Add installation instructions for nix flake and home-manager

README.md

@@ -25,6 +25,56 @@ $ go build -o ~/go/bin/snippets-ls main.go
 
 Don't forget to append `~/go/bin` to your `$PATH`.
 
+### Install via [nix flake](https://nixos.wiki/wiki/Flakes) with [home-manager](https://nix-community.github.io/home-manager/index.html#ch-nix-flakes)
+
+Include the following in the `inputs` of `flake.nix` for `home-manager`:
+```nix
+inputs = {
+  # load compatible nixpkgs and home-mananger repos; they need not be 23.05
+  nixpkgs = { url = "github:nixos/nixpkgs/nixos-23.05"; };
+  home-manager = {
+    url = "github:nix-community/home-manager/release-23.05";
+    inputs.nixpkgs.follows = "nixpkgs";
+  };
+  # ...
+  snippets-ls = {
+    url = "github:quantonganh/snippets-ls";
+    inputs.nixpkgs.follows = "nixpkgs";
+  };
+};
+```
+There are in turn many suitable ways to configure the `outputs` of `flake.nix`.  One option is to use an overlay with something like
+```nix
+outputs = inputs:
+  with inputs;
+  let
+    system = "x86_64-linux"; # or other system as applicable (such as "x86_64-darwin")
+    pkgs = import nixpkgs {
+      inherit system;
+      overlays = [ pkgs_overlay ];
+    };
+    # ...
+    pkgs_overlay = final: prev: {
+      # ...
+      external.snippets-ls = snippets-ls.packages.${prev.system}.snippets-ls;
+    };
+  in {
+    homeConfigurations.YOUR-USER-NAME-HERE = home-manager.lib.homeManagerConfiguration {
+      inherit pkgs;
+      modules = [ ./home.nix ];
+    };
+  };
+};
+```
+The use of this overlay allows you to call this packages with `pkgs.external.snippets-ls`, such the list of packages in `home.nix` can look something like
+```nix
+home.packages = with pkgs; [
+  # ...
+  external.snippets-ls
+];
+```
+
+
 ## Usage
 
 Create your own snippets follow [VSCode syntax](https://code.visualstudio.com/docs/editor/userdefinedsnippets#_create-your-own-snippets). Alternatively, you can make use of [pre-existing](https://github.com/microsoft/vscode-go/blob/master/snippets/go.json) [sample](https://github.com/rust-lang/vscode-rust/blob/master/snippets/rust.json) for various programming languages.

flake.nix

@@ -1,40 +1,36 @@
 {
   description = "Snippet LSP for helix";
 
-  # Nixpkgs / NixOS version to use.
+  # nixpkgs version to use
   inputs.nixpkgs.url = "nixpkgs/nixos-21.11";
 
   outputs = { self, nixpkgs }:
     let
-
-      # to work with older version of flakes
+      # work with older version of flakes
       lastModifiedDate =
         self.lastModifiedDate or self.lastModified or "19700101";
 
-      # Generate a user-friendly version number.
+      # user-friendly version number
       version = builtins.substring 0 8 lastModifiedDate;
 
-      # System types to support.
+      # system types to support
       supportedSystems =
         [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
 
-      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
+      # helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'
       forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
 
-      # Nixpkgs instantiated for supported system types.
+      # nixpkgs instantiated for supported system types
       nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
 
     in {
-
-      # Provide some binary packages for selected system types.
+      # provide some binary packages for selected system types
       packages = forAllSystems (system:
         let pkgs = nixpkgsFor.${system};
         in {
           snippets-ls = pkgs.buildGoModule {
             pname = "snippets-ls";
             inherit version;
-            # In 'nix develop', we don't need a copy of the source tree
-            # in the Nix store.
             src = ./.;
 
             # This hash locks the dependencies of this package. It is
@@ -46,15 +42,15 @@
             # To begin with it is recommended to set this, but one must
             # remeber to bump this hash when your dependencies change.
             #vendorSha256 = pkgs.lib.fakeSha256;
-
             vendorSha256 =
               "sha256-zH8N6Bw1I+bFxBiXQtRL/Y2UyE4ix/kdlEsEuwPSZXs=";
 
+            # rename binary from go-lsp to snippets-ls
             postInstall = "mv $out/bin/go-lsp $out/bin/snippets-ls";
           };
         });
 
-      # Add dependencies that are only needed for development
+      # add dependencies that are only needed for development
       devShells = forAllSystems (system:
         let pkgs = nixpkgsFor.${system};
         in {
@@ -63,9 +59,6 @@
           };
         });
 
-      # The default package for 'nix build'. This makes sense if the
-      # flake provides only one package or there is a clear "main"
-      # package.
       defaultPackage =
         forAllSystems (system: self.packages.${system}.snippets-ls);
     };