On Thu, Jun 6, 2019 at 12:00 PM David Storrs <david.sto...@gmail.com> wrote:
> My understanding is that Racket is call by value, not call by reference. > My application will often be passing around large-ish byte strings; will > they be copied every time I pass them, or will the interpreter use > copy-on-write? > "call-by-value" is used in two very different ways. Racket is call-by-value in the sense that all arguments to functions need to be evaluated before the function body is evaluated. This kind of "call-by-value" is distinguished from other evaluation strategies, like call-by-name or call-by-need. The other sense of the term -- and the one you're asking about -- has to do with whether arguments are copied from caller to callee. I find the terms "call-by-value" and "call-by-reference" in this context to be pretty confusing. (If the function argument in question is a mutable byte-string, why wouldn't passing it "by-value" imply that you pass the very same mutable byte-string, rather than making a copy of it?) At any rate, Racket does not copy arguments on function calls (except insofar as the copy is indistinguishable from the original -- as with a fixnum, for example). -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAKfDxxx8TxKvuASFRgNd8A205LvdEFzggG-BN7o8ocRN5pk%2BvQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
