Re: Naive DEFSYSTEM replacement

On Mon, 2025-07-28 at 09:25 -0500, Robert Goldman wrote:
> 
> On 27 Jul 2025, at 20:27, Adam Weaver wrote:
> > I still don't really get UIOP though. Sure, there are
> > inconsistencies
> > between implementations (vagaries in the standard?) but Peter
> > Seibel
> > wrote a 100-odd-line shim FAD for his textbook to paper over the
> > PATHNAME differences.
> 
> I don't mean to disparage Peter, but CL-FAD is much less ambitious,
> and really is not fit for purpose.  Consider, for example:
> (defun directory-pathname-p (pathspec)

[ snip short example which doesn't apparently work ]

> Note that this simply looks at the syntactic form of the pathname. 
> Note also that (as far as I can tell!) there is no part of the spec
> to tell us what the form of a directory pathname should be.  Peter
> has to assume that it is something that has NIL or :unspecific in its
> name and type properties.  There is no obligation for a lisp
> implementation to abide by Peter's intuitions.

Ok. I get that. But it's easy to go too far with this, if an
implementation is so fracked-up that it puts :SNOZZBERRY in not-
required PATHNAME slots, is *anything* that goes wrong really ASDF's
problem to hack around?

> Now compare this with what Fare did to make a reliable, portable
> version of probe-file that returns the absolute pathname of a file:
> +  (defun probe-file* (p &key truename)

[ snip heroically long example which *does* apparently work ]

> 
> If you want to have a portable system definition facility like ASDF,
> you simply can't do without this kind of thing.  It would be lovely
> if we could get the implementation maintainers to agree on a more
> robust portable approach to accessing the filesystem and build it
> themselves, but that is not the world we live in.

Ah, thank you. 


> To be honest, I can't imagine anyone but Fare who would have had the
> patience and determination to do all this and get it right.  

Yes it's a rare breed! I would've cracked it at the fourth
inconsistency, not worked my way through all of the major
implementations.

Thanks RG, that's brilliant. See I had no doubt that all the stuff in
ASDF was there for a **reason**, and you've just elucidated brilliantly
what that reason is. 

Much much better than faux-bravado from the peanut gallery with guesses
and insults :) Verity Stob (English tech comedy writer) had it right
when she said that "Common Lisp is famous for its use of parentheses
and condescension" :)

Thanks RG. Don't lose heart in ASDF (your comment in a sibling thread).
It is an important part of the CL ecosystem, and I for one appreciate
your and Fare's heroic efforts.

A.

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