cellfarm.lua

local rs = peripheral.find("redstoneIntegrator")
if not rs then error("No redstone integrator") end
local dandelifeon = "south"
local destructor = "north"
local constructor = "up"
local lever = "west"
local cancelKey = keys.c

local function pulse(direction, duration)
    if not duration then duration = 1 end
    rs.setOutput(direction, true)
    sleep(duration)
    rs.setOutput(direction, false)
end

local function initOutput(direction)
    rs.setOutput(direction, false)
end

initOutput(dandelifeon)
initOutput(destructor)
initOutput(constructor)

local function main()
    print("Cellular Block Farm")
    while true do
        if rs.getInput(lever) then
            sleep(1)
        else
            pulse(destructor)
            pulse(constructor)
            pulse(dandelifeon, 2)
        end
    end
end

local function canceller()
    print("Program is running now, press", keys.getName(cancelKey), "to cancel")
    while true do
        local event, key = os.pullEvent("key")
        if key == cancelKey then
            print("Okay, goodbye...")
            return
        end
    end
end

parallel.waitForAny(main, canceller)