DigWall v1.0

local StoneSlot = 1

function refuel()
    local slot = StoneSlot + 1
    while ( turtle.getFuelLevel() < 100 and slot < 15 ) do
        slot = slot + 1
        turtle.select(slot)
        turtle.refuel(10)
    end
    turtle.select(1)
end

function tryForward()
    refuel()
    if (turtle.getFuelLevel() < 100 ) then
        print "Ran out of fuel!"
        os.exit()
    end
    return turtle.forward()
end

function tryUp()
    refuel()
    if (turtle.getFuelLevel() < 100 ) then
        print "Ran out of fuel!"
        os.exit()
    end
    while ( not turtle.up() ) do
        turtle.digUp()
        os.sleep(1)
    end
end

function checkSpace()
    if ( turtle.getItemCount(15) > 0 ) then
        print "Ran out of space!"
        os.exit()
    end
end

function checkSquare()
    turtle.select(StoneSlot)
    if ( turtle.compare() ) then return end
    while ( turtle.detect() ) do
        turtle.dig()
    end
    checkSpace()
end

function digWall()
    local hitEnd = false;

    repeat
        checkSquare()
        turtle.turnRight()
        if ( tryForward()  ) then
            turtle.turnLeft()
        else
            hitEnd = true;
        end
    until ( hitEnd )
end

while ( turtle.detect() ) do
    for wall=1,4 do
        digWall()
    end
    tryUp()
end