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.


: bloopAbs
| bl m | 
   System.VERSION println
 
   Word find("bloop") ->bl
   bl isA(Constant) ifFalse: [ "bloop constant does not exist" println return ]
 
   "abs" asMethod ->m
   m ifNull: [ "abs method does not exist" println return ]
 
   System.Out "bloop value is : " << bl value << cr
   System.Out "bloop abs   is : " << bl value m perform << cr ;