title: How to use AND operator in IF statements in SML
body: <p>I am new to SML.
  How do I use the AND operator inside IF statements?
  Here is my code:</p>
  
  <pre><code>val y = 1;
  val x = 2;
  if (x = 1 AND y = 2) then print ("YES ") else print("NO ");
  </code></pre>
  
  <p>My error is:
  stdIn:66.9-67.3 Error: unbound variable or constructor: AND
  stdIn:66.3-67.9 Error: operator is not a function [literal]
    operator: int
    in expression:
      1 
  stdIn:66.3-67.9 Error: operator and operand don't agree [literal]
    operator domain: bool * bool
    operand:         bool * int
    in expression:
      x = (1 ) y = 2</p>
  
  <p>Thank you</p>