diff --git a/src/base/Proof.ml b/src/base/Proof.ml
index acea15fb..25e2821d 100644
--- a/src/base/Proof.ml
+++ b/src/base/Proof.ml
@@ -51,8 +51,24 @@ type proof_rule = t -> proof_step
 
 module Step_vec = struct
   type elt = proof_step
+  type t = elt Vec.t
 
-  include VecI32
+  let get = Vec.get
+  let size = Vec.size
+  let iter = Vec.iter
+  let iteri = Vec.iteri
+  let create ?cap:_ () = Vec.create ()
+  let clear = Vec.clear
+  let copy = Vec.copy
+  let is_empty = Vec.is_empty
+  let push = Vec.push
+  let fast_remove = Vec.fast_remove
+  let filter_in_place = Vec.filter_in_place
+  let ensure_size v len = Vec.ensure_size v ~elt:0l len
+  let pop = Vec.pop_exn
+  let set = Vec.set
+  let shrink = Vec.shrink
+  let to_iter = Vec.to_iter
 end
 
 let disable (self : t) : unit =
diff --git a/src/checker/drup_check.ml b/src/checker/drup_check.ml
index f0a02542..ed9b4664 100644
--- a/src/checker/drup_check.ml
+++ b/src/checker/drup_check.ml
@@ -30,8 +30,8 @@ end = struct
   let del_clause self c = Vec.push self.ops (Delete c)
   let get self i = Vec.get self.ops i
   let size self = Vec.size self.ops
-  let ops self = Vec.to_seq self.ops
-  let iteri self ~f = Vec.iteri f self.ops
+  let ops self = Vec.to_iter self.ops
+  let iteri self ~f = Vec.iteri ~f self.ops
 
   let pp_op out = function
     | Input c -> Fmt.fprintf out "(@[Input %a@])" Clause.pp c
@@ -43,19 +43,17 @@ end = struct
     let pp_c out c =
       Clause.iter c ~f:(fun a -> fpf out "%d " (a : atom :> int))
     in
-    Vec.iter
-      (function
-        | Input c -> fpf oc "i %a0\n" pp_c c
-        | Redundant c -> fpf oc "%a0\n" pp_c c
-        | Delete c -> fpf oc "d %a0\n" pp_c c)
-      self.ops
+    Vec.iter self.ops ~f:(function
+      | Input c -> fpf oc "i %a0\n" pp_c c
+      | Redundant c -> fpf oc "%a0\n" pp_c c
+      | Delete c -> fpf oc "d %a0\n" pp_c c)
 end
 
 (** Forward checking.
 
     Each event is checked by reverse-unit propagation on previous events. *)
 module Fwd_check : sig
-  type error = [ `Bad_steps of VecSmallInt.t | `No_empty_clause ]
+  type error = [ `Bad_steps of Veci.t | `No_empty_clause ]
 
   val pp_error : Trace.t -> error Fmt.printer
 
@@ -64,10 +62,10 @@ module Fwd_check : sig
       success. In case of error it returns [Error idxs] where [idxs] are the
       indexes in the trace of the steps that failed. *)
 end = struct
-  type t = { checker: Checker.t; errors: VecSmallInt.t }
+  type t = { checker: Checker.t; errors: Veci.t }
 
   let create cstore : t =
-    { checker = Checker.create cstore; errors = VecSmallInt.create () }
+    { checker = Checker.create cstore; errors = Veci.create () }
 
   (* check event, return [true] if it's valid *)
   let check_op (self : t) i (op : Trace.op) : bool =
@@ -87,15 +85,15 @@ end = struct
       Checker.del_clause self.checker c;
       true
 
-  type error = [ `Bad_steps of VecSmallInt.t | `No_empty_clause ]
+  type error = [ `Bad_steps of Veci.t | `No_empty_clause ]
 
   let pp_error trace out = function
     | `No_empty_clause -> Fmt.string out "no empty clause found"
     | `Bad_steps bad ->
-      let n0 = VecSmallInt.get bad 0 in
+      let n0 = Veci.get bad 0 in
       Fmt.fprintf out
         "@[<v>checking failed on %d ops.@ @[<2>First failure is op[%d]:@ %a@]@]"
-        (VecSmallInt.size bad) n0 Trace.pp_op (Trace.get trace n0)
+        (Veci.size bad) n0 Trace.pp_op (Trace.get trace n0)
 
   let check trace : _ result =
     let self = create (Trace.cstore trace) in
@@ -116,13 +114,13 @@ end = struct
         ) else (
           Log.debugf 10 (fun k ->
               k "(@[check.proof_rule.fail@ :idx %d@ :op %a@])" i Trace.pp_op op);
-          VecSmallInt.push self.errors i
+          Veci.push self.errors i
         ));
 
