _) Result.result t -> 'a t
 (** [keep_ok l] retains only elements of the form [Ok x].
-    @since 1.3 *)
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val all_some : 'a option t -> 'a t option
 (** [all_some l] returns [Some l'] if all elements of [l] are of the form [Some x],
     or [None] otherwise.
-    @since 1.3 *)
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val all_ok : ('a, 'err) Result.result t -> ('a t, 'err) Result.result
 (** [all_ok l] returns [Ok l'] if all elements of [l] are of the form [Ok x],
     or [Error e] otherwise (with the first error met).
-    @since 1.3 *)
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val sorted_merge : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
 (** Merge elements from both sorted list. *)
@@ -439,7 +461,8 @@ val iteri : (int -> 'a -> unit) -> 'a t -> unit
 val iteri2 : (int -> 'a -> 'b -> unit) -> 'a t -> 'b t -> unit
 (** Iter on two lists.
     @raise Invalid_argument when lists do not have the same length.
-    @since 2.0 *)
+    @since 2.0, but only
+    @since 2.2 with labels *)
 
 val foldi : ('b -> int -> 'a -> 'b) -> 'b -> 'a t -> 'b
 (** Like [fold] but it also passes in the index of each element to the folded function. Tail-recursive. *)
@@ -447,7 +470,8 @@ val foldi : ('b -> int -> 'a -> 'b) -> 'b -> 'a t -> 'b
 val foldi2 : ('c -> int -> 'a -> 'b -> 'c) -> 'c -> 'a t -> 'b t -> 'c
 (** Fold on two lists, with index.
     @raise Invalid_argument when lists do not have the same length.
-    @since 2.0 *)
+    @since 2.0, but only
+    @since 2.2 with labels *)
 
 val get_at_idx : int -> 'a t -> 'a option
 (** Get by index in the list.
@@ -457,7 +481,8 @@ val get_at_idx : int -> 'a t -> 'a option
 val nth_opt : 'a t -> int -> 'a option
 (** Safe version of {!nth}.
     @raise Invalid_argument if the int is negative.
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val get_at_idx_exn : int -> 'a t -> 'a
 (** Get the i-th element, or
@@ -564,8 +589,9 @@ module Assoc : sig
       @since 0.16 *)
 
   val update :
-    eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
-  (** [update k ~f l] updates [l] on the key [k], by calling [f (get l k)]
+    eq:('a->'a->bool) -> ('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
+      (* FIXME: the original no labels mli kept the ~f label ! *)
+  (** [update k f l] updates [l] on the key [k], by calling [f (get l k)]
       and removing [k] if it returns [None], mapping [k] to [v'] if it
       returns [Some v'].
       @since 0.16 *)
@@ -581,11 +607,13 @@ val assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b
 
 val assoc_opt : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b option
 (** Like [Assoc.get].
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.0 with labels *)
 
 val assq_opt : 'a -> ('a * 'b) t -> 'b option
 (** Safe version of {!assq}.
-    @since 1.5 *)
+    @since 1.5, but only
+    @since 2.0 with labels *)
 
 val mem_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * _) t -> bool
 (** Like [Assoc.mem].
diff --git a/src/core/CCListLabels.ml b/src/core/CCListLabels.ml
index 282134b4..e2f676b6 100644
--- a/src/core/CCListLabels.ml
+++ b/src/core/CCListLabels.ml
@@ -2,17 +2,3 @@
 (* This file is free software, part of containers. See file "license" for more details. *)
 
 include CCList
-
-(*$inject
-  module type L = module type of CCList
-  module type LL = module type of CCListLabels
-*)
-
-(*$R
-  ignore (module CCListLabels : L)
-*)
-
-(*$R
-  ignore (module CCList : LL)
-*)
-
diff --git a/src/core/CCListLabels.mli b/src/core/CCListLabels.mli
index c3372361..e1c96192 100644
--- a/src/core/CCListLabels.mli
+++ b/src/core/CCListLabels.mli
@@ -66,7 +66,10 @@ val fold_map : f:('acc -> 'a -> 'acc * 'b) -> init:'acc -> 'a list -> 'acc * 'b
     @since 0.14 *)
 
 val scan_left : f:('acc -> 'a -> 'acc) -> init:'acc -> 'a list -> 'acc list
-(** @since 2.2 *)
+(** [scan_left ~f ~init l] returns the list [[init; f init x0; f (f init x0) x1; ...]]
+    where [x0], [x1], etc. are the elements of [l].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val fold_map2 : f:('acc -> 'a -> 'b -> 'acc * 'c) -> init:'acc -> 'a list -> 'b list -> 'acc * 'c list
 (** [fold_map2] is to [fold_map] what [List.map2] is to [List.map].
@@ -84,7 +87,9 @@ val fold_flat_map : f:('acc -> 'a -> 'acc * 'b list) -> init:'acc -> 'a list ->
     @since 0.14 *)
 
 val count : f:('a -> bool) -> 'a list -> int
-(** @since 2.2 *)
+(** [count p l] counts how many elements of [l] satisfy predicate [p].
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val count_true_false : f:('a -> bool) -> 'a list -> int * int
 (** @since NEXT_RELEASE *)
@@ -95,21 +100,42 @@ val init : int -> f:(int -> 'a) -> 'a t
     @since 0.6 *)
 
 val combine : 'a list -> 'b list -> ('a * 'b) list
-(** @since 2.2 *)
+(** Like {!List.combine} but tail-recursive.
+    Transform a pair of lists into a list of pairs:
+    [combine [a1; ...; an] [b1; ...; bn]] is
+    [[(a1,b1); ...; (an,bn)]].
+    @raise Invalid_argument if the lists have distinct lengths.
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val combine_gen : 'a list -> 'b list -> ('a * 'b) gen
-(** @since 2.2 *)
+(** Lazy version of {!combine}.
+    Unlike {!combine}, it does not fail if the lists have different
+    lengths;
+    instead, the output has as many pairs as the smallest input list.
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val split : ('a * 'b) t -> 'a t * 'b t
-(** @since 2.2 *)
+(** A tail-recursive version of {!List.split}.
+    Transform a list of pairs into a pair of lists:
+    [split [(a1,b1); ...; (an,bn)]] is [([a1; ...; an], [b1; ...; bn])].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
 
 val compare_lengths : 'a t -> 'b t -> int
-(** @since 2.2 *)
+(** Equivalent to [compare (length l1) (length l2)] but more efficient.
+    Compare the lengths of two lists.
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val compare_length_with : 'a t -> int -> int
-(** @since 2.2 *)
+(** Equivalent to [compare (length l) x] but more efficient.
+    Compare the length of a list to an integer.
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 
@@ -126,10 +152,28 @@ val fold_product : f:('c -> 'a -> 'b -> 'c) -> init:'c -> 'a t -> 'b t -> 'c
 (** Fold on the cartesian product. *)
 
