[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Lexical syntax for boxes
Alan Watson scripsit:
> A SRFI is a mini-standard. You can invoke the spirit when you're
> designing it. However, the text needs to specify the behavior of eqv?
> and eq?.
Point. I'll add this to the next draft.
> My feeling is that the spirit of equal? is "equivalent same in the
> absence of mutation, eqv?, and eq?". However, R7RS abandoned this for
> records, presumably for a good reason.
Primarily because different Schemes do it in different ways: some use
`eqv?`, some descend into the object like Common Lisp `equalp` (but not
Common Lisp `equal`), some vary depending on whether the object contains
any mutable fields or not.
> Anyway, the SRFI needs to say what the behaviour of equal? is for
> boxes, regardless of whether you adopt vector-like or record-like
I don't believe it does need to. The answer can be left open, as it is
in R5RS and R7RS-small. In R6RS, it's defined to be `eqv?`, at least if
boxes are defined using records, but left open if they are magic.
At the end of the Metatarsal Age, the dinosaurs John Cowan
abruptly vanished. The theory that a single cowan@xxxxxxxx
catastrophic event may have been responsible http://www.ccil.org/~cowan
has been strengthened by the recent discovery of
a worldwide layer of whipped cream marking the
Creosote-Tutelary boundary. --Science Made Stupid