Proposal: Ignore sub-minor version components in package id

Ivan Lazar Miljenovic ivan.miljenovic at
Mon Oct 3 13:52:37 CEST 2011

On 3 October 2011 22:30, Joachim Breitner <mail at> wrote:
> Hi,
> Am Montag, den 03.10.2011, 13:27 +0200 schrieb Herbert Valerio Riedel:
>> On Mon, 2011-10-03 at 13:18 +0200, Joachim Breitner wrote:
>> > I’d like to propose that the package (shown by "ghc-pkg field <pkg> id"
>> > and used by "ghc-pkg field <pkg> depends") should only consist of the
>> > first three components of the package version, not all of them.
>> ...would this affect the ability to declare version constraints that use
>> more than the first 3 components? E.g. would the following Cabal
>> statement
>>  Build-depends:  aeson >= && <0.4
>> still work (and force at least version of aeson to be used)?
> yes, all other version-related machinery (dependencies in Cabal
> packages, hackage stuff etc) still work.
> I am only talking about the packages as registered with ghc-pkg, not the
> packages as specified by .cabal. In distribution-lingo, the former are
> binary packages and the latter are source packages.

Would this not make it harder to determine which exact version of a
package you have installed?  I believe cabal-install uses ghc-pkg to
know which versions are installed, so how would it know whether you
have the latest bug-fix release installed?

Ivan Lazar Miljenovic
Ivan.Miljenovic at

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