gistfile1.rb

# inject but doesn't need you to return the memo, uses the same object. Doesn't work with immutable (i.e. summing)
module Enumerable
  def inject_into(obj)
    each {|e| yield(obj, e)}
    obj
  end
end
 
a = [1,2,3].inject_into([]) do |m, e|
  m << (e + 1)
end
 
puts a.inspect # => [2,3,4]