Editing Sather (section)

== Hello World ==
<syntaxhighlight lang="eiffel" line>
 class HELLO_WORLD is
  main is 
   #OUT+"Hello World\n"; 
  end; 
 end;
</syntaxhighlight>
A few remarks:
* Class names are ALL CAPS; this is not only a convention but it's enforced by the compiler.
* The method called <code>main</code> is the entry point for execution. It may belong to any class, but if this is different from <code>MAIN</code>, it must be specified as a compiler option.
* <code>#</code> is the constructor symbol: It calls the <code>create</code> method of the class whose name follows the operator. In this example, it's used for instantiating the <code>OUT</code> class, which is the class for the [[Standard streams#Standard_output_(stdout)|standard output]].
* The <code>+</code> operator has been overloaded by the class to append the string passed as argument to the stream.
* Operators such as <code>+</code> are [[syntactic sugar]] for conventionally named method calls: <code>a + b</code> stands for <code>a.plus(b)</code>. The usual arithmetic precedence conventions are used to resolve the calling order of methods in complex formulae.