title: OCaml "to" keyword?
body: <p>I was writing some OCaml code, and noticed my syntax highlighting treated <code>to</code> in a special way. So I fired up my OCaml repl (<a href="https://github.com/ocaml-community/utop" rel="nofollow noreferrer">utop</a>) and tried to instantiate a variable with the name <code>to</code>.</p>
  
  <pre><code>let to = 1;;
  </code></pre>
  
  <p>and I get a SyntaxError with the <code>to</code> underlined. I also tried to see if it was an operator,</p>
  
  <pre><code>(to);;
  </code></pre>
  
  <p>but that also raised a SyntaxError. <strong>I'm wondering: what is the <code>to</code> keyword, and is there a full list of OCaml keywords?</strong></p>