bug#62448: [PATCH] doc: Note that `guix shell` should contain base language packages.

[Josselin Poiret via Bug reports for GNU Guix <bug-guix@gnu.org>]

* doc/guix.texi (Invoking guix shell): Explain that python must be included in
the invocation even if it is already available in the external environment.

Suggested-by: Skyler <skyvine@protonmail.com>
---
 doc/guix.texi | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index c49e51b72e..879a526b77 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -96,7 +96,7 @@ Copyright @copyright{} 2021 Domagoj Stolfa@*
 Copyright @copyright{} 2021 Hui Lu@*
 Copyright @copyright{} 2021 pukkamustard@*
 Copyright @copyright{} 2021 Alice Brenon@*
-Copyright @copyright{} 2021, 2022 Josselin Poiret@*
+Copyright @copyright{} 2021, 2022, 2023 Josselin Poiret@*
 Copyright @copyright{} 2021 muradm@*
 Copyright @copyright{} 2021, 2022 Andrew Tropin@*
 Copyright @copyright{} 2021 Sarah Morgensen@*
@@ -5959,6 +5959,14 @@ building or downloading any missing package, and runs the
 guix shell python python-numpy -- python3
 @end example
 
+Note that it is necessary to include the main @code{python} package in
+this command even if it is already installed into your environment. This
+is so that the shell environment knows to set @env{PYTHONPATH} and other
+related variables. The shell environment cannot check the previously
+installed environment, because then it would be non-deterministic.  This
+is true for most libraries: their corresponding language package should
+be included in the shell invocation.
+
 @quotation Note
 @cindex shebang, for @command{guix shell}
 @command{guix shell} can be also be used as a script interpreter, also

base-commit: be5e280e5fe26f93bd5a6e3f76e4502edb913a94
-- 
2.39.2