On 2020-10-08 22:06 +0200, Marc Nieper-Wißkirchen wrote:
> Am Do., 8. Okt. 2020 um 21:59 Uhr schrieb Wolfgang Corcoran-Mathe
> <xxxxxx@sigwinch.xyz>:
>
> > On 2020-10-08 21:52 +0200, Marc Nieper-Wißkirchen wrote:
> > > Am Do., 8. Okt. 2020 um 21:45 Uhr schrieb Wolfgang Corcoran-Mathe
> > > <xxxxxx@sigwinch.xyz>:
> > >
> > > > Yes.  This is one reason why I'm rather sad that vector-set! can't be
> > > > linear update--there are plenty of immutable implementations of vectors
> > > > which can guarantee O(log n) access.
> > >
> > > What do you mean by linear-update here?
> > >
> > > Do you mean a non-destructive update instead?
> >
> > Yes, of course.  I meant "linear update" in the sense of SRFI 1's
> > use of the term:
> >
> > > A "linear update" procedure is allowed -- but not required -- to
> > > side-effect its arguments in order to construct its result.
>
> But Scheme's vector-set! is already linear-update in this sense, more
> precisely, the following procedure is:
>
> (define (vector-amend! vec i obj)
>   (vector-set! vec i obj)
>   vec)
>
> Or do you complain about the existence of vector-set!, which means
> that Scheme vectors cannot be truly immutable?

Yes, that's a bit limiting, in my humble opinion.  And I do tend
to use vector-amend! in my own work, since it allows procedures
written in functional style to be easily adapted to vectors.

But this is tangential.  I do appreciate the implementation
freedom that linear update semantics provide.

--
Wolfgang Corcoran-Mathe  <xxxxxx@sigwinch.xyz>

"All this currying's just a phase, though it seldom hinders."
--Fritz Ruehr