rb~
I believe that local variables are nulled after their last usage to prevent
exactly this behavior. In fact, you can find code like:
Object dummy(Object o, Object dummy) { return o; }
call_stuff(dummy(var, var = null));
In the Clojure source to accomplish this.
Matt
On Wed, Oct 27, 2010 at 4:12 PM, rb <ruzsa.bal...@gmail.com> wrote:
>
>
> On Oct 27, 4:36 pm, Chris Maier <christopher.ma...@gmail.com> wrote:
> > On Wed, Oct 27, 2010 at 10:18 AM, rb <ruzsa.bal...@gmail.com> wrote:
> > > P.s. I still don't understand though why the 'calls' argument to the
> > > store-calls function is not a held reference to the head of the lazy
> > > seq...
> >
> > I think (and someone please correct me if I'm wrong) that the head of
> > 'calls' isn't being retained because you recur on (rest calls),
> > replacing your hold on the head with the next item downstream. Now
> > nobody's holding on to the head, so it gets GC'd. Keep recurring, and
> > you just move down the sequence, always dropping what you were holding
> > onto, thus allowing it all to be GC'd.
> >
> > Chris
>
> Yes, this is quite clear in the case of the loop construct:
>
> (loop [calls calls
> conn nil
> stmt nil
> year nil
> month nil]
> (if-let [c (first calls)]
> ...
> (recur (rest calls) conn stmt year month))))
>
> The 'calls' variable bound in the loop is clearly not retained.
>
> What bothers me is the function argument:
>
> (defn store-calls
> [source calls]
> ...
>
> Here the lazy seq coming in as the second arg is bound to a local
> variable named 'calls'. I would think this counts as retainment of the
> head of the lazy seq (for the lifetime of the function), but it
> apparently doesn't.
>
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