build: add nix flake

.envrc

@@ -0,0 +1,2 @@
+export DIRENV_WARN_TIMEOUT=2m
+use flake

.gitignore

@@ -2,3 +2,4 @@ target
 .vscode
 tests/*/npm
 lib/pkg
+.direnv

README.md

@@ -768,3 +768,18 @@ let output_result = transform(TransformOptions {
   specifier_mappings: None,
 }).await?;
 ```
+
+## Developing on DNT
+You'll need `Deno`, `rustup` and `Cargo`. If you're a [Nix](https://nixos.org/) user you can just run:
+```shell
+nix develop
+```
+in this folder to get a shell with all dependencies satisfied.
+You can then build DNT via:
+```shell
+deno task build
+```
+and run the tests after via
+```
+deno task test
+```

flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "Dnt dev";
+
+  nixConfig.bash-prompt = "[dnt-dev]> ";
+
+  inputs = {
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:NixOS/nixpkgs";
+  };
+
+  outputs = inputs@{ self, flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems =
+        [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      perSystem = { config, self', inputs', pkgs, ... }: {
+        # Per-system attributes can be defined here. The self' and inputs'
+        # module parameters provide easy access to attributes of the same
+        # system.
+
+        # NOTE: You can also use `config.pre-commit.devShell`
+        devShells.default = pkgs.mkShell {
+          shellHook = ''
+            echo 1>&2 "Welcome to the DNT development shell!"
+          '';
+          buildInputs = with pkgs; [
+            deno
+            rustup
+            cargo
+          ];
+        };
+      };
+    };
+}