Testing the waters.

Chris Bitmead uid(x22068) Chris.Bitmead@Alcatel.com.au
Fri, 09 May 1997 13:35:32 +1000

>Who said other versions of lisp won't have a POS? I seem to
>remember a certain employee of a certain lisp company saying they were
>interested in the idea of a POS. 

Nobody said they won't. I'm sure some do already. The point is that a
CL program that assumes a POS, is not a fully portable CL application.

I don't care, because it's worth it.

>And since a POS hasn't been designed
>and built yet, you're only speculating on how hard it might be to

It may well be quite feasible to port. But you'll probably need the
source to the lisp implementation, and it still won't make it a
bog-standard CL program.

I don't care, because it's worth it.

>Sure, OS support might make things faster/more efficient for a
>POS but one might also be able to implement one without all of that OS

You need support from the language implementation rather than the OS.

>  And besides, who says ever LispOS app has to use the POS intimently?
>I can imagine a lot of apps being written to use a POS if one's
>available, otherwise simulate one using plain old text files. 

If you have a POS, you will want to write all your algorithms without
thinking about the disk. If you move to a non-POS environment you
would have to load all objects into memory up front before setting
your algorithms into action. This is of course an appalling waste of

Alternatively you can pollute your entire source code with file
handling stuff. Very ugly by comparision.

You will also notice that conventional file systems mean that you
write very state-ful, very side-effect making code. 
POS code can be made 99% functional.

>And the
>LispOS had better support writing portable apps including those that
>store things in persistent arrays of string char or the LispOS will be
>a flop before it ever gets built.

I'm sure LispOS will support this, and many other legacy things.

>>You may get your existing CL lisp programs working on LispOS, but they
>>won't do things the LispOS way, so they fall into the general category
>>of how to get legacy applications working on LispOS.
>  We don't have a LispOS. We don't have a POS. But we do have a LispOS
>way? Ya, right!

You don't want a POS?