Set up nix shell, aniseed

nix/aniseed.nix

@@ -0,0 +1,24 @@
+{pkgs, ...}: let
+  aniseed = pkgs.vimUtils.buildVimPluginFrom2Nix {
+    pname = "aniseed";
+    version = "v3.32.0";
+    src = pkgs.fetchFromGitHub {
+      owner = "Olical";
+      repo = "aniseed";
+      rev = "a7445c340fb7a0529f3c413eb99d3f8d29f50ba2";
+      sha256 = "sha256-KTNImPjifuoj0/ahuYcqMtutGgOR4XnYruv/JVjyrTk=";
+    };
+    meta.homepage = "https://github.com/Olical/aniseed";
+  };
+in
+  pkgs.stdenv.mkDerivation {
+    name = "init.vim";
+    phases = ["installPhase" "fixupPhase"];
+    installPhase = ''
+      mkdir $out
+      cat << EOF > $out/init.vim
+      set runtimepath+=${aniseed}
+      let g:aniseed#env = v:true
+      EOF
+    '';
+  }