Wall.lua

function restock()
    local i

    i=3
    while i<=16 and turtle.getItemCount(2) < 64 do
        turtle.select(i)
        if turtle.compareTo(2) then
            turtle.transferTo(2)
        end
        i = i+1
    end
    turtle.select(2)
end

function singleStep()
    if turtle.getFuelLevel() < 10 then
        turtle.select(1)
        turtle.refuel(1)
    end
    if turtle.getItemCount(2) < 3 then
        restock()
    end
    turtle.select(2)
    turtle.placeDown()
    turtle.forward()
end

function main()
    local i, j

    turtle.up()
    for i=1,4,1 do
        for j=1,49,1 do
            singleStep()
        end
        turtle.turnRight()
    end
end
main()