Extended 12 days of Christmas Sonic Pi Project based on https://projects.raspberrypi.org/en/projects/code-a-carol adding harmony

TheTwelveDaysOfChristmas

#12 days of Christmas
#based on https://projects.raspberrypi.org/en/projects/code-a-carol
#tune altered slightly, based on https://sheetmusic-free.com/download/6888/
#I've added sustain/release for each note
#using pl function, also ability to play chords with pl
#also  added simple accompaniment part.
#I cycle synth used each verse, and adjust tempo last two verses
#also added slight reverb.
#I modifiy many of the functions to allow refinements for each day,
#by utilising a days parameter.

define :pl do |notes,durations| #allows for sustain and release values appropriate to duration
  notes.zip(durations).each do |n,d|
    if n.respond_to?(:each) #allow for chords
      n.each do |nv| #if chord notes in [..] play them all together
        play nv,sustain: 0.9*d,release: 0.1*d
      end
    else #otherwise play the single note entry
      play n,sustain: 0.9*d,release: 0.1*d
    end
    sleep d #sleep for note/chord duration
  end
end

define :intro do |days|
  extra=0.5
  extra=0 if days==1 #amend last note durations for day 1
  notes=[:c4,:c4,:c4,:f4,:f4,:f4,:e4,:f4,:g4,:a4,:bb4,:g4,:a4]
  durations=[0.5,0.5,1,0.5,0.5,1,0.5,0.5,0.5,0.5,0.5,0.5,1.5+extra]
  notesb=[:r,[:f3,:a3],:bb3,:c4,:f3]
  durationsb=[1,4,1,1,1.5,0.5+extra]
  in_thread do
    pl notesb,durationsb
  end
  pl notes,durations
  
end

define :partridge do |days|
  extra=0
  extra=1 if days==12 #allow changed duration for last verse
  notes=[:bb4,:c5,:d5,:bb4,:a4,:f4,:g4,:f4]
  durations=[0.5,1,0.5,0.5,0.5,0.5,1,3+extra]
  notesb=[:r,:a3,:bb3,:c4,:bb3,:a3,:g3,:f3]
  durationsb=[0.5,1,1,1,1,1,1,0.5+extra]
  in_thread do
    pl notesb,durationsb #play part 2 in a thread
  end
  pl notes,durations
  
end
define :item do |days|
  if days <5
    notes=[:c5,:g4,:a4,:bb4]
    durations=[1,0.5,0.5,1]
  else
    notes=[:c5,:g4,:a4,:bb4,:g4]
    durations=[1,0.5,0.5,0.5,0.5]
  end
  notesb=[:c4]
  durationsb=[3]
  in_thread do
    pl notesb,durationsb #play part 2 in a thread
  end
  pl notes,durations
end
define :five_gold_rings do
  notes=[:c5,:d5,:b4,:c5]
  durations=[2,1,1,4]
  notesb=[[:a3,:c4],[:gs3,:b3],[:g3,:bb3]]
  durationsb=[2,2,4]
  in_thread do
    pl notesb,durationsb #play part 2 in a thread
  end
  pl notes,durations
end
define :four_three_two do
  notes=[:c5,:bb4,:a4,:g4,:f4,:bb4,:d4,:f4,:g4,:f4,:e4,:d4,:c4]
  durations=[0.5,0.5,0.5,0.5,1,1,01,1,0.5,0.5,0.5,0.5,1]
  notesb=[:f3,:d3,:bb3,:c3]
  durationsb=[2,1,3,3]
  in_thread do
    pl notesb, durationsb #play part 2 in a thread
  end
  pl notes,durations
end

#play everything
with_fx :reverb,room: 0.6,mix: 0.6 do
  days=1
  12.times do
    use_synth (ring :pulse,:chiplead,:fm,:saw).tick
    if current_synth == :fm
      use_transpose 12 #:fm defaults to an octave low, so compensate
    else
      use_transpose 0
    end
    use_transpose current_transpose+2 if days >10 #bump last 2 verses up a tone
    #next line allows different bmp setting for each verse.
    use_bpm [120,120,120,120,120,120,120,120,120,120,120,160].look
    intro days
    if days >=5
      repeat = days - 5
      repeat.times do
        item days
      end
      use_bpm 120 if days == 12 #slow five gold rings last verse
      five_gold_rings
      use_bpm 110 if days == 12 #slow remainder last verse
      four_three_two
      pl [:a4], [0.5] #extra note/duration sent as lists to pl
    elsif days > 1
      repeat = days - 1
      repeat.times do
        item days
      end
      pl [:a4], [0.5] #extra note/duration sent as lists to pl
    end
    use_bpm 100 if days == 12 #rall for last partridge
    partridge days
    days = days + 1
  end
end