Laziness is the bomb. Don't give up on it. ;-)
On Mar 2, 8:12 am, max3000 <maxime.lar...@gmail.com> wrote:
> Thanks for the pointers. I was indeed able to make it work with
> dorun. ;)
>
> Still, I'm not sure I understand what all the fuss is about regarding
> laziness. I'll take your word for it for now but I hope to grock it
> eventually.
>
> Thanks!
>
> Max
>
> On Mar 2, 12:30 am, David Nolen <dnolen.li...@gmail.com> wrote:
>
> > Remember that you can force lazy sequences if you need to as you are with
> > doseq with doall (retains head) and dorun (does not) as well.
> > You probably want
>
> > (dorun (map #(add-watch % watcher callback-fn) all-agents))
>
> > I think it's pretty clear here what's going on. Your code needs
> > side-effects. In Clojure side-effect code tends to stands out.
>
> > I sympathize with your frustration, I remember getting excited about Lisp
> > macros but spending many many long hours trying to understand how to write
> > even a simple one.
>
> > Similarly I think lazy sequences are worth the initial frustration ;)
>
> > On Mon, Mar 2, 2009 at 12:06 AM, max3000 <maxime.lar...@gmail.com> wrote:
>
> > > Hi,
>
> > > I find the laziness in clojure very hard to wrap my head around. I
> > > understand the idea and it's probably nice in theory. However, in real
> > > life it doesn't seem really useful beyond hardcore mathematical
> > > problems.
>
> > > Case in point, I just spent 2 hours debugging a piece of code (shown
> > > below) that seemed simple enough. This is the 3rd time this week that
> > > I've lost substantial time to laziness. I'm pretty pissed to tell the
> > > truth and I find myself wrapping things in doseq more and more just to
> > > be sure. I rarely use 'for' anymore, what's the point?
>
> > > Here is the code that gave me trouble:
>
> > > (map #(add-watch % watcher callback-fn) all-agents)
>
> > > This was not executing. I had to change it to the below expression:
>
> > > (doseq [agent all-labor-agents]
> > > (add-watch agent total-labor-agent callback-fn))
>
> > > This second expression seems less elegant than the map above. Why
> > > doesn't clojure realize that an add-watch really should actually loop
> > > over all-agents? Why is it that Java calls are not made in similar
> > > expressions?
>
> > > Is laziness so useful that we should waste time investigating and
> > > fixing errors like this? Sure, there could be special constructs for
> > > laziness when we really need it. However, clojure shouldn't default to
> > > it IMO. At this point, laziness is a nice concept but it feels
> > > somewhat removed from reality to tell the truth. Of course I want to
> > > iterate over my collection when I'm doing an add-watch!
>
> > > What am I missing?
>
> > > Thanks,
>
> > > Max
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Clojure" group.
To post to this group, send email to clojure@googlegroups.com
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
-~----------~----~----~----~------~----~------~--~---
