i’ve adapted to a nixos only desktop and i’m facing new problems every day, lately i wanted to use kdevelop but it wasn’t able to import a normal ‘Makefile’based project. next i installed lots of packages somehow mentioned at . still that alone didn’t help so i ran:
kbuildsycoca4 is a utility which generates a cache of .desktop files and such to be used by programs. PovAddictemail@example.com recommended to set KDEDIRS correctly because when doing so running kbuildsycoca4 manually wouldn’t be neccessary.
not sure how to solve this problem correctly yet but in case i find out i will add it to this post.
in /etc/nixos/configuration.nix write:
environment.systemPackages = with pkgs; [ kde4.kdevelop ];
after nixos-rebuild kdevelop will have makefile and cmake support. however, at least for proper cmake support, needed when kdevelop should build the project, you will need to prepare a decent environment where all the needed programs and dependencies are listed, see 
another point which bugs me is that auto-completion doesn’t work correctly as there is no such thing as /usr/include on nixos as one might expect when coming from a different linux distribution. didn’t find a solution here yet either…
update: 30.06.2012 – found a nice solution to this problem, just have a look at  as well