 val cartesian_product : 'a t t -> 'a t t
-(** @since 2.2 *)
+(** Produce the cartesian product of this list of lists,
+    by returning all the ways of picking one element per sublist.
+    {b NOTE} the order of the returned list is unspecified.
+    For example:
+    {[
+      # cartesian_product [[1;2];[3];[4;5;6]] |> sort =
+      [[1;3;4];[1;3;5];[1;3;6];[2;3;4];[2;3;5];[2;3;6]];;
+      # cartesian_product [[1;2];[];[4;5;6]] = [];;
+      # cartesian_product [[1;2];[3];[4];[5];[6]] |> sort =
+      [[1;3;4;5;6];[2;3;4;5;6]];;
+    ]}
+    invariant: [cartesian_product l = map_product id l].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val map_product_l : f:('a -> 'b list) -> 'a list -> 'b list list
-(** @since 2.2 *)
+(** [map_product_l f l] maps each element of [l] to a list of
+    objects of type ['b] using [f].
+    We obtain [[l1;l2;...;ln]] where [length l=n] and [li : 'b list].
+    Then, it returns all the ways of picking exactly one element per [li].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val diagonal : 'a t -> ('a * 'a) t
 (** All pairs of distinct positions of the list. [list_diagonal l] will
@@ -149,7 +193,7 @@ val group_by : ?hash:('a -> int) -> ?eq:('a -> 'a -> bool) ->
     precondition: for any [x] and [y], if [eq x y] then [hash x=hash y] must hold.
     @since 2.3 *)
 
-val join : join_row:('a -> 'b -> 'c option) -> 'a t -> 'b t -> 'c t
+val join : join_row:(('a -> 'b -> 'c option) [@keep_label]) -> 'a t -> 'b t -> 'c t
 (** [join ~join_row a b] combines every element of [a] with every
     element of [b] using [join_row]. If [join_row] returns None, then
     the two elements do not combine. Assume that [b] allows for multiple
@@ -158,7 +202,7 @@ val join : join_row:('a -> 'b -> 'c option) -> 'a t -> 'b t -> 'c t
 
 val join_by : ?eq:('key -> 'key -> bool) -> ?hash:('key -> int) ->
   ('a -> 'key) -> ('b -> 'key) ->
-  merge:('key -> 'a -> 'b -> 'c option) ->
+  merge:(('key -> 'a -> 'b -> 'c option) [@keep_label]) ->
   'a t ->
   'b t ->
   'c t
@@ -173,7 +217,7 @@ val join_by : ?eq:('key -> 'key -> bool) -> ?hash:('key -> int) ->
 
 val join_all_by : ?eq:('key -> 'key -> bool) -> ?hash:('key -> int) ->
   ('a -> 'key) -> ('b -> 'key) ->
-  merge:('key -> 'a list -> 'b list -> 'c option) ->
+  merge:(('key -> 'a list -> 'b list -> 'c option) [@keep_label]) ->
   'a t ->
   'b t ->
   'c t
@@ -201,7 +245,6 @@ val group_join_by : ?eq:('a -> 'a -> bool) -> ?hash:('a -> int) ->
     precondition: for any [x] and [y], if [eq x y] then [hash x=hash y] must hold.
     @since 2.3 *)
 
-
 val sublists_of_len :
   ?last:('a list -> 'a list option) ->
   ?offset:int ->
@@ -212,24 +255,43 @@ val sublists_of_len :
     By default, these sub-lists are non overlapping:
     [sublists_of_len 2 [1;2;3;4;5;6]] returns [[1;2]; [3;4]; [5;6]].
 
+    Examples:
+
+    - [sublists_of_len 2 [1;2;3;4;5;6] = [[1;2]; [3;4]; [5;6]]].
+    - [sublists_of_len 2 ~offset:3 [1;2;3;4;5;6] = [1;2];[4;5]].
+    - [sublists_of_len 3 ~last:CCOpt.return [1;2;3;4] = [1;2;3];[4]].
+    - [sublists_of_len 2 [1;2;3;4;5] = [[1;2]; [3;4]]].
+
+    @param offset the number of elements skipped between two consecutive
+      sub-lists. By default it is [n]. If [offset < n], the sub-lists
+      will overlap; if [offset > n], some elements will not appear at all.
+    @param last if provided and the last group of elements [g] is such
+      that [length g < n], [last g] is called. If [last g = Some g'],
+      [g'] is appended; otherwise [g] is dropped.
+      If [last = CCOpt.return], it will simply keep the last group.
+      By default, [last = fun _ -> None], i.e. the last group is dropped if shorter than [n].
+    @raise Invalid_argument if [offset <= 0] or [n <= 0].
     See {!CCList.sublists_of_len} for more details.
 
-    @since 1.5 *)
+    @since 1.0, but only
+    @since 1.5 with labels *)
 
 val intersperse : x:'a -> 'a list -> 'a list
 (** Insert the first argument between every element of the list.
-    @since 2.2 *)
+    @since 2.1, but only
+    @since 2.2 with labels *)
 
 val interleave : 'a list -> 'a list -> 'a list
 (** [interleave [x1…xn] [y1…ym]] is [x1,y1,x2,y2,…] and finishes with
     the suffix of the longest list.
-    @since 2.2 *)
+    @since 2.1, but only
+    @since 2.2 with labels *)
 
 val pure : 'a -> 'a t
 (** [pure] is [return]. *)
 
 val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
-(** [funs <*> l] is [product fun f x -> f x) funs l]. *)
+(** [funs <*> l] is [product (fun f x -> f x) funs l]. *)
 
 val (<$>) : ('a -> 'b) -> 'a t -> 'b t
 (** [(<$>)] is [map]. *)
@@ -264,7 +326,9 @@ val drop_while : f:('a -> bool) -> 'a t -> 'a t
     @since 0.13 *)
 
 val take_drop_while : f:('a -> bool) -> 'a t -> 'a t * 'a t
-(** @since 2.2 *)
+(** [take_drop_while p l] = [take_while p l, drop_while p l].
+    @since 1.2, but only
+    @since 2.2 with labels *)
 
 val last : int -> 'a t -> 'a t
 (** [last n l] takes the last [n] elements of [l] (or less if
@@ -288,7 +352,9 @@ val find_pred : f:('a -> bool) -> 'a t -> 'a option
     @since 0.11 *)
 
 val find_opt : f:('a -> bool) -> 'a t -> 'a option
-(** @since 2.2 *)
+(** Safe version of {!find}.
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val find_pred_exn : f:('a -> bool) -> 'a t -> 'a
 (** Unsafe version of {!find_pred}.
@@ -309,7 +375,8 @@ val find_idx : f:('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx p x] returns [Some (i,x)] where [x] is the [i]-th element of [l],
     and [p x] holds. Otherwise returns [None]. *)
 
