I've a function that binds a list of lists to to variable 'world', and a function that prints out this world.
(def makeworld (x)
(let z nil
(repeat x (= z (cons nil z)))
(repeat x (= z (map [cons nil _] z)))
(= world z)))
(def show ()
(each x world
(each y x
(pr (if (is y nil) #\. y) #\space))
(pr #\linefeed)))
The world can then be seeded with trees, or shrubs or monsters or whatever. Anyway, as the world is a list of lists, it functions as a two-dimensional array.
If in arc I want to access a point in this two-dimensional list / array, I need to enter ((world 0) 3), and the basic question was how to change arc (macrowise) to make (world 0 3) be equivalent to ((world 0) 3). I already worked around it by now.
To answer your question: you're assuming that there is a list called 'list', and in my initial example I described a function that took the name of the list as first argument.
The problem with multiple values being subsequent accesses is it would also interfere with a useful syntax (not actually in Arc, but I mean insofar as deciding which it should mean), and that's subsequence indexing. It's been discussed all over the place, e.g. http://arclanguage.org/item?id=449
With the assumption that one of them takes that syntax, what should be used for the other? How about (seq '(0 3 ...)) or (seq (0 3 ...))? It would similarly be fitting for any number of arguments, be they dimensions or indices, though I would vouch to use the list for n-dimensional indexing as the case of subsequences seems more common. Plus the use of a list distinguishes the one type of access from the other without having to go (...((seq 0) 3) ...).
Not that any of this helps your problem. Just something I noticed.
Oh, I get it. No, this is not something you can do with macrology because there is no room for a macro in your desired syntax (where you just want the list itself and the index values). As you say, if you'll make room for another token it can just be a function (which would be fun to generalize to N dimensions). As for making ((list (list 42)) 0 0) return 42, I think you need to is suggest it as a (very reasonable) enhancement to Arc.
