title: How do I find out if a variable is a letter in Scheme?
body: <p>Simple question, simple answer for someone who actually uses scheme. How can I find out if a variable is a letter of the alphabet?</p>
  
  <p>I assumed it was something like this (letter? x) where x is some indefinate type. Can anyone tell me what boolean function could be used?</p>
  
  <p>edit:</p>
  
  <p>How could I make something that looks like this: (somFunction-isALetter? a)
  Return: #t</p>
  
  <p>Where a is not a variable.</p>