Thank you! I will try that. Sorry for the delayed response. Got caught up in another project.
On Sat, Jan 4, 2014 at 9:40 AM, Gustavo Massaccesi <gust...@oma.org.ar>wrote: > There are more complex closures, that share an external variable. For > example: > ;----- > #lang racket > (define-values (up! down!) > (let () > (define counter 0) > (define (up!) (set! counter (add1 counter)) counter) > (define (down!) (set! counter (sub1 counter)) counter) > (values up! down!))) > (up!) ;==> 1 > (up!) ;==> 2 > (down!) ;==> 1 > ;----- > If you need to send “up!” and “down!” in different interactions but > they nevertheless have to modify the same counter then this problem is > very difficult. > > For some cases, I guess that you can uses something similar to the > “Stateless Servlets” > > http://docs.racket-lang.org/web-server/stateless.html#(part._considerations) > . I didn’t use it, but it can serialize and deserialize functions and > continuations. I don’t know how much transparent are the structures it > use, so I’m not sure if it’s possible to inspect them. I’m not sure > that you can deserialize the continuation in another server, but you > can deserialize it after a server reboot, so I guess it’s possible. > > (And as Neil Toronto said, you should also use sandboxing to avoid > unexpected problems.) > > Gustavo > > > On Fri, Jan 3, 2014 at 5:10 PM, Neil Toronto <neil.toro...@gmail.com> > wrote: > > What kind of inspection? > > > > If it's for security purposes, you're better off running the procedures > in a > > sandbox (see the `racket/sandbox' module). You can even control the > amount > > of time something is allowed to run. Also, `serial-lambda' might be > > something you could use, if the sender and receiver are both running the > > same program. (It might work in other circumstances; I don't know.) > > > > Neil ⊥ > > > > > > On 01/02/2014 09:41 AM, Alegria Baquero wrote: > >> > >> Thank you for your kind responses. Your solutions are good ones but > >> unfortunately don't fit my purpose. Imagine a mobile code scenario where > >> you have no control of the definition of a closure. What I want to do is > >> to be able to print the body of any incoming closure that arrives in a > >> message. So if server A sends server B a closure (lambda () (displayln > >> "hello world")), B could grab that incoming closure and capture it as > >> the string "(lambda () (displayln "hello world"))" so it can be > >> inspected before executing it. Does this make sense? How can I then > >> construct a function procedure->string that transforms at runtime > >> (without using macros) a closure's body to a string? > >> > >> Thank you again and happy new year. > >> > >> Alegria > >> > >> > >> On Tue, Dec 31, 2013 at 10:53 AM, Alexander D. Knauth > >> <alexan...@knauth.org <mailto:alexan...@knauth.org>> wrote: > >> > >> Yes, you can do it with a struct with the property prop:procedure. > >> > >> #lang racket > >> > >> (require rackunit) > >> > >> (struct my-proc (proc str) > >> #:property prop:procedure (struct-field-index proc)) > >> > >> (define f > >> (my-proc (lambda (x) (+ x 1)) > >> "(lambda (x) (+ x 1))")) > >> > >> (check-true (procedure? f)) > >> (check-equal? (f 1) 2) > >> (check-equal? (my-proc-str f) > >> "(lambda (x) (+ x 1))") > >> > >> (define-syntax-rule (my-lambda args body ...) > >> (my-proc (lambda args body ...) > >> (substring (~v '(lambda args body ...)) 1))) > >> > >> (define f2 > >> (my-lambda (x) (+ x 1))) > >> > >> (check-true (procedure? f2)) > >> (check-equal? (f2 1) 2) > >> (check-equal? (my-proc-str f2) > >> "(lambda (x) (+ x 1))") > >> > >> > >> On Dec 29, 2013, at 10:45 PM, Alegria Baquero wrote: > >> > >>> Hello, > >>> > >>> is there any way to transform a function's body to a string such > >>> as "(lambda(x)...)"? > >>> > >>> Thanks > >>> > >>> Alegria > >>> ____________________ > >>> Racket Users list: > >>> http://lists.racket-lang.org/users > >> > >> > >> > >> > >> > >> -- > >> > >> > --------------------------------------------------------------------------------------- > >> PhD candidate > >> Department of Informatics > >> Donald Bren School of Information and Computer Sciences > >> University of California, Irvine > >> > >> > >> ____________________ > >> Racket Users list: > >> http://lists.racket-lang.org/users > >> > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > -- --------------------------------------------------------------------------------------- PhD candidate Department of Informatics Donald Bren School of Information and Computer Sciences University of California, Irvine
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