Hi Julien, thank you! That does work.
So if I understand correctly, #$ doesn't only escape #~ but also unquotes
quoted lists. That's good to know! It's possible a good fraction of my
recurring troubles with gexps came from not realizing that.
On Mon, Dec 09 2024, Julien Lepiller wrote:
> Hi Yulran,
>
> I think this is related to how gexps are expanded. In your first gexp, you
> use #$accounts, which expands to ("account1" "account2"), and it's
> interpreted as a procedure call.
>
> Untested, but '#$accounts should work.
>
> It might be easier to work with a single gexp, like so:
>
> #~(job '(next-second (range 1 61 10))
> (lambda ()
> (let ((accounts …))
> …
> (system …))))
>
> Le 9 décembre 2024 13:36:45 GMT+01:00, Yulran <yul...@posteo.net> a écrit :
>>Hi guix,
>>
>>I'm having trouble with nesting g-expressions when defining a mcron job. I
>>want the job to run the same "mastodon-archive" commands for several
>>accounts, so I define a list of accounts and use 'map' to build the complete
>>command. This works well when there are only strings involved, but I can't
>>make it work with gexps.
>>
>>Here's a simplified example with only strings:
>>
>>--8<---------------cut here---------------start------------->8---
>>(define succeeding-job
>> (let* ((accounts '("account1" "account2"))
>> (cmd (apply string-append
>> (map
>> (lambda (acct)
>> (string-append
>> "mastodon-archive archive " acct "; "))
>> accounts))))
>> #~(job '(next-second (range 1 61 10))
>> (lambda ()
>> (system (string-append "echo '" #$cmd "'")))
>> "mastodon-archive")))
>>--8<---------------cut here---------------end--------------->8---
>>
>>The job succeeds and the mcron log prints as expected "mastodon-archive
>>archive account1; mastodon-archive archive account2;". Now to use the full
>>path to the mastodon-archive binary, cmd must be a gexp:
>>
>>--8<---------------cut here---------------start------------->8---
>>(define failing-job
>> (let* ((accounts '("account1" "account2"))
>> (cmd #~(apply string-append
>> (map
>> (lambda (acct)
>> (string-append
>> #$mastodon-archive "/bin/mastodon-archive archive
>> " acct "; "))
>> #$accounts))))
>> #~(job '(next-second (range 1 61 10))
>> (lambda ()
>> (system (string-append "echo '" #$cmd "'")))
>> "mastodon-archive")))
>>--8<---------------cut here---------------end--------------->8---
>>
>>The home configuration builds fine, but the mcron job fails with the error:
>>(wrong-type-arg #f Wrong type to apply: ~S (account1) (account1))
>>
>>I played around with gexp-ing the string-append in the lambda, ungexp-ing
>>acct, and trying every other combination of gexp/ungexp I could think of, but
>>I could only make it worse.
>>
>>Any idea what I'm doing wrong?
>>
