separate out a midi event hook in midi-dump.hs

1 files changed, 9 insertions, 7 deletions

diff --git a/midi-dump.hs b/midi-dump.hs
index aa19def..0f714ed 100644
--- a/midi-dump.hs
+++ b/midi-dump.hs
@@ -1,18 +1,19 @@
-{-# LANGUAGE NondecreasingIndentation #-}
 import AlsaSeq
 import Control.Concurrent (threadDelay)
 import qualified Sound.ALSA.Exception as AlsaExc
 import qualified Data.Set as Set
 
-main = (do
+main = main' `AlsaExc.catch` handler
+  where
+  handler e = putStrLn $ "alsa_exception: " ++ AlsaExc.show e
 
-  withAlsaInit $ \h public private q publicAddr privateAddr -> do
+main' = withAlsaInit $ \h public private q publicAddr privateAddr -> do
   cmdlineAlsaConnect h public
 
   let
     forwardNOW = forwardNoteEvent h q publicAddr
     go keysDown = do
-      keysDown' <- parseAlsaEvents h keysDown forwardNOW
+      keysDown' <- parseAlsaEvents h keysDown (\ev -> do forwardNOW ev; hook ev)
       if (keysDown == keysDown') then
         threadDelay 15000 -- 15ms.  Seems like a lot, but it sounds OK.  Cuts CPU down to 2%.
       else do
@@ -20,6 +21,7 @@ main = (do
       go keysDown'
 
   putStrLn "Rock on!"
-  go Set.empty)
-     `AlsaExc.catch` \e ->
-       putStrLn $ "alsa_exception: " ++ AlsaExc.show e
+  go Set.empty
+
+hook :: MidiHook
+hook ev = return ()