-    Log.debugf 10 (fun k -> k "found %d errors" (VecSmallInt.size self.errors));
+    Log.debugf 10 (fun k -> k "found %d errors" (Veci.size self.errors));
     if not !has_false then
       Error `No_empty_clause
-    else if VecSmallInt.size self.errors > 0 then
+    else if Veci.size self.errors > 0 then
       Error (`Bad_steps self.errors)
     else
       Ok ()
diff --git a/src/core/Sidekick_core.ml b/src/core/Sidekick_core.ml
index 5965a048..504931cd 100644
--- a/src/core/Sidekick_core.ml
+++ b/src/core/Sidekick_core.ml
@@ -169,7 +169,7 @@ module type SAT_PROOF = sig
   type proof_step
   (** identifier for a proof *)
 
-  module Step_vec : Vec_sig.S with type elt = proof_step
+  module Step_vec : Vec_sig.BASE with type elt = proof_step
   (** A vector of steps *)
 
   type lit
diff --git a/src/drup/sidekick_drup.ml b/src/drup/sidekick_drup.ml
index b3a525ba..895bf1d5 100644
--- a/src/drup/sidekick_drup.ml
+++ b/src/drup/sidekick_drup.ml
@@ -5,7 +5,7 @@
 *)
 
 module Fmt = CCFormat
-module VecSmallInt = VecSmallInt
+module Veci = Veci
 
 (* TODO: resolution proof construction, optionally *)
 
@@ -130,7 +130,7 @@ module Make () : S = struct
     end
 
     module Stack = struct
-      include VecSmallInt
+      include Veci
 
       let create () = create ()
     end
diff --git a/src/sat/Heap.ml b/src/sat/Heap.ml
index 78e60e38..468cb99a 100644
--- a/src/sat/Heap.ml
+++ b/src/sat/Heap.ml
@@ -4,10 +4,10 @@ module type S = Heap_intf.S
 module Make (Elt : RANKED) = struct
   type elt_store = Elt.store
   type elt = Elt.t
-  type t = { store: elt_store; heap: VecSmallInt.t (* vec of elements *) }
+  type t = { store: elt_store; heap: Veci.t (* vec of elements *) }
 
   let _absent_index = -1
-  let create store : t = { store; heap = VecSmallInt.create () }
+  let create store : t = { store; heap = Veci.create () }
   let[@inline] left i = (i lsl 1) + 1 (* i*2 + 1 *)
 
   let[@inline] right i = (i + 1) lsl 1 (* (i+1)*2 *)
@@ -16,17 +16,17 @@ module Make (Elt : RANKED) = struct
 
   (*
   let rec heap_property cmp ({heap=heap} as s) i =
-    i >= (VecSmallInt.size heap)  ||
+    i >= (Veci.size heap)  ||
       ((i = 0 || not(cmp (Vec. get heap i) (Vec.get heap (parent i))))
        && heap_property cmp s (left i) && heap_property cmp s (right i))
 
   let heap_property cmp s = heap_property cmp s 1
   *)
 
-  let[@inline] get_elt_ self i = Elt.of_int_unsafe (VecSmallInt.get self.heap i)
+  let[@inline] get_elt_ self i = Elt.of_int_unsafe (Veci.get self.heap i)
 
   let[@inline] set_elt_ self i elt =
-    VecSmallInt.set self.heap i (elt : Elt.t :> int)
+    Veci.set self.heap i (elt : Elt.t :> int)
 
