title: Check whether a symbol can be safely evaluated
body: <p>I have a string <code>x</code>. I think that <code>x</code> is a string representation of a type that is a subtype of <code>Number</code>. For example, <code>x</code> might take the value <code>"Float64"</code>. I could check this using:</p>
  
  <pre><code>eval(parse(x)) &lt;: Number
  </code></pre>
  
  <p>However, it is possible that <code>x</code> contains something dangerous, like some variant on <code>"rm(something_important)"</code>, so using <code>eval</code> is a bad idea until I'm sure <code>x</code> is safe.</p>
  
  <p>Is there any way I can safely check whether <code>x</code> is a string representation of a subtype of <code>Number</code>?</p>
  
  <p>(other than building an array of strings of all possible sub-types of <code>Number</code> and comparing...)</p>