>
> From
> <
http://www.complang.tuwien.ac.at/forth/gforth/Docs-html/Assertions.html>:
>
> It is a good idea to make your programs self-checking, especially if
> you make an assumption that may become invalid during maintenance (for
> example, that a certain field of a data structure is never zero).
> Gforth supports assertions for this purpose. They are used like this:
>
> assert( flag )
>
> The code between assert( and ) should compute a flag, that should be
> true if everything is alright and false otherwise. It should not change
> anything else on the stack. The overall stack effect of the assertion
> is ( -- ). E.g.
>
> assert( 1 1 + 2 = ) \ what we learn in school
> assert( dup 0<> ) \ assert that the top of stack is not zero
> assert( false ) \ this code should not be reached
>
> - anton