   (* [elt] is above or at its expected position. Move it up the heap
      (towards high indices) to restore the heap property *)
@@ -43,7 +43,7 @@ module Make (Elt : RANKED) = struct
     Elt.set_heap_idx self.store elt !i
 
   let percolate_down (self : t) (elt : Elt.t) : unit =
-    let sz = VecSmallInt.size self.heap in
+    let sz = Veci.size self.heap in
     let li = ref (left (Elt.heap_idx self.store elt)) in
     let ri = ref (right (Elt.heap_idx self.store elt)) in
     let i = ref (Elt.heap_idx self.store elt) in
@@ -83,7 +83,7 @@ module Make (Elt : RANKED) = struct
 
   let filter (self : t) filt : unit =
     let j = ref 0 in
-    let lim = VecSmallInt.size self.heap in
+    let lim = Veci.size self.heap in
     for i = 0 to lim - 1 do
       if filt (get_elt_ self i) then (
         set_elt_ self !j (get_elt_ self i);
@@ -92,24 +92,24 @@ module Make (Elt : RANKED) = struct
       ) else
         Elt.set_heap_idx self.store (get_elt_ self i) _absent_index
     done;
-    VecSmallInt.shrink self.heap (lim - !j);
+    Veci.shrink self.heap (lim - !j);
     for i = (lim / 2) - 1 downto 0 do
       percolate_down self (get_elt_ self i)
     done
 
-  let[@inline] size s = VecSmallInt.size s.heap
-  let[@inline] is_empty s = VecSmallInt.is_empty s.heap
+  let[@inline] size s = Veci.size s.heap
+  let[@inline] is_empty s = Veci.is_empty s.heap
 
   let clear self : unit =
-    VecSmallInt.iter self.heap ~f:(fun e ->
+    Veci.iter self.heap ~f:(fun e ->
         Elt.set_heap_idx self.store (Elt.of_int_unsafe e) _absent_index);
-    VecSmallInt.clear self.heap;
+    Veci.clear self.heap;
     ()
 
   let insert self elt =
     if not (in_heap self elt) then (
-      Elt.set_heap_idx self.store elt (VecSmallInt.size self.heap);
-      VecSmallInt.push self.heap (elt : Elt.t :> int);
+      Elt.set_heap_idx self.store elt (Veci.size self.heap);
+      Veci.push self.heap (elt : Elt.t :> int);
       percolate_up self elt
     )
 
@@ -128,21 +128,21 @@ module Make (Elt : RANKED) = struct
   *)
 
   let remove_min self =
-    match VecSmallInt.size self.heap with
+    match Veci.size self.heap with
     | 0 -> raise Not_found
     | 1 ->
-      let x = Elt.of_int_unsafe (VecSmallInt.pop self.heap) in
+      let x = Elt.of_int_unsafe (Veci.pop self.heap) in
       Elt.set_heap_idx self.store x _absent_index;
       x
     | _ ->
       let x = get_elt_ self 0 in
-      let new_hd = Elt.of_int_unsafe (VecSmallInt.pop self.heap) in
+      let new_hd = Elt.of_int_unsafe (Veci.pop self.heap) in
       (* heap.last() *)
       set_elt_ self 0 new_hd;
       Elt.set_heap_idx self.store x _absent_index;
       Elt.set_heap_idx self.store new_hd 0;
       (* enforce heap property again *)
-      if VecSmallInt.size self.heap > 1 then percolate_down self new_hd;
+      if Veci.size self.heap > 1 then percolate_down self new_hd;
       x
 end
 [@@inline]
diff --git a/src/sat/Solver.ml b/src/sat/Solver.ml
index b34b5f02..ef7d5f75 100644
--- a/src/sat/Solver.ml
+++ b/src/sat/Solver.ml
@@ -61,7 +61,7 @@ module Make (Plugin : PLUGIN) = struct
     let[@inline] var a = Var0.of_int_unsafe (a lsr 1)
     let[@inline] na v = ((v : var :> int) lsl 1) lor 1
 
-    module AVec = VecSmallInt
+    module AVec = Veci
     module ATbl = CCHashtbl.Make (CCInt)
   end
 
@@ -74,7 +74,7 @@ module Make (Plugin : PLUGIN) = struct
   end = struct
     include Int_id.Make ()
     module Tbl = Util.Int_tbl
-    module CVec = VecSmallInt
+    module CVec = Veci
   end
 
   type clause = Clause0.t
@@ -98,7 +98,7 @@ module Make (Plugin : PLUGIN) = struct
     type cstore = {
       c_lits: atom array Vec.t; (* storage for clause content *)
       c_activity: Vec_float.t;
-      c_recycle_idx: VecSmallInt.t; (* recycle clause numbers that were GC'd *)
+      c_recycle_idx: Veci.t; (* recycle clause numbers that were GC'd *)
       c_proof: Step_vec.t; (* clause -> proof_rule for its proof *)
       c_attached: Bitvec.t;
       c_marked: Bitvec.t;
@@ -158,7 +158,7 @@ module Make (Plugin : PLUGIN) = struct
           {
             c_lits = Vec.create ();
             c_activity = Vec_float.create ();
-            c_recycle_idx = VecSmallInt.create ~cap:0 ();
+            c_recycle_idx = Veci.create ~cap:0 ();
             c_proof = Step_vec.create ~cap:0 ();
             c_dead = Bitvec.create ();
             c_attached = Bitvec.create ();
@@ -172,7 +172,7 @@ module Make (Plugin : PLUGIN) = struct
 