-val remove : eq:('a -> 'a -> bool) -> key:'a -> 'a t -> 'a t
+val remove : eq:(('a -> 'a -> bool) [@keep_label]) -> key:'a -> 'a t -> 'a t
+    (* FIXME: the original CCList.mli uses ~x instead of ~key !! *)
 (** [remove ~key l] removes every instance of [key] from [l]. Tail-recursive.
     @param eq equality function.
     @since 0.11 *)
@@ -320,48 +387,59 @@ val filter_map : f:('a -> 'b option) -> 'a t -> 'b t
     Map and remove elements at the same time. *)
 
 val keep_some : 'a option t -> 'a t
-(** @since 2.2 *)
+(** [keep_some l] retains only elements of the form [Some x].
+    Like [filter_map CCFun.id].
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val keep_ok : ('a, _) Result.result t -> 'a t
-(** @since 2.2 *)
+(** [keep_ok l] retains only elements of the form [Ok x].
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val all_some : 'a option t -> 'a t option
-(** @since 2.2 *)
+(** [all_some l] returns [Some l'] if all elements of [l] are of the form [Some x],
+    or [None] otherwise.
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
 val all_ok : ('a, 'err) Result.result t -> ('a t, 'err) Result.result
-(** @since 2.2 *)
+(** [all_ok l] returns [Ok l'] if all elements of [l] are of the form [Ok x],
+    or [Error e] otherwise (with the first error met).
+    @since 1.3, but only
+    @since 2.2 with labels *)
 
-val sorted_merge : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
-(** Merges elements from both sorted list. *)
+val sorted_merge : cmp:(('a -> 'a -> int) [@keep_label]) -> 'a list -> 'a list -> 'a list
+(** Merge elements from both sorted list. *)
 
-val sort_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list
+val sort_uniq : cmp:(('a -> 'a -> int) [@keep_label]) -> 'a list -> 'a list
 (** Sort the list and remove duplicate elements. *)
 
-val sorted_merge_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
+val sorted_merge_uniq : cmp:(('a -> 'a -> int) [@keep_label]) -> 'a list -> 'a list -> 'a list
 (** [sorted_merge_uniq l1 l2] merges the sorted lists [l1] and [l2] and
     removes duplicates.
     @since 0.10 *)
 
-val is_sorted : cmp:('a -> 'a -> int) -> 'a list -> bool
+val is_sorted : cmp:(('a -> 'a -> int) [@keep_label]) -> 'a list -> bool
 (** [is_sorted l] returns [true] iff [l] is sorted (according to given order).
     @param cmp the comparison function (default [Pervasives.compare]).
     @since 0.17 *)
 
-val sorted_insert : cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list
+val sorted_insert : cmp:(('a -> 'a -> int) [@keep_label]) -> ?uniq:bool -> 'a -> 'a list -> 'a list
 (** [sorted_insert x l] inserts [x] into [l] such that, if [l] was sorted,
     then [sorted_insert x l] is sorted too.
     @param uniq if true and [x] is already in sorted position in [l], then
       [x] is not duplicated. Default [false] ([x] will be inserted in any case).
     @since 0.17 *)
 
-val uniq_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list
+val uniq_succ : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a list -> 'a list
 (** [uniq_succ l] removes duplicate elements that occur one next to the other.
     Examples:
     [uniq_succ [1;2;1] = [1;2;1]].
     [uniq_succ [1;1;2] = [1;2]].
     @since 0.10 *)
 
-val group_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list list
+val group_succ : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a list -> 'a list list
 (** [group_succ ~eq l] groups together consecutive elements that are equal
     according to [eq].
     @since 0.11 *)
@@ -379,13 +457,19 @@ val iteri : f:(int -> 'a -> unit) -> 'a t -> unit
     itself as second argument. *)
 
 val iteri2 : f:(int -> 'a -> 'b -> unit) -> 'a t -> 'b t -> unit
-(** @since 2.2 *)
+(** Iter on two lists.
+    @raise Invalid_argument when lists do not have the same length.
+    @since 2.0, but only
+    @since 2.2 with labels *)
 
 val foldi : f:('b -> int -> 'a -> 'b) -> init:'b -> 'a t -> 'b
 (** Like [fold] but it also passes in the index of each element to the folded function. Tail-recursive. *)
 
 val foldi2 : f:('c -> int -> 'a -> 'b -> 'c) -> init:'c -> 'a t -> 'b t -> 'c
-(** @since 2.2 *)
+(** Fold on two lists, with index.
+    @raise Invalid_argument when lists do not have the same length.
+    @since 2.0, but only
+    @since 2.2 with labels *)
 
 val get_at_idx : int -> 'a t -> 'a option
 (** Get by index in the list.
@@ -393,7 +477,10 @@ val get_at_idx : int -> 'a t -> 'a option
     of the list. *)
 
 val nth_opt : 'a t -> int -> 'a option
-(** @since 2.2 *)
+(** Safe version of {!nth}.
+    @raise Invalid_argument if the int is negative.
+    @since 1.5, but only
+    @since 2.2 with labels *)
 
 val get_at_idx_exn : int -> 'a t -> 'a
 (** Get the i-th element, or
@@ -424,38 +511,38 @@ val remove_at_idx : int -> 'a t -> 'a t
     Those operations maintain the invariant that the list does not
     contain duplicates (if it already satisfies it). *)
 
-val add_nodup : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val add_nodup : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> 'a t -> 'a t
 (** [add_nodup x set] adds [x] to [set] if it was not already present. Linear time.
     @since 0.11 *)
 
-val remove_one : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val remove_one : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> 'a t -> 'a t
 (** [remove_one x set] removes one occurrence of [x] from [set]. Linear time.
     @since 0.11 *)
 
-val mem : eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
+val mem : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> 'a t -> bool
 (** Membership to the list. Linear time. *)
 
-val subset : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
+val subset : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a t -> 'a t -> bool
 (** Test for inclusion. *)
 
-val uniq : eq:('a -> 'a -> bool) -> 'a t -> 'a t
+val uniq : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a t -> 'a t
 (** Remove duplicates w.r.t the equality predicate.
     Complexity is quadratic in the length of the list, but the order
     of elements is preserved. If you wish for a faster de-duplication
     but do not care about the order, use {!sort_uniq}. *)
 
-val union : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val union : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a t -> 'a t -> 'a t
 (** List union. Complexity is product of length of inputs. *)
 
-val inter : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val inter : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a t -> 'a t -> 'a t
 (** List intersection. Complexity is product of length of inputs. *)
 
 (** {2 Other Constructors} *)
 
-val range_by : step:int -> int -> int -> int t
+val range_by : step:(int [@keep_label]) -> int -> int -> int t
 (** [range_by ~step i j] iterates on integers from [i] to [j] included,
     where the difference between successive elements is [step].
-    use a negative [step] for a decreasing list.
+    Use a negative [step] for a decreasing list.
     @raise Invalid_argument if [step=0].
     @since 0.18 *)
 
