Add a Visual Studio Code extension

README.md

@@ -125,8 +125,8 @@ target/release/rcl fmt examples/tags.rcl
 
 RCL is usable and useful, well-tested, and well-documented. It is still pre-1.0,
 though backwards-incompatible changes have been rare in the past years. Syntax
-highlighting is available for major editors like Vim, Emacs, Helix, and Zed.
-RCL is a community project without commercial support.
+highlighting is available for major editors like Vim, Emacs, Helix, VSCode, and
+Zed. RCL is a community project without commercial support.
 
 ## Support RCL
 

build.rcl

@@ -17,12 +17,28 @@ let target_toml = contents => {
   contents = contents,
 };
 
+let target_json = contents => {
+  format = "json",
+  contents = contents,
+};
+
 {
   "Cargo.toml": target_toml(import "//Cargo.rcl"),
   "fuzz/Cargo.toml": target_toml(import "//fuzz/Cargo.rcl"),
   "grammar/tree-sitter-rcl/Cargo.toml": target_toml(
     import "//grammar/tree-sitter-rcl/Cargo.rcl",
   ),
+  "grammar/vscode/language-configuration.json": target_json(
+    import "//grammar/vscode/language-configuration.rcl",
+  ),
+  // TODO: Maybe instead of checking these generated json files
+  // in to the repository, we can just generate them at package build time.
+  "grammar/vscode/package.json": target_json(
+    import "//grammar/vscode/package.rcl",
+  ),
+  "grammar/vscode/rcl.tmLanguage.json": target_json(
+    import "//grammar/vscode/rcl.tmLanguage.rcl",
+  ),
   "grammar/zed/extension.toml": target_toml(
     import "//grammar/zed/extension.rcl",
   ),

docs/grammars.md

@@ -42,6 +42,26 @@ to use for highlighting, similar to scopes for Tree Sitter.
 
 [vim-groups]: https://vimhelp.org/syntax.txt.html#group-name
 
+## Visual Studio Code
+
+The `vscode` directory contains the Visual Studio Code plugin including TextMate
+grammar. The json version of the grammar is generated with <abbr>RCL</abbr>. The
+TextMate documentation has [a section on scope naming conventions][tm-scopes].
+Some helpful links:
+
+ * [TextMate language grammar documentation][tm-docs]
+ * [Helpful _lessons learned_ blog post][tm-lessons]
+ * [VSCode syntax highlighting docs][vscode-highlight]
+
+[tm-docs]:          https://macromates.com/manual/en/language_grammars
+[tm-scopes]:        https://macromates.com/manual/en/language_grammars#naming_conventions
+[tm-lessons]:       https://www.apeth.com/nonblog/stories/textmatebundle.html
+[vscode-highlight]: https://code.visualstudio.com/api/language-extensions/syntax-highlight-guide
+
+The Nix flake includes a <abbr>VSIX</abbr> extension package. To build it:
+
+    nix build .#vscode-extension
+
 ## Zed
 
 The `zed` directory contains the Zed plugin. This directory is the source of

docs/index.md

@@ -53,8 +53,8 @@ For an interactive demo in your browser, see <https://rcl-lang.org>.
 
 RCL is usable and useful, well-tested, and well-documented. It is still pre-1.0,
 though backwards-incompatible changes have been rare in the past years. Syntax
-highlighting is available for major editors like Vim, Emacs, Helix, and Zed.
-RCL is a community project without commercial support.
+highlighting is available for major editors like Vim, Emacs, Helix, VSCode, and
+Zed. RCL is a community project without commercial support.
 
 ## License
 

docs/syntax_highlighting.md

@@ -91,6 +91,19 @@ The directory `grammar/rcl.vim` contains support for highlighting in Vim.
 You can symlink the contents into your `~/.vim`, or use a plugin manager like
 Pathogen and symlink the directory into `~/.vim/bundle`.
 
