Prototype nix expression generation

There are some limitations to this implementation:

1. Using `runCommand` means this will re-run any time anything changes in the
repo. The solution is to use the existing import detection to make a list of
source files, and put that into a `stdenv.mkDerivation`, which I'll do next.

2. The `NeatInterpolation` usage is ugly. The templated nix code should be
extracted into its own file, such as `Biz/Bild/Builder.nix`.

3. I'm not actually calling it yet. The ideal thing would be to call
`nix-instantiate`, get the output drv path, and then call `nix-store --realise`
on that. To do that I need to refactor my `proc` function to return stdout to
the calling function, and I should probably just make helper functions like
`nixInstatiate :: Target -> IO DrvPath` and `nixStoreRealise :: DrvPath ->
NixStorePath`, or something like that.

1 files changed, 5 insertions, 0 deletions

diff --git a/Biz/Bild/Example.hs b/Biz/Bild/Example.hs
new file mode 100644
index 0000000..f812707
--- /dev/null
+++ b/Biz/Bild/Example.hs
@@ -0,0 +1,5 @@
+-- : out example
+module Biz.Bild.Example where
+
+main :: IO ()
+main = print "hi"