First attempt at porting https://gist.github.com/schollz/e2cc49425d54336b422e144e7eeb34cc to crow. WARNING: this may lock up your Crow / Just Friends! Needs work still!

melodies_crow.lua

-- melody generator

-- based on https://gist.github.com/schollz/e2cc49425d54336b422e144e7eeb34cc

function init()
  ii.jf.mode(1)
  local chords={"I","vi","IV","iii"} -- change to any chords
  local move_left=6 -- change to 0-12
  local move_right=6 -- change to 0-12
  local stay_on_chord=0.95 -- change to 0-1
  play(chords,1,move_left,move_right,stay_on_chord)
end

function clamp(v, min, max)
  if v < min then return min
  elseif v > max then return max
  else return v end
end

function play(chord_structure,factor,move_left,move_right,stay_scale)
  stay_scale=clamp(stay_scale,0,1)
  local notes_to_play={}
  local chords={}
  for i,v in ipairs(chord_structure) do
    local scale=generate_scale(12,1,8) -- select scale here
    local chord_notes=generate_chord_roman(12,1,v)
    local notes_in_chord={}
    for _,u in ipairs(chord_notes) do
      notes_in_chord[u]=true
      for j=1,8 do
        notes_in_chord[u+(12*j)]=true
      end
    end
    local note_start=4
    print(note_start) -- this works, it prints 4!
    for jj=1,4*factor do
      local notes_to_choose={}
      for _,note in ipairs(scale) do
        if note > note_start - move_left and note < note_start + move_right then
          table.insert(notes_to_choose,note)
        end
      end
      local weights={}
      local scale_size=#notes_to_choose
      for i,note in ipairs(notes_to_choose) do
        weights[i]=notes_in_chord[note]~=nil and scale_size or scale_size*(1-stay_scale)
      end
      local note_next=choose_with_weights(notes_to_choose,weights)
      table.insert(notes_to_play,note_next)
      note_start=note_next
    end
  end

  local notei=0
  local note_last=0
  clock.run(function()
    while true do
      clock.sync(1/factor)
      notei=(notei)%#notes_to_play+1
      local note_next=notes_to_play[notei]
      if note_next~=note_last then
        print(note_next)
        ii.jf.play_note(note_next/12, 2)
      end
      note_last=note_next
    end
  end)
end

function choose_with_weights(choices,weights)
  local totalWeight=0
  for _,weight in pairs(weights) do
    totalWeight=totalWeight+weight
  end

  local rand=math.random()*totalWeight
  local choice=nil
  for i,weight in pairs(weights) do
    if rand<weight then
      choice=choices[i]
      break
    else
      rand=rand-weight
    end
  end
  return choice
end

-- adapted from norns/musicutil.lua:

SCALES = {
{name = "Dorian", intervals = {0, 2, 3, 5, 7, 9, 10, 12}, chords = {{14, 15, 17, 18, 19, 20, 21, 22, 23}, {14, 15, 17, 19}, {1, 2, 3, 4, 5}, {1, 2, 4, 8, 9, 10, 11, 14, 15}, {14, 15, 17, 19, 21, 22}, {24, 26}, {1, 2, 3, 4, 5, 6, 7, 14}, {14, 15, 17, 18, 19, 20, 21, 22, 23}}}
}
CHORDS = {
{name = "Maj", intervals = {0, 4, 7}},
{name = "Maj6", intervals = {0, 4, 7, 9}},
{name = "Maj7", intervals = {0, 4, 7, 11}},
{name = "Maj69", intervals = {0, 4, 7, 9, 14}},
{name = "Maj9", intervals = {0, 4, 7, 11, 14}},
{name = "Maj11", intervals = {0, 4, 7, 11, 14, 17}},
{name = "Maj13", intervals = {0, 4, 7, 11, 14, 17, 21}},
{name = "Dom7", intervals = {0, 4, 7, 10}},
{name = "Ninth", intervals = {0, 4, 7, 10, 14}},
{name = "Eleventh", intervals = {0, 4, 7, 10, 14, 17}},
{name = "Thirteenth", intervals = {0, 4, 7, 10, 14, 17, 21}},
{name = "Aug", intervals = {0, 4, 8}},
{name = "Aug7", intervals = {0, 4, 8, 10}},
{name = "Sus4", intervals = {0, 5, 7}},
{name = "SeventhSus4", intervals = {0, 5, 7, 10}},
{name = "MinMaj7", intervals = {0, 3, 7, 11}},
{name = "Min", intervals = {0, 3, 7}},
{name = "Min6", intervals = {0, 3, 7, 9}},
{name = "Min7", intervals = {0, 3, 7, 10}},
{name = "Min69", intervals = {0, 3, 7, 9, 14}},
{name = "Min9", intervals = {0, 3, 7, 10, 14}},
{name = "Min11", intervals = {0, 3, 7, 10, 14, 17}},
{name = "Min13", intervals = {0, 3, 7, 10, 14, 17, 21}},
{name = "Dim", intervals = {0, 3, 6}},
{name = "Dim7", intervals = {0, 3, 6, 9}},
{name = "HalfDim7", intervals = {0, 3, 6, 10}}
}