     (** iterate on variables *)
     let iter_vars self f =
-      Vec.iteri (fun i _ -> f (Var0.of_int_unsafe i)) self.v_level
+      Vec.iteri self.v_level ~f:(fun i _ -> f (Var0.of_int_unsafe i))
 
     module Var = struct
       include Var0
@@ -339,10 +339,10 @@ module Make (Plugin : PLUGIN) = struct
         in
         (* allocate new ID *)
         let cid =
-          if VecSmallInt.is_empty c_recycle_idx then
+          if Veci.is_empty c_recycle_idx then
             Vec.size c_lits
           else
-            VecSmallInt.pop c_recycle_idx
+            Veci.pop c_recycle_idx
         in
 
         (* allocate space *)
@@ -447,7 +447,7 @@ module Make (Plugin : PLUGIN) = struct
         Vec.set c_lits cid [||];
         Vec_float.set c_activity cid 0.;
 
-        VecSmallInt.push c_recycle_idx cid;
+        Veci.push c_recycle_idx cid;
         (* recycle idx *)
         ()
 
@@ -659,7 +659,7 @@ module Make (Plugin : PLUGIN) = struct
 
     let descr = P.descr
     let add c = Vec.push clauses_ c
-    let iter ~f = Vec.iter f clauses_
+    let iter ~f = Vec.iter ~f clauses_
     let push_level () = ()
     let pop_levels _ = ()
     let size () = Vec.size clauses_
@@ -816,10 +816,10 @@ module Make (Plugin : PLUGIN) = struct
       } =
         self
       in
-      Vec.iter (fun (c, p) -> add_clause_pool c p) clauses_to_add_in_pool;
+      Vec.iter clauses_to_add_in_pool ~f:(fun (c, p) -> add_clause_pool c p);
       CVec.iter ~f:add_clause_learnt clauses_to_add_learnt;
-      Vec.iter decision decisions;
-      Vec.iter (fun (p, lvl, c) -> propagate p ~lvl c) prop;
+      Vec.iter ~f:decision decisions;
+      Vec.iter prop ~f:(fun (p, lvl, c) -> propagate p ~lvl c);
       clear self;
       ()
   end
@@ -847,7 +847,7 @@ module Make (Plugin : PLUGIN) = struct
        store them here. *)
     trail: AVec.t;
     (* decision stack + propagated elements (atoms or assignments). *)
-    var_levels: VecSmallInt.t; (* decision levels in [trail]  *)
+    var_levels: Veci.t; (* decision levels in [trail]  *)
     assumptions: AVec.t; (* current assumptions *)
     mutable th_head: int;
     (* Start offset in the queue {!trail} of
@@ -911,7 +911,7 @@ module Make (Plugin : PLUGIN) = struct
       th_head = 0;
       elt_head = 0;
       trail = AVec.create ();
-      var_levels = VecSmallInt.create ();
+      var_levels = Veci.create ();
       assumptions = AVec.create ();
       order = H.create store;
       var_incr = 1.;
@@ -944,10 +944,10 @@ module Make (Plugin : PLUGIN) = struct
   let iter_clauses_learnt_ (self : t) ~f : unit =
     let[@inline] iter_pool (module P : CLAUSE_POOL) = P.iter ~f in
     iter_pool self.clauses_learnt;
-    Vec.iter iter_pool self.clause_pools;
+    Vec.iter ~f:iter_pool self.clause_pools;
     ()
 
-  let[@inline] decision_level st = VecSmallInt.size st.var_levels
+  let[@inline] decision_level st = Veci.size st.var_levels
   let[@inline] nb_clauses st = CVec.size st.clauses_hyps
   let stat self = self.stat
 
