Re: Find an element in a functional set (guile-pfds)

[Zelphir Kaltstahl]

On 07.07.24 13:30, Zelphir Kaltstahl wrote:
> On 07.07.24 13:01, Maxime Devos wrote:
> > >Maybe bbtree-fold can be used, but
> >
> > that would not "early exit" as soon as it has found an item, that satisfies some
> >
> > specified predicate.
> >
> > You can use escape continuations to do an early exit:
> >
> > ;; On success, return stuff-to-return. Otherwise, return the symbol ‘no-match’.
> >
> > (let/ec escape
> >
> >   (bbtree-fold [...] [... when a match is found, use (escape 
> > stuff-to-return)] [...])
> >
> >   'no-match)
> >
> > Best regards,
> >
> > Maxime Devos.
> Ah what wonderful idea! I did not think of it! Thank you!
>
> There is one more issue though: The underlying tree implementation cannot be 
> accessed from the functions exported by the set module. I guess I could get at 
> that using some @@ magical thing?
>
> In the end it would still feel a bit like a hack to hack around the limited 
> exports of the module, but I guess I would have exported that function anyway, 
> had I to write this implementation, so I figure that would be OK.

OK thanks again for the idea with the continuation. I now have a solution in the 
repository and set-find is implemented. Neat!

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repositories: https://notabug.org/ZelphirKaltstahl