Task

Select certain elements from an Array into a new Array in a generic way.



To demonstrate, select all even numbers from an Array.

As an option, give a second solution which filters destructively,
by modifying the original Array rather than creating a new Array.




var arr = [1,2,3,4,5];
 
# Creates a new array
var new = arr.grep {|i| i %% 2};
say new.dump;     # => [2, 4]
 
# Destructive (at variable level)
arr.grep! {|i| i %% 2};
say arr.dump;    # => [2, 4]