div/little_things/Note.hs

   1 module Note where
   2
   3 import MIDI
   4
   5 isNoteOn :: Message -> Bool
   6 isNoteOn (NoteOn _ _ _) = True
   7 isNoteOn _ = False
   8
   9 isNoteOff :: Message -> Bool
  10 isNoteOff (NoteOff _ _ _) = True
  11 isNoteOff _ = False
  12
  13 changePitch :: (Pitch -> Pitch) -> Message-> Message
  14 changePitch f (NoteOn  c p v) = NoteOn  c (f p) v
  15 changePitch f (NoteOff c p v) = NoteOff c (f p) v
  16
  17 changeVelocity :: (Velocity -> Velocity) -> Message-> Message
  18 changeVelocity f (NoteOn  c p v) = NoteOn  c p (f v)
  19 changeVelocity f (NoteOff c p v) = NoteOff c p (f v)
  20
  21 switchOnOff :: Message-> Message
  22 switchOnOff (NoteOn  c p v) = NoteOff c p v
  23 switchOnOff (NoteOff c p v) = NoteOn  c p v
  24
  25 perfectFifth :: Message-> Message
  26 perfectFifth = changePitch (toPitch . (+7) . fromPitch)
  27
  28 majorThird :: Message-> Message
  29 majorThird = changePitch (toPitch . (+4) . fromPitch)
  30
  31 minorThird :: Message-> Message
  32 minorThird = changePitch (toPitch . (+3) . fromPitch)