function generate_scale(root_num, scale_type, octaves)
  local scale_data = lookup_data(SCALES, scale_type)
  local length = octaves * #scale_data.intervals -- (math.floor(octaves) - 1) -- TODO round?
  return generate_scale_array(root_num, scale_data, length)
end

function generate_scale_array(root_num, scale_data, length)
  local out_array = {}
  local scale_len = #scale_data.intervals
  local note_num
  local i = 0
  while #out_array < length do
    if i > 0 and i % scale_len == 0 then
      root_num = root_num + scale_data.intervals[scale_len]
    else
      note_num = root_num + scale_data.intervals[i % scale_len + 1]
      if note_num > 127 then break
      else table.insert(out_array, note_num) end
    end
    i = i + 1
  end
  return out_array
end

function generate_chord_roman(root_num, scale_type, rct)
  local scale_data = lookup_data(SCALES, scale_type)
  local degree_string, augdim_string, added_string, bass_string, inv_string =
    string.match(rct, "([ivxIVX]+)([+*]?)([0-9]*)-?([0-9]?)([bcdefg]?)")
  local d = string.lower(degree_string)
  local major = degree_string ~= d
  local augmented = augdim_string == "+"
  local diminished = augdim_string == "*"
  local seventh = added_string == "7"
  local chord_type = nil
  if major then
    if augmented then
      if seventh then
        chord_type = "Aug7"
      else
        chord_type = "Aug"
      end
    elseif diminished then
      if seventh then
        chord_type = "Dim7"
      else
        chord_type = "Dim"
      end
    elseif added_string == "6" then
      if bass_string == "9" then
        chord_type = "Maj69"
      else
        chord_type = "Maj6"
      end
    elseif seventh then
      chord_type = "Maj7"
    elseif added_string == "9" then
      chord_type = "Maj9"
    elseif added_string == "11" then
      chord_type = "Maj11"
    elseif added_string == "13" then
      chord_type = "Maj13"
    else
      chord_type = "Maj"
    end
  else
    if augmented then
      if seventh then
        chord_type = "Aug7"
      else
        chord_type = "Aug"
      end
    elseif diminished then
      if seventh then
        chord_type = "Dim7"
      else
        chord_type = "Dim"
      end
    elseif added_string == "6" then
      if bass_string == "9" then
        chord_type = "Min69"
      else
        chord_type = "Min6"
      end
    elseif seventh then
      chord_type = "Min7"
    elseif added_string == "9" then
      chord_type = "Min9"
    elseif added_string == "11" then
      chord_type = "Min11"
    elseif added_string == "13" then
      chord_type = "Min13"
    else
      chord_type = "Min"
    end
  end
  local degree = nil
  for i,v in pairs({"i","ii","iii","iv","v","vi","vii"}) do
    if(v == d) then
      degree = i
      break
    end
  end
  local inv = string.lower(inv_string)
  local inversion = 0
  for i,v in pairs({"b","c","d","e","f","g"}) do
    if(v == inv) then
      inversion = i
      break
    end
  end
  local degree_note = root_num + scale_data.intervals[degree]
  return generate_chord(degree_note, chord_type, inversion)
end

function generate_chord(root_num, chord_type, inversion)
  if type(root_num) ~= "number" or root_num < 0 or root_num > 127 then return nil end
  local chord_data = lookup_data(CHORDS, chord_type)
  local out_array = {}
  for i = 1, #chord_data.intervals do
    local note_num = root_num + chord_data.intervals[i]
    if note_num > 127 then break end
    table.insert(out_array, note_num)
  end
  for i = 1, clamp(inversion, 0, #out_array - 1) do
    local head = table.remove(out_array, 1)
    table.insert(out_array, head + 12)
  end
  return out_array
end

function lookup_data(lookup_table, search)
  if type(search) == "string" then
    for i = 1, #lookup_table do
      if lookup_table[i].name == search then
        search = i
        break
      end
    end
  end
  return lookup_table[search]
end