diff --git a/src/sigs/sidekick_sigs.ml b/src/sigs/sidekick_sigs.ml
index 8fb16dd9..4cbcd6b6 100644
--- a/src/sigs/sidekick_sigs.ml
+++ b/src/sigs/sidekick_sigs.ml
@@ -18,10 +18,12 @@ module type HASH = sig
   val hash : t -> int
 end
 
+type 'a printer = Format.formatter -> 'a -> unit
+
 module type PRINT = sig
   type t
 
-  val pp : t CCFormat.printer
+  val pp : t printer
 end
 
 module type EQ_HASH_PRINT = sig
@@ -37,4 +39,46 @@ module type EQ_ORD_HASH_PRINT = sig
   include PRINT with type t := t
 end
 
-type 'a printer = Format.formatter -> 'a -> unit
+module type DYN_BACKTRACKABLE = sig
+  val n_levels : unit -> int
+  (** Number of levels *)
+
+  val push_level : unit -> unit
+  (** Push a backtracking point *)
+
+  val pop_levels : int -> unit
+  (** [pop_levels n] removes [n] levels *)
+end
+
+module type BACKTRACKABLE0 = sig
+  type t
+
+  val n_levels : t -> int
+  (** Number of levels *)
+
+  val push_level : t -> unit
+  (** Push a backtracking point *)
+
+  val pop_levels : t -> int -> unit
+  (** [pop_levels st n] removes [n] levels *)
+end
+
+module type BACKTRACKABLE1 = sig
+  type 'a t
+
+  val n_levels : _ t -> int
+  (** Number of levels *)
+
+  val push_level : _ t -> unit
+  (** Push a backtracking point *)
+
+  val pop_levels : _ t -> int -> unit
+  (** [pop_levels st n] removes [n] levels *)
+end
+
+module type BACKTRACKABLE1_CB = sig
+  include BACKTRACKABLE1
+
+  val pop_levels : 'a t -> int -> f:('a -> unit) -> unit
+  (** [pop_levels st n ~f] removes [n] levels, calling [f] on every removed item *)
+end
diff --git a/src/util/Backtrack_stack.mli b/src/util/Backtrack_stack.mli
index ced0f18f..d71ea285 100644
--- a/src/util/Backtrack_stack.mli
+++ b/src/util/Backtrack_stack.mli
@@ -10,13 +10,6 @@ val push : 'a t -> 'a -> unit
 val push_if_nonzero_level : 'a t -> 'a -> unit
 (** Push an element onto the stack if level > 0 *)
 
-val n_levels : _ t -> int
-(** Number of levels *)
-
-val push_level : _ t -> unit
-(** Push a backtracking point *)
-
-val pop_levels : 'a t -> int -> f:('a -> unit) -> unit
-(** [pop_levels st n ~f] removes [n] levels, calling [f] on every removed item *)
+include Sidekick_sigs.BACKTRACKABLE1_CB with type 'a t := 'a t
 
 val iter : f:('a -> unit) -> 'a t -> unit
diff --git a/src/util/Backtrackable_ref.mli b/src/util/Backtrackable_ref.mli
index bb686ff3..1b2fb56b 100644
--- a/src/util/Backtrackable_ref.mli
+++ b/src/util/Backtrackable_ref.mli
@@ -16,14 +16,4 @@ val get : 'a t -> 'a
 val update : 'a t -> ('a -> 'a) -> unit
 (** Update the reference's current content *)
 
-val push_level : _ t -> unit
-(** Push a backtracking level, copying the current value on top of some
-    stack. The [copy] function will be used if it was provided in {!create}. *)
-
-val n_levels : _ t -> int
-(** Number of saved values *)
-
-val pop_levels : _ t -> int -> unit
-(** Pop [n] levels, restoring to the value the reference was storing [n] calls
-    to [push_level] earlier.
-    @raise Invalid_argument if [n] is bigger than [n_levels]. *)
+include Sidekick_sigs.BACKTRACKABLE1 with type 'a t := 'a t
diff --git a/src/util/Backtrackable_tbl.ml b/src/util/Backtrackable_tbl.ml
index 08c1bfc1..ccdcfdbf 100644
--- a/src/util/Backtrackable_tbl.ml
+++ b/src/util/Backtrackable_tbl.ml
@@ -14,9 +14,8 @@ module type S = sig
   val to_iter : 'a t -> (key * 'a) Iter.t
   val add : 'a t -> key -> 'a -> unit
   val remove : _ t -> key -> unit
-  val push_level : _ t -> unit
-  val pop_levels : _ t -> int -> unit
-  val n_levels : _ t -> int
+
+  include Sidekick_sigs.BACKTRACKABLE1 with type 'a t := 'a t
 end
 
 module type ARG = sig
diff --git a/src/util/Backtrackable_tbl.mli b/src/util/Backtrackable_tbl.mli
index f5cb8896..90181801 100644
--- a/src/util/Backtrackable_tbl.mli
+++ b/src/util/Backtrackable_tbl.mli
@@ -16,9 +16,8 @@ module type S = sig
   val to_iter : 'a t -> (key * 'a) Iter.t
   val add : 'a t -> key -> 'a -> unit
   val remove : _ t -> key -> unit
-  val push_level : _ t -> unit
-  val pop_levels : _ t -> int -> unit
-  val n_levels : _ t -> int
+
+  include Sidekick_sigs.BACKTRACKABLE1 with type 'a t := 'a t
 end
 
 module type ARG = sig
diff --git a/src/util/Sidekick_util.ml b/src/util/Sidekick_util.ml
index e1ffadf7..44a0af18 100644
--- a/src/util/Sidekick_util.ml
+++ b/src/util/Sidekick_util.ml
@@ -13,7 +13,7 @@ module Int_id = Int_id
 module Int_tbl = Util.Int_tbl
 module Int_set = Util.Int_set
 module Int_map = Util.Int_map
-module IArray = IArray
+module Event = Event
 module Backtrack_stack = Backtrack_stack
 module Backtrackable_tbl = Backtrackable_tbl
 module Backtrackable_ref = Backtrackable_ref
@@ -24,4 +24,3 @@ module Stat = Stat
 module Hash = Hash
 module Profile = Profile
 module Chunk_stack = Chunk_stack
-module Intf = Sidekick_sigs