title: defrecord with optional keys
body: <p>I am a total newbie to clojure and trying to follow some tutorials basically. I have a question about <code>defrecord</code>s.</p>
  
  <p>Here is the thing that I am trying to do :</p>
  
  <pre><code>(defrecord somemap [key1 key2 key3 key4])
  
  (defn give-me-map [m1 m2]
    (somemap. m1 m2))
  </code></pre>
  
  <p>On the code above, i would like to have <code>key3</code> and <code>key4</code> as optional, so that i wont need to give values to them each time a create a <code>somemap</code> object.</p>
  
  <p>there is a similar question <a href="https://stackoverflow.com/questions/4580606/create-optional-fields-on-clojure-record">here</a>, but it does the reverse of what i am trying to do here. </p>
  
  <p>So the is it possible to define <code>defrecord</code> with optional fields? </p>