A New Service

A couple months ago I made a post explaining Stackage server, its motivations and use-cases, and that it would be available in the coming months. It's now officially available in beta!

Stackage server.

As a quick recap: the essence of Stackage is that rather than publishing at the granularity of packages, like Hackage, it publishes at the granularity of package sets: Either everything builds together, or nothing is published until it does. We call these published things “snapshots.”

Note: A snapshot is an exact image that can be reproduced at any time. With the snapshot's digest hash, you can download and install the same index and install packages based on that index all the time. Subsequently generated snapshots have no effect on previous ones.

I've been using it for a couple months for every project I've worked on, private and public. It's perfect for application developers and teams who want to share a common always-building package set. Provided you're using one of the 500+ packages we're publishing in the snapshots, there will always be a build plan for the package you want to use in your project.

And if your library is in Stackage, as explained in the previous post, you will get a heads up on Github if your updates or other people's updates cause a build failure related to your library.

How it Works

Snapshots are built every couple days. It takes about 16 hours to complete a build. You can view the build progress at jenkins.stackage.org.

There are two types of snapshots published by FP Complete:

Exclusive: this excludes packages not specified in the Stackage configuration. This means anything that you try to install from this snapshot will have a build plan. Inclusive: this includes Hackage packages not known to build. If you try to install a package not tracked by Stackage, it may or may not build.

You can use whichever suites your needs. If you want everything to always build, the former is an attractive choice. If you need to use a package not currently on Stackage, the latter choice makes sense.

Try it Right Now

Choose a snapshot. Each snapshot applies to a specific GHC version. For example, the latest (as of writing) GHC 7.8 build. You'll see something like this:

To use, copy the following to your ~/.cabal/config :

remote-repo: stackage:https://www.stackage.org/stackage/604a3649795771f6dd8b80bfd4eeb748e1d97599

Note: Remove or comment out any existing remote-repo line.

Run the following to update your packages:

$ cabal update

If you already have installed some packages, it's better to clear out your package set. See this page in the FAQ for how to do that.

Sandboxes

How does this interact with sandboxes? Good question. Here's the rundown:

hsenv: Yes, works fine. Edit the .hsenv/cabal/config file and off you go.

file and off you go. cabal sandbox: Not yet! There is an open issue about this. But I have tried cabal sandboxes inside hsenv, which worked.

We've added this to the FAQ on the wiki. Contributions to this wiki page are welcome!

Feedback

Personally, I'm very satisfied with this service so far. I just use my existing tools with a different remote-repo .

Others familiar with Nix have asked how they compare. They are very similar solutions in terms of versioning and curation (although Stackage has full-time maintenance); the main advantage to Stackage is that it just uses existing tools, so you don't have to learn a new tool and way of working to have a better user experience.

We'd like feedback on a few points:

Is the inclusive/exclusive separation useful?

Is the process of using Stackage in an existing system (clearing the package set and starting fresh) easy?

Should we establish a convention for storing Stackage snapshot hashes in projects source-tracking repositories?

And any other feedback you come up with while using it.

Stackage for businesses

As part of my last announcement for Stackage I mentioned there will also be custom services for businesses looking to build their development platform on Stackage.

These commercial services include:

Premium support - FP Complete will quickly respond and make improvements or fixes to the public Stackage server as they need to happen. Private snapshots with premium support - very helpful for commercial users looking to add proprietary or custom libraries. Validated pre-compiled build images based on public or private snapshots. These can be used on developer systems or automated build systems. Packaged Jenkins server using the pre-compiled build images.

All these additional commercial services are meant to be helpful add-ons and we look forward to hearing more about what features you think would be beneficial to you. For more information email us at: sales@fpcomplete.com

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