Add taffybar shell nix files

dotfiles/config/taffybar/cabal.project

@@ -0,0 +1 @@
+packages: . taffybar/

dotfiles/config/taffybar/imalison-taffybar.cabal

@@ -33,8 +33,6 @@ executable imalison-taffybar
                      , taffybar>=3.2.0
                      , transformers
                      , xdg-basedir
-                     , xmonad-contrib>=0.13
-                     , xmonad>=0.13
   default-language:    Haskell2010
 
 source-repository head

dotfiles/config/taffybar/shell.nix

@@ -0,0 +1,7 @@
+let
+  pkgs = import <nixpkgs> { overlays = [
+    (import ./taffybar/overlay.nix) (import ../xmonad/overlay.nix)
+  ]; };
+  source = pkgs.lib.sourceByRegex ./. ["taffybar.hs" "imalison-taffybar.cabal"];
+  imalison-taffybar = pkgs.haskellPackages.callCabal2nix "imalison-taffybar" source { };
+in pkgs.haskellPackages.shellFor { packages = _: [imalison-taffybar pkgs.haskellPackages.taffybar]; }