Cabal cannot resolve dependencies for my Yesod website

[Philip White]

Hello, all,

I am trying to make the next big thing with Yesod -- but for now, just a Hello World website. After getting it running locally, I tried to integrate it with Circle CI, which has support for cabal-based Haskell projects.

Circle CI runs the following commands:
cabal sandbox init
cabal install --upgrade-dependencies --constraint="template-haskell installed" --dependencies-only --enable-tests

With this invocation, cabal cannot resolve dependencies no matter how I change the cabal config. If, however, I run just `cabal install`, everything works.

This cabal failure occurs both on a CircleCI host and my laptop exactly the same way, so I know it's not my environment.

I wrote a StackOverflow question with more details: http://stackoverflow.com/questions/31010999/cabal-cannot-resolve-dependencies-chooses-wrong-version-of-containers

The github repo, for ease of reproducing the problem: https://github.com/philipmw/yesod-website

I hope that someone on the list is able to help. Thanks.

-- 
Philip