Re: comparator in match pattern

[Damien Mattei <damien.mattei@gmail.com>]

seems to works now:

scheme@(guile-user)> (match (list 1 /) ((c (? (cut equal? <> /))) 'cool))
$2 = cool

On Wed, Jun 28, 2023 at 9:47 PM Damien Mattei <damien.mattei@gmail.com> wrote:
>
> thank you, ok , i understand ,my Scheme+ redefined <> to not = , this
> was the problem, i apologize
>
> On Wed, Jun 28, 2023 at 5:27 PM Vivien Kraus <vivien@planete-kraus.eu> wrote:
> >
> > Le mercredi 28 juin 2023 à 17:10 +0200, Damien Mattei a écrit :
> > > Vivien , your solution is not working:
> > >
> > > (let ((/ 42))
> > >   (match (list 1 42)
> > >     ((c (? (cut equal? <> /)))
> > >      c)))
> > > ;;; <stdin>:30:2: warning: wrong number of arguments to `#<tree-il
> > > (lambda () (lambda-case ((() #f #f #f () ()) (call (toplevel equal?)
> > > (toplevel <>) (lexical / /-1dff1b83541ce327-407)))))>'
> > > ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> > > Wrong number of arguments to 42
> >
> > It works on my side (see screenshot). You did not quote the module
> > import line in your reply, did you forget to paste it?
> >
> > (use-modules (ice-9 match) (srfi srfi-26))
> >
> > Otherwise it is likely a problem with your guile installation, and I
> > can’t really help.
> >
> > > and / is  not a variable , it is simply a separator , the / procedure
> > > too,and it is not quoted
> >
> > I do not understand. Do you want to match against the '/ symbol or the
> > variable/procedure bound to "/"?
> >
> > If you want to match against something that is bound to "/", then the
> > cut-equal solution is relevant. If you want to match against the /
> > symbol, then you can do either one of these:
> >
> > (use-modules (ice-9 match))
> > (match (list 1 '/)
> >   (`(,c /)
> >    c))
> >
> > or
> >
> > (use-modules (ice-9 match))
> > (match (list 1 '/)
> >   ((c '/)
> >    c))
> >
> > > in Racket this works:
> > >
> > > (match (list container index1-or-keyword index2-or-keyword)
> > >
> > >           ((list c (== /) (== /)) (displayln "T[/ /]"))
> >
> > This is not a self-contained example, I don’t know what is index*-or-
> > keyword. Is it the division function or whatever is bound to / at that
> > time? The / symbol?
> >
> > Vivien