Editing Vienna Development Method (section)

===The ''max'' function===
This is an example of an implicit function definition. The function returns the largest element from a set of positive integers:
<syntaxhighlight lang="rsl">
 max(s:set of nat)r:nat
 pre card s > 0
 post r in set s and
      forall r' in set s & r' <= r
</syntaxhighlight>
The postcondition characterizes the result rather than defining an algorithm for obtaining it. The precondition is needed because no function could return an r in set s when the set is empty.