title: simple-type-error
body: <p>I've made an executable that includes calls to arrays. When I execute the program, I get the error</p>
  
  <pre><code>Condition of type: SIMPLE-TYPE-ERROR
  In function AREF, the index into the object
   #(0.00387149 3.0345068e-4 5.9720734e-4 -1.6648759e-5 0.058811672).
  takes a value 5 out of the range (INTEGER 0 4).
  </code></pre>
  
  <p>I looked up  simple-type-error, and I believe it occurs when a value is of an unexpected type. However I was of the impression that you don't have to specify types in Lisp. </p>