Proposal on the platform API policy question

Duncan Coutts duncan.coutts at
Wed May 20 18:54:13 EDT 2009


Thanks to everyone who took part in the recent discussion on API
compatibility in minor platform releases. In response to the points
raised, Don and I would like to propose the following:

      * Bug fix only in minor releases
      * Change platform version numbers to follow the PVP
      * 4 month major release cycles for the first 12 months
      * Review major release cycle frequency after 12 months

We hope we can achieve consensus around this proposal. Please could
people indicate if they think they can support this.

Note that there are plenty of other issues that we have yet to address,
so don't worry that we're not talking about those yet. We raised this
issue first because we need a decision.


      * "bug fix only" means no api changes or additions in library
        packages and no new user-accessible features in programs. In
        terms of the PVP it means only the 4th digit may increment, eg
        X.Y.Z.0 -> X.Y.Z.1.
      * Having the platform following the PVP means the next minor
        release will be 2009.2.0.1 (rather than 2009.2.1) to indicate
        that it has (or more accurately it's constituents have)  the
        exact same API as the previous major release. In general the
        version will be of the form "X.Y.0.Z" with "X.Y" being the major
        version and Z the minor.
      * Initially using a 4 month major release cycle means we'll get
        one release before ghc 6.12 and another after (assuming 6.12 is
        released in November again).
      * After 12 months we'll review (via this mailing list) the release
        cycle frequency based on the experience of 4 month release
        cycles and with input from HP users, HP package maintainers and
        HP release wranglers.


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