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:

1. 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.

2. 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.

• 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:

1. Premium support - FP Complete will quickly respond and make

   improvements or fixes to the public Stackage server as they need to

   happen.

2. Private snapshots with premium support - very helpful for

   commercial users looking to add proprietary or custom

   libraries.

3. Validated pre-compiled build images based on public or private

   snapshots. These can be used on developer systems or automated

   build systems.

4. 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