On Oct 24, 2014, at 6:11 AM, Joan Arnaldich <jarnald...@gmail.com> wrote:
> Hi there, > > I stumbled upon this thread when searching for generics. I really like > Alexander's solution, but if I understand it correctly, the my-match-lambda- > append function should read something like: > > (define my-match-lambda-append > (case-lambda > [() (case-lambda)] > [(f1 . f2) (lambda args > (with-handlers ([exn:fail:my-match-lambda:no-match:next- > clause? > (λ (e) (apply (apply my-match-lambda-append > f2) args))]) > (parameterize ([within-my-match-lambda-append? #t]) > (apply f1 args))))])) > > > Notice the dot clause and the recursive call. Otherwise it wouldn't work > with more than 2 clauses... I actually changed this later to do something sort of similar to work with more than 2 clauses (and handle keywords): https://github.com/AlexKnauth/hash-lambda/blob/master/mutable-match-lambda/mutable-match-lambda-procedure.rkt#L46 (define mutable-match-lambda-clause-append (case-lambda [() (case-lambda)] [(f) f] [(f1 f2) (keyword-lambda (kws kw-args . args) (with-handlers ([exn:fail:mutable-match-lambda:no-match:next-clause? (λ (e) (keyword-apply f2 kws kw-args args))]) (parameterize ([within-mutable-match-lambda-clause-append? #t]) (keyword-apply f1 kws kw-args args))))] [(f1 . rst) (mutable-match-lambda-clause-append f1 (apply mutable-match-lambda-clause-append rst))] )) By the way I'm thinking of rewriting the whole thing further to use something a bit more like this idea (if I can): http://www.greghendershott.com/2013/06/a-case-with-fall-through.html > > Just for completeness, I created a gist with the full code and updated tests: > https://gist.github.com/jarnaldich/056a5856d3b1ce05c312#file-my-match-lambda- > rkt > > Cheers, > > Joan > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users
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