For source-code-only modules with *nix env. as example

1) Default is using newest awailable module (last installed one).

Storage subsystem:

/usr/lib/perl6/compiler-version/modules/Foo/Bar.pm.0.98.auth_name
/usr/lib/perl6/compiler-version/modules/Foo/Bar.pm.0.98.another_name
/usr/lib/perl6/compiler-version/modules/Foo/Bar/MOP.pm.0.98.auth_name
/usr/lib/perl6/compiler-version/modules/Foo/Bar/MOP.pm.0.99.auth_name

Links to newest modules (or copy of newest modules), updated by package manager, in:

/usr/lib/perl6/compiler-version/lib/Foo/Bar.pm  # ver. 0.98, auth which was last instaled
/usr/lib/perl6/compiler-version/lib/Foo/Bar/MOP.pm # ver. 0.99

So 'use Foo::Bar;' looks in '/usr/lib/perl6/compiler-version/lib' for newest modules.
Means MOP v.0.99 is used by default.

Then 'use Foo::Bar::MOP:ver.a.bc' must be used to get required version. This overrides if newer version
was loaded.

Loader subsystem:

If things must be complicated then middle-ware app can be used for manage set of modules and used as:

perl6 -I manifest.mft  App.pl

or

use Loader::Versions('my_set');


Modules sets can be modified/edited. Sets can be a way to 'deploy' modules into production environment.



Precompilation:

Resolving right module is done by searching for right Code::Source.pm6 and then cache can be checked.

Middle-ware can also define 'sets' of modules, precompile them, allow to switch to other set, etc.


'Auth' influence not fully used here. 'Auth' means source probably. Can be resolved in middle-ware sets.



Any modifications hereby are allowed.