Scroll

Interactive notebook for March — Livebook-style in the browser.

Notebooks are plain Markdown files (.scrollmd) with fenced March code blocks. Open them in the browser, run cells interactively, and save changes back to disk.

Requirements

A March toolchain new enough to contain these fixes — without them scroll builds but misbehaves, in ways that do not always look like a toolchain problem:

• Registry deps for archive tasks (march#133) — required as of scroll 0.1.4, which declares bastion as a registry dependency. Older forge gave an archive task no search path for a registry dep, so forge check/build/ test passed and then forge scroll.serve failed with Unknown module Router / Middleware / Static. The same fix also makes forge deps fetch a registry package's own dependencies (bastion → depot), without which the build fails with Module Pool not found.
• forge test transitive dependency resolution (march#127) — scroll reaches bastion's own dependency (depot) through bastion. Older forge resolved that for check/build but not test, so tests failed with Unknown module Pool.
• The (-led-statement parser fix (march#129) — a line holding only () used to be glued onto the previous line as a call.

forge toolchain list shows what you have installed.

Installation

Scroll is a forge tool: installing it adds the scroll.serve command. It's listed on the forge registry at https://forgepm.org/packages/scroll.

Install directly from the GitHub source:

forge install https://github.com/march-language/scroll

Or from a local checkout:

git clone https://github.com/march-language/scroll
forge install ./scroll

Building from a checkout

Dependencies are fetched explicitly — forge check does not fetch them, so a fresh clone must resolve first or every bastion module reads as unknown:

git clone https://github.com/march-language/scroll
cd scroll
forge deps      # clones bastion (and its own dep, depot) into ~/.march/cas
forge test

Usage

Start a notebook server

# Open an existing notebook
forge scroll.serve mynotebook.scrollmd

# Create a new notebook (opens a blank one in the browser)
forge scroll.serve

# Specify a port (default: 4040)
forge scroll.serve mynotebook.scrollmd --port 8080

Notebook format

A .scrollmd file is standard Markdown. Code cells use fenced March blocks:

# My Notebook

Some prose here.

```march
let x = 6 * 7
```

```march
x
```

• Markdown cells — rendered as HTML in the browser
• Code cells — run in sequence; each cell sees bindings from earlier cells
• let bindings are silent (no auto-print), just like a REPL assignment
• Plain expressions auto-print their value if non-unit

Server cells

Long-running processes (HTTP servers, background workers) use the march:server fence:

```march:server
HttpServer.start(3000)
```

Server cells run as background processes with Start/Stop controls in the UI.

Running tests

cd /path/to/scroll

# Unit tests (149 tests)
MARCH_LIB_PATH=lib march test test/test_scroll.march

# End-to-end tests over the notebook WebSocket protocol
python3 test/test_scroll.py

Note: forge test currently fails to link the compiled test binary due to three upstream march toolchain bugs (nested-namespace name mangling in the linker, a module init-order bug in the interpreter, and a hang in compiled test binaries on arm64 macOS). Use march test in interpreter mode instead — it runs the same 117 unit tests without those issues.

Development

After editing lib/scroll.march, changes are live immediately — no reinstall needed when installed as a path archive (forge install scroll@./).