functy

Language support for functy — a small imperative language whose statement layer is functy's own (func/var/if/for/return) and whose expressions are real HCL expressions. functy source files use the .cty extension.

Features

• Syntax highlighting — statement keywords, function declarations, type annotations, and shared HCL-style expression syntax (strings with ${} / %{} interpolation, heredocs, numbers, operators, and function calls).
• Editing — // and # line comments, /* */ block comments, bracket matching, auto-closing pairs, and indentation.
• Outline — func, const, var, type, and test declarations appear in the Outline view, breadcrumbs, sticky scroll, and "Go to Symbol" (⇧⌘O). Namespace-local (_-prefixed) declarations are listed too, marked private.
• Namespaces — a namespaced file's declarations nest under its namespace node, so breadcrumbs and sticky scroll keep telling you which namespace you are editing (math.cty > acme::math > double) — the fact that matters, since a namespace changes the registered name of every function in the file. The namespace declaration and qualified calls (acme::math::double(21)) are highlighted, and a qualified name selects as a single word (double-click, ⌘D, word motions).
• Snippets — namespace, func, _func, funcret, if, ifelse, forin, forc, while, switch, trycatch, test, var, const, type.
• Commands — functy: Run File (functy run) and functy: Check File (functy check), with output in the functy output channel. Errors (including runtime errors) land in the Problems panel at their source location.
• Check on save — .cty files are type-checked on save by default (a side-effect-free functy check); toggle with functy.checkOnSave. For live checking as you type, enable functy.checkOnType (opt-in).
• Workspace — functy: Check Workspace and functy: Format Workspace commands, plus a functy task provider (check / test / fmt) for tasks.json.
• Get Started — a walkthrough (Help → Welcome) and functy: Open Sample File to try everything on a ready-made example.
• REPL — functy: Start REPL opens functy repl with the active file loaded; functy: Send Selection to REPL (also on the editor context menu) sends the selection, or the current line, to the running REPL.
• Evaluate Selection — functy: Evaluate Selection evaluates the selection (or current line) via functy eval and shows the result inline.
• Run with Arguments — functy: Run with Arguments… prompts for an entry function and arguments, then runs.
• Formatting — Format Document / format-on-save backed by functy fmt.
• Testing — co-located test "…" { … } blocks appear in the native Test Explorer, run via functy test --json. println() output and per-test results show in the Test Results view; a running test can be cancelled. Continuous run re-runs the affected tests when their file is saved.

Requirements

The extension shells out to the functy binary, and requires functy 0.9.0 or newer (it relies on eval, symbols, check --json -, and the --json reports). It warns on startup if the binary is missing or too old.

The namespace features degrade cleanly rather than requiring a newer binary: the syntax highlighting and word selection are static, and the outline's namespace and private markers come from optional symbols --json fields that an older functy simply omits. They light up once the binary supports namespaces.

Install it on macOS with Homebrew:

brew install tsarna/tap/functy

…or on any platform with Go:

go install github.com/tsarna/functy/cmd/functy@latest

By default the extension runs functy from your PATH. Point it elsewhere with the functy.path setting.

Settings

Format-on-save uses the standard editor.formatOnSave setting.

License

MIT © Tyler C. Sarna