add nix flake (#117)

adds:
 - a flake that:
   - has a devshell with the packages:
     - `cargo`
     - `rustc`
     - `git`
   - can build goboscript from `default.nix`
- a vscode settings entry that lists the added flake as the desired nix
environment
 - a gitignore entry for the `nix build` output directory (`./result`)
 - a `default.nix` file that contains the goboscript package

Author: aspizu

.gitignore

@@ -4,6 +4,7 @@
 /playground
 node_modules
 site
+/result
 # Added by goreleaser init:
 dist/
 .intentionally-empty-file.o

.vscode/settings.json

@@ -5,5 +5,6 @@
         "./Cargo.toml",
         "./Cargo.toml"
     ],
-    "rust-analyzer.showUnlinkedFileNotification": false
+    "rust-analyzer.showUnlinkedFileNotification": false,
+    "nixEnvSelector.nixFile": "${workspaceRoot}/flake.nix"
 }

default.nix

@@ -0,0 +1,18 @@
+{ lib, rustPlatform }:
+
+rustPlatform.buildRustPackage {
+  pname = "goboscript";
+  version = "3.0.0";
+
+  src = ./.;
+
+  cargoLock = {
+    lockFile = ./Cargo.lock;
+  };
+
+  meta = {
+    description = "Scratch compiler";
+    homepage = "https://github.com/aspizu/goboscript";
+    license = lib.licenses.mit;
+  };
+}

flake.lock

@@ -0,0 +1,23 @@
+{
+  description = "Scratch compiler";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = inputs@{ self, nixpkgs, flake-utils, ... }:
+  flake-utils.lib.eachSystem [ "x86_64-linux" ] (system: let
+    pkgs = nixpkgs.legacyPackages.${system};
+  in rec {
+    packages.goboscript = pkgs.callPackage ./default.nix { };
+
+    legacyPackages = packages;
+
+    defaultPackage = packages.goboscript;
+
+    devShell = pkgs.mkShell {
+      buildInputs = with pkgs; [ cargo rustc git ];
+    };
+  });
+}