diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index 506ae9df..a70fd23e 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -1,5 +1,20 @@
 = Changelog
 
+== 0.21
+
+- (breaking) make default `start`/`stop` arguments empty in printers (#82)
+
+- add `CCFormat.{with_color_sf,fprintf_dyn_color,sprintf_dyn_color}`
+- add `CCFormat.Dump` for easy debugging (see #82)
+- add `CCArray.Sub.to_list`
+- add `CCArray.{sorted,sort_indices,sort_ranking}` (closes #81)
+
+- handle '\r` in CCSexpM (fixes #83)
+- add alias `Containers.IO`
+- bugfixes in `CCArray.Sub`
+- bugfix + tests for `CCArray.Sub.sub`
+- disable parallel build to support cygwin
+
 == 0.20
 
 - bugfix in `CCArray.equal`
diff --git a/_oasis b/_oasis
index 1fbf5c55..ba273d42 100644
--- a/_oasis
+++ b/_oasis
@@ -1,6 +1,6 @@
 OASISFormat: 0.4
 Name:        containers
-Version:     0.20
+Version:     0.21
 Homepage:    https://github.com/c-cube/ocaml-containers
 Authors:     Simon Cruanes
 License:     BSD-2-clause
@@ -10,7 +10,8 @@ OCamlVersion: >= 4.00.1
 BuildTools:  ocamlbuild
 AlphaFeatures: ocamlbuild_more_args
 
-XOCamlbuildExtraArgs: "-j 0"
+# cygwin fails with anything else
+XOCamlbuildExtraArgs: "-j 1"
 
 Synopsis:    A modular standard library focused on data structures.
 Description:
diff --git a/opam b/opam
index 566581e8..d1bb2e04 100644
--- a/opam
+++ b/opam
@@ -1,6 +1,6 @@
 opam-version: "1.2"
 name: "containers"
-version: "0.20"
+version: "0.21"
 author: "Simon Cruanes"
 maintainer: "simon.cruanes@inria.fr"
 build: [
diff --git a/setup.ml b/setup.ml
index 7db329de..657cf17a 100644
--- a/setup.ml
+++ b/setup.ml
@@ -1,7 +1,7 @@
 (* setup.ml generated for the first time by OASIS v0.4.4 *)
 
 (* OASIS_START *)
-(* DO NOT EDIT (digest: 1ed8a841a820b1830b239987cd022aa8) *)
+(* DO NOT EDIT (digest: 5a4456e803f365ce3410624a599bc76f) *)
 (*
    Regenerated by OASIS v0.4.7
    Visit http://oasis.forge.ocamlcore.org for more information and
@@ -6980,7 +6980,7 @@ open OASISTypes;;
 let setup_t =
   {
      BaseSetup.configure = InternalConfigurePlugin.configure;
-     build = OCamlbuildPlugin.build ["-use-ocamlfind"; "-j 0"];
+     build = OCamlbuildPlugin.build ["-use-ocamlfind"; "-j 1"];
      test =
        [
           ("all",
@@ -7049,7 +7049,7 @@ let setup_t =
        {
           oasis_version = "0.4";
           ocaml_version = Some (OASISVersion.VGreaterEqual "4.00.1");
-          version = "0.20";
+          version = "0.21";
           license =
             OASISLicense.DEP5License
               (OASISLicense.DEP5Unit
@@ -9689,7 +9689,7 @@ let setup_t =
        };
      oasis_fn = Some "_oasis";
      oasis_version = "0.4.7";
-     oasis_digest = Some "\223\133\236\175X\030c\221\172i#\201\\\181\1865";
+     oasis_digest = Some "v\210\236\240,\180C\195X\143\011\\\217Y\180\206";
      oasis_exec = None;
      oasis_setup_args = [];
      setup_update = false
diff --git a/src/core/CCArray.ml b/src/core/CCArray.ml
index cc7b622f..f881489e 100644
--- a/src/core/CCArray.ml
+++ b/src/core/CCArray.ml
@@ -51,6 +51,29 @@ module type S = sig
   val reverse_in_place : 'a t -> unit
   (** Reverse the array in place *)
 
