Going back to a point I'm sure others have made already... Perhaps you
guys have a good sense of how many people would be affected by any
incompatibilities in this case?
Most people use "open-output-file" and hash tables, so you wanted to
migrate all those people gently somehow. A relatively small percentage
of people used mutable pairs, at least outside of textbooks, so a harsh
migration path was more acceptable there.
I assume that the Web Server is somewhere between "open-output-file" and
mutable pairs in popularity. If the tradeoff costs of
backward-compatibility work and moving the platform forward
expeditiously are unclear, perhaps you could poll the stakeholders.
Neil Van Dyke wrote at 11/30/2010 01:11 PM:
I don't have any important dependencies on the Web Server right now,
but just wanted to add that even small backwards-incompatibilities in
PLT/Racket have ruffled feathers of consulting clients of mine in the
past.
When there are backward-incompats, it's *much* better that they be
detected at compile time. Example: renaming the hash table procedures
was an annoyance when code wouldn't compile, but the changes to
"open-output-file" and friends to use keyword arguments resulted in
much more insidious runtime errors.
(BTW, Not using Typed Racket yet. Large code base that has been
evolving since PLT 1xx/2xx.)
When thinking about how you want people to be alerted to incompats,
also remember that not everyone reads the release notes. A few times
I've seen a programmer install the latest version of PLT to try, which
happens to constitute a jump of several versions, and s/he smoke-tests
their code with the new version *before* going and reading the release
notes for all the intermediate versions. I think that having the
platform inform them of incompatibilities through compile-time error
messages or compile-time Java-like deprecation warnings gives more
confidence in the platform than errors that occur significantly after
time T0 in run-time.
--
http://www.neilvandyke.org/
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