Might there be benefit to combining 3 and 4, making the stable subset
explicit (perhaps supported by tests so as to be machine checkable)?
On Apr 9, 2014 1:47 AM, "Michael Snoyman"
I would like to propose the following changes to the PVP. These are the same changes that I recently published on the Yesod blog[1]. For more information on the motivations behind these changes, please see that blog post.
1. The goal of the PVP needs to be clarified. Its purpose is not to ensure reproducible builds of non-published software, but rather to provide for more reliable builds of libraries on Hackage. Reproducible builds should be handled exclusively through version freezing, the only known technique to actually give the necessary guarantees.
2. Upper bounds should not be included on non-upgradeable packages, such as base and template-haskell (are there others?). Alternatively, we should establish some accepted upper bound on these packages, e.g. many people place base < 5 on their code.
3. We should be distinguishing between mostly-stable packages and unstable packages. For a package like text, if you simply import Data.Text (Text, pack, reverse), or some other sane subset, there's no need for upper bounds. (Note that this doesn't provide a hard-and-fast rule like the current PVP, but is rather a matter of discretion. Communication between library authors and users (via documentation or other means) would be vital to making this work well.)
4. For a package version A.B.C, a bump in A or B indicates some level of breaking change. As an opt-in approach, package authors are free to associated meaning to A and B beyond what the PVP requires. Libraries which use these packages are free to rely on the guarantees provided by package authors when placing upper bounds. (Note that this is very related to point (3).)
Discussion period: 3 weeks.
[1] http://www.yesodweb.com/blog/2014/04/proposal-changes-pvp
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