+  val sorted : ('a -> 'a -> int) -> 'a t -> 'a array
+  (** [sorted cmp a] makes a copy of [a] and sorts it with [cmp].
+      @since 0.21 *)
+
+  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 of the [i]-th element of [a] in [sort cmp a].
+      In other words, [map (fun i -> a.(i)) (sort_indices a) = sorted cmp a].
+      [a] is not modified.
+      @since 0.21 *)
+
+  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],
+      such that [b.(i)] is the position in [sorted cmp a] of the [i]-th
+      element of [a].
+      [a] is not modified.
+
+      In other words, [map (fun i -> (sorted cmp a).(i)) (sort_ranking cmp a) = a].
+
+      Without duplicates, we also have
+      [lookup_exn a.(i) (sorted a) = (sorted_ranking a).(i)]
+      @since 0.21 *)
+
   val find : ('a -> 'b option) -> 'a t -> 'b option
   (** [find f a] returns [Some y] if there is an element [x] such
       that [f x = Some y], else it returns [None] *)
@@ -260,6 +283,18 @@ let _shuffle _rand_int a i j =
   let b = Array.copy a in shuffle_with st a; a <> b
 *)
 
+let _sort_indices cmp a i j =
+  let len = j-i in
+  let b = Array.init len (fun k->k) in
+  Array.sort (fun k1 k2 -> cmp a.(k1+i) a.(k2+i)) b;
+  b
+
+let _sorted cmp a i j =
+  let len = j-i in
+  let b = Array.sub a i len in
+  Array.sort cmp b;
+  b
+
 let _choose a i j st =
   if i>=j then raise Not_found;
   a.(i+Random.State.int st (j-i))
@@ -366,6 +401,48 @@ let reverse_in_place a =
     a = [| 6;5;4;3;2;1 |]
 *)
 
+let sorted cmp a = _sorted cmp a 0 (Array.length a)
+
+(*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+  [||] (sorted Pervasives.compare [||])
+  [|0;1;2;3;4|] (sorted Pervasives.compare [|3;2;1;4;0|])
+  *)
+
+(*$Q
+  Q.(array int) (fun a -> \
+    let b = Array.copy a in \
+    Array.sort Pervasives.compare b; b = sorted Pervasives.compare a)
+*)
+
+let sort_indices cmp a = _sort_indices cmp a 0 (Array.length a)
+
+(*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+  [||] (sort_indices Pervasives.compare [||])
+  [|4;2;1;0;3|] (sort_indices Pervasives.compare [|"d";"c";"b";"e";"a"|])
+*)
+
+(*$Q
+  Q.(array printable_string) (fun a -> \
+    let b = sort_indices String.compare a in \
+    sorted String.compare a = Array.map (Array.get a) b)
+*)
+
+let sort_ranking cmp a =
+  let cmp_int : int -> int -> int = Pervasives.compare in
+  sort_indices cmp_int (sort_indices cmp a)
+
+(*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+  [||] (sort_ranking Pervasives.compare [||])
+  [|3;2;1;4;0|] (sort_ranking Pervasives.compare [|"d";"c";"b";"e";"a"|])
+*)
+
+(*$Q
+  Q.(array printable_string) (fun a -> \
+    let b = sort_ranking String.compare a in \
+    let a_sorted = sorted String.compare a in \
+    a = Array.map (Array.get a_sorted) b)
+*)
+
 let rev a =
   let b = Array.copy a in
   reverse_in_place b;
@@ -618,7 +695,15 @@ module Sub = struct
 
   let copy a = Array.sub a.arr a.i (length a)
 
-  let sub a i len = make a.arr ~len:(a.i + i) len
+  let sub a i len = make a.arr (a.i + i) ~len
+  (*$=
+    [ 3;4 ] \
+      (let a = Sub.make (0--10) 2 5 in Sub.sub a 1 2 |> Sub.to_list)
+    [ ] \
+      (let a = Sub.make (0--10) 2 5 in Sub.sub a 1 0 |> Sub.to_list)
+    [ 5 ] \
+      (let a = Sub.make (0--10) 1 9 in Sub.sub a 4 1 |> Sub.to_list)
+  *)
 
   let equal eq a b =
     length a = length b && _equal eq a.arr a.i a.j b.arr b.i b.j
@@ -632,6 +717,10 @@ module Sub = struct
       else _fold (f acc a.arr.(i)) (i+1) j
     in _fold acc a.i a.j
 
+  let to_list a =
+    let l = fold (fun l x -> x::l) [] a in
+    List.rev l
+
   let foldi f acc a = _foldi f acc a.arr a.i a.j
 
   let fold_while f acc a =
@@ -689,22 +778,95 @@ module Sub = struct
     Sub.reverse_in_place s; a = [| 1; 2; 5; 4; 3; 6 |]
   *)
 
