Add flake for dev environment on nix

Author: fidgetingbits

.envrc

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

.gitignore

@@ -1,3 +1,4 @@
+/.direnv/
 /.make-work/
 /.metals/
 /.vscode-test/

README.md

@@ -59,6 +59,39 @@ When working with WSL, the host vscode instance connects to a vscode server on t
 - If you're adding language support to `vscode-parse-tree`, you need to clone that as well, build it, and link it into the `vscode-server` extension folder: `ln -s ~/your/code/vscode-parse-tree ~/.vscode-server/extensions/parse-tree` for instance.
 - If you get errors about needing to install the `Remote-WSL` extension, you might need to manually delete the extension from the host side and try again.
 
+### Developing on Nix
+
+There is a `.envrc` file included to trigger the flake usage.
+
+As of 2023-09 emscripten seems to have some issues related to caching folder on
+Nix. After running the `yarn` command you will see something like this:
+
+```
+$ yarn add -D tree-sitter-nix
+[SNIPPED]
+OSError: [Errno 30] Read-only file system: '/nix/store/ykh9rm7z5mr248hsc408zr1csh6ss0vz-emscripten-3.1.42/share/emscripten/cache/symbol_lists.lock'
+make: *** [Makefile:63: vendor/web-tree-sitter/0.20.4/README.md] Error 1
+error Command failed with exit code 2.
+```
+
+In order to work around that error you will have to run the commands included below. Note the `/nix/store/` path comes from the error above.
+
+```bash
+$ cp -R /nix/store/ykh9rm7z5mr248hsc408zr1csh6ss0vz-emscripten-3.1.42/share/emscripten/cache/ ~/.emscripten_cache
+$ chmod u+rwX -R ~/.emscripten_cache
+$ export EM_CACHE=~/.emscripten_cache
+$ yarn add -D ...
+```
+
+See https://github.com/NixOS/nixpkgs/issues/139943 for background on this
+issue.
+
+In order to run `yarn compile` it will attempt to run `npx tree-sitter` which
+will fail. You can use `steam-run` instead:
+
+`steam-run yarn compile`
+
+
 ### Updating `web-tree-sitter`
 
 We build a custom version of `web-tree-sitter` to ensure that we can always use the latest version and fix any problems as they come up.

flake.lock

@@ -0,0 +1,27 @@
+{
+  description = "A Nix-flake-based Node.js development environment";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+
+  outputs = { self, nixpkgs }:
+    let
+      overlays = [
+        (final: prev: rec {
+          nodejs = prev.nodejs-18_x;
+          pnpm = prev.nodePackages.pnpm;
+          yarn = (prev.yarn.override { inherit nodejs; });
+        })
+      ];
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import nixpkgs { inherit overlays system; config.allowUnfree = true; };
+      });
+    in
+    {
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [ node2nix nodejs pnpm yarn emscripten python310 steam-run];
+        };
+      });
+    };
+}