[sago]

After RTFM, I can answer my own question:

> In Arc, data structures can be used wherever functions are, and they behave as functions from indices to whatever's stored there.

(quoted from the Arc tutorial)

So

   arc> (l 0)
   1

and so on. So the GP makes sense.

[dmead]

that's confusing as hell. there's a reason this didn't take off (Besides the competition from clojure)

[etatoby]

I don't like the Arc language because it's dynamically typed and thus inherently unsafe (see other threads for this sort of discussion.)

But I like this particular feature. If you think about it, an array is a mathematical function, or map, from indices to values. So it makes sense to be able to apply it to indices to get the respective values.

[DavidSJ]

In that sense, map just composes its two arguments.

[JadeNB]

That's cool! I'm a mathematician and so inclined to (over-)abstract programming, but it had never occurred to me to think of it that way.

[sova]

Learn you a lisp for great justice

[quadcore]

It's kinda cool to be able to write (myarray i).