%w(foo bar baz).map(&:to_sym) can be written with %i from Ruby2.0 %i(foo bar baz) http://doc.ruby-lang.org/ja/2.0.0/doc/spec=2fliteral.html %i!STRING! : 要素がシンボルの配列(空白区切り) %I!STRING! : 要素がシンボルの配列(空白区切り)。式展開…