# from Programming Ruby, Dave Thomas

def fib_up_to(max)    
  i,j = 1,1
  while i < max
    yield i                  # passes i to the block
    i, j = j, i+j
  end
end
fib_up_to(ARGV[0].to_i){     # {}, block only appears next
   |t| print t, " "}         # to method

puts
p [1,3,5,7,9].find{
         |v| v*v >30}        # find uses iterator

class Array
  def find
    for i in 0...size
      value = self[i]
      return value if yield(value)
    end
    return nil
  end
end 
p [1,3,5,7,9].find{
         |v| v*v >30}    
 
p [1,3,5,7].inject(0){       # s=0, the updates with sum
            |s,e| s+e}       # e runs through the array
p [1,3,5,7].inject(5){
            |s,e| s+e}
                             # See Generator for 
                             # external iterator