@@ -485,49 +572,52 @@ val repeat : int -> 'a t -> 'a t
 module Assoc : sig
   type ('a, 'b) t = ('a*'b) list
 
-  val get : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b option
+  val get : eq:(('a->'a->bool) [@keep_label]) -> 'a -> ('a,'b) t -> 'b option
   (** Find the element. *)
 
-  val get_exn : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b
+  val get_exn : eq:(('a->'a->bool) [@keep_label]) -> 'a -> ('a,'b) t -> 'b
   (** Like [get], but unsafe.
       @raise Not_found if the element is not present. *)
 
-  val set : eq:('a->'a->bool) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
+  val set : eq:(('a->'a->bool) [@keep_label]) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
   (** Add the binding into the list (erase it if already present). *)
 
-  val mem : eq:('a->'a->bool) -> 'a -> ('a,_) t -> bool
+  val mem : eq:(('a->'a->bool) [@keep_label]) -> 'a -> ('a,_) t -> bool
   (** [mem x l] returns [true] iff [x] is a key in [l].
       @since 0.16 *)
 
   val update :
-    eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
+    eq:(('a->'a->bool) [@keep_label]) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
+      (* FIXME: the original no labels mli kept the ~f label ! *)
   (** [update k ~f l] updates [l] on the key [k], by calling [f (get l k)]
       and removing [k] if it returns [None], mapping [k] to [v'] if it
       returns [Some v'].
       @since 0.16 *)
 
-  val remove : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> ('a,'b) t
+  val remove : eq:(('a->'a->bool) [@keep_label]) -> 'a -> ('a,'b) t -> ('a,'b) t
   (** [remove x l] removes the first occurrence of [k] from [l].
       @since 0.17 *)
 end
 
-val assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b
+val assoc : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> ('a * 'b) t -> 'b
 (** Like [Assoc.get_exn].
     @since 2.0 *)
 
-val assoc_opt : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b option
+val assoc_opt : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> ('a * 'b) t -> 'b option
 (** Like [Assoc.get].
-    @since 2.0 *)
+    @since 1.5, but only
+    @since 2.0 with labels *)
 
 val assq_opt : 'a -> ('a * 'b) t -> 'b option
 (** Safe version of {!assq}.
-    @since 2.0 *)
+    @since 1.5, but only
+    @since 2.0 with labels *)
 
-val mem_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * _) t -> bool
+val mem_assoc : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> ('a * _) t -> bool
 (** Like [Assoc.mem].
     @since 2.0 *)
 
-val remove_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> ('a * 'b) t
+val remove_assoc : eq:(('a -> 'a -> bool) [@keep_label]) -> 'a -> ('a * 'b) t -> ('a * 'b) t
 (** Like [Assoc.remove].
     @since 2.0 *)
 
@@ -567,7 +657,6 @@ module type MONAD = sig
 
   val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
   (** Monadic [bind]. *)
-
 end
 
 module Traverse(M : MONAD) : sig
@@ -599,19 +688,22 @@ val to_seq : 'a t -> 'a sequence
 (** Return a [sequence] of the elements of the list. *)
 
 val of_seq : 'a sequence -> 'a t
-(** Build a list from a given [sequence]. *)
+(** Build a list from a given [sequence].
+    In the result, elements appear in the same order as they did in the source [sequence]. *)
 
 val to_gen : 'a t -> 'a gen
 (** Return a [gen] of the elements of the list. *)
 
 val of_gen : 'a gen -> 'a t
-(** Build a list from a given [gen]. *)
+(** Build a list from a given [gen].
+    In the result, elements appear in the same order as they did in the source [gen]. *)
 
 val to_klist : 'a t -> 'a klist
 (** Return a [klist] of the elements of the list. *)
 
 val of_klist : 'a klist -> 'a t
-(** Build a list from a given [klist]. *)
+(** Build a list from a given [klist].
+    In the result, elements appear in the same order as they did in the source [klist]. *)
 
 (** {2 Infix Operators}
     It is convenient to {!open CCList.Infix} to access the infix operators
diff --git a/src/core/CCString.mli b/src/core/CCString.mli
index eb4734f2..5632b169 100644
--- a/src/core/CCString.mli
+++ b/src/core/CCString.mli
@@ -1,3 +1,5 @@
+(*  AUTOGENERATED FROM CCStringLabels.mli  *)
+
 
 (* This file is free software, part of containers. See file "license" for more details. *)
 
@@ -142,7 +144,7 @@ val replace : ?which:[`Left|`Right|`All] -> sub:string -> by:string -> string ->
     @raise Invalid_argument if [sub = ""].
     @since 0.14 *)
 
-val is_sub : sub:string -> int -> string -> int -> len:int -> bool
+val is_sub : sub:string -> int -> string -> int -> sub_len:int -> bool
 (** [is_sub ~sub i s j ~len] returns [true] iff the substring of
     [sub] starting at position [i] and of length [len] is a substring
     of [s] starting at position [j]. *)
@@ -333,12 +335,12 @@ module Find : sig
 
   val rcompile : string -> [ `Reverse ] pattern
 
-  val find : ?start:int -> pattern:[`Direct] pattern -> string -> int
+  val find : ?start:int -> pattern:([`Direct] pattern) -> string -> int
   (** Search for [pattern] in the string, left-to-right.
       @return the offset of the first match, -1 otherwise.
       @param start offset in string at which we start. *)
 
