fix: Replace implicit NIX_PATH pinning with flake.lock

Author: sshine

.envrc

@@ -1 +1 @@
-use nix
+use flake

default.nix

@@ -1,6 +1,4 @@
-let
-  # Use nixpkgs available on the system
-  pkgs = import <nixpkgs> {};
+{ pkgs, ... }: let
   haskellDependencies = with pkgs.haskellPackages; [
     stack
     cabal-install
@@ -16,15 +14,5 @@ let
     root = ./.;
     modifier = drv: addBuildTools drv haskellDependencies;
   };
-
-  # Extend the build environment with pre-commit installed and activated
-  withPreCommitHook = old: {
-    nativeBuildInputs = (old.nativeBuildInputs or []) ++ [ pkgs.pre-commit ];
-    shellHook = (old.shellHook or "") + ''
-      if [ -d .git ]; then
-        pre-commit install --hook-type pre-push
-      fi
-    '';
-  };
 in
-  package.overrideAttrs withPreCommitHook
+  package

flake.lock

@@ -0,0 +1,15 @@
+{
+  description = "Opcode types for Ethereum Virtual Machine (EVM)";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+  };
+
+  outputs = inputs:
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [ "x86_64-linux" "aarch64-darwin" ];
+      perSystem = { config, self', pkgs, ... }: {
+        packages.default = import ./default.nix { inherit pkgs; };
+      };
+    };
+}