bug#15602: Compiling several files in the same session [2.0.9]

[Andy Wingo <wingo@pobox.com>]

Hi,

On Sun 13 Oct 2013 15:51, ludo@gnu.org (Ludovic Courtès) writes:

> $ guile --no-auto-compile -L . -c '(use-modules (system base compile)) (for-each compile-file (list "one.scm" "two.scm" "three.scm"))'
>
> $ guile --no-auto-compile -L . -c '(use-modules (system base compile)) (for-each compile-file (list "three.scm" "two.scm" "one.scm"))'
>
> $ guile --no-auto-compile -L . -c '(use-modules (system base compile)) (for-each compile-file (list "one.scm" "three.scm" "two.scm"))'
> Backtrace:

I understand this is now fixed in Guix.  You can of course do this
for-each compile-file thing, but if modules use each other you need to
topologically sort in order to make the run-time bindings visible.  Or,
as Taylan notes, just load after compiling.

> I think the right thing would be to use a separate module hierarchy in
> the dynamic extent of ‘compile-file’, somehow, such that all module side
> effects are isolated.

I don't think this is going to happen, for what that's worth :/

> Of course the above can be worked around by running ‘compile-file’ in a
> child process, but forking alone is more expensive than ‘compile-file’,
> so that’s not really a solution when there are many files.

It's the N^2 expansion that's the problem, not the forking.  If you have
N files which depend on each other, then compiling each one will require
the expansion of approximately all N files, so N*N costs in number of
files.  Or N log N if you have a tree ordering of your files.  Anyway
it's badness.

Glad to know that Taylan has fixed this one in Guix.  However I'm not
sure that there's more to do on Guile's side though.  Closing; please
re-open or file a new bug if you think there is something Guile should
do.

Andy