title: How to implement a functional language
body: <p>I'm trying to learn the differences between imperative and functional languages.<br>
  And also, I want to learn about closures and how garbage collectors are implemented.  So I decided to try to implement an interpreter for a functional language.</p>
  
  <p>Since I'm not familiar with functional languages, it's too difficult for me to design one.  Are there some resources about the syntax and semantics of a simple functional language?  A tutorial on how to do this would be very helpful.</p>