fin language support

This experimental extension for Visual Studio Code enables language support for the fin plain-text accounting system.

Current features:

• Syntax highlighting for the journal format, as implemented by fin
• Diagnostics: what fin finds in the journal, in the Problems panel
• Formatting with fin format, so format-on-save works
• Ctrl-click an include path to open the file it names
• Outline view over org-mode style * headings
• Completion of account names, from the open directives of the journal

The highlighting, the outline and the completions work on their own; everything else needs the fin binary, see Configuration.

The extension is not published in the market place. For now, clone this repo and build it manually:

git clone https://github.com/sboehler/language-fin
cd language-fin
npm install
npx vsce package

With Nix the same package is built without a toolchain of your own, and without cloning first:

nix build github:sboehler/language-fin

Either way, install the VSIX file that comes out — in the repository, or under the result the Nix build links to:

code --install-extension result/language-fin-0.0.1.vsix

Configuration

Setting	What it does
fin.executable	The fin binary. A bare name is looked up on PATH. Defaults to fin.
fin.journal	The root journal, as a path relative to the workspace folder. See below.
fin.diagnostics.enable	Whether to check journals at all. Defaults to true.

With fin.journal set, journals are checked with fin balance over that file. That follows includes, so it also reports accounts booked to before they are opened, and balance assertions that do not hold. An error found in an included file is reported against that file.

Left empty, only the edited file is checked, with fin parse, which reports syntax errors alone. That is the safe default: an included fragment does not open the accounts it books to, so checking one on its own would invent errors.

fin reads from disk, so journals are checked when opened and when saved, not while being typed into.

Account names are completed from the open directives the journal holds, which the extension reads itself: with fin.journal set, from the root journal and everything it includes, and otherwise from the edited file, its includes, and every other .fin file in the workspace. An account is offered as soon as it is opened, before the file it is opened in has been saved.

Development

Requires Node.js 22 or later. A Nix flake is provided, so nix develop (or direnv allow) gets you a shell with the right toolchain.

npm install
npm run watch                # rebuild the bundle on change
npm run lint
npm test                     # grammar snapshots, then tsc, eslint and the VS Code tests
npm run test:grammar -- -u   # update the grammar snapshots after a change

The tests that drive fin are skipped unless FIN_TEST_BIN points at a built binary:

FIN_TEST_BIN=../fin/target/release/fin npm test

Press F5 to launch a VS Code window with the extension loaded.

Release Notes

0.0.1

Add syntax highlighting Add outline view