-  val rfind : ?start:int -> pattern:[`Reverse] pattern -> string -> int
+  val rfind : ?start:int -> pattern:([`Reverse] pattern) -> string -> int
   (** Search for [pattern] in the string, right-to-left.
       @return the offset of the start of the first match from the right, -1 otherwise.
       @param start right-offset in string at which we start. *)
diff --git a/src/core/CCStringLabels.ml b/src/core/CCStringLabels.ml
new file mode 100644
index 00000000..e12f316a
--- /dev/null
+++ b/src/core/CCStringLabels.ml
@@ -0,0 +1,4 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+include CCString
diff --git a/src/core/CCStringLabels.mli b/src/core/CCStringLabels.mli
new file mode 100644
index 00000000..87b710d4
--- /dev/null
+++ b/src/core/CCStringLabels.mli
@@ -0,0 +1,472 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Basic String Utils} *)
+
+type 'a gen = unit -> 'a option
+type 'a sequence = ('a -> unit) -> unit
+type 'a klist = unit -> [`Nil | `Cons of 'a * 'a klist]
+
+(** {2 Common Signature} *)
+
+module type S = sig
+  type t
+
+  val length : t -> int
+  (** Return the length (number of characters) of the given string. *)
+
+  val blit : src:t -> src_pos:int -> dst:Bytes.t -> dst_pos:int -> len:int -> unit
+  (** Like {!String.blit}.
+      Compatible with the [-safe-string] option.
+      @raise Invalid_argument if indices are not valid. *)
+
+  (*
+  val blit_immut : t -> int -> t -> int -> int -> string
+  (** Immutable version of {!blit}, returning a new string.
+      [blit a i b j len] is the same as [b], but in which
+      the range [j, ..., j+len] is replaced by [a.[i], ..., a.[i + len]].
+      @raise Invalid_argument if indices are not valid. *)
+     *)
+
+  val fold : f:('a -> char -> 'a) -> init:'a -> t -> 'a
+  (** Fold on chars by increasing index.
+      @since 0.7 *)
+
+  (** {2 Conversions} *)
+
+  val to_gen : t -> char gen
+  (** Return the [gen] of characters contained in the string. *)
+
+  val to_seq : t -> char sequence
+  (** Return the [sequence] of characters contained in the string. *)
+
+  val to_klist : t -> char klist
+  (** Return the [klist] of characters contained in the string. *)
+
+  val to_list : t -> char list
+  (** Return the list of characters contained in the string. *)
+
+  val pp_buf : Buffer.t -> t -> unit
+  (** Renamed from [pp] since 2.0. *)
+
+  val pp : Format.formatter -> t -> unit
+  (** Print the string within quotes.
+
+      Renamed from [print] since 2.0. *)
+end
+
+(** {2 Strings} *)
+
+include module type of struct include StringLabels end
+
+val equal : string -> string -> bool
+(** Equality function on strings. *)
+
+val compare : string -> string -> int
+
+val is_empty : string -> bool
+(** [is_empty s] returns [true] iff [s] is empty (i.e. its length is 0).
+    @since 1.5 *)
+
+val hash : string -> int
+
+val init : int -> (int -> char) -> string
+(** Like [Array.init].
+    @since 0.3.3 *)
+
+val rev : string -> string
+(** [rev s] returns the reverse of [s].
+    @since 0.17 *)
+
+val pad : ?side:[`Left|`Right] -> ?c:char -> int -> string -> string
+(** [pad n str] ensures that [str] is at least [n] bytes long,
+    and pads it on the [side] with [c] if it's not the case.
+    @param side determines where padding occurs (default: [`Left]).
+    @param c the char used to pad (default: ' ').
+    @since 0.17 *)
+
+val of_char : char -> string
+(** [of_char 'a'] is ["a"].
+    @since 0.19 *)
+
+val of_gen : char gen -> string
+(** Convert a [gen] of characters to a string. *)
+
+val of_seq : char sequence -> string
+(** Convert a [sequence] of characters to a string. *)
+
+val of_klist : char klist -> string
+(** Convert a [klist] of characters to a string. *)
+
+val of_list : char list -> string
+(** Convert a list of characters to a string. *)
+
+val of_array : char array -> string
+(** Convert an array of characters to a string. *)
+
+val to_array : string -> char array
+(** Return the array of characters contained in the string. *)
+
+val find : ?start:int -> sub:(string [@keep_label]) -> string -> int
+(** Find [sub] in string, returns its first index or [-1]. *)
+
+val find_all : ?start:int -> sub:(string [@keep_label]) -> string -> int gen
+(** [find_all ~sub s] finds all occurrences of [sub] in [s], even overlapping
+    instances.
+    @param start starting position in [s].
+    @since 0.17 *)
+
+val find_all_l : ?start:int -> sub:(string [@keep_label]) -> string -> int list
+(** [find_all_l ~sub s] finds all occurrences of [sub] in [s] and returns
+    them in a list.
+    @param start starting position in [s].
+    @since 0.17 *)
+
+val mem : ?start:int -> sub:(string [@keep_label]) -> string -> bool
+(** [mem ~sub s] is [true] iff [sub] is a substring of [s].
+    @since 0.12 *)
+
+val rfind : sub:(string [@keep_label]) -> string -> int
+(** Find [sub] in string from the right, returns its first index or [-1].
+    Should only be used with very small [sub].
+    @since 0.12 *)
+
+val replace : ?which:[`Left|`Right|`All] -> sub:(string [@keep_label]) -> by:(string [@keep_label]) -> string -> string
+(** [replace ~sub ~by s] replaces some occurrences of [sub] by [by] in [s].
+    @param which decides whether the occurrences to replace are:
+      {ul
+        {- [`Left] first occurrence from the left (beginning).}
+        {- [`Right] first occurrence from the right (end).}
+        {- [`All] all occurrences (default).}
+      }
+    @raise Invalid_argument if [sub = ""].
+    @since 0.14 *)
+
+val is_sub : sub:(string [@keep_label]) -> sub_pos:int -> string -> pos:int -> sub_len:(int [@keep_label]) -> bool
+(** [is_sub ~sub i s j ~len] returns [true] iff the substring of
+    [sub] starting at position [i] and of length [len] is a substring
+    of [s] starting at position [j]. *)
+
+val repeat : string -> int -> string
+(** The same string, repeated n times. *)
+
+val prefix : pre:(string [@keep_label]) -> string -> bool
+(** [prefix ~pre s] returns [true] iff [pre] is a prefix of [s]. *)
+
+val suffix : suf:(string [@keep_label]) -> string -> bool
