title: remove all variables except functions
body: <p>I have loaded in a R console different type of objects.
  I can remove them all using</p>
  
  <pre><code>rm(list=ls())
  </code></pre>
  
  <p>or remove only the functions (but not the variables) using</p>
  
  <pre><code>rm(list=lsf.str())
  </code></pre>
  
  <p>My question is:
  is there a way to remove all variables except the functions</p>