[sledge] Add Trm.height

Reviewed By: da319

Differential Revision: D24532357

fbshipit-source-id: 32fb92d91

sledge/src/trm.ml

@@ -496,3 +496,4 @@ let subtrms e = Iter.from_labelled_iter (iter_subtrms e)
 (** Query *)
 
 let fv e = Var.Set.of_iter (vars e)
+let rec height e = 1 + Iter.fold ~f:(fun x -> max (height x)) (subtrms e) 0

sledge/src/trm.mli

@@ -96,6 +96,7 @@ val map : t -> f:(t -> t) -> t
 val seq_size_exn : t -> t
 val seq_size : t -> t option
 val fv : t -> Var.Set.t
+val height : t -> int
 
 (** Traverse *)