a full year ago, I made the first commit into the Stackage
repository, and the announcement
blog post describes the project’s motivations. Since then, as
part of our work at FP Complete, there’s been a lot of activity on
this project. The community contributions have been amazing as
well, with a huge number of package authors signing up to
contribute and maintain their packages on Stackage. I want to recap
where the project is right now, in terms of the package set, its
own codebase, and how FP Complete is working with Stackage.
The package set
To date, users have contributed roughly 200 separate packages to
the Stackage package collection. When you include all of the deep
dependencies of these packages, we are currently building about 480
total packages in a full Stackage build, or roughly 9% of all
This is great news for anyone using Stackage directly to build a
package database, as they gain direct access to a huge number of
the most popular Haskell packages, without worries of
compatibility. (We’ll touch on that a bit more in the FP Complete
section.) But the work we’re doing with Stackage has probably
already directly benefitted all Haskell users, even those who have
never touched Stackage.
As part of regular Stackage maintenance, I maintain a total of
three separate daily Stackage builds, one using the most recent
Haskell Platform, one using the previous release, and one using
vanilla GHC 7.4 (no Haskell Platform constraints). Every day, these
jobs run, try to compile all of these packages, and run the full
set of test suites. The process has found a large number of simple
compilation issues, overly restrictive cabal version bounds, and a
number of actual bugs. In my opinion, Stackage is living up to its
goal of helping maintainers raise the quality of their code.
At this point, I’ve certainly lost track of how many patches
either myself or one of my coworkers at FP Complete have sent based
on Stackage build results. In the cases where we haven’t been able
to put a patch together, maintainers have been incredibly
responsive, and I’d really like to thank everyone in the community
who has participated.
So on this note, there’s only one thing I’d like to ask from
people: get involved! If you’ve written some code that you’re
actively maintaining, get it in Stackage. You’ll be widening the
potential audience of users for your code by getting your package
into FP Haskell Center, and you’ll get some helpful feedback from
the automated builds so that users can more reliably build your
The Stackage codebase itself has become pretty stable. The
initial goal was simply to try building a bunch of packages at the
same time. At this point, it handles a lot more than that:
- Performs an audit of uploaders to Hackage, to ensure no one
accidentally (or purposefully) hijacks another user’s package. I’ve
been running these audits approximately twice a week for the past
few months, and as usual have gotten great responses from the
community. (Once Hackage 2 goes live, this process will be
obsoleted, but for now it’s providing a valuable service.)
- The ability to add local patches to packages from Hackage. This
has been very useful in quickly modifying cabal version
- Ability to snapshot builds, which will capture all packages and
their versions to be built. When combined with the previous point,
this allows us to create stable package sets which can include bug
- Fully sandboxed builds, optional Haskell Platform constraints,
and helpful output to determine the cause of conflicts in version
- And for my own sanity: the ability to take advantage of
cabal-install’s parallel build option to build all 480 packages in
a (semi-)reasonable amount of time. It usually takes about 1.5
hours to do a full build on my desktop.
But we’re not finished yet! Security is a big concern for both
FP Complete and Galois, and we’ve been talking about ways to
leverage Stackage to improve the security situation of Hackage.
Some concrete steps we’re hoping to take in the near future
- Package signing, to ensure authorship.
- Facilitate code reviews.
- Set up a web of trust for code.
Since this blog post is about the state of Stackage, and not its
future, I don’t want to belabor these points too much. But expect
to hear more about them in the future. In the meanwhile, if you’re
interested in taking part in this process, please be in touch with
me, or even better, write to the Stackage mailing
FP Complete is the company behind Stackage. So what are we
getting out of this? Firstly, everything I’ve listed above. FP
Complete is obviously very invested in the Haskell community, and
benefits greatly from all of the wonderful work being done by that
community. So anything we can do to help facilitate that continued
progress is a boon to our progress as well. Getting a higher
quality set of packages on Hackage and lowering the barrier to
entry by reducing installation problems is something we’re very
More directly, many people know that we use Stackage to build
the set of packages we provide on FP Haskell Center itself. When
you write a School of Haskell tutorial, you have access to all 480
packages in our package database. When you start a new project in
FP Haskell Center, you can immediately import any module in that
package database, without concerns of diamond dependencies.
By running Stackage as such an open project, and having our
system built on top of Stackage, we’ve created a natural way for
users to get additional libraries onto our system. Instead of
having a centralized body controlling which packages can make it
onto our servers, we can open things up to a much more user-driven
approach. This takes us out of the role of gate-keepers (or, said
another way, bottlenecks) and instead lets us simply be
The Hackage uploader vetting has been invaluable as well. We
take security very seriously, as do our users, and we need some way
to ensure that when you start using package X, it hasn’t been
replaced by a nefarious user. Of course, package signing will give
us even more guarantees about this.
FP Complete is promoting two sets of packages currently:
bleeding edge (called unstable), and the stable 13.09 package set.
This latter set is based on a snapshot taken just before our first
release at the beginning of this month. Using Stackage’s
snapshotting and patching abilities, we are able to provide users
with stable APIs from vetted packages, while fixing any bugs or
security holes found in those packages on behalf of our users. And
for those of you looking to be more experimental, our unstable
environment can be updated much more regularly.
Stackage is fulfilling the role I’d hoped it would, both for the
community in general, and at FP Complete. We’re going to be
broadening its intended feature set over the next few months to
include more security features, and hope to provide yet another
benefit to the Haskell community. This is an exciting project to be
a part of, and I hope even more of you will take part in it.
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