enable kakoune, spruce up elm and nix vim setups

nix/home.nix

@@ -28,6 +28,26 @@ let
     };
   };
 
+  elm-vim = pkgs.vimUtils.buildVimPlugin {
+    name = "elm-vim";
+    src = pkgs.fetchFromGitHub {
+      owner = "ElmCast";
+      repo = "elm-vim";
+      rev = "4b71facd77297cb33bbb3b14894676cff0a9bd1d";
+      sha256 = "1kxkjm6fzmircg5gh7w2bmvjgk8ly5vvq9l31m4p6ql48azg2ilc";
+    };
+  };
+
+  vim-nix = pkgs.vimUtils.buildVimPlugin {
+    name = "vim-nix";
+    src = pkgs.fetchFromGitHub {
+      owner = "LnL7";
+      repo = "vim-nix";
+      rev = "d733cb96707a2a6bdc6102b6d89f947688e0e959";
+      sha256 = "12k2gwm8b1n02361gpjhsldql99yd7qsh80a3lbwc5c5gz5j8jsb";
+    };
+  };
+
 in {
   home.packages = with pkgs; [
     git-plan
@@ -152,6 +172,17 @@ in {
     };
   };
 
+  programs.kakoune = {
+    enable = true;
+    config = {
+      numberLines = {
+        enable = true;
+        highlightCursor = true;
+        relative = true;
+      };
+    };
+  };
+
   programs.neovim = {
     enable = true;
     vimAlias = true;
@@ -162,6 +193,8 @@ in {
       alchemist-vim
       vimtex
       vim-elixir
+      elm-vim
+      vim-nix
       vim-airline
       rainbow
       vim-signify
@@ -227,7 +260,7 @@ in {
 
       " LanguageClient-neovim
       let g:LanguageClient_serverCommands = {
-        \ 'elm': ['elm-language-server', '--stdio'],
+        \ 'elm': ['elm-language-server'],
         \ 'javascript': ['flow', 'lsp'],
         \ 'javascript.jsx': ['flow', 'lsp'],
         \ 'javascriptreact': ['flow', 'lsp'],