LOGO-L> Re: Logo with parallel processes vs. ToonTalk

["Ken Kahn" <KenKahn@ToonTalk.com>]

Brian Harvey wrote
>I still don't see the point.  If you take a computation that is naturally
>expressed as ONE PROCESS with 100,000 procedure calls, and instead make it
>100,000 processes, each with (in effect) one procedure call, you haven't
>saved any storage.  If Logo would have needed 100,000 procedure calls, it's
>because there are 100,000 pieces of saved state needed for the computation.
>Why does it matter whether those 100,000 frames are on one stack or
>divided among 100,000 processes?
>
>If you're saying that you can't have 100,000 processes each doing 100,000
>procedure calls, then I agree -- but that's not a fair argument.  Logo
>doesn't do that.  No language does that.
>
>Maybe I should put it this way:  Instead of 100,000 stack frames, you have
>100,000 bird nests.  (If you're not using birds, then you are doing
something
>that would be a tail call in Logo, and it's not going to grow the stack.)
>

100,000 houses. Bird nests are only needed if a computation in a house needs
to receive data or requests from other houses.

And yes, languages like ToonTalk can have 100,000 processes each doing
procedure calls. I just tried to fill a ToonTalk city with 160,000 houses
(it started getting too slow and paging too much after 50,000). In every
house a robot is working away counting (they needn't be doing the same
thing - I'm just lazy). If you want to try it yourself, change the city size
to 200 (that is 200x200 blocks where each block holds 4 houses). You can
find a remote control for the size of your city in the Options notebook.
Then train a robot to get the robot that repeatedly adds 1 and load him in a
truck together with a box with a 1 in it. If you are patient enough you can
then just let that robot start up the other 159,999 processes but once some
of those processes start working that robot won't get a time slice very
often. So train another robot to drop copies of the robot you trained into a
truck. Wait a few minutes and then start flying around the city visiting
houses.

Why would kids want so many processes? Because I think each object should be
a process. And I believe that kids think so to. The idea of objects that are
"dead" unless they are processing some message from the outside is strange,
even if it is the way C++, Java, Object Logo, etc. work.

>
>That's why I proposed a compromise:  Allow a process to mutate only its
>own private variables.  So as long as you avoid mutation you can have
>shared data.

So are objects private to a process? How do they communicate between
processes? Or is it that the instance variables of the objects are private
to the process, but object references are global?

Best,

-ken kahn






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