[bug#50614] [PATCH] build: utils: Add ‘list-when’ macro.

[Sarah Morgensen]

Hi,

Liliana Marie Prikler <liliana.prikler@gmail.com> writes:

> Am Freitag, den 17.09.2021, 10:26 +0200 schrieb Xinglu Chen:
>> * guix/build/utils.scm (list-when): New syntax
>> * tests/build-utils.scm ("list-when: expr1 is non-#f", list-when:
>> expr1 is #f"):
>>   Test it.
>> * guix.texi (Build Utilities): Document it.
>> ---
>> Changes since v1:
>> 
>> * Rename ‘optional’ to ‘list-when’.
>> 
>> * Make
>> 
>>     (list-when test consequent ...)
>> 
>>   equivalent to
>> 
>>     (if tests
>>         (list consequent ...)
>>         '())
> LGTM, but let's wait on more opinions.  IIRC, changing (guix build)
> causes a world rebuild, no?  So this patch might go to core-updates
> first.

Do we actually use this idiom anywhere build-side?  (If not, does it
belong in (guix utils)?  Or should we stick it in (guix build utils)
just to be safe?)

--
Sarah