title: Common Lisp HyperSpec: unbound symbol handling in conforming implementations
body: <p>This is a pretty technical question about conforming implementations of the ANSI Lisp spec:</p>
  
  <p>In <a href="http://www.lispworks.com/documentation/HyperSpec/Body/02_cd.htm" rel="nofollow noreferrer">Section 2.3.4</a>, it says that a token read as a symbol that's not available in the current package is interred as a new symbol in the current package.</p>
  
  <p>In <a href="http://www.lispworks.com/documentation/HyperSpec/Body/03_aba.htm" rel="nofollow noreferrer">Section 3.1.2.1</a>, it says that if a symbol isn't bound, an error is given.</p>
  
  <p>What happens to unbound symbols between iterations of the REPL? 
  Will a conforming implementation remove unbound symbols from the current package, or will it keep interning symbols until the REPL occupies all available memory?</p>