[Rd] [RFC] A case for freezing CRAN

[Jeroen Ooms]

On Wed, Mar 19, 2014 at 6:55 PM, Michael Weylandt
<michael.weylandt at gmail.com> wrote:
> Reading this thread again, is it a fair summary of your position to say "reproducibility by default is more important than giving users access to the newest bug fixes and features by default?" It's certainly arguable, but I'm not sure I'm convinced: I'd imagine that the ratio of new work being done vs reproductions is rather high and the current setup optimizes for that already.

I think that separating development from released branches can give us
both reliability/reproducibility (stable branch) as well as new
features (unstable branch). The user gets to pick (and you can pick
both!). The same is true for r-base: when using a 'released' version
you get 'stable' base packages that are up to 12 months old. If you
want to have the latest stuff you download a nightly build of r-devel.
For regular users and reproducible research it is recommended to use
the stable branch. However if you are a developer (e.g. package
author) you might want to develop/test/check your work with the latest
r-devel.

I think that extending the R release cycle to CRAN would result both
in more stable released versions of R, as well as more freedom for
package authors to implement rigorous change in the unstable branch.
When writing a script that is part of a production pipeline, or sweave
paper that should be reproducible 10 years from now, or a book on
using R, you use stable version of R, which is guaranteed to behave
the same over time. However when developing packages that should be
compatible with the upcoming release of R, you use r-devel which has
the latest versions of other CRAN and base packages.


> What I'm trying to figure out is why the standard "install the following list of package versions" isn't good enough in your eyes?

Almost nobody does this because it is cumbersome and impractical. We
can do so much better than this. Note that in order to install old
packages you also need to investigate which versions of dependencies
of those packages were used. On win/osx, users need to manually build
those packages which can be a pain. All in all it makes reproducible
research difficult and expensive and error prone. At the end of the
day most published results obtain with R just won't be reproducible.

Also I believe that keeping it simple is essential for solutions to be
practical. If every script has to be run inside an environment with
custom libraries, it takes away much of its power. Running a bash or
python script in Linux is so easy and reliable that entire
distributions are based on it. I don't understand why we make our
lives so difficult in R.

In my estimation, a system where stable versions of R pull packages
from a stable branch of CRAN will naturally resolve the majority of
the reproducibility and reliability problems with R. And in contrast
to what some people here are suggesting it does not introduce any
limitations. If you want to get the latest stuff, you either grab a
copy of r-devel, or just enable the testing branch and off you go.
Debian 'testing' works in a similar way, see
http://www.debian.org/devel/testing.