From 600fec4852ce2f8333a0aa8aa07e9179ed3a1f16 Mon Sep 17 00:00:00 2001
From: Felipe Lessa <felipe.lessa@gmail.com>
Date: Mon, 20 Aug 2012 11:34:50 -0300
Subject: [PATCH] wai-eventsource: Do not Flush needlessly on
 ioToRepEventSource.

---
 yesod-eventsource/Yesod/EventSource.hs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/yesod-eventsource/Yesod/EventSource.hs b/yesod-eventsource/Yesod/EventSource.hs
index 501b4e61..14948bd5 100644
--- a/yesod-eventsource/Yesod/EventSource.hs
+++ b/yesod-eventsource/Yesod/EventSource.hs
@@ -68,10 +68,13 @@ ioToRepEventSource initial act = do
   let -- Get new events to be sent.
       getEvents s = do
         (evs, s') <- liftIO (act polyfill s)
-        let (builder, continue) = joinEvents evs []
-        C.yield (C.Chunk builder)
-        C.yield C.Flush
-        when continue (getEvents s')
+        case evs of
+          [] -> getEvents s'
+          _  -> do
+            let (builder, continue) = joinEvents evs []
+            C.yield (C.Chunk builder)
+            C.yield C.Flush
+            when continue (getEvents s')
 
       -- Join all events in a single Builder.  Returns @False@
       -- when we the connection should be closed.