title: What does "let () = " mean in Ocaml?
body: <p>There are codes like </p>
  
  <pre><code>let () = print_string "something" in
  fn
  </code></pre>
  
  <p>in some OCaml codes.</p>
  
  <p>What does this mean? Is there special meaning on "()"? or Is it same meaning as</p>
  
  <pre><code>print_string "something";
  fn
  </code></pre>