RCMA/Global/Clock.hs

   1 module RCMA.Global.Clock ( tempo
   2                          , metronome
   3                          , tempoToDTime
   4                          ) where
   5
   6 import FRP.Yampa
   7 import RCMA.Auxiliary.Auxiliary
   8 import RCMA.Semantics
   9
  10 tempo :: Tempo -> SF () Tempo
  11 tempo = constant
  12
  13 -- The initial value is arbitrary but never appears because the switch
  14 -- is immediate.
  15 metronome :: SF Tempo (Event Beat)
  16 metronome = switch ((repeatedly (tempoToDTime 60) ())
  17                      &&&
  18                     (onChange')) (metronome')
  19   where metronome' :: Tempo -> SF Tempo (Event Beat)
  20         metronome' t = (switch ((repeatedly (4 * tempoToDTime t) ())
  21                                  &&&
  22                                  onChange) (metronome'))
  23
  24 -- Tempo is the number of whole notes per minute.
  25 tempoToDTime :: Tempo -> DTime
  26 tempoToDTime = (15/) . fromIntegral