Re: on cabal revisions

[Ricardo Wurmus]

Hi,

>> What I’m imagining is something roughly like this:
>>
>>    (source
>>      (origin
>>        (method url-fetch)
>>        (uri “https://hackage.haskell.org/package-sources.tar.gz”))
>>        (sha256 …))
>>      (origin
>>        (destination “package.cabal”)
>>        (method url-fetch)
>>        (uri “https://hackage.haskell.org/package/1.cabal”)
>>        (sha256 …)))
>>
>> probably with some way to specify how the sources should be
>> combined, by default unpacking over the previous result
>> sequentially. Would that be possible? A good idea even?
>
> This makes sense, but I’m not sure it’s a common enough use case to
> warrant a specialized interface.  Besides these Cabal revisions, only a
> handful of packages (that I’ve seen) need to download extra non-patch
> stuff.

One notorious class of packages that could benefit from a general
mechanism like this: the TeX Live packages.  They consist of various
subsets of a big SVN repository.  Currently, we pick an arbitrary
directory of the SVN repository as the main source and add all the other
locations as native inputs.

I wanted to add a procedure that accepts multiple locations in the SVN
repository, creates a union, and computes the single hash of the union.
This would make the texlive-* packages a lot simpler.

--
Ricardo