One object.
Every boundary.
Write ordinary Python state. Add history, Redis durability, local services, or live browser synchronization without changing the object underneath.
A value is not a dead end.
Every XO path can hold a value and descendants at the same time. Reassigning the value leaves its structure intact.
from xo import XO
app = XO("app")
app.user = "Tami"
app.user.status = "online"
assert app.user.value == "Tami"The path stays the path.
app.user.status → event → history → Redis → RPC → JavaScript
One canonical tuple path and immutable event contract cross every capability. There is no parallel state engine hiding behind persistence or transport.
Measured, bounded, explicit.
Local use starts no service and needs no dependency. Network frames, queues, streams, deadlines, and shutdown are bounded. Strict persistence fails before local visibility rather than pretending a write succeeded.
| Operation | Median |
|---|---|
| Existing read | 0.325 µs |
| Scalar set | 1.627 µs |
| Cached formula read | 1.592 µs |