gistfile1.txt

# Write a MathService module that has a method that can sum an Array of Numbers
# It should raise an exception if not given an Array.
# It should raise an exception if any elements are not Numeric.

module MathService
  def sum array_of_numbers
    raise unless array_of_numbers.is_a? Array
    sum = array_of_numbers.inject(0) do |s,n|
      raise unless n.is_a? Numeric
      s += n
      s
    end
    return sum
  end
  extend self
end

######################################################################

begin
  puts MathService.sum([1, 2, 3]) # => 6
end