Tunneling

-- mining program

local currentPosition = vector.new(gps.locate(5))
local startPos = vector.new(gps.locate(5))

function getPosition()
    currentPosition = vector.new(gps.locate(5))
end

function digAround()
    for i = 0, 3, 1 do
        turtle.dig()
        turtle.turnRight()
    end
end

function moveUp()
    while currentPosition.y < startPos.y do
        turtle.up()
        getPosition()
    end
end

function firstRun()
    print("Going down!")

    while currentPosition.y > 13 do
        print("Current Y position: " .. currentPosition.y)
        turtle.digDown()
        turtle.down()
        print("Getting new position...")
        getPosition()
    end
end

function secondRun()
    while currentPosition.y > 3 do
        print("Digging...")
        digAround()
        turtle.digDown()
        if not turtle.down() then
            break
        end
        getPosition()
    end
end

firstRun()
print("We are at Y 13!")
print("Initiating lower-dig protocol...")
secondRun()
print("Going back up!")
moveUp()