This is a little bit of documentation/technical writing around an issue that I had for a while. SBCL is a Common Lisp implementation that I use, and would recommend as a good starting point for people interested in tinkering with Common Lisp. SLIME is an emacs-based development tool kit that lets you interact with a lisp session in real time.

SLIME works as you're writing code and makes it possible to connect to (potentially any) running lisp process and execute code and access documentation, among other functions. The connection between Emacs/Slime and the running application is provided by a connector called "Swank." Lisp is pretty cool, Common Lisp is really nifty, but SLIME is what makes working with Lisp fun/easy and really powerful.

Ok. Here's what happens. You upgrade SBCL (which happens every now and then for me with Arch Linux,) and you probably have to recompile a number of things to work with the new package. That's a bit annoying, but it's not a huge burden. Then you try and load Swank, and it bombs. You reinstall Slime but no dice, and you still can't connect to your application in slime.

This is where I lingered for about 3 months. No working Slime meant going back to interacting with my lisp applications in the conventional manner, which kind of sucked.

Here's the fix, and it's crazy simple. In emacs run "M-x slime" Restart the application or reload the swank loader, and then try and connect to the application with Slime. Bingo.

Turns out that Slime (and therefore swank) build a few .fasl files that are version specific to SBCL that hang around after the upgrade. The only way these files are rebuilt is if you load slime, which you may only do by way of swank, which won't work unless you reload slime. It's a chicken and egg issue.

Problem solved. Sorry it wasn't more interesting: most aren't terribly.