makes the turtle dig a cube

dig_cube.lua

turn_right = true 

function dig_forward()
  turtle.dig()
  turtle.forward()
end

function dig_down()
  turtle.digDown()
  turtle.down()
end

function next_row_and_dig()
  if turn_right then 
    turtle.turnRight()
    turtle.dig()
    turtle.forward()
    turtle.turnRight()

    turn_right = false
  else 
    turtle.turnLeft()
    turtle.dig()
    turtle.forward()    
    turtle.turnLeft()

    turn_right = true
  end
end

function dig_row(length)
  local times_dug = 0

  repeat

  dig_forward()
	times_dug = times_dug + 1
  until times_dug == length
end

function turn_around()
  turtle.turnLeft()
  turtle.turnLeft()
end

function down_level()
  dig_down()
  turn_around()
end

function up_level()
	turtle.up()
	turn_around()
end

function dig_rectangle(length, width)
  local rows_dug = 0

  repeat
    dig_row(length)
    rows_dug = rows_dug + 1

    if rows_dug < width then 
      next_row_and_dig()
    end    
  until rows_dug == width
end

function dig_cube(length, width, height)
  local levels_dug = 0

  repeat
    dig_rectangle(length, width)
    levels_dug = levels_dug + 1

    if levels_dug < height then 
      down_level()
    end
  until levels_dug == height
end

function fill_forward()
  turtle.placeDown()
  turtle.forward()
end

function fill_row(length)
  local times_dug = 0

  repeat

    fill_forward()
	times_dug = times_dug + 1
  until times_dug == length
end

function next_row_and_fill()
  if turn_right then 
    turtle.turnRight()
    turtle.placeDown()
    turtle.forward()
    turtle.turnRight()

    turn_right = false
  else 
    turtle.turnLeft()
    turtle.placeDown()
    turtle.forward()    
    turtle.turnLeft()

    turn_right = true
  end
end


function fill_rectangle(length, width)
  local rows_dug = 0

  repeat
    fill_row(length)
    rows_dug = rows_dug + 1

    if rows_dug < width then 
      next_row_and_fill()
    end    
  until rows_dug == width
end

function fill_cube(length, width, height)
  local levels_dug = 0

  repeat
    fill_rectangle(length, width)
    levels_dug = levels_dug + 1

    if levels_dug < height then 
      up_level()
    end
  until levels_dug == height
end


function build_rect_wall(length, width, height)
    local levels_built = 0

    repeat	
		fill_row(length)
		turtle.turnRight()
		fill_row(width)
		turtle.turnRight()
		fill_row(length)
		turtle.turnRight()
		fill_row(width)
		turtle.placeDown() -- we run into the wall we just built
		turtle.up()
		turtle.forward()
		turtle.turnRight()
		levels_built = levels_built + 1
	until levels_built == height
end


function strafe_left()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
end

function strafe_right()
  turtle.turnRight()
  turtle.forward()
  turtle.turnLeft()
end



build_rect_wall(5,5,5)