(0..9).to_a.inject(0.0,:+) #=> 45.0 (0..9).to_a.inject(:+) #=> 45

[['2014/12/24', 'eve'], ['2014/12/25', 'dooooon!!']].each{|date, label| p "#{date} -> #{label}"} # "2014/12/24 -> eve" # "2014/12/25 -> dooooon!!" さらに、each_with_object等を使うとき... [['2014/12/24', 'eve'], ['2014/12/25', 'dooooon!!']]…