[Haskell-cafe] Package versioning policy - Harmless type changes?

Joachim Breitner mail at joachim-breitner.de
Thu Sep 22 16:39:24 CEST 2011


Hi,

Am Donnerstag, den 22.09.2011, 08:32 -0300 schrieb Felipe Almeida Lessa:
> On Thu, Sep 22, 2011 at 7:37 AM, Heinrich Apfelmus
> <apfelmus at quantentunnel.de> wrote:
> Given that you are following the PVP, I would put the following constraint:
> 
>   Build-depends: foo >= 0.1 && < 0.2
> 
> However, if someone with an older version of foo installed on their
> system tried to install my package, they would get a type error, since
> I haven't put a "Typeable a =>" context on my bar.

would you? I think you would use foo >= 0.1.3 && < 0.2, because 0.1.3 is
allowed to have API additions that are not in 0.1.2, so if you develop
your library against 0.1.3, there is no guarantee that foo was not empty
in 0.1.2.

Under this interpretation, removing a constraint should be equivalent to
an API addition, hence rule 2 on
http://www.haskell.org/haskellwiki/Package_versioning_policy#Version_numbers ought to apply.

Greetings,
Joachim

-- 
Joachim "nomeata" Breitner
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