Proposal: remove versionTags from Data.Version
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...
On Tue, 23 Sep 2014, Thomas Miedema wrote:
## 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].
How are versions of pkg-config handled? pkg-config does not always return numeric versions.
On Wed, 2014-09-24 at 00:01 +0200, Henning Thielemann wrote:
On Tue, 23 Sep 2014, Thomas Miedema wrote:
## 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].
How are versions of pkg-config handled? pkg-config does not always return numeric versions.
The pkg-config versions with string (e.g. 0.9.8b) do not map cleanly onto the Version type, neither with tags nor without. The strings in pkg-config versions are part of the version and are included in the (complicated) ordering rules, where as Data.Version version tags are explicitly an unordered set, so the pkg-config alphanumeric versions do not map onto those tags. Basically pkg-config style versions need handling specially if you want to cover the full alphanumeric versions. In practice Cabal has always done this wrong, by only handling the common numeric subset. It's never been a high enough priority to handle in full. Except for old versions of OpenSSL this has not been too much of problem in practice. Duncan
On Tue, 2014-09-23 at 23:57 +0200, Thomas Miedema wrote:
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.
Cabal is probably the primary user of this type. With my Cabal maintainer's hat on I support this change. Cabal has for a long time deprecated the version tags feature. It accepts but ignores tags in most places, and never emits tags (Cabal uses its own parser and printer). Packages using tags in their version are not allowed on hackage for example. The tags idea turned out not to really work. The fact that it's not part of the Ord instance causes all sorts of problems (think package indexes), but then it's not clear what an Ord instance including an unordered set of tags should be. It does not map onto other package system's versions (which have strings like "beta" but they're part of the version number, not an additional unordered set). In short, Cabal tried to make sense of the tags but it just causes too many problems and so Cabal has for years now pretended that the tags feature does not exist. Duncan
On 2014-09-23 at 23:57:47 +0200, Thomas Miedema wrote:
Version in Data.Version from base is defined as:
data Version = Version { versionBranch :: [Int], versionTags :: [String] }
[...]
## Proposal Remove the `versionTags` field from this type.
+1 (possibly with a DEPRECATE-cycle during GHC 7.10, and actual removal with GHC 7.12)
This proposal is now accepted, with support from Duncan, Herbert and
myself. No objections were raised.
If all goes well, versionTags will be deprecated in GHC 7.10, and removed
in GHC 7.12.
Code review: https://phabricator.haskell.org/D395
Ticket: https://ghc.haskell.org/trac/ghc/ticket/2496
On Tue, Sep 23, 2014 at 11:57 PM, Thomas Miedema
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...
participants (4)
-
Duncan Coutts -
Henning Thielemann -
Herbert Valerio Riedel -
Thomas Miedema