call-by is a notion of time, pass-by refers to entity that is used (location if you so will). You can create a 2-dimension table of these options and you'll be able to find some language for almost any cell in this table.
The common meaning of call-by-value is call-by-value/pass-by-reference. Both Java and Racket and a whole lot of languages use this combination. Call-by-name is also a common reference to call-by-name/pass-by-reference, see Algol 60 for an example. You can also create a calculus for any cell in this table. Google for Crank and Felleisen and POPL and you'll find something. With that I mean (1) a calculus whose basic axiom(s) capture/s the mechanics of parameter passing (2) and that satisfies Church-Rosser and has a Standardization Theorem (which defines a deterministic strategy for evaluation terms) (3) and whose ST coincides with the conventional evaluator/abstract machine This holds for call-by-name, call-by-value (common meanings), in purely functional or imperative settings, and it extends to call-by-copy and several other mechanisms. The phrase "call-by-value is a reduction strategy" has no meaning per se but is a left over from the time when people hadn't figured out the above (pre 1070). It sounds like you're taking a course on PL and got some exercises to solve. I am glad we can help, and I assume you will give credit to the mailing list. On Jul 20, 2014, at 2:44 PM, Jon Zeppieri wrote: > On Sun, Jul 20, 2014 at 5:02 AM, קוראל אלימלך <coral2...@gmail.com> wrote: >> Hey :) >> How the arguments are passed in racket? >> by value/ reference/name? >> >> If u can add an example it will b good :) >> Thank U ! >> > > I suspect two different things are being conflated here: > > 1. the reduction semantics of the language > 2. the question of whether or not data is copied at procedure-call boundaries. > > > For (1), Racket's reduction strategy is call-by-value. As Jos Koot has > demonstrated, in a procedure-call expression: > > (fn-expr argn-expr...) > > all of the sub-expressions will be reduced (that is, evaluated) to > values before the function is applied. > > For (2), Racket does not copy data at procedure-call boundaries. If > you pass a mutable struct, the callee is able to make changes to it > that are visible to the caller. This is unlike in C, where you would > need to pass a pointer to a struct in order to allow the callee to > operate on the same instance as the caller. > > Unfortunately, "call-by-X" terminology is used to refer to both things > and usually in ways that make matters far more confusing than they > need be. See, e.g., > [http://en.wikipedia.org/wiki/Evaluation_strategy], which is just > awful. > > -Jon > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
