I noticed that this fails in (at least) 2.0, 2.2 and 3.0:
(use-modules (oop goops)) (define (foo . rest) 'fallback) (define-method (foo (x <string>)) <string>) e.g.: $ guile-3.0 -s test.scm Backtrace: In ice-9/boot-9.scm: 1736:10 6 (with-exception-handler _ _ #:unwind? _ # _) In unknown file: 5 (apply-smob/0 #<thunk 558f3c1bbb80>) In ice-9/boot-9.scm: 718:2 4 (call-with-prompt _ _ #<procedure default-prompt-handle?>) In ice-9/eval.scm: 619:8 3 (_ #(#(#<directory (guile-user) 558f3c28bf00>))) In ice-9/boot-9.scm: 2806:4 2 (save-module-excursion _) 4351:12 1 (_) In oop/goops.scm: 1585:2 0 (_ _ _) And then I found that the the manual says this: If symbol was previously bound to a Scheme procedure (or procedure-with-setter), the old procedure (and setter) is incorporated into the new generic function as its default procedure (and setter). So I wondered if this might be a bug, or was expected behavior. It's also easy to work around -- just change the first define to a define-method. Thanks -- Rob Browning rlb @defaultvalue.org and @debian.org GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4