+  let sorted cmp a = _sorted cmp a.arr a.i a.j
+
+  (*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+    [||] \
+      (let a = 1--6 in let s = Sub.make a 2 ~len:0 in \
+       Sub.sorted Pervasives.compare s)
+    [|2;3;4|] \
+      (let a = [|6;5;4;3;2;1|] in let s = Sub.make a 2 ~len:3 in \
+      Sub.sorted Pervasives.compare s)
+  *)
+
+  (*$Q
+    Q.(array int) (fun a -> \
+    Array.length a > 10 ==> ( Array.length a > 10 && \
+    let s = Sub.make a 5 ~len:5 in \
+    let b = Array.sub a 5 5 in \
+    Array.sort Pervasives.compare b; b = Sub.sorted Pervasives.compare s))
+  *)
+
+  let sort_ranking cmp a =
+    let idx = _sort_indices cmp a.arr a.i a.j in
+    let cmp_int : int -> int -> int = Pervasives.compare in
+    sort_indices cmp_int idx
+
+  (*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+    [||] \
+       (let a = 1--6 in let s = Sub.make a 2 ~len:0 in \
+       Sub.sort_ranking Pervasives.compare s)
+    [|2;1;3;0|] \
+      (let a = [|"d";"c";"b";"e";"a"|] in let s = Sub.make a 1 ~len:4 in \
+      Sub.sort_ranking Pervasives.compare s)
+  *)
+
+  (*$Q
+    Q.(array printable_string) (fun a -> \
+    Array.length a > 10 ==> ( Array.length a > 10 && \
+    let s = Sub.make a 5 ~len:5 in \
+    let b = Sub.sort_indices String.compare s in \
+    Sub.sorted String.compare s = Array.map (Sub.get s) b))
+  *)
+
+  let sort_indices cmp a = _sort_indices cmp a.arr a.i a.j
+
+  (*$= & ~cmp:(=) ~printer:Q.Print.(array int)
+    [||] \
+       (let a = 1--6 in let s = Sub.make a 2 ~len:0 in \
+       Sub.sort_indices Pervasives.compare s)
+    [|3;1;0;2|] \
+      (let a = [|"d";"c";"b";"e";"a"|] in let s = Sub.make a 1 ~len:4 in \
+      Sub.sort_indices Pervasives.compare s)
+  *)
+
+  (*$Q
+    Q.(array printable_string) (fun a -> \
+    Array.length a > 10 ==> ( Array.length a > 10 && \
+    let s = Sub.make a 5 ~len:5 in \
+    let b = Sub.sort_ranking String.compare s in \
+    let a_sorted = Sub.sorted String.compare s in \
+    Sub.copy s = Array.map (Array.get a_sorted) b))
+  *)
+
+
   let find f a = _find (fun _ -> f) a.arr a.i a.j
 
   let findi f a = _find (fun i -> f (i-a.i)) a.arr a.i a.j
 
   let find_idx p a =
-    _find (fun i x -> if p x then Some (i,x) else None) a.arr a.i a.j
+    _find (fun i x -> if p x then Some (i-a.i,x) else None) a.arr a.i a.j
+
+  (*$=
+    (Some (1,"c")) (Sub.find_idx ((=) "c") (Sub.make [| "a"; "b"; "c" |] 1 2))
+    *)
 
   let lookup_exn ?(cmp=Pervasives.compare) k a =
-    _lookup_exn ~cmp k a.arr a.i (a.j-1)
+    _lookup_exn ~cmp k a.arr a.i (a.j-1) - a.i
 
   let lookup ?(cmp=Pervasives.compare) k a =
-    try Some (_lookup_exn ~cmp k a.arr a.i (a.j-1))
+    try Some (_lookup_exn ~cmp k a.arr a.i (a.j-1) - a.i)
     with Not_found -> None
 
+  (*$=
+    (Some 1) (Sub.lookup "c" (Sub.make [| "a"; "b"; "c" |] 1 2))
+    *)
+
   let bsearch ?(cmp=Pervasives.compare) k a =
-    bsearch_ ~cmp k a.arr a.i (a.j - 1)
+    match bsearch_ ~cmp k a.arr a.i (a.j - 1) with
+      | `At m -> `At (m - a.i)
+      | `Just_after m -> `Just_after (m - a.i)
+      | res -> res
 
   let for_all p a = _for_all p a.arr a.i a.j
 
@@ -738,7 +900,8 @@ module Sub = struct
 
   let pp ?(sep=", ") pp_item buf a = _pp ~sep pp_item buf a.arr a.i a.j
 
-  let pp_i ?(sep=", ") pp_item buf a = _pp_i ~sep pp_item buf a.arr a.i a.j
+  let pp_i ?(sep=", ") pp_item buf a =
+    _pp_i ~sep (fun out k x -> pp_item out (k-a.i) x) buf a.arr a.i a.j
 
   let print ?(sep=", ") pp_item fmt a = _print ~sep pp_item fmt a.arr a.i a.j
 
diff --git a/src/core/CCArray.mli b/src/core/CCArray.mli
index 8206d2cb..11be5ebd 100644
--- a/src/core/CCArray.mli
+++ b/src/core/CCArray.mli
@@ -53,6 +53,29 @@ module type S = sig
   val reverse_in_place : 'a t -> unit
   (** Reverse the array in place *)
 
