From: Chris Hecker <checker@d6.com>
To: Xavier Leroy <xavier.leroy@inria.fr>,
Francois Pottier <francois.pottier@inria.fr>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Re: generic programming
Date: Fri, 05 Jul 2002 02:57:57 -0700 [thread overview]
Message-ID: <4.3.2.7.2.20020705024112.038909f0@mail.d6.com> (raw)
In-Reply-To: <20020705112551.B16273@pauillac.inria.fr>
>Like François, I find functional iterators so much cleaner
>and better structured. Moreover, the extra "power" of imperative iterators
>isn't obvious to me.
I think this is a very important point, but I totally disagree with your
conclusion. Giving up explicit control over the flow of your program is a
serious problem in my opinion, and callback solutions force you to do
that. Iterating over two things at once is an obvious example of where it
breaks down, but it happens in a lot of places. Real closures make it less
painful to deal with this than in languages without closures, because you
can have the map/iter code right there acting locally, but closures still
don't really eliminate the problem that you aren't in control of when that
code gets called anymore.
As another example, this idiom/pattern actually shows up a lot in GUI APIs
for things like events. I think it's pretty clear at this point that
callback based event handling code leads to more lines of less readable and
harder to understand code than having the client code be able to pull
things off a queue when it's ready for the events. I'm sure some disagree
with this statement.
Both of these are examples of "push versus pull" interfaces, and pull just
seems to work better. Having data pushed at you means you often end up
buffering it on your end to manage your flow control anyway unless you're
just doing some trivial processing.
Furthermore, it seems like it's a common trap to fall into saying the
familiar "you don't want to do that" (like your comment about hashtables)
when there's a fair amount of evidence that it's reasonable thing to want
to do (and I think better in a lot of ways). It seems like it's something
a good language should support well.
I'm not saying that callback/push interfaces are always bad, just that
there are strengths and weaknesses to both. To reference the XML thread,
there's a reason there are both DOM and SAX interfaces. I wish Ocaml
supported imperative/pull coding styles better, which is why I'm interested
in this thread.
It's late...hopefully this mail made some sense.
Chris
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next prev parent reply other threads:[~2002-07-05 10:15 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-03 2:49 [Caml-list] " Oleg
2002-07-03 8:37 ` [Caml-list] " Ketanu
2002-07-03 17:29 ` Chris Hecker
2002-07-03 20:07 ` Oleg
2002-07-03 20:34 ` Alessandro Baretta
2002-07-04 15:33 ` John Max Skaller
[not found] ` <3D249B27.5080807@baretta.com>
[not found] ` <3D25D27B.2020005@ozemail.com.au>
2002-07-07 20:42 ` Alessandro Baretta
2002-07-08 0:59 ` John Max Skaller
2002-07-08 7:29 ` Alessandro Baretta
2002-10-15 0:10 ` Eray Ozkural
2002-07-03 21:55 ` Peter Wood
2002-07-04 2:02 ` james woodyatt
2002-07-04 15:18 ` John Max Skaller
2002-07-05 8:42 ` Francois Pottier
2002-07-05 9:25 ` Xavier Leroy
2002-07-05 9:57 ` Chris Hecker [this message]
2002-07-05 13:54 ` Xavier Leroy
2002-07-05 17:59 ` Chris Hecker
2002-07-05 20:31 ` John Max Skaller
2002-07-05 19:33 ` John Max Skaller
2002-07-05 19:31 ` John Max Skaller
2002-07-05 8:33 ` Francois Pottier
2002-07-05 23:05 ` Dave Berry
2002-07-08 9:54 ` Francois Pottier
2002-07-08 15:49 ` John Max Skaller
2002-08-02 14:49 ` [Caml-list] Streams Diego Olivier Fernandez Pons
2002-08-02 15:29 ` Alain Frisch
2002-08-03 14:19 ` Diego Olivier Fernandez Pons
2002-07-03 8:42 ` [Caml-list] generic programming Johan Baltié
[not found] ` <002301c22270$fb4ca160$2be213c3@youngkouzdra>
[not found] ` <20020703092753.M39371@wanadoo.fr>
2002-07-05 10:38 ` Anton Moscal
2002-07-03 9:10 ` Jun P.FURUSE
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