diff --git a/behavior.ml b/behavior.ml
index 43c14cfb..32ae6f83 100644
--- a/behavior.ml
+++ b/behavior.ml
@@ -77,9 +77,9 @@ let test_signal s = TestFun (fun () -> React.S.value s)
 
 let wait e = Wait e
 
-let timeout f = Sequence (false, [Timeout f; Fail])
+let timeout f = Sequence (false, [Timeout f; fail])
 
-let delay f = Sequence (false, [Timeout f; Succeed])
+let delay f = Sequence (false, [Timeout f; succeed])
 
 let do_ act = Do act
 
@@ -87,10 +87,16 @@ let do_succeed act = Do (fun () -> act (); true)
 
 let if_ s then_ else_ = If (s, then_, else_)
 
+let when_ s t = if_ s t succeed
+
+let while_ s l = Sequence (true, (test_signal s) :: l)
+
 let sequence ?(loop=false) l =
   assert (l <> []);
   Sequence (loop, l)
 
+let repeat t = sequence ~loop:true [t]
+
 let select ?(strat=strategy_inorder) l =
   assert (l <> []);
   Select (strat, l)
diff --git a/behavior.mli b/behavior.mli
index 428d7746..6a06238d 100644
--- a/behavior.mli
+++ b/behavior.mli
@@ -109,9 +109,18 @@ val do_succeed : (unit -> unit) -> tree
 val if_ : bool React.signal -> tree -> tree -> tree
   (** Conditional choice, based on the current value of the signal *)
 
+val when_ : bool React.signal -> tree -> tree
+  (** Run the given tree if the signal is true, else succeed *)
+
+val while_ : bool React.signal -> tree list -> tree
+  (** While the signal is true, run the subtrees *)
+
 val sequence : ?loop:bool -> tree list -> tree
   (** Sequence of sub-trees to run *)
 
+val repeat : tree -> tree
+  (** Repeat the same tree indefinitely *)
+
 val select : ?strat:select_strategy -> tree list -> tree
   (** Choice among the subtrees. The strategy defines in which order subtrees
       are tried. *)