@@ -1172,7 +1172,7 @@ module Make (Plugin : PLUGIN) = struct
   let new_decision_level st =
     assert (st.th_head = AVec.size st.trail);
     assert (st.elt_head = AVec.size st.trail);
-    VecSmallInt.push st.var_levels (AVec.size st.trail);
+    Veci.push st.var_levels (AVec.size st.trail);
     Plugin.push_level st.th;
     ()
 
@@ -1206,7 +1206,7 @@ module Make (Plugin : PLUGIN) = struct
     else (
       Log.debugf 5 (fun k -> k "(@[sat.cancel-until %d@])" lvl);
       (* We set the head of the solver and theory queue to what it was. *)
-      let head = ref (VecSmallInt.get self.var_levels lvl) in
+      let head = ref (Veci.get self.var_levels lvl) in
       self.elt_head <- !head;
       self.th_head <- !head;
       (* Now we need to cleanup the vars that are not valid anymore
@@ -1239,7 +1239,7 @@ module Make (Plugin : PLUGIN) = struct
       assert (n > 0);
       (* Resize the vectors according to their new size. *)
       AVec.shrink self.trail !head;
-      VecSmallInt.shrink self.var_levels lvl;
+      Veci.shrink self.var_levels lvl;
       Plugin.pop_levels self.th n;
       Delayed_actions.clear_on_backtrack self.delayed_actions;
       (* TODO: for scoped clause pools, backtrack them *)
@@ -1598,7 +1598,7 @@ module Make (Plugin : PLUGIN) = struct
     Step_vec.clear self.temp_step_vec;
 
     (* cleanup marks *)
-    Vec.iter (Store.clear_var store) to_unmark;
+    Vec.iter ~f:(Store.clear_var store) to_unmark;
     Vec.clear to_unmark;
 
     (* put high-level literals first, so that:
@@ -2213,7 +2213,7 @@ module Make (Plugin : PLUGIN) = struct
     in
 
     gc_pool self.clauses_learnt;
-    Vec.iter gc_pool self.clause_pools;
+    Vec.iter ~f:gc_pool self.clause_pools;
 
     let n_collected = CVec.size to_be_gc in
 
diff --git a/src/simplex/sidekick_simplex.ml b/src/simplex/sidekick_simplex.ml
index 32b6fa86..f9a396cf 100644
--- a/src/simplex/sidekick_simplex.ml
+++ b/src/simplex/sidekick_simplex.ml
@@ -353,23 +353,21 @@ module Make (Arg : ARG) :
         (Fmt.iter ~sep:(Fmt.return "@ ") ppi)
         CCInt.(0 -- (n_cols self - 1));
 
-      Vec.iteri
-        (fun i row ->
+      Vec.iteri self.rows ~f:(fun i row ->
           let hd =
             CCString.pad ~side:`Left 6
             @@ Printf.sprintf "r%d (v%d)" i row.vs.idx
           in
           Fmt.fprintf out "@,{@[<hov2>%9s: %a@]}" hd
             (Fmt.iter ~sep:(Fmt.return "@ ") (Q.pp_approx 6))
-            (Vec.to_seq row.cols))
-        self.rows;
+            (Vec.to_iter row.cols));
       Fmt.fprintf out "@;<0 -1>}@]"
 
     let to_string = Fmt.to_string pp
 
     let add_column self =
       self.n_cols <- 1 + self.n_cols;
-      Vec.iter (fun r -> Vec.push r.cols Q.zero) self.rows
+      Vec.iter self.rows ~f:(fun r -> Vec.push r.cols Q.zero)
 
     let add_row_and_column self ~f : var_state =
       let n = n_rows self in
@@ -393,7 +391,7 @@ module Make (Arg : ARG) :
       Vec.set r.cols j n
 
     let[@inline] iter_rows ?(skip = ~-1) (self : t) f : unit =
-      Vec.iteri (fun i row -> if i <> skip then f i row.vs) self.rows
+      Vec.iteri self.rows ~f:(fun i row -> if i <> skip then f i row.vs)
 
     let[@inline] iter_cols ?(skip = ~-1) (self : t) f : unit =
       for i = 0 to n_cols self - 1 do
@@ -498,7 +496,7 @@ module Make (Arg : ARG) :
 
