Support add-source

[lukerandall]

We use a number of packages not on hackage, and would appreciate being able to use add-source to point to (for eg) a GitHub repo to add it as a source.

[rehno-lindeque]

This is by no means a solution, but see also #9

[mietek]

Thanks. This is planned as part of #4. See also #26 for a more concrete description.

[mietek]

Support for declaring sandbox sources is pending.

[mietek]

Declaring sandbox sources is now supported. You will need:

1. A .halcyon/sandbox-sources magic file:

   [email protected]:circuithub/circuithub-entities#0.0.28
   [email protected]:circuithub/circuithub-prelude#0.0.4
   [email protected]:circuithub/comparable-key
   [email protected]:circuithub/octopart#0.0.3
   [email protected]:circuithub/persistent-chunked
   [email protected]:circuithub/persistent-mysql-extra
   

2. A BUILDPACK_SSH_PRIVATE_KEY config var, for authenticating with GitHub:

   heroku config:set "BUILDPACK_SSH_PRIVATE_KEY=$( <~/.ssh/buildpack-ssh-private-key )"
   

As an example, my fork of tryhaskell now declares sandbox sources in this fashion, but using a public (HTTPS) git URL.

[mietek]

A more advanced, closed-source example, circuithub-api uses as many as 6 sandbox sources, plus additional dependencies, which cabal-install alone is unable to handle. (haskell/cabal#220, haskell/cabal#779). This includes OS libraries, such as libpcre, and executable-only Cabal packages, such as alex.

• See circuithub-api build log