Coco Programming Language for Visual Studio Code

The VS Code Coco Programming Language extension provides language support for the Coco programming language, including syntax highlighting, real-time error diagnostics, Go to Definition and context-aware completion.

Compatibility

v0.4.2 targets Coco 0.9.2 with PISA 0.8.0 — what coco nut init writes and what new projects use. The pre-0.6 vocabulary (persistent / ephemeral / readonly qualifiers, state persistent: blocks, the Receiver and State superglobals) is no longer supported; sources still written that way get highlighting for the parts they share with 0.9.2 and no diagnostics.

Within the modern syntax the extension still respects your target: the checks that depend on it read [target.pisa] version from the coco.nut next to your source, so a 0.7.1 project is told that payer, Environment.StorageResult() and the actor methods are not available to it, and is not told that Environment.VolumeAvailable() has gone. With no coco.nut in the directory the extension assumes 0.8.0.

What it checks

The language server reads your whole module — every .coco file next to the one you are editing that declares the same coco <Module> — plus its coco.nut, and reports:

Area	Examples
State qualifiers	endpoint GetName() that observes state must say static; an omitted qualifier means pure, not static. Requirements propagate through called functions, asset methods and cross-logic interface calls.
enlist endpoints	endpoint enlist … no longer compiles as of Coco 0.9.2, on any PISA target: delete the endpoint, or make it dynamic and guard it.
payer clause (PISA 0.8.0)	mutate v -> M.Logic.f payer Logic | Sender | Actor(id) — rejected on observe, on actor state, and on pre-0.8.0 targets.
Actor methods (PISA 0.8.0)	Actor(id).Exists(), .HasSigned(), .Param(name: …) — unknown methods, wrong arity, wrong argument names and types, and the (exists) <- return-capture names.
Environment	Environment.StorageResult(account_id, payer_id) on 0.8.0; VolumeCapacity() / VolumeAvailable() flagged as removed there, and still accepted below it.
Superglobal arguments	Since Coco 0.9.1 a labelled or bare-variable argument to Environment, Builtins or an Actor method must use the name declared at its position — a bare identifier supplies its own name, so Builtins.Sha256(blob) is wrong where data is declared. Literals, casts and Sender need no label.
Named outputs	Since Coco 0.9.2 (timestamp) <- Environment.Timestamp() works on Environment, Invocation, Builtins and asset calls too. The captured names must be the declared output names, in order and all of them — (added, removed) <- Environment.StorageResult(…).
Constants	Single-line const and grouped const: blocks (Coco 0.9.2) are known names, highlighted as constants.
Field-name shorthand	Person{name, age} is understood; a bare name that is not a field of the class is reported.
Reserved words	memory payer = ... or an argument named actor is caught before the compiler's Unrecognized token.
Atomic storage	mutate v -> M.Logic.someMap is rejected — maps, arrays and classes in state can only be moved with a mutate block and disperse. A map can't be gathered back out of storage, and neither can anything that holds one in its field tree. Dispersing a map works again as of 0.9.2, and merges into the stored map.
Asset methods	Names, arities, argument labels and output names, checked against the compiler's own table (note there is no asset.Define — assets are created through Cocolab's create).
Types and members	class/event literal fields, field access, f-string expressions, emit payloads, state paths, undefined variables.

Supported files

File	Language id	What you get
*.coco	coco	Syntax highlighting, diagnostics, Go to Definition, semantic tokens, completion
coco.nut / *.nut	coco_nut	Syntax highlighting for the project manifest
*.lab	cocolab	Syntax highlighting for Cocolab REPL scripts, including grant/wipe/get storage_mutate

Install from the Extension Marketplace

This extension can be installed from the Visual Studio Code Extension Marketplace here.

Install from a VSIX

A .vsix files comes bundled with every release and can be downloaded from here.

Alternatively, it can be built from this repository source with the following command (requires NPM) resulting in the creation of a file named a file coco-v*.*.*.vsix with the release version.

npm run package

However, you obtain the .vsix file, it can then be used to install the extension to Visual Studio Code using the following command. Read more here for other ways to install from a VSIX

code --install-extension coco.vsix

Development

npm install             # one manifest, one lockfile, no nested workspaces
npm run typecheck       # tsc --noEmit over client/src and server/src
npm run bundle          # esbuild -> dist/extension.js + dist/server.js
npm run compile         # typecheck + bundle
npm run lint            # eslint, flat config in eslint.config.mjs
npm test                # run the fixtures through the bundled language server
npm run test:compile    # build every fixture project with the real `coco` compiler
npm run verify          # everything above, in order — what CI runs
npm run test:scan <dir> # scan an external tree of .coco files for false positives
npm run package         # cocolang-<version>.vsix

esbuild produces what ships. dist/extension.js and dist/server.js are the only two JavaScript files in the .vsix; the LSP libraries are inlined and vscode is the sole external. TypeScript is used for type checking only, which is why npm test runs against dist/server.js — the suite exercises the artifact users install. Press F5 to launch a development window; the watch task runs esbuild and tsc --watch side by side.

The extension re-implements a slice of the compiler's checks in TypeScript, so the suite is built around agreeing with coco rather than with itself:

Fixture group	Contract
test/fixtures/valid/	Every feature of Coco 0.9.2 / PISA 0.8.0, in its correct form. No diagnostics allowed.
test/fixtures/corpus/	Five complete modules of realistic Coco — a token ledger, a native asset, a CRUD registry, cross-logic interfaces and participant queries. No diagnostics allowed.
test/fixtures/invalid/	One mistake per file. Each // EXPECT: <text> must be matched by a diagnostic, and nothing else may be reported.
test/fixtures/legacy/	The same, against a coco.nut targeting PISA 0.7.1, so the version gates are exercised in both directions.

Every project under valid/ and corpus/ is compiled by npm run test:compile, which is what keeps "the language server stays silent on this" honest. That step skips itself when coco is not on PATH.

Feedback and Issues

If you encounter any issues with the Coco Programming Language extension or have suggestions for improvements, please check the extension's GitHub repository for issue tracking. You can open a new issue to report problems or submit feature requests.