 <p>This is very slow &amp; incorrect way to create string from seq of characters. The main problem, that changes aren't propagated - ref creates new reference to existing string, but after it exits from function, reference is destroyed. </p> <p>The correct way to do this is:</p> <pre><code>(apply str seq) </code></pre> <p>for example, </p> <pre><code> user=&gt; (apply str [\1 \2 \3 \4]) "1234" </code></pre> <p>If you want to make it more effective, then you can use Java's StringBuilder to collect all data in string. (Strings in Java are also immutable)</p>