Coda Hales http://codahale.com/a-small-nice-thing/ in ruby

arrays_sum.rb

a = [1,2,3]
b = [4,5,6]

# ruby can be quite functional sadly we don't have a sum by default
sum = lambda { |args| args.reduce(:+) }
# with this we can do 
a.zip(b).map(&sum)

# extending does not change much
c = [7,8,9]
a.zip(b,c).map(&sum)

# Or with active support we have sum available
require "active_support/core_ext/enumerable"
a.zip(b,c).map(&:sum)