[REBOL] Re: Model hacking
From: lmecir:mbox:vol:cz at: 22-Jun-2001 22:44
> Inspired by the style of your "Evaluation" essay, this leads me
> to define
> >> elementary?: func [x] [error? try [first x]]
> >> composite?: func [x] [not elementary? x]
Now I know.
5) SYSTEM vs. USER -- Some types are predefined by REBOL and
the user cannot create values of that
type (e.g., op!) while other types can be created at will
by the user's expressions (object! and function!)
6) CLOSED vs. OPEN -- Some types (logic! and datatype!) have
a set-in-concrete set of possible
values, while others are open-ended and new values may be
created at will (function! and block!)
5) and 6) look like being "unifiable"