diff --git a/CHANGELOG.md b/CHANGELOG.md
index 357c8dba..21485845 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,33 @@
 # Changelog
 
+## 0.12
+
+### breaking
+
+- change type of `CCString.blit` so it writes into `Bytes.t`
+- better default opening flags for `CCIO.with_{in, out}`
+
+### non-breaking
+
+note: use of `containers.io` is deprecated (its only module has moved to `containers`)
+
+- add `CCString.mem`
+- add `CCString.set` for updating immutable strings
+- add `CCList.cons` function
+- enable `-safe-string` on the project; fix `-safe-string` issues
+- move `CCIO` from `containers.io` to `containers`, add dummy module in `containers.io`
+- add `CCIO.read_all_bytes`, reading a whole file into a `Bytes.t`
+- add `CCIO.with_in_out` to read and write a file
+- add `CCArray1` in containers.bigarray, a module on 1-dim bigarrays (experimental)
+- add module `CCGraph` in `containers.data`, a simple graph abstraction similar to `LazyGraph`
+- add a lot of string functions in `CCString`
+- add `CCError.catch`, in prevision of the future standard `Result.t` type
+- add `CCError.Infix` module
+- add `CCHashconsedSet` in `containers.data` (set with maximal struct sharing)
+
+- fix: use the proper array module in `CCRingBuffer`
+- bugfix: `CCRandom.float_range`
+
 ## 0.11
 
 - add `CCList.{remove,is_empty}`
diff --git a/_oasis b/_oasis
index d39a25cd..0afbb4d2 100644
--- a/_oasis
+++ b/_oasis
@@ -1,6 +1,6 @@
 OASISFormat: 0.4
 Name:        containers
-Version:     0.11
+Version:     0.12
 Homepage:    https://github.com/c-cube/ocaml-containers
 Authors:     Simon Cruanes
 License:     BSD-2-clause
@@ -18,8 +18,9 @@ Description:
     extend the stdlib (e.g. CCList provides safe map/fold_right/append, and
     additional functions on lists).
 
-    It also features an optional library for dealing with strings, and a `misc`
-    library full of experimental ideas (not stable, not necessarily usable).
+    It also features optional libraries for dealing with strings, helpers for unix,
+    threads, lwt and a `misc` library full of experimental ideas (not stable, not
+    necessarily usable).
 
 Flag "misc"
   Description:  Build the misc library, with experimental modules still susceptible to change
diff --git a/src/bigarray/CCArray1.mli b/src/bigarray/CCArray1.mli
index 62643361..1a6dab57 100644
--- a/src/bigarray/CCArray1.mli
+++ b/src/bigarray/CCArray1.mli
@@ -26,8 +26,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 (** {1 Bigarrays of dimension 1}
 
-    {b status: unstable}
-    @since NEXT_RELEASE *)
+    {b status: experimental}
+    @since 0.12 *)
 
 (** {2 used types} *)
 
diff --git a/src/core/CCError.ml b/src/core/CCError.ml
index 1d56ba6b..47498964 100644
--- a/src/core/CCError.ml
+++ b/src/core/CCError.ml
@@ -52,9 +52,6 @@ let fail_printf format =
 
 (* TODO: easy ways to print backtrace/stack *)
 
-(* TODO: something of type  [ ('a -> 'b) -> ('err -> 'b) -> ('a, 'err) t -> 'b]
-   to make it easier to switch into a regular variant if it happens *)
-
 let _printers = ref []
 
 let register_printer p = _printers := p :: !_printers
diff --git a/src/core/CCError.mli b/src/core/CCError.mli
index dac93dc1..072ecc96 100644
--- a/src/core/CCError.mli
+++ b/src/core/CCError.mli
@@ -81,7 +81,7 @@ val catch : ('a, 'err) t -> ok:('a -> 'b) -> err:('err -> 'b) -> 'b
     This is useful for code that does not want to depend on the exact
     definition of [('a, 'b) t] used, for instance once OCaml gets a
     standard [Result.t] type.
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val flat_map : ('a -> ('b, 'err) t) -> ('a, 'err) t -> ('b, 'err) t
 
@@ -130,7 +130,7 @@ val (<*>) : ('a -> 'b, 'err) t -> ('a, 'err) t -> ('b, 'err) t
 
 (** {2 Infix}
 
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 module Infix : sig
   val (>|=) : ('a, 'err) t -> ('a -> 'b) -> ('b, 'err) t
diff --git a/src/core/CCIO.mli b/src/core/CCIO.mli
index e4633952..79a8ce64 100644
--- a/src/core/CCIO.mli
+++ b/src/core/CCIO.mli
@@ -55,7 +55,7 @@ Examples:
 
 @since 0.6
 
-@before NEXT_RELEASE was in 'containers.io', now moved into 'containers'
+@before 0.12 was in 'containers.io', now moved into 'containers'
 
 *)
 
