[PATCH RFC 0/4] Getting rid of input labels?

[Ludovic Courtès]

Hello Guix!

Here’s a proposal for a soft revolution: getting rid of input labels
in package definitions.  Instead of writing:

    (native-inputs
     `(("autoconf" ,autoconf)
       ("automake" ,automake)
       ("pkg-config" ,pkg-config)
       ("guile" ,guile-3.0)))
    
one can write:

    (native-inputs (list autoconf automake pkg-config guile-3.0))

With this patch set, this is just syntactic sugar: ‘package-inputs’
and friends still return a list of tuples.  (These patches are
against ‘core-updates’ but that works equally well on ‘master’,
without a world rebuild.)

My understanding of the code is that this change adds no overhead
for packages written in the old style, and negligible overhead for
packages written in the new style (calling ‘package-name’
instead of referring to a literal string for the label.)  I haven’t
tried to measure it though as it would require a massive conversion
to the new style to be really measurable.

I don’t think I need to expound on the benefits.  :-)

There are issues and open questions:

  • This hides labels, but they’re still visible as soon as one
    fiddles with ‘package-inputs’ & co.  So this lowers the barrier
    to entry, but the difficulty of dealing with input tuples
    does not disappear entirely.

  • Both styles would be supported for a long time so contributors
    would still have to know about input tuples anyway.

  • There are packages that use custom labels as some sort of an
    abstraction.  For instance, the “kernel-headers” label is
    associated either with ‘linux-libre-headers’ or with
    ‘hurd-headers’.  In this case, the simplified style would
    use the package name as the label, which isn’t appropriate,
    or at least would require adjustments in packages that
    rely on this.

  • There are packages with same-named but different inputs,
    and they rely on having a different input label.

  • Some packages rely on labels that differ from the package
    name (this is what the ‘guix lint -c input-labels’ patch
    detects).  For instance, commencement.scm has things like:

      `(("guile" ,%bootstrap-guile))

    Automatic labeling would convert it to:

      `(("guile-bootstrap" ,%bootstrap-guile))

    Not necessarily a problem: we can keep the old style for these.
    Common Lisp packages typically lack the “cl-” prefix in
    input labels but most likely they don’t actually refer to
    those labels, so we should be fine.

  • Packages such as ‘tzdata’ use labels to refer to non-package
    inputs.  These cannot be converted to the automatic labeling
    style, or not without extra changes.

  • Currently, something like:

      (inputs (list glib))

    is converted to:

      (inputs `(("glib" ,glib)))

    Should it, instead, be converted to:

     (inputs `(("glib" ,glib)
               ("glib:bin" ,glib "bin")))

    ?  This would make the concise style strictly less
    expressive, but maybe good enough?

Ludovic Courtès (4):
  records: Support field sanitizers.
  DRAFT packages: Allow inputs to be plain package lists.
  DRAFT gnu: Change inputs of core packages to plain lists.
  DRAFT lint: Add 'input-labels' checker.

 gnu/packages/base.scm  | 30 +++++++--------
 gnu/packages/guile.scm | 87 ++++++++++--------------------------------
 gnu/packages/mes.scm   | 23 ++++-------
 guix/lint.scm          | 35 +++++++++++++++++
 guix/packages.scm      | 35 +++++++++++++++--
 guix/records.scm       | 65 ++++++++++++++++++++++++-------
 tests/records.scm      | 38 ++++++++++++++++++
 7 files changed, 198 insertions(+), 115 deletions(-)

-- 
2.31.1