Re: [Chicken-users] pdf: chicken 5 port

[felix . winkelmann]

> I got in touch with m...@gushee.net who indicated that he is no longer
> working on scheme. He was the last node in a chain of authors porting this
> code from CL -> Racket -> Chicken. He did mention that Felix had been
> working on another pdf extension that was to be merged with this one. So it
> seems like there is no maintainer but I am curious if there is another
> implementation that is preferred?

Sorry, I can't recall. I may have helped in porting or given genberal
advice, but I can not remember doing any work on a specific pdf extension.


felix


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Re: [Chicken-users] pdf: chicken 5 port

[Robert Jensen]

Hello,

I got in touch with m...@gushee.net who indicated that he is no longer
working on scheme. He was the last node in a chain of authors porting this
code from CL -> Racket -> Chicken. He did mention that Felix had been
working on another pdf extension that was to be merged with this one. So it
seems like there is no maintainer but I am curious if there is another
implementation that is preferred?

All the best,
Rob

On Tue, Jul 16, 2019 at 1:06 AM Mario Domenech Goulart 
wrote:

> Hi Rob,
>
> On Mon, 15 Jul 2019 19:20:00 -0400 Robert Jensen <
> robert.cole.jen...@gmail.com> wrote:
>
> > I ported pdf [1] to chicken 5 [2]. I set up a release-info pointing at
> > the 1.1.0 tag. I have contacted the original author to inquire about
> > future maintenance.
> >
> > [1] http://wiki.call-cc.org/eggref/4/pdf
> > [2] https://github.com/r1b/pdf
>
> Thanks.  Please let us know what the original author says, so that we
> can point the egg index to the right location.
>
> All the best.
> Mario
> --
> http://parenteses.org/mario
>
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[Chicken-users] Interaction of subprocess and condition handling

[Lassi Kortela]

How do you handle errors signaled by the 'process' procedure from the 
(chicken process) module in Chicken 5?


When I try things like

  (receive (from-child to-child child)
  (condition-case
  (process command args)
(_ ()
   (values #f #f #f)))
...)

I get weird results - I have some 'display' calls, and according to 
'current-process-id' some of them are coming from a different PID (I 
assume 'process' does fork/exec internally, so somehow some of the 
display code actually ends up running in the forked child process.


I guess normally the unix execve() call succeeds so the child process 
stops running the Chicken programs and executes the desired command. But 
when execve() fails (e.g. due to a missing executable file) then the 
child process continues running Chicken code instead of exiting?


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[Chicken-users] Scheme Coding Competition

[Amirouche Boubekki]

I am organizing a Scheme coding competition where you have
to build a static blog generator with a mystery feature (that will
be revealed little by little in the next few months).

We already have sourcehut.org as a sponsor and I am actively looking
for other sponsors to reward the participants (goodies, cloud credits,
books...).

More information after the jump:

https://git.sr.ht/~schemers/competition-2019-static-blog-generator#schemers-competition-2019

Ultimately the goal is to contribute a scheme presence at
https://www.staticgen.com/

Follow @schemers@mastodon.technology 
for more regular updates.

Good read and good luck!
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Re: [Chicken-users] wrong number of arguments to continuation when escaping?

[felix . winkelmann]

> On Thu, Jul 18, 2019 at 08:13:53AM +0200, Marco Maggi wrote:
> > Not sure if I understand.  The problem  lies in the context in which the
> > call to DOIT is performed?
> 
> Yes, exactly.
> 
> > it expects any number of values in:
> > 
> >(call-with-values
> >doit
> >  (lambda args (apply values args)))
> > 
> > so no error?
> 
> Right.  call-with-values sets up a different type of continuation,
> one that accepts an arbitrary number of values.  Standard continuations
> allow only one argument.
> 

See also R5RS and R7RS. R5RS only accepts multiple values in
a context created by call-with-values (this is currently what CHICKEN
does, modulo some places where it is easy to be more lax).

R7RS explicitly allows a mismatch in the number of values in 
the non-final position of expression sequences created by
"begin", "let", etc.


felix


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Re: [Chicken-users] wrong number of arguments to continuation when escaping?

[Peter Bex]

On Thu, Jul 18, 2019 at 08:13:53AM +0200, Marco Maggi wrote:
> Not sure if I understand.  The problem  lies in the context in which the
> call to DOIT is performed?

Yes, exactly.

> it expects any number of values in:
> 
>(call-with-values
>doit
>  (lambda args (apply values args)))
> 
> so no error?

Right.  call-with-values sets up a different type of continuation,
one that accepts an arbitrary number of values.  Standard continuations
allow only one argument.

Cheers,
Peter


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Re: [Chicken-users] wrong number of arguments to continuation when escaping?

[Marco Maggi]

Peter Bex wrote:

> On Thu, Jul 18, 2019 at 06:43:06AM +0200, Marco Maggi wrote:
>> I do not understand why some place expects 1 argument.  The problem goes
>> away if I replace:

>>(escape)

>> with:

>>(escape 1)

> Hi Marco,

> This is a known "issue", see #1390 and #1601.  Improving this so
> that such non-explicit "value" continuations accept different argument
> counts would have a big impact on performance because every single
> continuation would then need to start checking its argument count.

> It's unfortunate, but easy to fix; just use something like "receive"
> or "call-with-values" to explicitly allow the continuation to handle
> multiple values.

Not sure if I understand.  The problem  lies in the context in which the
call to DOIT is performed?  The code expects 1 value from:

   (doit)

so error; it expects one value in:

   (begin
 (doit)
 #t)

so error; it expects one value in:

   (let ()
 (doit)
 #f)

so error; it expects any number of values in:

   (call-with-values
   doit
 (lambda args (apply values args)))

so no error?
-- 
Marco Maggi

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