Changes for clojure.core/compare-and-set!

franks42 on Sat, 24 Nov 2012
user=> (def a (atom 0))
#'user/a
user=> (compare-and-set! a 10 20)
false
user=> @a
0
user=> (compare-and-set! a 0 10)
true
user=> @a
10
yasuto on Mon, 20 Jun 2011
user=> (def a (atom 0))
#'user/a
user=> (compare-and-set! a 10 20)
false
user=> (compare-and-set! a 0 10)
true
user=> @a
10