Computer Craft - Place Torches

local count = 1
local length
local width

function forward(n)
    for i=1,n do
        if turtle.detect() then
            turtle.dig()
        end
        turtle.forward()
    end
end

function turnAround()
    turtle.turnRight()
    turtle.turnRight()
end

function placeTorch()
        turtle.select(1)
        turnAround()
        turtle.place()
        turnAround()
end

function firstTorch()
    forward(1)
    placeTorch()
end

function buildRow()
    for i=1,length do
        forward(12)
        placeTorch()
    end
end

function nextRow()
    if count % 2 == 0 then -- Turn right for even numbered rows
        forward(5)
        turtle.turnRight()
        forward(8)
        placeTorch()
        turtle.turnRight()
        forward(1)
        turtle.turnRight()
        forward(1)
        turtle.turnLeft()
    else -- Turn left for odd numbered rows
        forward(5)
        turtle.turnLeft()
        forward(8)
        placeTorch()
        turtle.turnLeft()
        forward(1)
        turtle.turnLeft()
        forward(1)
        turtle.turnRight()
    end
    count = count + 1
end

function driver()
    for i = 1,width do
        buildRow()
        if i < width then -- Avoids extra row at end
            nextRow()
        end
    end
end

turtle.select(1) -- Select torches

print("How far forward? (length)")
length = tonumber(read()) / 18
print("How far left? (width)")
width = tonumber(read()) / 8

firstTorch()
driver()