+  val sorted : ('a -> 'a -> int) -> 'a t -> 'a array
+  (** [sorted cmp a] makes a copy of [a] and sorts it with [cmp].
+      @since 0.21 *)
+
+  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 of the [i]-th element of [a] in [sort cmp a].
+      In other words, [map (fun i -> a.(i)) (sort_indices a) = sorted cmp a].
+      [a] is not modified.
+      @since 0.21 *)
+
+  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],
+      such that [b.(i)] is the position in [sorted cmp a] of the [i]-th
+      element of [a].
+      [a] is not modified.
+
+      In other words, [map (fun i -> (sorted cmp a).(i)) (sort_ranking cmp a) = a].
+
+      Without duplicates, we also have
+      [lookup_exn a.(i) (sorted a) = (sorted_ranking a).(i)]
+      @since 0.21 *)
+
   val find : ('a -> 'b option) -> 'a t -> 'b option
   (** [find f a] returns [Some y] if there is an element [x] such
       that [f x = Some y], else it returns [None] *)
@@ -224,6 +247,10 @@ module Sub : sig
   (** Convert into a triple [(arr, i, len)] where [len] is the length of
       the subarray of [arr] starting at offset [i] *)
 
+  val to_list : 'a t -> 'a list
+  (** Convert directly to a list
+      @since 0.21 *)
+
   val full : 'a array -> 'a t
   (** Slice that covers the full array *)
 
diff --git a/src/core/CCFormat.ml b/src/core/CCFormat.ml
index c7b82288..a02f6b23 100644
--- a/src/core/CCFormat.ml
+++ b/src/core/CCFormat.ml
@@ -25,7 +25,7 @@ let int64 fmt n = Format.fprintf fmt "%Ld" n
 let nativeint fmt n = Format.fprintf fmt "%nd" n
 let string_quoted fmt s = Format.fprintf fmt "\"%s\"" s
 
-let list ?(start="[") ?(stop="]") ?(sep=", ") pp fmt l =
+let list ?(start="") ?(stop="") ?(sep=", ") pp fmt l =
   let rec pp_list l = match l with
   | x::((_::_) as l) ->
     pp fmt x;
@@ -39,7 +39,7 @@ let list ?(start="[") ?(stop="]") ?(sep=", ") pp fmt l =
   pp_list l;
   Format.pp_print_string fmt stop
 
-let array ?(start="[") ?(stop="]") ?(sep=", ") pp fmt a =
+let array ?(start="") ?(stop="") ?(sep=", ") pp fmt a =
   Format.pp_print_string fmt start;
   for i = 0 to Array.length a - 1 do
     if i > 0 then (
@@ -50,7 +50,7 @@ let array ?(start="[") ?(stop="]") ?(sep=", ") pp fmt a =
   done;
   Format.pp_print_string fmt stop
 
-let arrayi ?(start="[") ?(stop="]") ?(sep=", ") pp fmt a =
+let arrayi ?(start="") ?(stop="") ?(sep=", ") pp fmt a =
   Format.pp_print_string fmt start;
   for i = 0 to Array.length a - 1 do
     if i > 0 then (
@@ -61,7 +61,7 @@ let arrayi ?(start="[") ?(stop="]") ?(sep=", ") pp fmt a =
   done;
   Format.pp_print_string fmt stop
 
-let seq ?(start="[") ?(stop="]") ?(sep=", ") pp fmt seq =
+let seq ?(start="") ?(stop="") ?(sep=", ") pp fmt seq =
   Format.pp_print_string fmt start;
   let first = ref true in
   seq (fun x ->
@@ -279,8 +279,28 @@ let sprintf_ c format =
     fmt
     format
 
+let with_color_sf s fmt =
+  let buf = Buffer.create 64 in
+  let out = Format.formatter_of_buffer buf in
+  if !color_enabled then set_color_tag_handling out;
+  Format.pp_open_tag out s;
+  Format.kfprintf
+    (fun out ->
+       Format.pp_close_tag out ();
+       Format.pp_print_flush out ();
+       Buffer.contents buf)
+    out fmt
+
 let sprintf fmt = sprintf_ true fmt
 let sprintf_no_color fmt = sprintf_ false fmt
+let sprintf_dyn_color ~colors fmt = sprintf_ colors fmt
+
+let fprintf_dyn_color ~colors out fmt =
+  let old_tags = Format.pp_get_mark_tags out () in
+  Format.pp_set_mark_tags out colors; (* enable/disable tags *)
+  Format.kfprintf
+    (fun out -> Format.pp_set_mark_tags out old_tags)
+    out fmt
 
