A.9.3 Use of unification

Instead of using the {}/1 predicate, you can also use the standard unification mechanism to store constraints. The following code samples are equivalent:

• Unification with a variable
  

  {X =:= Y}
  {X = Y}
  X = Y

• Unification with a number
  

  {X =:= 5.0}
  {X = 5.0}
  X = 5.0