From: Leo Prikler <leo.prikler@student.tugraz.at>
To: Joshua Branson <jbranso@dismail.de>
Cc: 48974@debbugs.gnu.org
Subject: bug#48974: A possible shepherd bug (it's very minor)
Date: Fri, 25 Jun 2021 20:28:14 +0200 [thread overview]
Message-ID: <595245e54b3199173b9e47992d770caa4f807312.camel@student.tugraz.at> (raw)
In-Reply-To: <875yy1vmy7.fsf@dismail.de>
Am Freitag, den 25.06.2021, 14:06 -0400 schrieb Joshua Branson:
> Leo Prikler <leo.prikler@student.tugraz.at> writes:
>
> > Hi,
> >
> > Am Freitag, den 25.06.2021, 05:31 -0400 schrieb Joshua Branson:
> > > Leo Prikler <leo.prikler@student.tugraz.at> writes:
> > >
> > > > Hi,
> > > >
> > > > Am Samstag, den 12.06.2021, 20:09 +0000 schrieb
> > > > jbranso@dismail.de:
> > > > > June 12, 2021 3:39 PM, "Leo Prikler" <
> > > > > leo.prikler@student.tugraz.at>
> > > > > wrote:
> > > > >
> > > > > > Am Samstag, den 12.06.2021, 09:26 -0400 schrieb Joshua
> > > > > > Branson:
> > > > > >
> > > > > > > Hello!
> > > > > > >
> > > > > I'll tell you what, why don't we leave this "bug" open for a
> > > > > week...I'll try to write
> > > > > the code that does what I want, and I'll email the answer.
> > > > >
> > > > > Then I'll edit the manual to provide an example!
> > > Well, it's been about a week. Here is my current code that
> > > doesn't
> > > work.
> > > haha.
> > >
> > > #+BEGIN_SRC scheme
> > > (define %my-desktop-services
> > > (modify-services %desktop-services ;;end of remove services
> > > (mingetty-service-type config =>
> > > (mingetty-configuration
> > > (inherit config)
> > > ;; ERROR at the NEXT LINE
> > > (auto-login-to-tty-3 config)
> > > ))))
> > >
> > > (define (auto-login-to-tty-3 config)
> > > (if (string=? "3" (mingetty-configuration-tty config))
> > > '(auto-login "joshua")
> > > '(auto-login #f)))
> > > #+END_SRC
> > >
> > > It obviously doesn't work because I am treating modify-services
> > > as if
> > > it were a procedure. In fact, it is a macro. :)
> > That's not the issue here, the issue is that you're treating
> > mingetty-
> > configuration as… I'm not really sure what exactly, when it is in
> > fact
> > a record constructor.
>
> Oh!!!! Light bulb! I knew that! I've made quite a few record
> constructors for endlessh and my almost complete sway service:
>
> http://issues.guix.gnu.org/39136
> https://notabug.org/jbranso/guix-config/src/master/sway-service.scm
>
> > Try the following:
> >
> > #+BEGIN_SRC scheme
> > (define (auto-login-to-tty tty user)
> > ;; TODO: you might want to implement this as match-lambda instead
>
> I will try that!
>
> > (lambda (config)
> > (if (string=? tty (mingetty-configuration-tty mingetty-config))
> > (mingetty-configuration
> > (inherit config)
> > (auto-login user))
> > config)))
> >
> > (define %my-desktop-services
> > (modify-services %desktop-services
> >
> > (mingetty-service-type config =>
> > (auto-login-
> > to-tty "3" "joshua"))))
> > #+END_SRC
> >
>
> Hmmm. Is that (define (auto-login-to-tty tty user) ...) a
> closure? I
> wonder why you need that lambda inside of it...Probably to pass the
> config variable into the function...hmmm. I still don't understand
> why
> it is necessary. I'll think about that a bit later on.
Yes, I've made it a bit more generic, so that you could also add let's
say (auto-login-to-tty "4" "nsa-backdoor") if you wanted ;)
You need a single-argument procedure in the config => proc part. So
you generate a closure to do everything else. You could do the same
with let-bindings inside the scope of modify-services, but I found it
more useful to extract that.
> > > #+BEGIN_SRC scheme
> > > (define (auto-login-to-tty-3 mingetty-service)
> > > (if (string=? "3" (mingetty-configuration-tty config))
> > > '(mingetty-configuration
> > > (auto-login "joshua")
> > > (tty "3"))
> > > mingetty-service))
> > Don't quote mingetty-configuration et al. They're first-class
> > syntax,
> > not just weird lists.
>
> Yeah that's true. I do actually like (guix records)! I feel like
> that file should be upstreamed into guile!
Haha, yes, guixy records are a charm, but they're subject to quicker
iteration than guile's.
> > > (define (my-modify-%desktop-services-to-auto-login-on-tty-3
> > > %desktop-
> > > services)
> > > ;; to be written
> > > ;; though I think fold, or map, may be useful functions here.
> > >
> > > ;;somehow I will use this function...
> > > (auto-login-to-tty-3 mingetty-service)
> > > )
> > >
> > > (define %my-desktop-services
> > > (my-modify-%desktop-services-to-auto-login-on-tty-3
> > > %desktop-
> > > services))
> > I don't think you need to implement modify-services on your own,
> > rather
> > just use the existing thing in the "correct" way – i.e. adhering to
> > the
> > expectations given by the already existing procedure (or macro).
>
> Thanks again! The current code doesn't quite work for me yet. I'll
> try using match-lambda to define it. I'll post again when I have a
> free moment. When i get it working, I'll send a patch to the manual
> via guix-patches and CC you. Is that ok? Or would you rather that
> documentation be in the cookbook?
Did I make a mistake or does it do the job only in a somewhat inelegant
way? I'm perfectly fine with the latter as I'm not the one using the
code :P
I think the cookbook is a better destination for stuff like this.
Regards,
Leo
next prev parent reply other threads:[~2021-06-25 18:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-12 13:26 bug#48974: A possible shepherd bug (it's very minor) Joshua Branson via Bug reports for GNU Guix
2021-06-12 19:39 ` Leo Prikler
2021-06-12 20:09 ` jbranso--- via Bug reports for GNU Guix
2021-06-12 21:13 ` Leo Prikler
2021-06-25 9:31 ` Joshua Branson via Bug reports for GNU Guix
2021-06-25 9:56 ` Leo Prikler
2021-06-25 18:06 ` Joshua Branson via Bug reports for GNU Guix
2021-06-25 18:28 ` Leo Prikler [this message]
2021-07-02 22:57 ` Joshua Branson via Bug reports for GNU Guix
2021-07-03 6:41 ` Leo Prikler
2021-07-03 7:37 ` pelzflorian (Florian Pelz)
2021-07-05 23:59 ` Joshua Branson via Bug reports for GNU Guix
2021-06-12 23:34 ` jbranso--- via Bug reports for GNU Guix
2021-06-13 7:48 ` Leo Prikler
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