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.