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Re: Continuations

At 3:21 AM +0000 8/11/03, Paul Graham wrote:
>--Dan Sugalski wrote:
>>  At 2:09 PM -0700 8/9/03, Serguei Mourachov wrote:
>>  >But now I have another question about continuations: how useful 
>>they are for
>>  >*masses* of developers?
>>  >Does typical programmer need to know about and use continuations?
>>  >What kind of advantages continuations bring into development process?
>>  No, and none, respectively. They allow for some really powerful
>>  techniques, and they make some relatively bizarre things easier (like
>>  implementing interpreters, compilers, and dynamic syntax extension)
>>  but for most of the stuff you'll do with computers they're not
>  > particularly useful.
>I argued this in my dissertation, but now I think I was wrong.
>They're extremely useful for overcoming the statelessness of
>CGI scripts.

You have no idea how much I'd love a good way to overcome the 
statelessness of CGI (or, since you've written your share of CGI 
code, perhaps you do :) but I'm not sure that it's the right way in 
many circumstances, and not for the availability reasons most folks 
have posited. (This is the web--either it's not a big deal if you 
lose state or you restore from the data you've backed to the DB 
because you know that this sort of thing is inherently unstable) Most 
CGI apps would be better served with a mixed save-game/continuation 
sort of deal rather than a true continuation.

I'm also not certain that going with a pure continuation in a CGI 
context is the right thing to do, since it either makes the system 
more complex (as you need to freeze the data to disk for proper 
regeneration) or lead even more programmers down the path of bad CGI 
in the face of system failure...

--------------------------------------"it's like this"-------------------
Dan Sugalski                          even samurai
dan@sidhe.org                         have teddy bears and even
                                       teddy bears get drunk