Tree-sitter Grammar for Formaggio

A tree-sitter grammar for the Formaggio geospatial data pipeline language.

Expression blocks ({ ... }) are parsed as opaque nodes and delegated to tree-sitter-maparoni via language injection. YAML front matter is similarly injected as YAML.

Language Features

• YAML front matter between --- delimiters
• Pipelines with |> operator
• Variable assignments ($name = pipeline) and concatenation ($a + $b)
• Sections (### View: Name, ### Data Pipeline)
• Directives (@default, @view-id: identifier)
• Operations in four forms:
  • bare: all, parse_geojson, input_data
  • with expression block: fetch { "url" }, filter { expr }
  • with parameters: parse_json(path: "$.items", location: [...])
  • with parameters and block: sort(order: .descending) { expr }
• Map with lambda: map { item -> item |> set(.title) { expr } }
• If/then/else: if { condition } then { l -> pipeline } else { l -> pipeline }
• Comments: # line comment

Example

---
name: "Major Earthquakes"
category: "Global"
---

fetch { "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_month.geojson" }
|> parse_geojson
|> sort(order: .descending) { `mag` }
|> map { l ->
  l
  |> set(.title) { value('place') }
  |> set(.style) { fillColor(circle(`mag` * 5), gradient(`mag`, 'traffic', 5, 8)) }
}

### View: Nearby
@default
all
|> filter { distance(coordinate, currentLocation) <= 5000km }
|> sort { distance(coordinate, currentLocation) }

Development

# Install dependencies
npm install

# Generate the parser
npx tree-sitter generate

# Run tests
npx tree-sitter test

# Parse a file
npx tree-sitter parse example.formaggio

Using with Zed

To add Formaggio syntax highlighting to Zed, create a local extension that references this grammar.

1. Create the extension directory

Create a directory for your extension (e.g., ~/zed-formaggio/) with this structure:

zed-formaggio/
├── extension.toml
└── languages/
    └── formaggio/
        ├── config.toml
        ├── highlights.scm
        ├── injections.scm
        ├── indents.scm
        └── brackets.scm

2. extension.toml

id = "formaggio"
name = "Formaggio"
version = "0.1.0"
schema_version = 1
authors = ["Your Name"]
description = "Formaggio language support"

[grammars.formaggio]
repository = "file:///Users/you/Development/tree-sitter-formaggio"
rev = ""

Set repository to a file:// URL pointing at your local clone of this repo during development. For distribution, point it at the remote git URL and set rev to a commit hash.

3. languages/formaggio/config.toml

name = "Formaggio"
grammar = "formaggio"
path_suffixes = ["formaggio"]
line_comments = ["# "]
tab_size = 2

4. Copy query files

Copy the .scm files from this repo's queries/ directory into languages/formaggio/:

cp queries/highlights.scm languages/formaggio/
cp queries/injections.scm languages/formaggio/
cp queries/indents.scm languages/formaggio/
cp queries/brackets.scm languages/formaggio/

5. Install as a dev extension in Zed

In Zed, open the command palette and run zed: install dev extension, then select your zed-formaggio/ directory. Zed will build the grammar from source and load the extension.

After making changes, run zed: rebuild extensions to reload.

Expression highlighting via injection

Expression blocks delegate to tree-sitter-maparoni for highlighting. For this to work, you also need the maparoni grammar registered. Add it to your extension.toml:

[grammars.maparoni]
repository = "file:///Users/you/Development/tree-sitter-maparoni"
rev = ""

And create a minimal languages/maparoni/config.toml:

name = "Maparoni"
grammar = "maparoni"
path_suffixes = ["mpex"]

With corresponding query files from the tree-sitter-maparoni repo.

Grammar Structure

source_file
├── yaml_front_matter        → injected as YAML
└── body
    ├── section_header       ### View: Name
    ├── directive            @default, @view-id: value
    ├── variable_assignment  $name = pipeline
    └── pipeline
        ├── operation        name / name { } / name(...) / name(...) { }
        ├── variable         $name
        ├── map_operation    map { param -> pipeline }
        └── if_operation     if { } then { } else { }

expression_block { ... }     → injected as maparoni

File Extension

.formaggio

License

MIT