Some lisp implementation can be run on different architectures. If users keep the same home on different computers this will lead to collision in ~/.slime/fasl/* directories. To generate the directory name for fasl files, I use the following function, adding the machine type: (defun first-word (text) (let ((pos (position (character " ") text))) (if pos (subseq text 0 pos) text))) (defun implementation-id () (format nil "~A-~A-~A" (first-word (lisp-implementation-type)) (first-word (lisp-implementation-version)) (first-word (machine-type))));;implementation-id -- __Pascal Bourguignon__ http://www.informatimago.com/ Voting Democrat or Republican is like choosing a cabin in the Titanic.