[bug#51319] [PATCH 0/2] Better interoperability between guix and Julia built-in package manager

[Jean-Baptiste Volatier]

With this patch, when a user install a package using Julia package manager,
the package manager finds packages that were already installed in the guix
profile and use them.

First patch of the serie does the implementation, the second patch is an 
example using
sundials_jll package.

Sundials_jll is a julia package that wraps the sundials library, it is 
typically not
installed on its own but as a dependency of DifferentialEquations.jl for 
example.

As DifferentialEquations.jl is not currently packaged in julia, a fallback is to
install it with julia package manager. Unfortunately that will also install
sundials_jll and downloads some .so that will fail to load on Guix because of
linker incompatilibities.

Now with the proposed patch, the user can install sundials_jll using guix,
and then julia package manager will use this package instead of downloading some
binary files.

As for the patch itself, it works by following more closely the directory
structure that Julia expects in JULIA_DEPOT_PATH. Namely the packages
subfolder should not contain packages but packages/XXXX/ where XXXX is
a string encoding package uuid and sha1 of package files.

$JULIA_DEPOT_PATH/packages was also used as JULIA_LOAD_PATH, this will not
work anymore as packages are behind a layer of XXXX sub directories.
So instead I added a new subfolder $JULIA_DEPOT_PATH/loadpath where the package
is installed and $JULIA_DEPOT_PATH/packages/XXXX is a symlink to it.

Jean-Baptiste Volatier (2):
  build-system/julia: Enable Julia Pkg to find installed packages
  gnu: Add julia-sundials-jull

 gnu/packages/julia-jll.scm        | 38 +++++++++++++++++++++++++
 gnu/packages/julia-xyz.scm        |  2 +-
 gnu/packages/julia.scm            |  2 +-
 gnu/packages/maths.scm            | 24 ++++++++++++++++
 guix/build/julia-build-system.scm | 46 ++++++++++++++++++++++++++++---
 5 files changed, 106 insertions(+), 6 deletions(-)

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2.33.1