OCamlPro's opam builder (
http://opam.ocamlpro.com/builder/html/report-last.html ) really needs to
be more advertised and its UI a bit polished to encourage people to
actually look at it. Also a report per maintainer (with emails sent
automatically?) could be useful.
The release cycle is certainly important for this matter, and I hope the
new policy (smaller and more regular releases) will help significantly.
Simply announcing the next release date (ans sticking to it) sends a
signal to package authors about when they should start checking their
code works with trunk. Of course, smaller releases also make it simpler
to update the code and less risky to upgrade to for larger organization
(and thus packages maintained by them are more likely to be fixed
quickly). Hopefully the 4.03 experience was a bit exceptional (increased
development pace, very long release, moving release date, breaking
changes in the last months).
There is certainly things to learn and do to minimize the breakage of
ppx and their consequences. Introducing abstraction/compatibility
layers should help (either things such as Ast_convenience.Constant in
ppx_tools, or more ambitious stable APIs over the Parsetree).
It would also be interesting to understand in more details the reasons
of the breakages for so many packages in 4.03. It'd be a tedious work
to collect this information, but it will probably guide both core
maintainers and the community on how to improve the process. There are
two really important pieces of information: which changes in OCaml
cause the more breakage, and which broken packages cause the more
transitive breakage.
I've to say that I'm also a bit scared by the inflation of dependencies
across packages, including for relatively core packages that could
themselves potentially block many others. It's not because OPAM makes
it easy to depend on external packages that it's always a good idea to
do so. As an example, see
https://github.com/ocsigen/js_of_ocaml/blob/master/opam, and this does
not account for transitive dependencies, which include e.g. oasis (whose
own dependencies are themselves a bit scary). More atomic packages
could help in some respect (e.g. a package with only the js_of_ocaml
compiler, with precompiled menhir parsers, could only depnd on cmdliner,
I guess). Same for ocamlnet (which is still not available for 4.03, and
probably causing some further breakages; if it were split into smaller
packages, at least some of them should work on 4.03 already).
Alain
On 29/06/2016 18:40, Gabriel Scherer wrote:
Dear platform,
TL;DR: I propose that we change the OCaml release process to remain in
"beta" stage while there remain OPAM packages that are broken by the new
releases and their version bounds have not been updated.
I'm a bit frustrated with the time it takes for the OCaml ecosystem to
catch up with the 4.03 release -- which has been released two months ago
now, on April 25.
A large chunk of my personal hacking time following the release was
spent on updating Batteries, with a 4.03-compatible release happening on
May 12, so two weeks after the release -- a time I would still consider
too long for our downstream users waiting to try the 4.03 goodness but
held back by a Batteries dependency. I recently helped make atdgen
compatible with 4.03 (it's a dependency of IOCaml for example), and just
today found out that Coq releases (or its CoqIDE part) did not work on
4.03 (with no upper-bound in opam, it would just miscompile).
I find it frustrating because that means that there is a large time
window where we advertise (externally, to beginners, etc.) that the best
OCaml versions ever is 4.03.0, while running opam from this switch to
install any major software whatsoever feels like playing a rigged
russian roulette. I feel bad whenever I'm informed that my software (or
anyone else's, in fact) does not work by end-users that would rather
have spent their day doing something else than trying broken software.
Do you agree that this is a problem? What could we do to fix that?
When I started writing this email I intended to send it to Damien
Doligez, as the release manager of the compiler distribution, with the
following suggestion: maybe we could have a *much longer* beta-testing
period for OCaml versions that would be used not (only) for finding bugs
in the new version, but also to let important pieces of the ecosystem
update to the new version. Say, at least a month. We could have a fixed
set of software that we monitor, or in fact all of what's in OPAM, and
delay the release until they get updated/fixed or their OPAM version
bounds get fixed. (Aha, a Platform indeed!)
Does that sound like a reasonable idea to you? Should we monitor all
OPAM, or only a subset?
This suggestion is rooted in the idea that when we announce the release
to our end-users, stuff should just work -- or refuse to install itself.
Maybe this is an old idea of the SVN times and we're now in the era of
continuously-released, always-broken stuff?
Finally, there has been all this work on the "OPAM weather services",
continuous build of opam packages etc., plus the work that Damien is
doing around release time. It doesn't seem to have worked very well for
4.03. Who is monitoring this stuff? Do we need to fix them to make them
work better, or to fix our process to use them better? To be honest, I'm
never looking at these services -- I just don't think of using them. Can
I get an email whenever they detect that my stuff is broken? Say I'm a
new package manager, are there guidelines somewhere on what the best
practices are and what I should do?
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