   (* for debug purposes *)
   let _check_invariants self : unit =
-    Vec.iteri (fun i v -> assert (v.idx = i)) self.vars;
+    Vec.iteri self.vars ~f:(fun i v -> assert (v.idx = i));
     let n = Vec.size self.vars in
     assert (Matrix.n_rows self.matrix = 0 || Matrix.n_cols self.matrix = n);
     Matrix.iter_rows self.matrix (fun i x_i ->
@@ -507,12 +505,10 @@ module Make (Arg : ARG) :
         assert (Q.(Matrix.get self.matrix x_i.basic_idx x_i.idx = minus_one));
 
         (* basic vars are only defined in terms of non-basic vars *)
-        Vec.iteri
-          (fun j x_j ->
+        Vec.iteri self.vars ~f:(fun j x_j ->
             if Var_state.(x_i != x_j) && Q.(Matrix.get self.matrix i j <> zero)
             then
-              assert (Var_state.is_n_basic x_j))
-          self.vars;
+              assert (Var_state.is_n_basic x_j));
 
         (* sum of each row must be 0 *)
         let sum =
@@ -786,8 +782,7 @@ module Make (Arg : ARG) :
     assert (Var_state.is_basic x_i);
     let map_res = ref [] in
     let bounds = ref V_map.empty in
-    Vec.iteri
-      (fun j x_j ->
+    Vec.iteri self.vars ~f:(fun j x_j ->
         if j <> x_i.idx then (
           let c = Matrix.get self.matrix x_i.basic_idx j in
           if Q.(c <> zero) then (
@@ -817,8 +812,7 @@ module Make (Arg : ARG) :
                 bounds := V_map.add x_j.var (op, u) !bounds
               | None -> assert false (* we could increase [x_j]?! *))
           )
-        ))
-      self.vars;
+        ));
     !map_res, !bounds
 
   let add_constraint ?(is_int = false) ~on_propagate (self : t)
@@ -1159,7 +1153,7 @@ module Make (Arg : ARG) :
             | _ -> eps
           in
           eps)
-        default_eps (Vec.to_seq self.vars)
+        default_eps (Vec.to_iter self.vars)
     in
     if Q.(eps >= one) then
       Q.one
@@ -1171,7 +1165,7 @@ module Make (Arg : ARG) :
     Log.debugf 50 (fun k ->
         k "(@[simplex.model@ :epsilon-val %a@])" pp_q_dbg eps);
     let subst =
-      Vec.to_seq self.vars
+      Vec.to_iter self.vars
       |> Iter.fold
            (fun subst x ->
              let { base; eps_factor } = x.value in
diff --git a/src/util/Sidekick_util.ml b/src/util/Sidekick_util.ml
index e5e22699..e1ffadf7 100644
--- a/src/util/Sidekick_util.ml
+++ b/src/util/Sidekick_util.ml
@@ -2,8 +2,7 @@
 module Fmt = CCFormat
 module Util = Util
 module Vec = Vec
-module VecSmallInt = VecSmallInt
-module VecI32 = VecI32
+module Veci = Veci
 module Vec_float = Vec_float
 module Vec_unit = Vec_unit
 module Vec_sig = Vec_sig
diff --git a/src/util/Vec.ml b/src/util/Vec.ml
index 43ed3329..a25099bc 100644
--- a/src/util/Vec.ml
+++ b/src/util/Vec.ml
@@ -53,7 +53,7 @@ let ensure_size_with self f n =
     self.sz <- n
   )
 
-let ensure_size self x n = ensure_size_with self (fun () -> x) n
+let ensure_size self ~elt:x n = ensure_size_with self (fun () -> x) n
 
 (* grow the array *)
 let[@inline never] grow_to_double_size t x : unit =
@@ -125,22 +125,21 @@ let sort t f : unit =
   Array.fast_sort f sub_arr;
   t.data <- sub_arr
 
-let[@inline] iter f t =
+let iter ~f t =
   for i = 0 to size t - 1 do
     f (Array.unsafe_get t.data i)
   done
 
-let[@inline] iteri f t =
+let iteri ~f t =
   for i = 0 to size t - 1 do
     f i (Array.unsafe_get t.data i)
   done
 
