[mercury-users] Pred defns

[Bart Demoen]

Peter Schachte wrote:

>         main ::-
>                 print("Hello world\n"),
>                 #x = 42,
>                 ##x = #x + 1,
>                 print("42 + 1 ="),
>                 print(#x).
> 
> I think that is easier to write, read, understand and maintain than the
> original. This is the syntax my global variables package supports.


I guess he meant

        main ::-
                print("Hello world\n"),
                $x := 42,
                $x := $x + 1,
                print("42 + 1 ="),
                print($x).

instead. Hoorah, back to simplicity !

The next step is not to require argument threading for implementing
this; it has problems related to modules and higher-order. Of course,
use argument threading for explaining it if you really want (but
higher-order is going to make that difficult or clumsy as well)

Bart