 (*$T
   sprintf "yolo %s %d" "a b" 42 = "yolo a b 42"
@@ -301,3 +321,31 @@ let ksprintf ~f fmt =
   Format.kfprintf
     (fun _ -> Format.pp_print_flush out (); f (Buffer.contents buf))
     out fmt
+
+
+module Dump = struct
+  type 'a t = 'a printer
+  let unit = unit
+  let int = int
+  let string = string_quoted
+  let bool = bool
+  let float = float
+  let char = char
+  let int32 = int32
+  let int64 = int64
+  let nativeint = nativeint
+  let list pp = within "[" "]" (hovbox (list ~sep:";" pp))
+  let array pp = within "[|" "|]" (hovbox (array ~sep:";" pp))
+  let option pp out x = match x with
+    | None -> Format.pp_print_string out "None"
+    | Some x -> Format.fprintf out "Some %a" pp x
+  let pair p1 p2 = pair p1 p2
+  let triple p1 p2 p3 = triple p1 p2 p3
+  let quad p1 p2 p3 p4 = quad p1 p2 p3 p4
+end
+
+(*$= & ~printer:(fun s->s)
+  "[1;2;3]" (to_string Dump.(list int) [1;2;3])
+  "Some 1" (to_string Dump.(option int) (Some 1))
+  "[None;Some \"a b\"]" (to_string Dump.(list (option string)) [None; Some "a b"])
+*)
diff --git a/src/core/CCFormat.mli b/src/core/CCFormat.mli
index 7d2fd22b..98ddcc46 100644
--- a/src/core/CCFormat.mli
+++ b/src/core/CCFormat.mli
@@ -137,6 +137,16 @@ val with_colorf : string -> t -> ('a, t, unit, unit) format4 -> 'a
     {b status: experimental}
     @since 0.16 *)
 
+val with_color_sf : string -> ('a, t, unit, string) format4 -> 'a
+(** [with_color_sf "Blue" out "%s %d" "yolo" 42] will behave like
+    {!sprintf}, but wrapping the content with the given style
+    Example:
+    {[
+      CCFormat.with_color_sf "red" "%a" CCFormat.Dump.(list int) [1;2;3] |> print_endline;;
+    ]}
+    {b status: experimental}
+    @since 0.21 *)
+
 (** {2 IO} *)
 
 val output : t -> 'a printer -> 'a -> unit
@@ -153,10 +163,28 @@ val sprintf_no_color : ('a, t, unit, string) format4 -> 'a
 (** Similar to {!sprintf} but never prints colors
     @since 0.16 *)
 
+val sprintf_dyn_color : colors:bool -> ('a, t, unit, string) format4 -> 'a
+(** Similar to {!sprintf} but enable/disable colors depending on [colors].
+    Example:
+    {[
+      (* with colors *)
+      CCFormat.sprintf_dyn_color ~colors:true "@{<Red>%a@}"
+        CCFormat.Dump.(list int) [1;2;3] |> print_endline;;
+
+      (* without colors *)
+      CCFormat.sprintf_dyn_color ~colors:false "@{<Red>%a@}"
+        CCFormat.Dump.(list int) [1;2;3] |> print_endline;;
+    ]}
+    @since 0.21 *)
+
 val fprintf : t -> ('a, t, unit ) format -> 'a
 (** Alias to {!Format.fprintf}
     @since 0.14 *)
 
+val fprintf_dyn_color : colors:bool -> t -> ('a, t, unit ) format -> 'a
+(** Similar to {!fprintf} but enable/disable colors depending on [colors]
+    @since 0.21 *)
+
 val ksprintf :
   f:(string -> 'b) ->
   ('a, Format.formatter, unit, 'b) format4 ->
@@ -172,3 +200,39 @@ val ksprintf :
 