+(** [suffix ~suf s] returns [true] iff [suf] is a suffix of [s].
+    @since 0.7 *)
+
+val chop_prefix : pre:(string [@keep_label]) -> string -> string option
+(** [chop_prefix ~pre s] removes [pre] from [s] if [pre] really is a prefix
+    of [s], returns [None] otherwise.
+    @since 0.17 *)
+
+val chop_suffix : suf:(string [@keep_label]) -> string -> string option
+(** [chop_suffix ~suf s] removes [suf] from [s] if [suf] really is a suffix
+    of [s], returns [None] otherwise.
+    @since 0.17 *)
+
+val take : int -> string -> string
+(** [take n s] keeps only the [n] first chars of [s].
+    @since 0.17 *)
+
+val drop : int -> string -> string
+(** [drop n s] removes the [n] first chars of [s].
+    @since 0.17 *)
+
+val take_drop : int -> string -> string * string
+(** [take_drop n s = take n s, drop n s].
+    @since 0.17 *)
+
+val lines : string -> string list
+(** [lines s] returns a list of the lines of [s] (splits along '\n').
+    @since 0.10 *)
+
+val lines_gen : string -> string gen
+(** [lines_gen s] returns a generator of the lines of [s] (splits along '\n').
+    @since 0.10 *)
+
+val concat_gen : sep:(string [@keep_label]) -> string gen -> string
+(** [concat_gen ~sep g] concatenates all strings of [g], separated with [sep].
+    @since 0.10 *)
+
+val unlines : string list -> string
+(** [unlines l] concatenates all strings of [l], separated with '\n'.
+    @since 0.10 *)
+
+val unlines_gen : string gen -> string
+(** [unlines_gen g] concatenates all strings of [g], separated with '\n'.
+    @since 0.10 *)
+
+val set : string -> int -> char -> string
+(** [set s i c] creates a new string which is a copy of [s], except
+    for index [i], which becomes [c].
+    @raise Invalid_argument if [i] is an invalid index.
+    @since 0.12 *)
+
+val iter : f:(char -> unit) -> string -> unit
+(** Alias to {!String.iter}.
+    @since 0.12 *)
+
+val iteri : f:(int -> char -> unit) -> string -> unit
+(** Iter on chars with their index.
+    @since 0.12 *)
+
+val map : f:(char -> char) -> string -> string
+(** Map chars.
+    @since 0.12 *)
+
+val mapi : f:(int -> char -> char) -> string -> string
+(** Map chars with their index.
+    @since 0.12 *)
+
+val filter_map : f:(char -> char option) -> string -> string
+(** [filter_map f s] calls [(f a0) (f a1) ... (f an)] where [a0 ... an] are the characters of s.
+    It returns the string of characters [ci] such as [f ai = Some ci] (when [f] returns [None],
+    the corresponding element of [s] is discarded).
+    @since 0.17 *)
+
+val filter : f:(char -> bool) -> string -> string
+(** [filter f s] discards characters not satisfying [f].
+    @since 0.17 *)
+
+val flat_map : ?sep:string -> f:(char -> string) -> string -> string
+(** Map each chars to a string, then concatenates them all.
+    @param sep optional separator between each generated string.
+    @since 0.12 *)
+
+val for_all : f:(char -> bool) -> string -> bool
+(** True for all chars?
+    @since 0.12 *)
+
+val exists : f:(char -> bool) -> string -> bool
+(** True for some char?
+    @since 0.12 *)
+
+include S with type t := string
+
+val drop_while : f:(char -> bool) -> t -> t
+(** [drop_while f s] discards any characters starting from the left,
+    up to the first character [c] not satisfying [f c].
+    @since 2.2 *)
+
+val rdrop_while : f:(char -> bool) -> t -> t
+(** [rdrop_while f s] discards any characters starting from the right,
+    up to the first character [c] not satisfying [f c].
+    @since 2.2 *)
+
+val ltrim : t -> t
+(** Trim space on the left (see {!String.trim} for more details).
+    @since 1.2 *)
+
+val rtrim : t -> t
+(** Trim space on the right (see {!String.trim} for more details).
+    @since 1.2 *)
+
+(** {2 Operations on 2 strings} *)
+
+val map2 : f:(char -> char -> char) -> string -> string -> string
+(** Map pairs of chars.
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+val iter2: f:(char -> char -> unit) -> string -> string -> unit
+(** Iterate on pairs of chars.
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+val iteri2: f:(int -> char -> char -> unit) -> string -> string -> unit
+(** Iterate on pairs of chars with their index.
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+val fold2: f:('a -> char -> char -> 'a) -> init:'a -> string -> string -> 'a
+(** Fold on pairs of chars.
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+val for_all2 : f:(char -> char -> bool) -> string -> string -> bool
+(** All pairs of chars respect the predicate?
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+val exists2 : f:(char -> char -> bool) -> string -> string -> bool
+(** Exists a pair of chars?
+    @raise Invalid_argument if the strings have not the same length.
+    @since 0.12 *)
+
+(** {2 Ascii functions}
+
+    Those functions are deprecated in {!String} since 4.03, so we provide
+    a stable alias for them even in older versions. *)
+
+val capitalize_ascii : string -> string
+(** See {!String}.
+    @since 0.18 *)
+
+val uncapitalize_ascii : string -> string
+(** See {!String}.
+    @since 0.18 *)
+
+val uppercase_ascii : string -> string
+(** See {!String}.
+    @since 0.18 *)
+
+val lowercase_ascii : string -> string
+(** See {!String}.
+    @since 0.18 *)
+
+val equal_caseless : string -> string -> bool
+(** Comparison without respect to {b ascii} lowercase.
+    @since 1.2 *)
+
+(** {2 Finding}
+
+    A relatively efficient algorithm for finding sub-strings.
+    @since 1.0 *)
+
+module Find : sig
+  type _ pattern
+
+  val compile : string -> [ `Direct ] pattern
+
+  val rcompile : string -> [ `Reverse ] pattern
+
+  val find : ?start:int -> pattern:(([`Direct] pattern) [@keep_label]) -> string -> int
+  (** Search for [pattern] in the string, left-to-right.
+      @return the offset of the first match, -1 otherwise.
+      @param start offset in string at which we start. *)
+
+  val rfind : ?start:int -> pattern:(([`Reverse] pattern) [@keep_label]) -> string -> int
+  (** Search for [pattern] in the string, right-to-left.
