Currently, ls() returns nil, and then after the program is finished executing it finally prints out a list of files to the console. Making it's output completely inaccessible to the cart program.

Can it return an array of file name strings or something please? Maybe if you call ls(1) or ls(true) or something instead, if it's too hard to separate from user console input?

This is important for... reasons. We're totally planning something fun involving arbitrary carts.

Mm... multicarts?

If my assumption is correct and you have a list of carts to load, couldn't you just hardcode the names and bundle relevant carts with the game, like that monster game did (can't remember the name).

Well yes, I'll have to just hardcode the names for now, but this is for a special collaborative project where carts are expected to be added all willy-nilly.