From 268bc37fc1c5040949dbd7b001dfc02ccf8987ba Mon Sep 17 00:00:00 2001
From: Jeremy Yallop <yallop@gmail.com>
Date: Fri, 16 Sep 2016 16:28:46 +0100
Subject: [PATCH] Add a pp function for Lwt_engine.Ev_backend.t (suggested by
 @avsm).

---
 src/unix/lwt_engine.ml  | 11 +++++++++++
 src/unix/lwt_engine.mli |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/src/unix/lwt_engine.ml b/src/unix/lwt_engine.ml
index 7d3394cf67..d87b956d5b 100644
--- a/src/unix/lwt_engine.ml
+++ b/src/unix/lwt_engine.ml
@@ -146,6 +146,17 @@ struct
   let kqueue = EV_KQUEUE
   let devpoll = EV_DEVPOLL
   let port = EV_PORT
+
+  let name = function
+    | EV_DEFAULT -> "EV_DEFAULT"
+    | EV_SELECT -> "EV_SELECT"
+    | EV_POLL -> "EV_POLL"
+    | EV_EPOLL -> "EV_EPOLL"
+    | EV_KQUEUE -> "EV_KQUEUE"
+    | EV_DEVPOLL -> "EV_DEVPOLL"
+    | EV_PORT -> "EV_PORT"
+
+  let pp fmt t = Format.pp_print_string fmt (name t)
 end
 
 external ev_init : Ev_backend.t -> ev_loop = "lwt_libev_init"
diff --git a/src/unix/lwt_engine.mli b/src/unix/lwt_engine.mli
index b2c9cac4c8..726f637f41 100644
--- a/src/unix/lwt_engine.mli
+++ b/src/unix/lwt_engine.mli
@@ -139,6 +139,8 @@ sig
   val kqueue : t
   val devpoll : t
   val port : t
+
+  val pp : Format.formatter -> t -> unit
 end
 
   (** Type of libev loops. *)