Write your first tool

A node is just a decorated Python function. Here is the whole thing.

Scaffold a package#

The quickest start is a scaffold — it writes a working tool.py, an lsd_package.json, and a README:

lsd package new my-pkg

Or write tool.py by hand#

# tool.py
from lsdtools import Tool, Table

tool = Tool("my", label="My Tool")

@tool.shape
def top(t: Table, limit: int = 10) -> Table:
    """Keep the highest-scoring rows."""
    return t.sort("score", descending=True).head(limit)

• tool = Tool("my") — one Tool per package, at module scope.
• @tool.shape — makes a transform node (my.top).
• t: Table — an input port (wire it from an upstream node).
• limit: int = 10 — a parameter; it renders as a number field.

See it on the canvas#

In the desktop app, use the Package Manager's "Add local…" and pick the folder. Your node appears in the add-node palette with a generated form. Edit tool.py and it hot-reloads — the tight loop is: change the function, see the node update.

Run it without the desktop#

You don't even need the app to try it:

from lsdtools import Engine, Table

data = Table({"name": ["a", "b", "c"], "score": [3, 9, 5]})
result = Engine().run(top(data, limit=2))
result.output.print()
# → name:["b","c"] score:[9,5]

Next#

• Where to go next — the map of these docs.
• Go deeper on the Tool object and parameters vs ports.

Related#

Learn — The Tool object · Load steps

API — Tool · Table · Engine

Examples — Your first tool