title: clojure for loop, store the values in a set or map
body: <p>This one has been bothering me for a while now,
  How should we store a value in a set or map in a for loop?</p>
  
  <pre><code>(let [s #{}]
       (for [ i (range 10)
              j (range 10) ]
        (into s [i j])))
  </code></pre>
  
  <p>i know this will not work, but i want a functionality similar to this , where the set will finally contain [0 0] [0 1]...[0 9] [1 0]...[9 9]</p>
  
  <p>Thanks</p>