README: add example usage

README.md

@@ -7,3 +7,95 @@ Customizations include things such as:
 - Toggling compile-time features.
 - Adding external plugins, either baking them in statically or using dynamic linking.
 - Cross-compiling for various architectures.
+
+### Example usage
+
+```nix
+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  inputs.nix-sqlite = "git+https://git.pvv.ntnu.no/mugiten/nix-custom-sqlite.git?ref=main";
+  inputs.nix-sqlite.inputs.nixpkgs.follows = "nixpkgs";
+
+  outputs = { self, nixpkgs, nix-sqlite }: {
+    devshells.x86_64-linux.default = let
+      pkgs = nixpkgs.legacyPackages.x86_64-linux;
+      customSqlite = nix-sqlite.mkSqlite {
+        # This lets you specify which `pkgs` instance to build from
+        pkgs = pkgs;
+
+        # This is particularly useful if you want to build a cross-compiled sqlite:
+        # pkgs = import nixpkgs {
+        #   allowUnfree = true;
+        #   localSystem = "x86_64-linux";
+        #   crossSystem = lib.systems.examples.aarch64-android-prebuilt;
+        # };
+
+        # By default, we toggle on a bunch of `ENABLE_<OPTION>` feature flags.
+        # If you'd rather want to start configuring from nothing, only enabling the
+        # stuff you need, you can set this to true and enable the missing pieces in
+        # `features`.
+        enableMinimal = true;
+
+        # Enabling this will turn on a list of features flags that are useful for debugging.
+        enableDebug = false;
+
+        # Enabling this will add libraries 'ncurses' and 'readline' to the sqlite cli executable.
+        enableInteractive = true;
+
+        # Setting this to false will make it so that the source code is not amalgamated before
+        # compilation. See https://sqlite.org/amalgamation.html for more details about what
+        # this entails.
+        amalgamate = false;
+
+        # This option lets you enable and disable compile time feature flags for SQLite.
+        # See https://sqlite.org/compile.html for a total list of available options.
+        #
+        # Please note that all `SQLITE_` prefixes have been stripped from the options, so
+        # you need to take this into account when translating from the docs to nix code.
+        features = {
+          ENABLE_FTS5 = true;
+          ENABLE_ICU = true;
+          SOUNDEX = false;
+        };
+
+        # This option lets you bake in both static and dynamic extensions at compile time,
+        # resulting in the sqlite binary eagerly loading the extension at startup automatically
+        # without needing to `.load` them.
+        #
+        # Static extensions will be baked into the sqlite library/executable itself, while
+        # dynamic extensions will be added to sqlite's rpath.
+        extensions = [
+          {
+            # Path to the .a or .so file that contains the SQLite extension.
+            library = "${pkgs.my-custom-extension}/lib/my-custom-extension.a";
+
+            # The symbol pointing to the function that initializes the extension
+            init = "sqlite3_init_mycustomextension";
+
+            # The symbol point to the destructor function of the extension (if there is any).
+            shutdown = "sqlite3_shutdown_mycustomextension";
+          }
+
+          {
+            library = "${pkgs.my-custom-extension}/lib/my-other-extension.so";
+            init = "sqlite3_init_myotherextension";
+          }
+        ];
+      };
+    in pkgs.stdenv.mkShell {
+      env.AMALGAMATION_DIR = "${customSqlite.amalgamation}/";
+
+      buildInputs = [
+        customSqlite.sqlite
+        customSqlite.sqlite-static
+      ];
+
+      packages = [
+        customSqlite.sqlite-cli
+      ];
+      ...
+    };
+  };
+}
+```