(eq? (vector) (vector)) should evaluate to #t

[Abdulaziz Ghuloum]

(vector) and (string) should not allocate new data.
Also, maybe, (make-vector 0) and (make-string 0) too should not allocate.

[Michael D. Adams (mdmkolbe)]

Would that be legal for R6RS? The spec says that "vector" returns a "newly allocated vector". That makes it sound like "(vector)" could actually be a valid way to create a gensym.

[Abdulaziz Ghuloum (aghuloum)]

On Jan 2, 2008, at 9:08 PM, Michael D. Adams wrote:

> Would that be legal for R6RS? The spec says that "vector" returns a
> "newly allocated vector". That makes it sound like "(vector)" could
> actually be a valid way to create a gensym.

The only way to tell is by using "eq?", and eq?/eqv?
is unspecified on empty strings, vectors, bytevectors,
and records containing no mutable fields.

 From section 11.5:

   The eq? and eqv? predicates are guaranteed to have the
   same behavior on symbols, booleans, the empty list, pairs,
   procedures, non-empty strings, bytevectors, and vectors,
   and records. The behavior of eq? on number objects and
   characters is implementation-dependent, but it always re-
   turns either #t or #f, and returns #t only when eqv? would
   also return #t. The eq? predicate may also behave differ-
   ently from eqv? on empty vectors, empty bytevectors, and
   empty strings.

[Abdulaziz Ghuloum (aghuloum)]

Fixed in revision 1329.

[Abdulaziz Ghuloum (aghuloum)]

This bug report is about to be closed as the fix comitted
previously will be incorporated in the next 0.0.3 release of
Ikarus Scheme, scheduled for January 31, 2008. A release
candidate tarball is available for download from:
http://www.cs.indiana.edu/~aghuloum/ikarus/ikarus-0.0.3-rc1.tar.gz
Please do test it if you have the time and report any issues
you might encounter. Thank you very much for your support.
(Sorry for the duplicates; I'm updating every open bug.)