Make array literals require preceding @ character.

examples/primes.dst

@@ -3,12 +3,12 @@
 (defn primes
  "Returns a list of prime numbers less than n."
  [n]
- (def list [])
+ (def list @[])
  (for [i 2 n]
   (var isprime? true)
   (def len (length list))
   (for [j 0 len]
    (def trial (get list j))
-   (if (zero? (% i trial)) (varset! isprime? false)))
+   (if (zero? (% i trial)) (:= isprime? false)))
   (if isprime? (array-push list i)))
  list)