Hi! Would you be so nice and dd ability to use environment variables within stack.yam configuration files? This would be a life saver in a situation when a big team develops a set of libraries and every person keeps these libraries in different places, so the environment variable would point where are the sources that should override packages from Hackage.

Another small topic is to add extra dependencies recursively - all packages found in folder X. In such use case we can easily override packages for development time without changing stack yams configuration and this (n combination with the above idea) is a very useful utility, portable across developer environments.

Thank you! :)