<HTML><BODY> I've ported little collection for making CLOS-like generics <a href="https://github.com/Kalimehtar/gls" data-mce-href="https://github.com/Kalimehtar/gls">https://github.com/Kalimehtar/gls</a> It gives you possibility to make generics over any predicates or racket/class classes: Example (impossible in swindle): (define (fact x) (defgeneric fact0 (method ((n (and? <integer> (<=/c 1))) (acc <integer>)) acc) (method ((n <integer>) (acc <integer>)) (fact0 (- n 1) (* acc n)))) (fact0 x 1)) You may add methods dynamically: (defgeneric g) (add-method g (method ((x frame%)) (do-something-with-frame x ...))) (add-method g (method ((x button%)) (do-something-with-button x ...))) More examples in <a href="https://github.com/Kalimehtar/gls/blob/master/gls/test.rkt" data-mce-href="https://github.com/Kalimehtar/gls/blob/master/gls/test.rkt">https://github.com/Kalimehtar/gls/blob/master/gls/test.rkt</a> P. S. Can't add it to pkg.racket-lang.org. Press "login" then "Log in", but no email. :-( -- Roman Klochkov</BODY></HTML>