I feel stupid too! I like the trick of using list* to match _ on any number of trailing elements. The grammar given in the docs doesn't seem to include it; I'm curious by what rule is it "allowed" as a pattern?
On Wednesday, December 4, 2019 at 5:02:48 PM UTC-6, Sorawee Porncharoenwase wrote: > > This is super cool indeed. Now I feel stupid. > > On Wed, Dec 4, 2019 at 2:56 PM Matthew Butterick <[email protected] > <javascript:>> wrote: > >> >> On Dec 4, 2019, at 2:39 PM, 'Joel Dueck' via Racket Users < >> [email protected] <javascript:>> wrote: >> >> So it seems easy to match "*at least *N identical elements". >> But is there a method for matching "*no more than *N identical elements"? >> >> >> ? >> >> >> #lang racket >> (require rackunit) >> >> (define (super-cool? lst) >> (match lst >> [(and (list* _ ... a a _) >> (not (list* _ ... a a a _))) #t] >> [_ #f])) >> >> (check-true (super-cool? '(1 1 4))) >> (check-false (super-cool? '(1 1 1 4))) >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/racket-users/1734093C-0C39-4289-9747-41CAFB35851F%40mbtype.com >> >> <https://groups.google.com/d/msgid/racket-users/1734093C-0C39-4289-9747-41CAFB35851F%40mbtype.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/bde135bd-a69a-4c8d-8093-dbea6c9c93b9%40googlegroups.com.
