Ruby 2.4 implements Enumerable#sum

It is a common use case to calculate sum of the elements of an array or values from a hash. 1 2[1, 2, 3, 4] => 10 3 4{a: 1, b: 6, c: -3} => 4 5 Copy 1 2> [1, 2, 3, 4].sum 3 #=> 10 4 5> {a: 1, b: 6, c: -3}.sum{ |k, v| v**2 } 6 #=> 46 7 8> ['foo', 'bar'].sum # concatenation of strings 9 #=> "foobar" 10 11> [[1], ['abc'], [6, 'qwe']].sum # concatenation of arrays 12 #=> [1, "abc", 6, "qwe"] 13 Copy U