+## Visual Studio Code
+
+The [Visual Studio Code extension][vscode-ext] is available from the Visual
+Studio marketplace.
+
+If you want to install a development version of the extension, the extension
+is developed in the main repository. See [the section in the grammars
+chapter][grammars-vscode] for how to build it, then install the extension using
+_Extensions: Install from <abbr>VSIX</abbr>…_ from the command panel.
+
+[vscode-ext]: https://marketplace.visualstudio.com/items?itemName=rcl-lang.rcl
+[grammars-vscode]: grammars.md#visual-studio-code
+
 ## Zed
 
 The [Zed extension](https://github.com/rcl-lang/zed-rcl) is available from the

flake.nix

@@ -158,7 +158,7 @@
 
           pythonSources = pkgs.lib.sourceFilesBySuffices ./. [ ".py" ".pyi" ];
 
-          rclTomlSources = pkgs.lib.sourceFilesBySuffices ./. [ ".rcl" ".toml" ];
+          rclGeneratedSources = pkgs.lib.sourceFilesBySuffices ./. [ ".rcl" ".toml" ".json" ];
 
           goldenSources = ./golden;
 
@@ -412,6 +412,29 @@
             RUSTFLAGS = "-C instrument-coverage -C link-dead-code -C debug-assertions";
           });
 
+          vscode-extension = pkgs.stdenv.mkDerivation {
+            pname = "rcl-vscode";
+            inherit version;
+            src = ./grammar/vscode;
+            nativeBuildInputs = [ pkgs.vsce ];
+            doCheck = false;
+            buildPhase =
+              ''
+              # We want only the json files, not the RCL sources. Also, the
+              # `vsce` tool complains if there is no LICENSE file, so copy it
+              # in.
+              rm *.rcl
+              cp ${./LICENSE} LICENSE
+
+              # TODO: The VSIX file is just a zip file of the directory, with
+              # two additional XML files in it. One of them may be kind of a
+              # pain to generate, but on the other hand, we could skip nodejs
+              # if we build the zip file ourselves.
+              mkdir -p $out
+              vsce package --no-dependencies --out $out/rcl-${version}.vsix
+              '';
+          };
+
         in
           rec {
             devShells.default = pkgs.mkShell {
@@ -503,14 +526,14 @@
                 "check-fmt-rcl"
                 { buildInputs = [ debugBuild ]; }
                 ''
-                rcl format --check ${rclTomlSources}/**.rcl | tee $out
+                rcl format --check ${rclGeneratedSources}/**.rcl | tee $out
                 '';
 
               buildRcl = pkgs.runCommand
                 "check-rcl-build"
                 { buildInputs = [ debugBuild ]; }
                 ''
-                rcl build --check --directory ${rclTomlSources} | tee $out
+                rcl build --check --directory ${rclGeneratedSources} | tee $out
                 '';
 
               # Build documentation with warnings denied, so the check fails if
@@ -545,7 +568,7 @@
             };
 
             packages = {
-              inherit fuzzers-coverage rcl pyrcl pyrcl-wheel treeSitterRcl website;
+              inherit fuzzers-coverage rcl pyrcl pyrcl-wheel treeSitterRcl vscode-extension website;
 
               default = rcl;
               binaries = rcl-binaries;
@@ -561,7 +584,7 @@
                 RCL_BIN=${coverageBuild}/bin/rcl python3 ${goldenSources}/run.py
 
                 # Also run `rcl build` to make sure we cover that part of the application.
-                ${coverageBuild}/bin/rcl build --check --directory ${rclTomlSources}
+                ${coverageBuild}/bin/rcl build --check --directory ${rclGeneratedSources}
 
                 # Copy in the .profraw files from the tests.
                 cp ${coverageBuild}/prof/*.profraw .

grammar/vscode/CHANGELOG.md

@@ -0,0 +1,2 @@
+Changes to the VSCode extension are listed as part of
+[the regular RCL changelog](https://docs.ruuda.nl/rcl/changelog/).

grammar/vscode/README.md

@@ -0,0 +1,26 @@
+# The RCL Configuration Language
+
+This extension provides support for the [RCL configuration language][rcl-lang].
+The RCL configuration language is a domain-specific language that extends json
+into a simple, gradually typed, functional language that resembles Python and
+Nix. It reduces configuration boilerplate by enabling abstraction and reuse.
+
+ * [Website and online playground][rcl-lang]
+ * [General documentation][docs]
+
+[rcl-lang]: https://rcl-lang.org/
+[docs]: https://docs.ruuda.nl/rcl/
+
+# About
+
+This extension is official. It is developed upstream as part of the main
+repository, in the `grammar/vscode` directory. It is available from the
+following mirrors:
+
+ * <https://codeberg.org/ruuda/rcl>
+ * <https://github.com/ruuda/rcl>
+
+For hacking on the extension itself, see the [Grammars][docs-grammars] chapter
+of the documentation.
+
+[docs-grammars]: https://docs.ruuda.nl/rcl/grammars/#visual-studio-code

