I completely agree with Johan. The problem is to change core APIs too fast. Adding, say, SIMD instructions or having a new type extension (that needs to be explicitly activated with a -X option) shouldn't break packages.

I'm all for restricting major API changes to once a year, but why can't we have multiple updates to the code generator per year or generally release that don't affect a large number of packages on Hackage?

Manuel

Johan Tibell <johan.tibell@gmail.com>:
On Fri, Feb 8, 2013 at 6:28 AM, Simon Marlow <marlowsd@gmail.com> wrote:
For a while we've been doing one major release per year, and 1-2 minor releases.  We have a big sign at the top of the download page directing people to the platform.  We arrived here after various discussions in the past - there were always a group of people that wanted stability, and a roughly equally vocal group of people who wanted the latest bits.  So we settled on one API-breaking change per year as a compromise.

Since then, the number of packages has ballooned, and there's a new factor in the equation: the cost to the ecosystem of an API-breaking release of GHC.  All that updating of packages collectively costs the community a lot of time, for little benefit.  Lots of package updates contributes to Cabal Hell.  The package updates need to happen before the platform picks up the GHC release, so that when it goes into the platform, the packages are ready.

So I think, if anything, there's pressure to have fewer major releases of GHC.  However, we're doing the opposite: 7.0 to 7.2 was 10 months, 7.2 to 7.4 was 6 months, 7.4 to 7.6 was 7 months.  We're getting too efficient at making releases!

I think we want to decouple GHC "major" releases (as in, we did lots of work) from API breaking releases. For example, GCC has lots of major (or "big") releases, but rarely, if ever, break programs.

I'd be delighted to see a release once in a while that made my programs faster/smaller/buggy without breaking any of them.

-- Johan