+      @return the offset of the start of the first match from the right, -1 otherwise.
+      @param start right-offset in string at which we start. *)
+end
+
+(** {2 Splitting} *)
+
+module Split : sig
+  (** Specification of what to do with empty blocks, as in [split ~by:"-" "-a-b-"].
+
+      - [{first=false; last=false}] will return [""; "a"; "b"; ""]
+      - [{first=true; last=false}] will return ["a"; "b" ""]
+      - [{first=false; last=true}] will return [""; "a"; "b"]
+      - [{first=true; last=true}] will return ["a"; "b"]
+
+      The default value of all remaining functions is [Drop_none].
+      @since 1.5
+  *)
+  type drop_if_empty = {
+    first: bool;
+    last: bool;
+  }
+
+  val no_drop : drop_if_empty
+  (** Do not drop any group, even empty and on borders.
+      @since 1.5 *)
+
+  val list_ : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> (string*int*int) list
+  (** Split the given string along the given separator [by]. Should only
+      be used with very small separators, otherwise
+      use {!Containers_string.KMP}.
+      @return a list of slices [(s,index,length)] that are
+      separated by [by]. {!String.sub} can then be used to actually extract
+      a string from the slice.
+      @raise Failure if [by = ""]. *)
+
+  val gen : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> (string*int*int) gen
+
+  val seq : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> (string*int*int) sequence
+
+  val klist : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> (string*int*int) klist
+
+  (** {4 Copying functions}
+
+      Those split functions actually copy the substrings, which can be
+      more convenient but less efficient in general. *)
+
+  val list_cpy : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> string list
+
+  val gen_cpy : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> string gen
+
+  val seq_cpy : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> string sequence
+
+  val klist_cpy : ?drop:drop_if_empty -> by:(string [@keep_label]) -> string -> string klist
+
+  val left : by:(string [@keep_label]) -> string -> (string * string) option
+  (** Split on the first occurrence of [by] from the leftmost part of
+      the string.
+      @since 0.12 *)
+
+  val left_exn : by:(string [@keep_label]) -> string -> string * string
+  (** Split on the first occurrence of [by] from the leftmost part of the string.
+      @raise Not_found if [by] is not part of the string.
+      @since 0.16 *)
+
+  val right : by:(string [@keep_label]) -> string -> (string * string) option
+  (** Split on the first occurrence of [by] from the rightmost part of
+      the string.
+      @since 0.12 *)
+
+  val right_exn : by:(string [@keep_label]) -> string -> string * string
+  (** Split on the first occurrence of [by] from the rightmost part of the string.
+      @raise Not_found if [by] is not part of the string.
+      @since 0.16 *)
+
+end
+
+val split_on_char : by:char -> string -> string list
+(** Split the string along the given char.
+    @since 1.2 *)
+
+val split : by:(string [@keep_label]) -> string -> string list
+(** Alias to {!Split.list_cpy}.
+    @since 1.2 *)
+
+(** {2 Utils} *)
+
+val compare_versions : string -> string -> int
+(** [compare_versions a b] compares {i version strings} [ a] and [b],
+    considering that numbers are above text.
+    @since 0.13 *)
+
+val compare_natural : string -> string -> int
+(** Natural Sort Order, comparing chunks of digits as natural numbers.
+    https://en.wikipedia.org/wiki/Natural_sort_order
+    @since 1.3 *)
+
+val edit_distance : string -> string -> int
+(** Edition distance between two strings. This satisfies the classical
+    distance axioms: it is always positive, symmetric, and satisfies
+    the formula [distance a b + distance b c >= distance a c]. *)
+
+(** {2 Slices}
+
+    A contiguous part of a string *)
+
+module Sub : sig
+  type t = string * int * int
+  (** A string, an offset, and the length of the slice. *)
+
+  val make : string -> pos:int -> len:(int [@keep_label]) -> t
+
+  val full : string -> t
+  (** Full string. *)
+
+  val copy : t -> string
+  (** Make a copy of the substring. *)
+
+  val underlying : t -> string
+
+  val sub : t -> int -> int -> t
+  (** Sub-slice. *)
+
+  val get : t -> int -> char
+  (** [get s i] gets the [i]-th element, or fails.
+      @raise Invalid_argument if the index is not within [0 ... length - 1].
+      @since 1.2 *)
+
+  include S with type t := t
+
+end
diff --git a/src/core/containers.ml b/src/core/containers.ml
index b12a4a2c..cd572fa0 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -6,9 +6,11 @@
 module Array = CCArray
 module ArrayLabels = CCArrayLabels
 module Array_slice = CCArray_slice
+module Array_sliceLabels = CCArray_sliceLabels
 module Bool = CCBool
 module Char = Char
 module Equal = CCEqual
+module EqualLabels = CCEqualLabels
 module Float = CCFloat
 module Format = CCFormat
 module Fun = CCFun
@@ -43,6 +45,7 @@ module Ref = CCRef
 module Result = CCResult
 module Set = CCSet
 module String = CCString
+module StringLabels = CCStringLabels
 module Vector = CCVector
 module Monomorphic = CCMonomorphic
 module Utf8_string = CCUtf8_string
diff --git a/src/core/dune b/src/core/dune
index 00101fdf..fdc7f038 100644
--- a/src/core/dune
+++ b/src/core/dune
@@ -1,3 +1,32 @@
+(rule
+  (targets CCArray.mli)
+  (deps CCArrayLabels.mli)
+  (mode promote)
+  (action (run ../unlabel.exe %{deps} %{targets})))
+
+(rule
+  (targets CCArray_slice.mli)
+  (deps CCArray_sliceLabels.mli)
+  (mode promote)
+  (action (run ../unlabel.exe %{deps} %{targets})))
+
+(rule
+  (targets CCEqual.mli)
+  (deps CCEqualLabels.mli)
+  (mode promote)
+  (action (run ../unlabel.exe %{deps} %{targets})))
+
+(rule
+  (targets CCList.mli)
+  (deps CCListLabels.mli)
+  (mode promote)
+  (action (run ../unlabel.exe %{deps} %{targets})))
+
+(rule
+  (targets CCString.mli)
+  (deps CCStringLabels.mli)
+  (mode promote)
+  (action (run ../unlabel.exe %{deps} %{targets})))
 
