After reading the article, Discovered that instead of

  ["1","2","3"].map{|s| s.to_i}
    => [1, 2, 3] 

we can also do

  ["1","2","3"].map(&:to_i)
    => [1, 2, 3] 

This worked for me on Ruby 1.9 out of the box. And I think its an useful shortcut especially when its part of core ruby language & works WITHOUT using any external gems.