[bug#28690] provide a lib output for boost

[ludo@gnu.org (Ludovic Courtès)]

Thomas Danckaert <post@thomasdanckaert.be> skribis:

>>> I don't know if it helps, or is well-known anyhow, but you can
>>> check the
>>> dependencies of any that are in Debian by looking under
>>> https://packages.debian.org/sid/<package>.
>>
>> I don’t think it helps.  I suggest looking for the direct
>> dependencies
>> of Boost in Guix, possibly using ‘guix refresh -l boost’.
>
> Doesn't that also lists indirect dependencies (575 of them)? 

Yes it does.

> After some experimentation at the REPL, I came up with the following
> to find only packages directly depending on boost:
>
> (use-modules
>  (srfi srfi-1)
>  (guix packages)
>  (gnu packages)
>  (gnu packages boost)
>  (guix scripts refresh))
>
> (define (depends-on-boost pkg)
>   (any (lambda (p) (eq? p boost))
>        (map cadr (append (package-inputs pkg)
>                          (package-propagated-inputs pkg)
>                          (package-native-inputs pkg)))))
>
> (let ((all-deps (filter depends-on-boost (fold-packages cons '()))))
>   (format (current-output-port)
>           "~{~a~^~%~}~%" (map package-name all-deps)))
>
> Leading to the 97 dependencies in the attached file.

Neat!  We should add something like this to ‘guix refresh’.

> Is that approach correct?  There are also 3 packages which have boost
> as a propagated input (mdds, gpgmepp and librevenge).  That could lead
> to further packages depending on boost, which are missing from the
> list, but for now I'll assume that such cases are rare.

The approach looks correct, yes.

> Meanwhile I'll try to build those 97 packages, stay tuned ;-)

Awesome, let us know how it goes!

Thanks,
Ludo’.