 val to_file : string -> ('a, t, unit, unit) format4 -> 'a
 (** Print to the given file *)
+
+(** {2 Dump}
+
+    Print structures as OCaml values, so that they can be parsed back
+    by OCaml (typically, in the toplevel, for debugging).
+
+    Example:
+    {[
+      Format.printf "%a@." CCFormat.Dump.(list int) CCList.(1 -- 200);;
+
+      Format.printf "%a@." CCFormat.Dump.(array (list (pair int bool)))
+        [| [1, true; 2, false]; []; [42, false] |];;
+    ]}
+
+    @since 0.21 *)
+
+module Dump : sig
+  type 'a t = 'a printer
+  val unit : unit t
+  val int : int t
+  val string : string t
+  val bool : bool t
+  val float : float t
+  val char : char t
+  val int32 : int32 t
+  val int64 : int64 t
+  val nativeint : nativeint 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 quad :
+    'a t -> 'b t -> 'c t -> 'd t ->
+    ('a * 'b * 'c * 'd) t
+end
diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index 17a29a04..f09ea9fc 100644
--- a/src/core/CCList.ml
+++ b/src/core/CCList.ml
@@ -1221,7 +1221,7 @@ end
 
 (** {2 IO} *)
 
-let pp ?(start="[") ?(stop="]") ?(sep=", ") pp_item buf l =
+let pp ?(start="") ?(stop="") ?(sep=", ") pp_item buf l =
   let rec print l = match l with
     | x::((_::_) as l) ->
       pp_item buf x;
@@ -1232,10 +1232,10 @@ let pp ?(start="[") ?(stop="]") ?(sep=", ") pp_item buf l =
   in Buffer.add_string buf start; print l; Buffer.add_string buf stop
 
 (*$T
-  CCPrint.to_string (pp CCPrint.int) [1;2;3] = "[1, 2, 3]"
+  CCPrint.to_string (pp ~start:"[" ~stop:"]" CCPrint.int) [1;2;3] = "[1, 2, 3]"
   *)
 
-let print ?(start="[") ?(stop="]") ?(sep=", ") pp_item fmt l =
+let print ?(start="") ?(stop="") ?(sep=", ") pp_item fmt l =
   let rec print fmt l = match l with
     | x::((_::_) as l) ->
       pp_item fmt x;
diff --git a/src/core/CCMap.ml b/src/core/CCMap.ml
index 6dad0ad1..ee7c5f66 100644
--- a/src/core/CCMap.ml
+++ b/src/core/CCMap.ml
@@ -113,7 +113,7 @@ module Make(O : Map.OrderedType) = struct
   let to_list m =
     fold (fun k v acc -> (k,v)::acc) m []
 
-  let pp ?(start="{") ?(stop="}") ?(arrow="->") ?(sep=", ") pp_k pp_v buf m =
+  let pp ?(start="") ?(stop="") ?(arrow="->") ?(sep=", ") pp_k pp_v buf m =
     let first = ref true in
     Buffer.add_string buf start;
     iter
@@ -125,7 +125,7 @@ module Make(O : Map.OrderedType) = struct
       m;
     Buffer.add_string buf stop
 
-  let print ?(start="[") ?(stop="]") ?(arrow="->") ?(sep=", ") pp_k pp_v fmt m =
+  let print ?(start="") ?(stop="") ?(arrow="->") ?(sep=", ") pp_k pp_v fmt m =
     Format.pp_print_string fmt start;
     let first = ref true in
     iter
diff --git a/src/core/CCPrint.ml b/src/core/CCPrint.ml
index c0f1a4c7..3d1fd7b3 100644
--- a/src/core/CCPrint.ml
+++ b/src/core/CCPrint.ml
@@ -25,7 +25,7 @@ let float3 buf f = Printf.bprintf buf "%.3f" f
 let float buf f = Buffer.add_string buf (string_of_float f)
 let char buf c = Buffer.add_char buf c
 
-let list ?(start="[") ?(stop="]") ?(sep=", ") pp buf l =
+let list ?(start="") ?(stop="") ?(sep=", ") pp buf l =
   let rec pp_list l = match l with
   | x::((_::_) as l) ->
     pp buf x;
@@ -38,7 +38,7 @@ let list ?(start="[") ?(stop="]") ?(sep=", ") pp buf l =
   pp_list l;
   Buffer.add_string buf stop
 
-let array ?(start="[") ?(stop="]") ?(sep=", ") pp buf a =
+let array ?(start="") ?(stop="") ?(sep=", ") pp buf a =
   Buffer.add_string buf start;
   for i = 0 to Array.length a - 1 do
     (if i > 0 then Buffer.add_string buf sep);
@@ -46,7 +46,7 @@ let array ?(start="[") ?(stop="]") ?(sep=", ") pp buf a =
   done;
   Buffer.add_string buf stop
 
