Re: [Scheme-reports] clarification of proposal for eqv?/eq? on procedures

On Sun, Jun 9, 2013 at 9:51 PM, Taylan Ulrich B. <taylanbayirli@x> wrote:

I would constrain the returning-false condition via eqv?, indicating
that eqv? is always compatible and sometimes more capable:

On symbols, booleans, the empty list, pairs, records, and non-empty
strings, vectors, and bytevectors, eq? and eqv? are guaranteed to
have the same behavior. On procedures eq? returns true if the

arguments' location tags are equal, and returns false at least when
eqv? also does. On numbers and characters, eq?'s behavior is

implementation-dependent, but it will always return either true or
false, and will return true only when eqv? would also return
true. On empty strings, empty vectors, and empty bytevectors, eq?
may also behave differently from eqv?.

Thanks, this sounds better. Assuming the WG does not choose to

reverse our decision on requiring eq? and eqv? to behave the same

on procedures (ballot item #467), then I think we'll use this text.

BTW, for those interested, I checked the (chibi parse) test suite and

the cost of using eqv? (via assv) for procedures instead of eq? was

about a 2.8% slowdown (of the entire test suite, not a micro-benchmark).

The difference between the two procedures in Chibi is especially large,

but will be significant even in fast compilers because it's a difference

between simple pointer comparison vs multiple branches and dereferencing

memory you otherwise wouldn't need to.

[And of course, the slowdown is for all practical purposes infinite

if we can't use either eq? or eqv?.]

Alex