Miner

function GetCoal()
    local count = 16
    repeat
        local currentSlot = turtle.getSelectedSlot()
        local data = turtle.getItemDetail(currentSlot)
        if data.name == "minecraft:coal" then
            return true
        else
            turtle.select((currentSlot%16)+1)
            count = count - 1
        end

    until(count == 0)
    print("Can't find coal")
    return false
end

function RefuelCoal()
    if turtle.getFuelLevel() == 0 then
        local result = GetCoal()
        if result then
            print("Coal Found! Refueling")
            turtle.refuel(1)
        else
            print("No Coal Found!")
        end
        return result
    else
        return true
    end
end

amount = arg[1] or 50
print("Mining for " .. amount .. " blocks")
for i=1,amount,1 do
    result = RefuelCoal()
    if result then
        turtle.dig()
        turtle.digUp()
        turtle.forward()
    else
        error("OUT OF FUEL")
    end
end