Implement playing MIDI from the database

Currently, the "dump" command plays the entire database. Only the SQL
SELECT statement needs to be changed in order to play a specific
time-range.

1 files changed, 5 insertions, 0 deletions

diff --git a/Midi.hs b/Midi.hs
index 402f683..cc14eb6 100644
--- a/Midi.hs
+++ b/Midi.hs
@@ -59,6 +59,11 @@ instance ToRow CompleteRecording where
     where
       (CompleteRecording (TimeSpec s ns) (TimeSpec s' ns') (TimeSpec s'' ns'') (TimeSpec s''' ns''') midi) = reco
 
+instance Monoid CompleteRecording where
+    mempty = CompleteRecording 0 0 0 0 []
+    (CompleteRecording s _e f _l evts) `mappend` (CompleteRecording _s' e' _f' l' evts') =
+        CompleteRecording s e' f l' (evts' ++ evts)
+
 maybesnd :: forall t t1. (t, Maybe t1) -> Maybe (t, t1)
 maybesnd (_, Nothing) = Nothing
 maybesnd (x, Just y) = Just (x, y)