-let arrayi ?(start="[") ?(stop="]") ?(sep=", ") pp buf a =
+let arrayi ?(start="") ?(stop="") ?(sep=", ") pp buf a =
   Buffer.add_string buf start;
   for i = 0 to Array.length a - 1 do
     (if i > 0 then Buffer.add_string buf sep);
@@ -54,7 +54,7 @@ let arrayi ?(start="[") ?(stop="]") ?(sep=", ") pp buf a =
   done;
   Buffer.add_string buf stop
 
-let seq ?(start="[") ?(stop="]") ?(sep=", ") pp buf seq =
+let seq ?(start="") ?(stop="") ?(sep=", ") pp buf seq =
   Buffer.add_string buf start;
   let first = ref true in
   seq (fun x ->
diff --git a/src/core/CCSet.ml b/src/core/CCSet.ml
index f11d1981..59815a2d 100644
--- a/src/core/CCSet.ml
+++ b/src/core/CCSet.ml
@@ -51,7 +51,7 @@ module Make(O : Map.OrderedType) = struct
 
   let to_list = elements
 
-  let pp ?(start="{") ?(stop="}") ?(sep=", ") pp_x buf m =
+  let pp ?(start="") ?(stop="") ?(sep=", ") pp_x buf m =
     let first = ref true in
     Buffer.add_string buf start;
     iter
@@ -61,7 +61,7 @@ module Make(O : Map.OrderedType) = struct
       m;
     Buffer.add_string buf stop
 
-  let print ?(start="[") ?(stop="]") ?(sep=", ") pp_x fmt m =
+  let print ?(start="") ?(stop="") ?(sep=", ") pp_x fmt m =
     Format.pp_print_string fmt start;
     let first = ref true in
     iter
diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 240774fe..1c5362d0 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -737,7 +737,7 @@ let to_klist v =
     else `Cons (v.vec.(i), aux (i+1))
   in aux 0
 
-let pp ?(start="[") ?(stop="]") ?(sep=", ") pp_item buf v =
+let pp ?(start="") ?(stop="") ?(sep=", ") pp_item buf v =
   Buffer.add_string buf start;
   iteri
     (fun i x ->
@@ -746,7 +746,7 @@ let pp ?(start="[") ?(stop="]") ?(sep=", ") pp_item buf v =
     ) v;
   Buffer.add_string buf stop
 
-let print ?(start="[") ?(stop="]") ?(sep=", ") pp_item fmt v =
+let print ?(start="") ?(stop="") ?(sep=", ") pp_item fmt v =
   Format.pp_print_string fmt start;
   iteri
     (fun i x ->
diff --git a/src/core/META b/src/core/META
index 121c5e09..5a4f08ce 100644
--- a/src/core/META
+++ b/src/core/META
@@ -1,6 +1,6 @@
 # OASIS_START
-# DO NOT EDIT (digest: 5fef39d6aa86c783d2d134baf25c1157)
-version = "0.20"
+# DO NOT EDIT (digest: 2366633cbce20e67d6074e01f20927dc)
+version = "0.21"
 description = "A modular standard library focused on data structures."
 requires = "bytes result"
 archive(byte) = "containers.cma"
@@ -9,7 +9,7 @@ archive(native) = "containers.cmxa"
 archive(native, plugin) = "containers.cmxs"
 exists_if = "containers.cma"
 package "unix" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "bytes unix"
  archive(byte) = "containers_unix.cma"
@@ -20,7 +20,7 @@ package "unix" (
 )
 
 package "top" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires =
  "compiler-libs.common containers containers.data containers.bigarray containers.string containers.unix containers.sexp containers.iter"
@@ -32,7 +32,7 @@ package "top" (
 )
 
 package "thread" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "containers threads"
  archive(byte) = "containers_thread.cma"
@@ -43,7 +43,7 @@ package "thread" (
 )
 
 package "string" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "bytes"
  archive(byte) = "containers_string.cma"
@@ -54,7 +54,7 @@ package "string" (
 )
 
 package "sexp" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "bytes"
  archive(byte) = "containers_sexp.cma"
@@ -65,7 +65,7 @@ package "sexp" (
 )
 
 package "iter" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  archive(byte) = "containers_iter.cma"
  archive(byte, plugin) = "containers_iter.cma"
@@ -75,7 +75,7 @@ package "iter" (
 )
 
 package "io" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "bytes"
  archive(byte) = "containers_io.cma"
@@ -86,7 +86,7 @@ package "io" (
 )
 
 package "data" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "bytes"
  archive(byte) = "containers_data.cma"
@@ -97,7 +97,7 @@ package "data" (
 )
 
 package "bigarray" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "containers bigarray bytes"
  archive(byte) = "containers_bigarray.cma"
@@ -108,7 +108,7 @@ package "bigarray" (
 )
 
 package "advanced" (
- version = "0.20"
+ version = "0.21"
  description = "A modular standard library focused on data structures."
  requires = "containers sequence"
  archive(byte) = "containers_advanced.cma"
diff --git a/src/core/containers.ml b/src/core/containers.ml
index b8271589..470bae8f 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -81,6 +81,9 @@ module Vector = CCVector
 module Int64 = CCInt64
 (** @since 0.13 *)
 
