On 2015-03-25, at 11:40, Michael Snoyman
Every Stackage Nightly and LTS Haskell release has a YAML file[1] that provides a lot of information, included the exact versions of packages and package dependencies. The stackage-types[2] package provides the datatypes necessary to parse that YAML file. Putting those two together, it should be possible to write something that looks at a project's list of shallow package dependencies, and construct a list of precisely which package-version combinations are necessary to build the entire project, which I think is what you're saying you get from cabal freeze but not from the current cabal.config on stackage.org.
If I understand correctly, the result should be equivalent to configuring `cabal-remote-repo` to point to a particular Stackage snapshot, running `cabal freeze`, and parsing its output. Halcyon already does this — the following command will ignore any constraints declared by the application, and instead use the newest versions of all dependencies available in the specified Cabal repository: ``` $ halcyon install http://github.com/mietek/hello-yesod --ignore-all-constraints --cabal-remote-repo=stackage-lts-latest:http://www.stackage.org/lts ``` However, this means we’re using Stackage in “exclusive” mode. I’d like to support using Stackage in “inclusive” mode, with `cabal-remote-repo` pointing to Hackage, and a Stackage-flavoured `cabal.config`. -- Miëtek https://mietek.io