[Haskell-cafe] Version constraints and cabal.config files

[Michael Snoyman]

On Wed, Mar 25, 2015 at 4:58 PM Anthony Cowley <acowley at gmail.com> wrote:

>
>
> On Mar 25, 2015, at 10:51 AM, Michael Snoyman <michael at snoyman.com> wrote:
>
>
>
> On Wed, Mar 25, 2015 at 4:30 PM Anthony Cowley <acowley at seas.upenn.edu>
> wrote:
>
>> On Wed, Mar 25, 2015 at 10:24 AM, Michael Snoyman <michael at snoyman.com>
>> wrote:
>> >
>> >
>> > On Wed, Mar 25, 2015 at 4:17 PM Anthony Cowley <acowley at seas.upenn.edu>
>> > wrote:
>> >>
>> >> The suggestion to use "cabal install --dependencies-only ..." instead
>> >> of "cabal freeze" in that issue is really nicely presented. "cabal
>> >> freeze" is close to the right thing, but it's just not as fully
>> >> featured as "cabal install" (e.g. taking flags).
>> >>
>> >> As for Stackage, I think it would be helpful to cache the full build
>> >> plans computed for each package in Stackage. This is most of the work
>> >> my Nix tooling currently does, so it would be a big time saver.
>> >>
>> >>
>> >
>> > By "full build plans," do you mean the dist/setup-config file, or
>> something
>> > else? That file would be problematic since it's Cabal-library-version
>> > specific IIRC. If you're looking for the full listing of deep
>> dependencies
>> > and versions, we can extract that from the .yaml file using the
>> technique I
>> > mentioned earlier.
>> >
>> > Michael
>>
>> Yes, I meant the full listing of deep dependencies.
>>
>>
>>
> I've put together a Gist with an executable that does what I described:
>
> https://gist.github.com/snoyberg/5b244331533fcb614523
>
> You give it three arguments on the command line:
>
> * LTS version, e.g. 1.14
> * Name of package being checked
> * true == only include dependencies of the library and executable,
> anything else == include test and benchmark dependencies as well
>
> If that's useful, I can package that up and put it on Hackage.
>
> Michael
>
>
> This is very helpfulness, thanks! There is a bootstrapping issue, though,
> which is, I imagine, why both Miëtek and I have been writing much more bash
> than we'd like. But perhaps this becomes part of a cabal-install-like
> bootstrap.sh script to get things going.
>
> Anthony
>

Oh, that's actually a great idea. What if we had a program that:

1. takes a set of packages that needs to be installed, and an LTS version
2. computes the dependency tree
3. writes out a shell script (possibly batch program?) to wget, tar xf, and
runghc Setup.hs in the correct order to get all of those packages installed

As you can tell from the program I just threw together, stackage-types
supports this kind of thing pretty trivially.

Michael
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