Re: circumflex/caret

On Thu, Feb 26, 2009 at 2:50 AM, Paolo <[email protected]> wrote:
> On Thu, Feb 26, 2009 at 01:53:21AM +0100, Ger Hobbelt wrote:
> ...
>> distributed Monte Carlo simulation is running full out :-(((((((((((
>> </rant>
>
> no room left even for a coffe? ;))

Nope. I noticed the slowdown somewhat when banging away on my
keyboard, but didn't really watch the CPU monitors. Knew what I had
running in the background anyway. Turned out they stuck to the roof
for about 2 hours flat, which is a good number. Just hadn't thought of
FF quiting the JavaScript interpreter like that, so the gmail edits
went down the drain irrecoverably. Had 'saved draft' before, that was
nirvana'd too :-(
Clearly, FF doesn't check actual JS CPU usage, but looks at system
overall CPU load. Grmbl. Talk about 'side effect'.

>
>> In short: <keep> is used as a flag for isolate / match / eval / union
>> / intersect / call, i.e. all operations which can *instantiate*
>> variables, to instruct them to allocate that variable in global scope.
>
> ok, but what would that mean for
>
>  match <keep> (:: :x:) [:z:] /.../
>
> where :z: is local? this instatiate (binds) :x: somewhere along :z:, not
> :z: itself, hence on RETURN :z: is gone, then <keep> keeps what? just :x:
> with the piece it grabbed from :z:, ~like ISOLATE does now?

Not precisely like isolate. That's why using bound variables coming
from an outer scope, together with local scope :z: like that, is a
little hairy.
Since I consider this sort of thing 'bad' coding practice (or that's
the excuse anyway) the current state of affairs is that this sort of
thing will keep :x: 'intact' until the, by now invisible, variable
name :z: is re-instantiated in a subsequent 'call'.

The cop out there is to 'isolate' :x: before that time. And, yeah, I
know this is hairy. See previous response about time & effort and
such. It's simmering in the back of the brain, so when I have a good
idea I'll do it, but until then, this is a caveat.

In code:


isolate (:x:) //
call /:match_binding_etc_func:/
# :x: is still 'live' here.
...
...
...
#... no 'call' statements here... 'return's are okay, though
# they will make :x: invisible, due to the 'isolate' up there.
...
...
...
# from this point on, you can't be sure if :x: is still 'good'.
# It depends, whether :other_func:, or one of the subroutines
# it calls, uses the same variable name (:z:) which :x: got
# bound to previously.
call /:other_func:/





-- 
Met vriendelijke groeten / Best regards,

Ger Hobbelt

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