title: What is datatype binding?
body: <p>I am going through &quot;Programming Languages&quot; in coursera.
  I am having a hard time to understand what &quot;datatype bindings&quot; are.</p>
  <p><a href="https://www.coursera.org/lecture/programming-languages/datatype-bindings-vysQv" rel="nofollow noreferrer">https://www.coursera.org/lecture/programming-languages/datatype-bindings-vysQv</a></p>
  <p>Are datatype bindings similar to type alias(in Golang)?</p>
  <p>In SML this is the example given to explain datatype bindings.</p>
  <pre><code>datatype mytype = TwoInts of int * int 
      | Str of string
      | Pizza
  </code></pre>
  <p>Here, from what I understand <code>mytype</code> is a new custom defined datatype.
  It consists of two sub-parts, one of which is <code>TwoInts</code> of type <code>int*int</code> and another part <code>Str</code> of type <code>string</code>.
  I do not understand what <code>Pizza</code> is.</p>
  <p>I tried googling about <code>datatype</code> bindings. While I could find many interesting articles on <code>databindings</code> couldn't find useful articles on <code>datatype bindings</code>.</p>
  <p>I understand Golang and Ruby pretty well. So, any explain with examples from these languages if possible would be even more helpful.</p>
  <p>Thanks</p>