The recommended way to load ASDF is via:
All actively maintained Lisp implementations now include a copy of ASDF 3
that you can load this way using Common Lisp’s
If the implementation you are using doesn’t provide a recent ASDF 3, we recommend you upgrade it. If for some reason you would rather not upgrade it, we recommend you replace your implementation’s ASDF. See Replacing your implementation's ASDF. If all else fails, see see Loading ASDF from source below.
If you use an actively maintained implementation that fails to provide an up-to-date enough stable release of ASDF, you may also send a bug report to your Lisp vendor and complain about it — or you may fix the issue yourself if it’s free software.
As of the writing of this manual, the following implementations provide ASDF 3 this way: ABCL, Allegro CL, CLASP, Clozure CL, CMUCL, ECL, GNU CLISP, LispWorks, MKCL, SBCL. The following implementations only provide ASDF 2: MOCL, XCL. The following implementations don’t provide ASDF: Corman CL, GCL, Genera, MCL, SCL. The latter implementations are not actively maintained (except maybe GCL); if some of them are ever released again, they probably will include ASDF 3.
For maximum convenience you might want to have ASDF loaded
whenever you start your Lisp implementation,
for example by loading it from the startup script or dumping a custom core
— check your Lisp implementation’s manual for details.
SLIME notably sports a
slime-asdf contrib that makes life easier with ASDF.
NB: all implementations except GNU CLISP also accept
(require 'asdf) and
For portability’s sake, you should use