-- at (indexer) function, for lists and strings

-- out of values (hey, this isn't the Circus of Values!)
at([], _) -> -1.
at("", _) -> -1.

-- we've hit our target item
at(x::_, 0) -> x.

-- we've got more to go, keep iterating
at(x::xs, i) -> at(xs, i-1).

-- test
print(at([1, 2, 3, 4], 2)).
print(at("hi there", 1)).