Call/cc captures all required variables needed for its continuation, but it does not capture their states. How about a variable bound to a box that have been captured in a continuation? Alter the content of the box and call the continuation. It sees the very same box with the new content. Calling a continuation does not undo side effects. Jos
> -----Original Message----- > From: users-boun...@racket-lang.org > [mailto:users-boun...@racket-lang.org] On Behalf Of Keiko Nakata > Sent: 02 August 2010 16:10 > To: matth...@ccs.neu.edu > Cc: users@racket-lang.org > Subject: Re: [racket] begin vs + > > I may think how call/cc should deal with delay's > (call-by-need) is a moot point (theory vs implementation). > > Keiko > > From: Matthias Felleisen <matth...@ccs.neu.edu> > Subject: Re: [racket] begin vs + > Date: Mon, 2 Aug 2010 10:00:39 -0400 > > > > > call/cc captures the environment when it creates a > procedural representation of the continuation, just like > lambda. The two are doing more or less the same thing with > two differences: > > > > (1) lambda uses an explicit expression to create a procedure while > > call/cc uses an implicit expression (the current evaluation > context); > > > > (2) lambda create a mathematical abstraction if the > expression avoids effects and call/cc introduces an effect > into its procedure (abort). > > > > Note, a functional continuation creator (say F but NOT > shift) avoids the second difference. > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
