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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
> behaviour.

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.

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