Re: Recursion, Yo

On 18.04.2024 00:12, Lawrence D'Oliveiro wrote:

On Wed, 17 Apr 2024 18:09:06 +0100, Ben Bacarisse wrote:
 

Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>

On Mon, 15 Apr 2024 17:50:45 +0100, Ben Bacarisse wrote:
>

Algol 68 has no denotation for the empty value.

>
Section 8.1.5.1 of the Revised Report:
>
    void denotation : empty symbol.

>
Thanks.  If I had ever known that, I had forgotten.  It's almost never
used because values are coerced to void all the contexts where it might
be otherwise required.  I'm pretty sure I've never written it.

 
I also did a quick test in a68g that “BEGIN EMPTY END” is a valid program
(at least compiles without errors). But the last time I posted such a
thing, someone claimed that a68g was not necessarily a fully conforming
Algol 68 implementation ...

I don't see why it shouldn't be valid program; I mean you can write
programs like "BEGIN END", "BEGIN EMPTY END", "BEGIN SKIP END",
"BEGIN NIL END", "BEGIN 3.14 END", or, "BEGIN 42 END".
I wouldn't expect that these do anything; only in the latter cases
I'd at least see a point in returning that value to the environment
(which isn't done, though, with the Genie compiler).

Janis