Display MoreWell, i was thinking that item stacks play a dual role - as themselves, and as a symbol of themselves.
Like, if there is a non-full stack (of iron ore, for example), and droid have some ore iron ore lying around, then it will add ore to this stack. if this stak is after "place block" element, then dorid will take things from this, to place down.
For example, picture above is a (slightly bugged) program for making railroad with electric tracks, that uses those commands (with sugar,paper, sticks etc as placeholders for logic elements):
Book stack: start of subroutine
Paper stack: call subroutine
Sugar stack: loop next command N times
Sign:
place block from next stack, if it's size is 2 or more. If it's size is one,
then find and use blocks of same type from other stack of size 2 or
more.
Boots: step forward
Sticks stack: vertical (1-5) and horizontal (6-13) turns, in steps of 45 degrees
Pickaxe: dig
All other stacks - if stack is not full, pick drops of same type until stack is full.
This sounds like something individuals could use to figure out how to have self learning droids in IC^2. I'm pretty sure this is programming Inception. Just look at the crazy things people have done in MC(*COUGH*IC+ anything redstone*COUGH*)