[Nix-dev] How to add tools to a nix-shell environment for haskell development?

[Michael Alan Dorman]

In developing a haskell library, I would like to be able to maintain
both a default.nix (that represents the library dependencies, etc.), and
then have a shell.nix that adds things to it in order to build a
development environment---specifically some build tools, hasktags,
hlint, etc.

http://www.cse.chalmers.se/~bernardy/nix.html describes more or less
exactly what I would like in the "Per-Project Configuration" section (I
believe it's actually pulled from
https://gist.github.com/JLimperg/82019d5603df5021603a)...but predates
the haskell-ng work, and does not seem entirely compatible with it.

I wondered if anyone had any suggestions for how it could be made to
work?  This is the only example I've found of what seems to me a fairly
obvious development setup.

Mike.