Task

 verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old.
 check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes compute abs(bloop).


Extra credit

 Report the number of integer variables in global scope, and their sum.


 
; check Java version
(let [version (Double/parseDouble (re-find #"\d*\.\d*" (System/getProperty "java.version")))]
  (if (>= version 1.5)
    (println "Version ok") 
    (throw (Error. "Bad version"))))
 
; check Clojure version
(let [version (Double/parseDouble (re-find #"\d*\.\d*" (clojure-version)))]
  (if (>= version 1.0)
    (println "Version ok") 
    (throw (Error. "Bad version"))))
 