[bug#28960] [PATCH] services: Add murmur.

[Ludovic Courtès]

Hi nee,

nee <address@hidden> skribis:

>>> +(define murmur-shepherd-service
>>> …
>> Use the accessors instead.
>>
> Right, that grew way too big. I removed most of the match blocks.
> I like having the short names when it comes to stitching together the
> actual config though, so I kept that one.
> If that's still a no-go I'll make another update with accessors.
>
> If the main problem here is the positional binding, is there a function
> to match record fields by name that I could use instead?

Unfortunately no.

> It doesn't seem like it would be too complicated to write a macro for
> this with the record-accessor procedure from srfi-9.

Indeed.  I figured something like this works:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> (define-syntax match-record
                       (syntax-rules ()
                         ((_ record type (field fields ...) body ...)
                          (if (eq? (struct-vtable record) type)
                              (let ((field ((record-accessor type 'field) 
record)))
                                (match-record record type (fields ...) body 
...))
                              (throw 'wrong-type-arg record)))
                         ((_ record type () body ...)
                          (begin body ...))))
scheme@(guile-user)> (match-record coreutils (@@ (guix packages) <package>) 
(home-page) home-page)
$6 = "https://www.gnu.org/software/coreutils/";
scheme@(guile-user)> (match-record coreutils (@@ (guix packages) <package>) 
(home-page synopsis) (list synopsis home-page))
$7 = ("Core GNU utilities (file, text, shell)" 
"https://www.gnu.org/software/coreutils/";)
--8<---------------cut here---------------end--------------->8---

We could use that for now.

Eventually though, we should have something better in (guix records)
that (1) computes indices and report wrong-field-name errors at
expansion time, and (2) accounts for thunked/delayed fields.

WDYT?

If the above macro is good enough, we can add it to (guix records) with
a TODO comment.  That would already be better than the other options.

> I also noticed a missing equal sign after rememberchannel in the
> defaultconfig and added that.

I noticed a couple of obvious mistakes:

diff --git a/gnu/services/telephony.scm b/gnu/services/telephony.scm
index 0c30b409f..a305a1be8 100644
--- a/gnu/services/telephony.scm
+++ b/gnu/services/telephony.scm
@@ -240,7 +240,7 @@ Or set public-registration to #f")))))))))
 (define (murmur-activation config)
   #~(begin
       (use-modules (guix build utils))
-      (let ((log-dir (dirname #$(murmur-configuration-log-file config)))
+      (let* ((log-dir (dirname #$(murmur-configuration-log-file config)))
              (pid-dir (dirname #$(murmur-configuration-pid-file config)))
              (db-dir (dirname #$(murmur-configuration-database-file config)))
              (user (getpwnam #$(murmur-configuration-user config)))
@@ -283,7 +283,7 @@ Or set public-registration to #f")))))))))
          (documentation "Run the murmur mumble-server.")
          (requirement '(networking))
          (start #~(make-forkexec-constructor
-                   '(#$(file-append (murmur-configuration-package)
+                   '(#$(file-append (murmur-configuration-package config)
                                     "/bin/murmurd")
                      "-ini"
                      #$(or (murmur-configuration-file config)

This makes me think that it would be good to have a unit test.  Would
you like to try writing one now (see the examples in gnu/tests/*.scm),
or do you prefer to leave it for later?

In the latter case, please test the system to make sure it actually
works (that can be done in a VM.)

Thank you!

Ludo’.