Version in Data.Version from base is defined as: data Version = Version { versionBranch :: [Int], versionTags :: [String] } instance Eq Version where v1 == v2 = versionBranch v1 == versionBranch v2 && sort (versionTags v1) == sort (versionTags v2) -- tags may be in any order instance Ord Version where v1 `compare` v2 = versionBranch v1 `compare` versionBranch v2 ## Proposal Remove the `versionTags` field from this type. ## Motivation * The Eq and Ord instances of Version don't agree whether two versions with different versionTags are equal or not [1]: > a = Version [1] ["a"] > b = Version [1] ["b"] > compare a b EQ > a == b False * The Package versioning policy does not include version tags [2]. * Cabal no longer supports package version tags [3,4]. Discussion period: 2 weeks. Note: this is not a proposal to ignore trailing zeros when comparing versions. Neither is this is a proposal to change the Eq instance for Version to only consider the versionBranch field. This is a proposal to remove versionTags altogether. [1] https://ghc.haskell.org/trac/ghc/ticket/2496 [2] http://www.haskell.org/haskellwiki/Package_versioning_policy [3] https://github.com/haskell/cabal/issues/890 [4] http://www.haskell.org/cabal/users-guide/developing-packages.html#package-na...