 (library
   (name containers)
diff --git a/src/dune b/src/dune
index 001e66a9..853054a2 100644
--- a/src/dune
+++ b/src/dune
@@ -1,12 +1,16 @@
-
 (executable
   (name mkflags)
+  (modules mkflags)
   (libraries dune.configurator))
 
+(executable
+  (name unlabel)
+  (modules unlabel)
+  (libraries str compiler-libs.common))
+
 (rule
   (targets flambda.flags)
   (mode fallback)
   (action
     (run ./mkflags.exe))
   )
-
diff --git a/src/unlabel.ml b/src/unlabel.ml
new file mode 100644
index 00000000..a39d5d76
--- /dev/null
+++ b/src/unlabel.ml
@@ -0,0 +1,246 @@
+(* search for first occurence of pat in s *)
+let rec search pat s pos =
+  let rec compare i =
+    if i >= String.length pat
+    then true
+    else if pat.[i] = s.[pos+i]
+    then compare (i+1)
+    else false
+  in
+  if pos > String.length s - String.length pat
+  then raise Not_found
+  else if compare 0
+  then pos
+  else search pat s (pos+1)
+;;
+
+(* search all non-overlapping occurences of pat in s *)
+let search_all pat s =
+  let rec search_rest acc pos =
+    let next =
+      try Some (search pat s pos) with
+          Not_found -> None
+    in
+    match next with
+      | None -> acc
+      | Some pos -> search_rest (pos::acc) (pos + String.length pat)
+  in
+  List.rev (search_rest [] 0)
+;;
+
+(* replase first occurence of pat with subst in s *)
+let replace_first pat subst s =
+  let pos = search pat s 0 in
+  let patl = String.length pat
+  and substl = String.length subst in
+  let buf = Bytes.create (String.length s - patl + substl) in
+  Bytes.blit_string s 0 buf 0 pos;
+  Bytes.blit_string subst 0 buf pos substl;
+  Bytes.blit_string
+    s   (pos + patl)
+    buf (pos + substl)
+    (String.length s - pos - patl);
+  Bytes.unsafe_to_string buf
+;;
+
+(* replase first occurence of pat with subst in s *)
+let replace_all pat subst s =
+  let pos = search_all pat s in
+  let patl = String.length pat
+  and substl = String.length subst in
+  let len = String.length s + List.length pos * (substl - patl) in
+  let buf = Bytes.create len in
+  let rec loop src_pos dst_pos = function
+    | [] ->
+      Bytes.blit_string s src_pos buf dst_pos (String.length s - src_pos)
+    | pat_pos :: tail ->
+      let headl = pat_pos - src_pos in
+      Bytes.blit_string s src_pos buf dst_pos headl;
+      Bytes.blit_string subst 0 buf (dst_pos + headl) substl;
+      loop
+        (src_pos + headl + patl)
+        (dst_pos + headl + substl)
+        tail
+  in loop 0 0 pos;
+  Bytes.unsafe_to_string buf
+;;
+
+let match_closeparen s i =
+  assert (s.[i] = ')');
+  let rec loop i count =
+    match s.[i] with
+      | '(' when count = 0 -> i
+      | '(' -> loop (i-1) (count-1)
+      | ')' -> loop (i-1) (count+1)
+      | _ -> loop (i-1) count
+  in loop (i-1) 0
+;;
+
+let slurp_file file =
+  let ch = open_in file in
+  let buf = Buffer.create (min 1024 (in_channel_length ch)) in
+  try
+    while true do Buffer.add_channel buf ch 4096 done;
+    assert false
+  with
+    | End_of_file ->
+      close_in ch;
+      Bytes.unsafe_to_string (Buffer.to_bytes buf)
+;;
+
+let () =
+  assert (Array.length Sys.argv = 3);
+  let   labelled_filename = Sys.argv.(1) in (* CCArrayLabels.mli *)
+  let unlabelled_filename = Sys.argv.(2) in (* CCArray.ml *)
+  let labelled_name = (* ArrayLabels *)
+    let basename =
+      Compenv.module_of_filename Format.err_formatter
+        labelled_filename
+        labelled_filename
+    in
+    assert (basename.[0] = 'C' && basename.[1] = 'C');
+    String.sub basename 2 (String.length basename - 2)
+  in
+  let unlabelled_name = (* Array *)
+    replace_first "Labels" "" labelled_name
+  in
+  let labelled_text = slurp_file labelled_filename in
+  let lexbuf = Lexing.from_string labelled_text in
+  Location.init lexbuf labelled_filename;
+  let labelled_ast = Parse.interface lexbuf in
+  (* stack of replacements to perform on the labelled_text.
+   * perform them in one run later so that the character counts
+   * won't be affected by earlier replacements. *)
+  let replacements = ref [] in
+  (* function removing '~' from docstring attributes where appropriate. *)
+  let strip_attributes labels attributes =
+    List.iter
+      begin function
+        | ({ Asttypes.txt = "ocaml.doc"; _ },
+           Parsetree.PStr [{pstr_loc =
+                              { loc_start = {pos_cnum = start; _}
+                              ; loc_end = {pos_cnum = stop; _}
+                              ; _}
+                           ; _
+                           }]) ->
+          let docstring =
+            List.fold_left
+              (fun docstring label ->
+                 replace_all ("~" ^ label) label docstring)
+              (String.sub labelled_text start (stop-start))
+              labels
+          in
+          replacements := (start, stop-start, docstring) :: !replacements
+        | _ -> ()
+      end
+      attributes
+  in
+  let iterator =
+    let open Ast_iterator in
+    let open Parsetree in
+    { Ast_iterator.default_iterator with
+      value_description = begin fun iterator
+        { pval_name = { txt = _name; _ }
+        ; pval_type
+        ; pval_prim = _
+        ; pval_attributes
+        ; pval_loc
+        } ->
+        let rec loop = function
+          (* match function type with label *)
+          | { ptyp_desc = Ptyp_arrow (Labelled label, left, right)
+            ; ptyp_loc = {loc_start = {Lexing.pos_cnum = start; _}; _}
+            ; ptyp_attributes
+            ; _}
+            when
+              (* check that the argument type is not marked with [@keep_label] *)
+              List.for_all
+                (fun ({Asttypes.txt; _}, _) -> txt <> "keep_label")
+                left.ptyp_attributes
+            ->
+            assert (label = String.sub labelled_text start (String.length label));
+            let colon = String.index_from labelled_text start ':' in
+            (* remove label *)
+            replacements := (start, colon+1-start, "") :: !replacements;
+            (* remove labels from associated docstrings *)
+            strip_attributes [label] ptyp_attributes;
+            label :: loop right
+          | { ptyp_desc = Ptyp_arrow (_, _left, right); _} ->
+            loop right
+          | _ -> []
+        in
+        let labels = loop pval_type in
+        strip_attributes labels pval_attributes;
+        iterator.attributes iterator pval_attributes;
+        iterator.location iterator pval_loc;
+        iterator.typ iterator pval_type;
+      end
+    ; attribute = begin fun iterator
+        ({Asttypes.txt
+         ; loc =
+             { loc_start = {pos_cnum = start; _}
+             ; loc_end = {pos_cnum = stop; _}
+             ; _} as loc
+         }, _) ->
+        if txt = "keep_label"
+        then begin
+          (* start and stop positions mark the location of only the label name.
+           * Therefore search for enclosing brackets. *)
+          let start = String.rindex_from labelled_text start '['
+          and stop  = String. index_from labelled_text stop  ']' in
+          (* remove leading ' ', too *)
+          let start =
+            if labelled_text.[start-1] = ' ' then start-1 else start
+          in
+          (* if a closing paren follows, remove this and the matching paren,
+           * this will hopefully be the right thing to do. *)
+          let stop =
+            if labelled_text.[stop+1] = ')'
+            then
+              let openp = match_closeparen labelled_text (stop+1) in
+              replacements := (openp, 1, "") :: !replacements;
+              stop+1
+            else
+              stop
+          in
+          replacements := (start, stop-start+1, "") :: !replacements;
+        end;
+        iterator.location iterator loc
+      end
+    }
+  in
+  iterator.signature iterator labelled_ast;
+
+  (* sort replacements in ascending order. *)
+  let replacements =
+    List.sort (fun (p1,_,_) (p2,_,_) -> compare p1 p2) !replacements
+  in
+
+  (* perform the replacements by blitting to a buffer. *)
+  let unlabelled_text = Buffer.create (String.length labelled_text) in
+  List.fold_left begin fun start (pos,len,subst) ->
+    assert (pos >= start);
+    Buffer.add_substring unlabelled_text labelled_text start (pos - start);
+    Buffer.add_string unlabelled_text subst;
+    pos+len
+  end
+    0
+    replacements
+  |> fun start ->
+  Buffer.add_substring unlabelled_text
+    labelled_text start (String.length labelled_text - start);
+
+  let unlabelled_text =
+    Buffer.contents unlabelled_text
+    (* CCArrayLabels -> CCArray *)
+    |> replace_all labelled_name unlabelled_name
+  in
+
+  let out = open_out unlabelled_filename in
+  output_string out (
+    "(*  AUTOGENERATED FROM " ^
+    labelled_filename
+    ^ "  *)\n\n");
+  output_string out unlabelled_text;
+  close_out out;
+;;