I haven't asked any questions here for a long time, so hope it's OK to cross-post here:
https://racket.discourse.group/ (which I just discovered.) Cheers, Tim On Monday, December 12, 2022 at 10:28:22 PM UTC+1 [email protected] wrote: > hi, I'm trying to do something slightly harder than what the attached > example tries to do, but this example suffices to show that I, evidently, > am missing something about how for/fold and/or #:break work together. > > (I have used both before, but have gotten out of practice with racket of > late and am stuck longer on this than seems reasonable.) > > I expect both tests to pass, but both fail (the "j" for jewel in "xxjxx") > is seen but not "found", as it were. > > I'd be grateful for a bug fix and/or explanation. > > Cheers, > > Tim Hanson > > -------- > > #lang racket > > (require rackunit) > > (define (port->char-stream aport) > (printf "(port->char-stream aport)~n") > (define (process-next-ch-iter) > (let ([ch (read-char aport)]) > (printf "p->cs ch: ~a~n" ch) > (if (eof-object? ch) > empty-stream > (stream-cons > ch > (process-next-ch-iter))))) > > (process-next-ch-iter)) > > > (let ([my-port > (open-input-string "xxjxx")]) > > (let ([ch-stream (port->char-stream my-port)]) > (let-values ([(pos-found? pos) > (for/fold ([j-found? #f] > [pos 0]) > (#:break j-found? > ;#:final j-found? > [ch ch-stream] > [ch-idx (in-naturals 1)]) > (begin > (printf "ch: ~a~n" ch) > (printf "ch-idx: ~a~n" ch-idx) > (printf "(eq? ch #\\j): ~a~n" (eq? ch #\j)) > (values > (eq? ch #\j) > ch-idx)))]) > > (check-equal? pos-found? #t) > > (check-equal? pos 3) > > (close-input-port my-port)))) > > > -- 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/beaa2ef6-afd2-4686-829a-390eb69f5620n%40googlegroups.com. Beyond the Racket Users Google Group, Racket Discussions take place on Discourse ( https://racket.discourse.group/ ) and Discord ( https://discord.gg/6Zq8sH5 ). Discussion (but less active) also takes place on the Racket Slack https://racket.slack.com/ ( sign up at https://racket-slack.herokuapp.com/ ), and IRC #racket https://kiwiirc.com/nextclient/irc.libera.chat/#racket --- 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/1489252c-4a85-4250-81a0-ef73e270a6bfn%40googlegroups.com.