-let[@inline] to_seq a k = iter k a
-let to_iter v k = iter k v
-let exists p t = Iter.exists p @@ to_seq t
-let for_all p t = Iter.for_all p @@ to_seq t
-let fold f acc a = Iter.fold f acc @@ to_seq a
-let to_list a = Iter.to_list @@ to_seq a
+let to_iter v k = iter ~f:k v
+let exists p t = Iter.exists p @@ to_iter t
+let for_all p t = Iter.for_all p @@ to_iter t
+let fold f acc a = Iter.fold f acc @@ to_iter a
+let to_list a = Iter.to_list @@ to_iter a
 let to_array a = Array.sub a.data 0 a.sz
 
 let of_list l : _ t =
@@ -153,11 +152,9 @@ let of_list l : _ t =
 
 let pp ?(sep = ", ") pp out v =
   let first = ref true in
-  iter
-    (fun x ->
+  iter v ~f:(fun x ->
       if !first then
         first := false
       else
         Format.fprintf out "%s@," sep;
       pp out x)
-    v
diff --git a/src/util/Vec.mli b/src/util/Vec.mli
index b6898970..e94028a7 100644
--- a/src/util/Vec.mli
+++ b/src/util/Vec.mli
@@ -20,12 +20,11 @@ val to_list : 'a t -> 'a list
 
 val to_array : 'a t -> 'a array
 val of_list : 'a list -> 'a t
-val to_seq : 'a t -> 'a Iter.t
 
 val clear : 'a t -> unit
 (** Set size to 0, doesn't free elements *)
 
-val ensure_size : 'a t -> 'a -> int -> unit
+val ensure_size : 'a t -> elt:'a -> int -> unit
 (** ensure size is at least [n] *)
 
 val ensure_size_with : 'a t -> (unit -> 'a) -> int -> unit
@@ -79,12 +78,12 @@ val filter_in_place : ('a -> bool) -> 'a t -> unit
 val sort : 'a t -> ('a -> 'a -> int) -> unit
 (** Sort in place the array *)
 
-val iter : ('a -> unit) -> 'a t -> unit
+val iter : f:('a -> unit) -> 'a t -> unit
 (** Iterate on elements *)
 
 val to_iter : 'a t -> 'a Iter.t
 
-val iteri : (int -> 'a -> unit) -> 'a t -> unit
+val iteri : f:(int -> 'a -> unit) -> 'a t -> unit
 (** Iterate on elements with their index *)
 
 val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
diff --git a/src/util/VecI32.ml b/src/util/VecI32.ml
deleted file mode 100644
index 2987d2f9..00000000
--- a/src/util/VecI32.ml
+++ /dev/null
@@ -1,104 +0,0 @@
-module A = Bigarray.Array1
-
-type int32arr = (int32, Bigarray.int32_elt, Bigarray.c_layout) A.t
-type t = { mutable data: int32arr; mutable sz: int }
-
-let mk_arr_ sz : int32arr = A.create Bigarray.int32 Bigarray.c_layout sz
-let create ?(cap = 16) () : t = { sz = 0; data = mk_arr_ cap }
-let[@inline] clear self = self.sz <- 0
-let[@inline] shrink self n = if n < self.sz then self.sz <- n
-let[@inline] size self = self.sz
-let[@inline] is_empty self = self.sz = 0
-
-let copy self =
-  if size self = 0 then
-    create ~cap:0 ()
-  else (
-    (* copy bigarray *)
-    let data = mk_arr_ (size self) in
-    A.blit (A.sub self.data 0 (size self)) data;
-    { sz = self.sz; data }
-  )
-
-let[@inline] fast_remove t i =
-  assert (i >= 0 && i < t.sz);
-  A.unsafe_set t.data i @@ A.unsafe_get t.data (t.sz - 1);
-  t.sz <- t.sz - 1
-
-let filter_in_place f vec =
-  let i = ref 0 in
-  while !i < size vec do
-    if f (A.unsafe_get vec.data !i) then
-      incr i
-    else
-      fast_remove vec !i
-  done
-
-(* ensure capacity is [new_cap] *)
-let resize_cap_ self new_cap =
-  assert (A.dim self.data < new_cap);
-  let new_data = mk_arr_ new_cap in
-  A.blit self.data (A.sub new_data 0 (A.dim self.data));
-  self.data <- new_data
-
-let ensure_cap self (n : int) =
-  if n > A.dim self.data then (
-    let new_cap = max n (max 4 (A.dim self.data * 2)) in
-    resize_cap_ self new_cap
-  )
-
-let ensure_size self n =
-  if n > self.sz then (
-    ensure_cap self n;
-    self.sz <- n
-  )
-
-let[@inline] push (self : t) i : unit =
-  ensure_cap self (self.sz + 1);
-  self.data.{self.sz} <- i;
-  self.sz <- 1 + self.sz
-
-let[@inline] push_i32 self i =
-  ensure_cap self (self.sz + 1);
-  self.data.{self.sz} <- i;
-  self.sz <- 1 + self.sz
-
-let[@inline] pop self =
-  if self.sz > 0 then (
-    let x = self.data.{self.sz - 1} in
-    self.sz <- self.sz - 1;
-    x
-  ) else
-    failwith "vecI32.pop: empty"
-
-let[@inline] get self i : int32 =
-  assert (i >= 0 && i < self.sz);
-  A.unsafe_get self.data i
-
-let[@inline] set self i x : unit =
-  assert (i >= 0 && i < self.sz);
-  A.unsafe_set self.data i x
-
-let[@inline] set self i x : unit =
-  assert (i >= 0 && i < self.sz);
-  A.unsafe_set self.data i x
-
-let[@inline] iter ~f self =
-  for i = 0 to self.sz - 1 do
-    f self.data.{i}
-  done
-
-let[@inline] iteri ~f self =
-  for i = 0 to self.sz - 1 do
-    f i self.data.{i}
-  done
-
-include Vec_sig.Make_extensions (struct
-  type nonrec elt = int32
-  type nonrec t = t
-
-  let get = get
-  let size = size
-  let iter = iter
-  let iteri = iteri
-end)
diff --git a/src/util/VecI32.mli b/src/util/VecI32.mli
deleted file mode 100644
index 84403571..00000000
--- a/src/util/VecI32.mli
+++ /dev/null
@@ -1,5 +0,0 @@
-(** Vectors of int32 integers
-
-    These vectors are more optimized than {!Vec}. *)
-
-include Vec_sig.S with type elt := int32
diff --git a/src/util/Vec_float.ml b/src/util/Vec_float.ml
index a22d5e95..0546be01 100644
--- a/src/util/Vec_float.ml
+++ b/src/util/Vec_float.ml
@@ -84,10 +84,13 @@ let[@inline] iteri ~f self =
     f i self.data.{i}
   done
 
