title: Do Racket streams memoize their elements?
body: <p>Does Racket use memoization when computing large amounts of numbers from an infinite stream? So, for example, if I printed out (aka, computed and displayed) the first 400 numbers on the infinite stream of integers:
  (1 2 3 ... 399 400)
  And right after I asked to print the first 500 numbers on this infinite stream. Would this second set of computations use memoization? So the first 400 numbers would not be computed again?</p>
  
  <p>Or does this functionality need to be coded by the user/obtained from libraries?</p>