ruby map and reduce

map_reduce.rb

a = [1, 2, 3, 4]

puts a.inject(:+)

puts a.inject{|sum, x|  sum + x}

b = ["1", "2"]

c = b.map { |e| e.to_i }

puts c

puts a.reduce(:+)
puts a.reduce{|sum, x| sum + x}


class Pair
	attr_reader :v1, :v2
	def initialize(v1, v2)
		@v1 = v1
		@v2 = v2
	end
end

books = []

books << Pair.new(1, 2) 
books << Pair.new(2, 3) 

puts books.map{ |e|  e.v1}.reduce(:+)