+let to_iter v k = iter ~f:k v
+
 include Vec_sig.Make_extensions (struct
   type nonrec elt = float
   type nonrec t = t
 
+  let to_iter = to_iter
   let get = get
   let size = size
   let iter = iter
diff --git a/src/util/Vec_sig.ml b/src/util/Vec_sig.ml
index cf789303..fd50e110 100644
--- a/src/util/Vec_sig.ml
+++ b/src/util/Vec_sig.ml
@@ -7,6 +7,7 @@ module type BASE_RO = sig
   val get : t -> int -> elt
   val iter : f:(elt -> unit) -> t -> unit
   val iteri : f:(int -> elt -> unit) -> t -> unit
+  val to_iter : t -> elt Iter.t
 end
 
 module type BASE = sig
@@ -33,7 +34,6 @@ module type EXTENSIONS = sig
   type elt
   type t
 
-  val to_iter : t -> elt Iter.t
   val to_array : t -> elt array
   val fold_left : ('a -> elt -> 'a) -> 'a -> t -> 'a
   val pp : elt CCFormat.printer -> t CCFormat.printer
@@ -48,8 +48,6 @@ module Make_extensions (B : BASE_RO) :
   EXTENSIONS with type t := B.t and type elt := B.elt = struct
   include B
 
-  let[@inline] to_iter self k = iter ~f:k self
-
   let to_array self =
     if size self = 0 then
       [||]
diff --git a/src/util/VecSmallInt.ml b/src/util/Veci.ml
similarity index 97%
rename from src/util/VecSmallInt.ml
rename to src/util/Veci.ml
index e88ad6c6..48f74dd5 100644
--- a/src/util/VecSmallInt.ml
+++ b/src/util/Veci.ml
@@ -97,10 +97,13 @@ let[@inline] iteri ~f self =
     f i (Int32.to_int self.data.{i})
   done
 
+let[@inline] to_iter self k = iter ~f:k self
+
 include Vec_sig.Make_extensions (struct
   type nonrec elt = int
   type nonrec t = t
 
+  let to_iter = to_iter
   let get = get
   let size = size
   let iter = iter
diff --git a/src/util/VecSmallInt.mli b/src/util/Veci.mli
similarity index 100%
rename from src/util/VecSmallInt.mli
rename to src/util/Veci.mli