title: operator is, the list
body: <p>I use this function:</p>
  
  <pre><code>f(V):-V is [1,2,3,4,5].
  </code></pre>
  
  <p>But I get an error:</p>
  
  <pre><code>ERROR: '.'/2: Type error: `[]' expected, found `[2,3,4,5]' ("x" must hold one character)
  </code></pre>
  
  <p>What needs to be fixed?</p>