[bug#45984] [PATCH 0/5] Fix recursive importers

[zimoun]

Dear,

Currently, there is 2 issues:

 1. <from>->guix-package returning #f instead of (values #f '())
 2. error incorrectly handled by guix/scripts/import/<from>

This corner case #1 happens when the package does not exist; then the function
'lookup-node' is not able to "unpack" the 'values' and throw and ugly
backtrace, as exposed in bug#44114 <http://issues.guix.gnu.org/44115#3>.

With these trivial patches, it is fixed for all the importers except 'opam'
(because of 'and-let' which needs some care).

Now, instead of throwing an ugly backtrace, it simply say almost nothing:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix import cran do-not-exist -r
error: failed to retrieve package information from 
"https://cran.r-project.org/web/packages/do-not-exist/DESCRIPTION": 404 ("Not 
Found")

$ ./pre-inst-env guix import pypi do-not-exist -r
following redirection to `https://pypi.org/pypi/do-not-exist/json/'...
#f
--8<---------------cut here---------------end--------------->8---

This non-existent message is because the error is poorly handled.  With the 4
patches, the situation is the same as "guix import gem" for all the importers
with the recursive option.  One way for a better error handling is done in the
last commit for 'guix import gem' only; the same trick can be done for all.

--8<---------------cut here---------------start------------->8---
$ guix import gem do-not-exist -r
#f

$ ./pre-inst-env guix import gem do-not-exist -r
guix import: error: failed to download meta-data for package 'do-not-exist'
--8<---------------cut here---------------end--------------->8---

In my opinions, UI messages should not appear in guix/import/*.scm but only in
guix/scripts/*.scm.


If I understand correctly, then the way the errors are reported could be
uniformized between all the importers, and maybe the snippet in the subcommands
"guix import <from>" could be refactorized a bit.

WDYT?


All the best,
simon

zimoun (5):
  import: pypi: Return 'values'.
  import: hackage: Return 'values'.
  import: elpa: Return 'values'.
  import: cran: Return 'values'.
  scripts: import: gem: Fix recursive error handling.

 guix/import/cran.scm        |  5 ++---
 guix/import/elpa.scm        |  7 ++-----
 guix/import/hackage.scm     | 16 ++++++++++------
 guix/import/pypi.scm        | 10 +++++-----
 guix/scripts/import/gem.scm | 27 +++++++++++++++------------
 5 files changed, 34 insertions(+), 31 deletions(-)


base-commit: 2d9c6542c804eb2ef3d8934e1e3ab8b24e9bbafb
prerequisite-patch-id: 6ce76af47a26307f4b99162b5ae2b47f5e5f220f
prerequisite-patch-id: 32b0ac51a8fbe72cc9204c5a6d0e2b987af7b7f6
prerequisite-patch-id: 3fa663069818b59ab4d324cc69fabcd62c5a9b50
-- 
2.29.2