+module IO = CCIO
+(** @since 0.21 *)
+
 module Char = struct
   include Char
   include (CCChar : module type of CCChar with type t := t)
diff --git a/src/data/CCImmutArray.ml b/src/data/CCImmutArray.ml
index a775a586..e7e335c6 100644
--- a/src/data/CCImmutArray.ml
+++ b/src/data/CCImmutArray.ml
@@ -116,7 +116,7 @@ let to_gen a =
 
 type 'a printer = Format.formatter -> 'a -> unit
 
-let print ?(start="[|") ?(stop="|]") ?(sep=";") pp_item out a =
+let print ?(start="") ?(stop="") ?(sep=", ") pp_item out a =
   Format.pp_print_string out start;
   for k = 0 to Array.length a - 1 do
     if k > 0 then (
diff --git a/src/sexp/CCSexpM.ml b/src/sexp/CCSexpM.ml
index d714924f..3ecaf953 100644
--- a/src/sexp/CCSexpM.ml
+++ b/src/sexp/CCSexpM.ml
@@ -41,7 +41,7 @@ let _must_escape s =
     for i = 0 to String.length s - 1 do
       let c = String.unsafe_get s i in
       match c with
-      | ' ' | ';' | ')' | '(' | '"' | '\\' | '\n' | '\t' -> raise Exit
+      | ' ' | ';' | ')' | '(' | '"' | '\\' | '\n' | '\t' | '\r' -> raise Exit
       | _ when Char.code c > 127 -> raise Exit  (* non-ascii *)
       | _ -> ()
     done;
@@ -176,11 +176,11 @@ module MakeDecode(M : MONAD) = struct
   let rec expr k t =
     if t.i = t.len then _refill t (expr k) _error_eof
     else match _get t with
-    | ' ' | '\t' | '\n' -> expr k t
+    | ' ' | '\t' | '\r' | '\n' -> expr k t
     | c -> expr_starting_with c k t
 
   and expr_starting_with c k t = match c with
-    | ' ' | '\t' | '\n' -> assert false
+    | ' ' | '\t' | '\r' | '\n' -> assert false
     | ';' -> skip_comment (fun _ () -> expr k t) t
     | '(' -> expr_list [] k t
     | ')' -> _error t "unexpected ')'"
@@ -194,7 +194,7 @@ module MakeDecode(M : MONAD) = struct
   and expr_list acc k t =
     if t.i = t.len then _refill t (expr_list acc k) _error_eof
     else match _get t with
-    | ' ' | '\t' | '\n' -> expr_list acc k t
+    | ' ' | '\t' | '\r' | '\n' -> expr_list acc k t
     | ')' -> k None (`List (List.rev acc))
     | c ->
         expr_starting_with c
@@ -216,7 +216,7 @@ module MakeDecode(M : MONAD) = struct
     else match _get t with
     | '\\' -> _error t "unexpected '\\' in non-quoted string"
     | '"' -> _error t "unexpected '\"' in the middle of an atom"
-    | (' ' | '\n' | '\t' | '(' | ')') as c ->
+    | (' ' | '\r' | '\n' | '\t' | '(' | ')') as c ->
         _return_atom (Some c) k t
     | c ->
         Buffer.add_char t.atom c;
@@ -277,7 +277,7 @@ module MakeDecode(M : MONAD) = struct
     if t.i = t.len
     then _refill t (expr_or_end k) (fun _ -> M.return `End)
     else match _get t with
-    | ' ' | '\t' | '\n' -> expr_or_end k t
+    | ' ' | '\t' | '\r' | '\n' -> expr_or_end k t
     | c -> expr_starting_with c k t
 
   (* entry point *)
@@ -308,6 +308,8 @@ let parse_string s : t or_error =
 (*$T
   CCError.to_opt (parse_string "(abc d/e/f \"hello \\\" () world\" )") <> None
   CCError.to_opt (parse_string "(abc ( d e ffff   ) \"hello/world\")") <> None
+  (parse_string "(abc\r\n ( d e \r\tffff   ))") \
+    = `Ok (`List [`Atom "abc"; `List [`Atom "d"; `Atom "e"; `Atom "ffff"]])
 *)
 
 (*$inject