Add development environment

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -2,3 +2,4 @@
 /pkg
 Cargo.lock
 
+/.direnv

flake.nix

@@ -0,0 +1,58 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    systems.url = "github:nix-systems/default";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+
+    # Dev tools
+    treefmt-nix.url = "github:numtide/treefmt-nix";
+  };
+
+  outputs = inputs: inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+    systems = import inputs.systems;
+    imports = [
+      inputs.treefmt-nix.flakeModule
+    ];
+    perSystem = { config, self', pkgs, lib, system, rust-overlay, ... }:
+      let
+        rust-toolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+      in {
+        _module.args.pkgs = import inputs.nixpkgs {
+          inherit system;
+          overlays = [ (import inputs.rust-overlay) ];
+        };
+
+        # Rust dev environment
+        devShells.default = pkgs.mkShell {
+          inputsFrom = [
+            config.treefmt.build.devShell
+          ];
+          shellHook = ''
+            # For rust-analyzer 'hover' tooltips to work.
+            export RUST_SRC_PATH=${rust-toolchain.availableComponents.rust-src}
+            export PATH=~/.cargo/bin:$PATH
+          '';
+          nativeBuildInputs = with pkgs; [
+            rust-toolchain
+            rust-analyzer
+          ];
+
+          buildInputs = with pkgs; [
+            pkg-config
+            openssl
+          ];
+        };
+
+        # Add your auto-formatters here.
+        # cf. https://numtide.github.io/treefmt/
+        treefmt.config = {
+          projectRootFile = "flake.nix";
+          programs = {
+            nixpkgs-fmt.enable = true;
+            rustfmt.enable = true;
+          };
+        };
+      };
+  };
+}

rust-toolchain.toml

@@ -0,0 +1,5 @@
+[toolchain]
+channel = "nightly-2024-01-24"
+components = [ "clippy", "rustfmt", "rust-src" ]
+targets = [ "wasm32-unknown-unknown" ]
+profile = "minimal"