title: What is the difference between calling a hash-map against symbol versus calling a symbol against a hash-map?
body: <p>Hash map is a function in Clojure and it returns the value by the key which is provided as its first parameter. Say,</p>
  
  <pre><code>({:zero 0 :one 1} :zero)
  ;;=&gt; 0
  </code></pre>
  
  <p>But it also works other way around:</p>
  
  <pre><code>(:zero {:zero 0 :one 1})
  ;;=&gt; 0
  </code></pre>
  
  <p>What's the difference? Are there any cases when the two return different things? What is the conventional way? What is most industry recognized way (most widespread among those who create production-ready Clojure code)?</p>