grammar/vscode/language-configuration.json

@@ -0,0 +1,12 @@
+{
+  "autoCloseBefore": ":.,",
+  "autoClosingPairs": [
+    {"close": "}", "open": "{"},
+    {"close": "]", "open": "["},
+    {"close": ")", "open": "("},
+    {"close": "\"", "notIn": ["string"], "open": "\""}
+  ],
+  "brackets": [["{", "}"], ["[", "]"], ["(", ")"]],
+  "comments": {"lineComment": "//"},
+  "surroundingPairs": [["\"", "\""], ["(", ")"], ["[", "]"], ["{", "}"]]
+}

grammar/vscode/language-configuration.rcl

@@ -0,0 +1,29 @@
+// RCL -- A reasonable configuration language.
+// Copyright 2025 Ruud van Asseldonk
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// A copy of the License has been included in the root of the repository.
+
+let brackets = [
+  ["{", "}"],
+  ["[", "]"],
+  ["(", ")"],
+];
+
+{
+  comments = { lineComment = "//" },
+  brackets = brackets,
+  autoClosingPairs = [
+    for b in brackets: { open = b[0], close = b[1] },
+    { open = "\"", close = "\"", notIn = ["string"] },
+  ],
+  autoCloseBefore = ":.,",
+  surroundingPairs = {
+    for b in brackets: b,
+    ["\"", "\""],
+  },
+  // TODO: Add `folding`?
+  // TODO: Add `wordPattern`?
+  // TODO: Add `indentationRules`? I can't make sense of the example regex.
+}

grammar/vscode/package.json

@@ -0,0 +1,34 @@
+{
+  "author": {"name": "Ruud van Asseldonk"},
+  "categories": ["Programming Languages"],
+  "contributes": {
+    "configurationDefaults": {
+      "[rcl]": {"editor.insertSpaces": true, "editor.tabSize": 2}
+    },
+    "grammars": [
+      {
+        "language": "rcl",
+        "path": "./rcl.tmLanguage.json",
+        "scopeName": "source.rcl"
+      }
+    ],
+    "languages": [
+      {
+        "aliases": ["RCL"],
+        "configuration": "./language-configuration.json",
+        "extensions": [".rcl"],
+        "id": "rcl"
+      }
+    ]
+  },
+  "description": "Support for the RCL configuration language.",
+  "displayName": "RCL",
+  "engines": {"vscode": "^1.100.0"},
+  "homepage": "https://rcl-lang.org",
+  "license": "Apache-2.0",
+  "name": "rcl",
+  "preview": true,
+  "publisher": "rcl-lang",
+  "repository": {"type": "git", "url": "https://github.com/ruuda/rcl.git"},
+  "version": "0.13.0"
+}

grammar/vscode/package.rcl

@@ -0,0 +1,43 @@
+let root = import "//Cargo.rcl";
+
+{
+  name = "rcl",
+  displayName = "RCL",
+  description = "Support for the RCL configuration language.",
+  // TODO: Remove the preview designation once the extension is ready.
+  preview = true,
+  version = root.package.version,
+  license = root.package.license,
+  author = { name = "Ruud van Asseldonk" },
+  publisher = "rcl-lang",
+
+  engines = { vscode = "^1.100.0" },
+  categories = ["Programming Languages"],
+
+  repository = { type = "git", url = "https://github.com/ruuda/rcl.git" },
+  homepage = "https://rcl-lang.org",
+
+  contributes = {
+    languages = [
+      {
+        id = "rcl",
+        aliases = ["RCL"],
+        extensions = [".rcl"],
+        configuration = "./language-configuration.json",
+      },
+    ],
+    grammars = [
+      {
+        language = "rcl",
+        scopeName = "source.rcl",
+        path = "./rcl.tmLanguage.json",
+      },
+    ],
+    configurationDefaults = {
+      "[rcl]": {
+        "editor.tabSize": 2,
+        "editor.insertSpaces": true,
+      },
+    },
+  },
+}