POS, OOFS, CL v Scheme, etc.

[Henry G. Baker]

> Is there a reasonably complete Lisp spec or proposal somewhere
> that would meet many/most of your proposals -- something to use
> as a beginning?
> 
> -- Dwight

As far as 'functional'/'read-only' data types are concerned, my 'Equal
Rights' paper makes some concrete proposals.  In particular, if in
CLOS you define a new datatype with all 'readonly' slots, then you
should get a functional data structure.  Unfortunately, some other
things in CLOS would need fixing, and especially the Xerox CLOS
implementation which makes it impossible to properly initialize a
functional object.

One solution to the initialization problem is to incorporate _both_
linear/unique types and functional/readonly types at the same time.
When the storage for an object is first allocated, it is a
linear/unique object, and only when it has been fully initialized does
it get 'frozen' into a functional/readonly object.

The papers I referenced in the earlier posting suggest such an
approach, although it doesn't show how to reprogram CLOS in order to
actually do this.

--

The most obvious problem is to decide whether 'cons' returns a
functional or a non-functional list object.  I would vote for
_functional_, on the grounds that it would trap when you tried to
modify such an object, and would force you to think about how it is to
be used.

-- 
Henry Baker
www/ftp directory URL:
ftp://ftp.netcom.com/pub/hb/hbaker/home.html