{ write out all primes in [2..100], using 
  inefficient algorithm from lecture 1. }
(block
  (:= n 2)
  (while (<= n 100)
    (block 
      (:= p 1)  { flag indicating primeness: initialize to true }
      (:= d 2) 
      (while (<= d (- n 1))
        (block            {we have no mod operator...}
          (:= m (* d (/ n d)))  
          (if (<= n m)  { always have m <= n }
              (:= p 0)  { i.e., n = m, so d divides n, so set p false }
              (block))  { (block) is a no-op}
          (:= d (+ d 1))))
      (if p (write n) (block))
      (:= n (+ n 1)))))