@@ -92,7 +92,7 @@ val read_all : ?size:int -> in_channel -> string
 val read_all_bytes : ?size:int -> in_channel -> Bytes.t
 (** Read the whole channel into a mutable byte array
     @param size the internal buffer size
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {6 Output} *)
 
@@ -125,7 +125,7 @@ val with_in_out : ?mode:int -> ?flags:open_flag list ->
                   string -> (in_channel -> out_channel -> 'a) -> 'a
 (** Combines {!with_in} and {!with_out}.
     @param flags opening flags (default [[Open_creat]])
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {2 Misc for Generators} *)
 
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index 70f44bee..06cb20db 100644
--- a/src/core/CCList.mli
+++ b/src/core/CCList.mli
@@ -43,7 +43,7 @@ val (>|=) : 'a t -> ('a -> 'b) -> 'b t
 
 val cons : 'a -> 'a t -> 'a t
 (** [cons x l] is [x::l]
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val append : 'a t -> 'a t -> 'a t
 (** Safe version of append *)
diff --git a/src/core/CCString.mli b/src/core/CCString.mli
index 521ab379..e4954971 100644
--- a/src/core/CCString.mli
+++ b/src/core/CCString.mli
@@ -110,7 +110,7 @@ val find : ?start:int -> sub:string -> string -> int
 
 val mem : ?start:int -> sub:string -> string -> bool
 (** [mem ~sub s] is true iff [sub] is a substring of [s]
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (*$T
    mem ~sub:"bc" "abcd"
@@ -120,7 +120,7 @@ val mem : ?start:int -> sub:string -> string -> bool
 val rfind : sub:string -> string -> int
 (** Find [sub] in string from the right, returns its first index or [-1].
     Should only be used with very small [sub]
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (*$T
   rfind ~sub:"bc" "abcd" = 1
@@ -183,7 +183,7 @@ 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 NEXT_RELEASE *)
+    @since 0.12 *)
 
 (*$T
   set "abcd" 1 '_' = "a_cd"
@@ -193,32 +193,32 @@ val set : string -> int -> char -> string
 
 val iter : (char -> unit) -> string -> unit
 (** Alias to {!String.iter}
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val iteri : (int -> char -> unit) -> string -> unit
 (** iter on chars with their index
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val map : (char -> char) -> string -> string
 (** map chars
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val mapi : (int -> char -> char) -> string -> string
 (** map chars with their index
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val flat_map : ?sep:string -> (char -> string) -> string -> string
 (** map each chars to a string, then concatenates them all
     @param sep optional separator between each generated string
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val for_all : (char -> bool) -> string -> bool
 (** true for all chars?
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val exists : (char -> bool) -> string -> bool
 (** true for some char?
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 include S with type t := string
 
@@ -227,32 +227,32 @@ include S with type t := string
 val map2 : (char -> char -> char) -> string -> string -> string
 (** map pairs of chars
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val iter2: (char -> char -> unit) -> string -> string -> unit
 (** iterate on pairs of chars
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val iteri2: (int -> char -> char -> unit) -> string -> string -> unit
 (** iterate on pairs of chars with their index
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val fold2: ('a -> char -> char -> 'a) -> 'a -> string -> string -> 'a
 (** fold on pairs of chars
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val for_all2 : (char -> char -> bool) -> string -> string -> bool
 (** all pair of chars respect the predicate?
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val exists2 : (char -> char -> bool) -> string -> string -> bool
 (** exists a pair of chars?
     @raises Invalid_argument if the strings have not the same length
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {2 Splitting} *)
 
@@ -294,7 +294,7 @@ module Split : sig
   val left : by:string -> string -> (string * string) option
   (** Split on the first occurrence of [by] from the left-most part of
       the string
-      @since NEXT_RELEASE *)
+      @since 0.12 *)
 
   (*$T
     Split.left ~by:" " "ab cde f g " = Some ("ab", "cde f g ")
@@ -304,7 +304,7 @@ module Split : sig
   val right : by:string -> string -> (string * string) option
   (** Split on the first occurrence of [by] from the rightmost part of
       the string
-      @since NEXT_RELEASE *)
+      @since 0.12 *)
 
   (*$T
     Split.right ~by:" " "ab cde f g" = Some ("ab cde f", "g")
diff --git a/src/data/CCGraph.mli b/src/data/CCGraph.mli
index 3fb3bff4..e7f75193 100644
--- a/src/data/CCGraph.mli
+++ b/src/data/CCGraph.mli
@@ -44,7 +44,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
     {b status: unstable}
 
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 type 'a sequence = ('a -> unit) -> unit
 (** A sequence of items of type ['a], possibly infinite *)
diff --git a/src/data/CCHashconsedSet.mli b/src/data/CCHashconsedSet.mli
index d9ef01a7..972a0668 100644
--- a/src/data/CCHashconsedSet.mli
+++ b/src/data/CCHashconsedSet.mli
@@ -31,7 +31,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
     {b status: unstable}
 
-    @since NEXT_RELEASE
+    @since 0.12
 *)
 
 module type ELT = sig