Formal comment #138 (major)

The treatment of version number needs to be changed
Reported by: 	Mike Sperber
Version: 	5.91

This post by Marcin Kowalczyk describes the issue:

http://lists.r6rs.org/pipermail/r6rs-discuss/2006-September/000013.html

Quoting the post:

    6.1. As far as I understand it, it's possible to specify
    conditions in version references only in each subversion field
    separately. For example it's not possible to say "version (3 n)
    for n>=2 or version (m n) for m>=4" (i.e. "3.2 or newer"), nor
    even "(3 2 . m) for any tail m". Perhaps I misunderstood how
    version numbers would typically be used in practice. But wouldn't
    it be better if "and" and "or" were applicable to version
    conditions as a whole, rather than individual subversion fields?

How to fix the issue:

While the above disclaimer applies, I wrote the original versioning
spec, and this seems like a clear omission.

Here's how I'd like to fix it:

<version reference> -> <empty>
                     | <version spec>     ; new

<version spec> -> (<subversion reference> ...)
                | (and <version spec> ...)
                | (or <version spec> ...)
                | (not <version spec> ...)

This would allow saying:

(or (3 (>= 2))
    ((>= 4)))

which would match:

3.2, 3.3, 3.2.1, 3.5.2, etc., 4, 4.0, 4.1.1, etc.

I believe the dual occurrence of and', or', and `not' is unambiguous,
as crossing from <version spec> to <subversion reference> always
involves an additional open parenthesis, and there's no way back up.


RESPONSE:

Agreed.  The suggested change will be made in the next draft.