[racket-users] Racket v6.5
Racket version 6.5 is now available from http://racket-lang.org/ - Typed Racket and the `racket/contract` library generate code with lower overhead, speeding up typed/untyped interaction in a number of gradual typing programs we studied. - Macros written using `syntax-parse` automatically emit more accurate error messages. - The contract profiler captures costs from more contract combinators, including all those in the main distribution. - Hash table and set iteration, via both existing and new non-generic sequences, is more performant, up to twice as fast on microbenchmarks. - The Racket optimizer detects many more optimization opportunities, including when variables always hold numbers. - The `db` library supports single-result CALL statements in MySQL. - The `net/dns` library supports SRV records. - The `racket/unix-socket` library supports listen and accept operations. The following people contributed to this release: Adrien Tateno, Alex Knauth, Alexander Shopov, Alexis King, Andrew Kent, Asumu Takikawa, Ben Greenman, Chen Xiao, Chris Jester-Young, Daniel Feltey, Eric Dobson, Georges Dupéron, Gustavo Massaccesi, Ian Harris, Jay McCarthy, Jens Axel Søgaard, John Clements, Leandro Facchinetti, Lehi Toskin, Leif Andersen, Łukasz Dąbek, Marc Kaufmann, Matthew Flatt, Matthias Felleisen, Michael McConville, Mike Sperber, Paul Stansifer, Philippe Meunier, Robby Findler, Rodrigo Setti, Ryan Culpepper, Sam Caldwell, Sam Tobin-Hochstadt, Sorawee Porncharoenwase, Spencer Florence, Stephen Chang, Tony Garnock-Jones, Vincent St-Amour, WarGrey Gyoudmon Ju, and William J. Bowman. Feedback Welcome -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] the right way to use `syntax-local-introduce`?
On Apr 27, 2016, at 12:30 PM, Alex Knauth wrote: > > Well, it's not even that. This doesn't work: > (let () > (define-sli-foo) > (let () > (invoke-sli-foo))) Based on that, here's simpler example of why I find `syntax-local-introduce` confounding. It seems to break the #1 rule of hygienic macros — that macro-introduced identifiers retain their bindings from the macro-definition site — merely by proximity. Consider the examples below. The `invoke-foo` macro introduces `foo`, which, by the #1 rule, ought to refer to the `foo` function defined nearby. Example A: `invoke-foo` relies on the hygienic `foo` reference. As we would expect. Example B: But when `define-sli-foo` is used next to `invoke-foo`, `define-sli-foo` somehow manages to rebind the `foo` identifier inside `invoke-foo`. Example C: As Alex points out, when `invoke-foo` is moved into a sub-`let`, hygiene is restored (even though we'd ordinarily expect `define` bindings to carry through). Makes me nostalgic for the good old days of `datum->syntax` ... ;; #lang racket (define (foo) 'hygienic-func) (define-syntax-rule (invoke-foo) (foo)) (define-syntax (define-sli-foo stx) (syntax-case stx () [(_) (with-syntax ([sli-foo (syntax-local-introduce #'foo)]) #`(begin (define (sli-foo) 'sli-func)))])) (module* test #f (require rackunit) ;; example A (check-equal? (invoke-foo) 'hygienic-func) ; yes of course ;; example B (check-equal? (let () (define-sli-foo) (invoke-foo)) 'sli-func) ; um, why? ;; example C (check-equal? (let () (define-sli-foo) (let () (invoke-foo))) 'hygienic-func)) ; gaah why?!?!?!? -- 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
