Libraries Digest, Vol 87, Issue 16

[Duncan Coutts]

>> On 8 November 2010 08:35, Bryan O'Sullivan <bos at serpentine.com> wrote:
>> > Hlint isn't a library, right? And as an application, it presumably
>> > doesn't for any practical reason need its dependencies in the platform in
>> > order to itself be included?
>>
>> As I stated earlier, the policy seems to state that they do need to be
>> there (to be able to build the platform if nothing else):
>>
>> http://trac.haskell.org/haskell-platform/wiki/AddingPackages#PackageRequirements
>
> Well, the policy can be changed if necessary (not that I'm proposing that
> here).
> While packages may need to be present to build an application in the
> platform, they don't necessarily need to be exposed as part of the platform.

That's true for binary packaging systems. It would not be true for
source based ones e.g. gentoo, freebsd ports, macports or indeed
someone starting with just ghc and using cabal to install the platform
meta-package.

>  Rationale-8.5 seems to be targeted at libraries specifically.  That is, it
> claims there's no technical means to differentiate between blessed and
> non-blessed packages, which is why non-blessed packages can't be included.
>  But since an application doesn't expose libraries, there is a simple means
> to make this distinction.

My opinion is that we should keep the source based distribution
mechanisms in mind, in which case the rationale applies for programs
as well as libraries. If we all think it's a major problem then we
could look at technical solutions, but the current model is quite nice
where each cabal package is translated 1:1 into a native package.

In the case of HLint specifically, I think it's quite likely that
we'll get haskell-src-exts into the platform in the next round.

Duncan