Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

Find the sum of all the even-valued terms in the sequence which do not exceed four million.

+-;fibo
(defn fibo []
  (map first 
    (iterate 
      (fn [[a b]]
        [b (+ a b)])
      [0 1]
    )
  )
)

(defn p2 []
  (println
    (apply + (filter even? (take-while #(< % 4000001) (fibo))))
  )
)

p2()->
	p2(0,1,0).
p2(A,_,Sum) when A >= 4000000 ->
	io:format("~w~n",[Sum]);
p2(A,B,Sum)->
	if
		A band 1 ==0 ->
			p2(B,A+B,Sum+A);
		true ->
			p2(B,A+B,Sum)
	end.

+-#Enumerable
module Enumerable
  def sum
    self.inject{|u,v|u+v}
  end
  def product
    self.inject{|u,v|u*v}
  end
  def count(ob)
    self.select{|i|i==ob}.length
  end
  def take_while
    return [] unless yield(self.first)
    if(self.class==Range)
      evalPoint=self.first
      evalPoint=evalPoint.succ while yield(evalPoint.succ) and not evalPoint==self.last
      return self.first..evalPoint
    else
      s=self.to_a
      upTo=1
      upTo+=1 while yield(s[upTo]) and upTo<self.length
      return self[0...upTo]
    end
  end
end

def p2
  fib=[0,1]
  fib.push(fib[-1]+fib[-2]) while fib[-1]<4000000
  puts fib[0...-1].select{|i|i%2==0}.sum
end

def p2 {
  var fibo=List(1,0)
  while(fibo.head<=4000000)fibo=(fibo.head+fibo.tail.head)::fibo
  println(fibo.tail.filter(_%2==0).foldLeft(0)(_+_))
}