title: Is 'none' one of basic types in Lua?
body: <p>The basic types defined in Lua as below :</p>
  
  <pre><code>/*
  ** basic types
  */
  #define LUA_TNONE       (-1)
  #define LUA_TNIL        0
  #define LUA_TBOOLEAN        1
  #define LUA_TLIGHTUSERDATA  2
  #define LUA_TNUMBER     3
  #define LUA_TSTRING     4
  #define LUA_TTABLE      5
  #define LUA_TFUNCTION       6
  #define LUA_TUSERDATA       7
  #define LUA_TTHREAD     8
  #define LUA_NUMTAGS     9
  </code></pre>
  
  <p>As Lua Document says that there only <code>8</code> basic types in Lua. However, there gets <code>10</code>. I know <code>LUA_TLIGHTUSERDATA</code> and <code>LUA_TUSERDATA</code> could finnally represented as <code>userdata</code>, but what about <code>LUA_TNONE</code>? And what is the differences of <code>none</code> and <code>nil</code>?</p>