Re: I wonder if I'm missing something...

Hi everybody...

interesting (and still unresolved after decades: we are getting old) issue.

I have recently wor... ahem, wasted an inordinate amount of time on Emacs
Lisp.

I had to deal with similar issues and eventually used the bindat library,
which I found interesting w.r.t. its interface.

Any thoughts about it?

All the best

Marco


On Sat, Nov 8, 2025 at 10:19 AM Tim Bradshaw (as tfb at tfeb dot org) <
[email protected]> wrote:

> I think your approach is equivalent to mine except:
>
> - the transducers are explicitly symbols rather than opaque objects which
> the implementation gets to define (and there are potentially hundreds of
> distinct ones)
>
> - 'it should also support custom data types' turns it from a small soluble
> problem to a huge one with no general solution at all.
>
> On and the displaced array thing: (a) ick, just no, (b) this already
> solves David's problem (just make the displaced array be an array of
> (unsigned-byte 8)s and write-sequence does what you want.
>
> If you want C I hear that C compilers are quite commonly available now.
>
> --tim
>
> > On 7 Nov 2025, at 20:01, Yuri Davidovsky <[email protected]> wrote:
> >
> >
> >
> >> On 7 Nov 2025, at 20:21, Tim Bradshaw <[email protected]> wrote:
> >>
> >> Here is a sketch (which I may have mentioned here previously) of how
> functionality could be added to CL which would enable fast I/O of, for
> instance, vectors of floats without destroying the language by allowing
> arbitrary type punning, and also dealing with things like ensuring things
> are written in defined byte orders.
> >
> > Interesting. I was thinking of something different. Essentially any byte
> stream could be read (and written to) arbitrary data types using primitives
> like:
> >
> > (read-byte stream) — as is now.
> > (read-byte stream :uint32) — will read an unsigned 32 bit int.
> > (read-byte stream :float) — you start to get the idea.
> >
> > You could do the same with read-sequence by supplying the type of data
> to read and an array of appropriate type. It should also support custom
> data types.
> >
> > Also when creating a displaced array it should allow casting to a
> different type.
>
>
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