"{(x, random.randrange(100)) for x in ["x", "y", "z"]}" FWIW, it's possible to do it as a one liner in Ruby 1.9 without tap: Hash[[:x, :y, :z].map { |l| [l,

"{(x, random.randrange(100)) for x in ["x", "y", "z"]}" FWIW, it's possible to do it as a one liner in Ruby 1.9 without tap: Hash[[:x, :y, :z].map { |l| [l, rand(100)]}] There may be other ways to do it (like inject, as mentioned in the post). That said, tap is probably more confusing and not necessarily shorter than: result = {} [:x, :y, :z].map { |l| result[l] = rand(100)} result