--Set parameters--------------------------------------------------------------
rightFirst = TRUE
lineDepth = 100
nLines = 25

--Define functions------------------------------------------------------------
function digF()
    while turtle.detect() do
        turtle.dig()
        sleep(0.25)
    end
end

function digU()
    while turtle.detectUp() do
        turtle.digUp()
        sleep(0.25)
    end
end

function digD()
    while turtle.detectDown() do
        turtle.dig()
        sleep(0.25)
    end
end

--Begin run-------------------------------------------------------------------
for i in 1, nlines do
    for j in 1, lineDepth do
        digF()
        turtle.forward()
        digU()
        digD()
    end
    if rightFirst then
        turtle.turnRight()
        digF()
        turtle.forward()
        digU()
        digD()
        turtle.turnRight()
    else
        digF()
        turtle.forward()
        digU()
        digD()
        turtle.turnRight()
    end
end