Request for a professional opinion

Hi, I am fairly new to lua and am 100% self taught so I am undoubtedly teaching myself bad habits. I have written a short script that allows a turtle to sort items placed in slot[1]. I am pretty proud of the program and it seems to be running well at the moment, but I would like a second opinion or two, especially regarding ways that I can optimize the code. And please, if I am making big errors or doing things improperly, let me know, Its the only way i'll learn!

code: pastebin.com/yM8sveX6

cant really make it more efficicent
but you can get a peripheral like the CCC or the inventory turtle making sorting much much faster