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

I just downloaded the source code for SBCL to see one example of how things are implemented in Lisp. 

And I just discovered that READ-SEQUENCE is a Generic Function that can be applied to many different kinds of streams, including ones we make up for ourselves.

But then I also just realized that READ-SEQUENCE is really trying to join two different worlds together - a stream world, and a sequence world. And what I’m asking for is really more of a sequence world thing - being able to view the contents of a sequence in more than one way. We already have that with SYS:TYPED-AREF, but we don’t have Streams operating on them directly.

Alternatively, since, in my case, I know that I’m expecting a bunch of raw single-precision floats coming at me over the socket connection, I could try to fancy up a new Stream Class to incorporate the Socket Stream, and have that new stream chunk up the data into 4 bytes at a time, and then just deposit into a float array directly. Have that new stream class perform READ-SEQUENCE in the domain of the target types.

Or have the new stream class operate against a SYS:TYPED-AREF vector.





> On Nov 8, 2025, at 06:41, David McClain (as dbm at refined-audiometrics dot com) <[email protected]> wrote:
> 
> It looks like Bindat also makes copies of data.
> 
> The ideal solution would allow data to remain in place. It does not have to allow mutable access to the data. Most often the data are read-only. We just need to examine the data and make decisions based on values, or display them in graphs.
> 
> And since we are talking about read-only access, I really don’t understand the aversion to multi-type overloading access.
> 
> 
> 
>> On Nov 8, 2025, at 03:25, Marco Antoniotti <[email protected]> wrote:
>> 
>> 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] <mailto:[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] <mailto:[email protected]>> wrote:
>>> > 
>>> > 
>>> > 
>>> >> On 7 Nov 2025, at 20:21, Tim Bradshaw <[email protected] <mailto:[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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>> 
>> 
>> 
>> --
>> Marco Antoniotti, Professor, Director         tel. +39 - 02 64 48 79 01
>> DISCo, University of Milan-Bicocca U14 2043   http://dcb.disco.unimib.it <http://dcb.disco.unimib.it/>
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>