primitives

primitives

Signal-based reactive primitives and async Resource helper.

create_signal(value)

Create a reactive signal. Returns (getter, setter).

Works inside or outside components. Inside a stateful component the signal is captured by the render function's closure and persists naturally (no cursor system needed).

Example::

count, set_count = create_signal(0)
print(count())          # 0
set_count(5)
print(count())          # 5

create_effect(fn)

Create an auto-tracking reactive effect.

The effect runs immediately and re-runs whenever any signal read inside fn changes. on_cleanup may be called inside fn to register per-run cleanup (runs before re-execution and on disposal).

Inside a component, the effect is automatically disposed on unmount.

create_memo(fn)

Create an auto-tracking computed value. Returns a getter function.

Re-computes only when signals read inside fn change. Inside a component, the underlying computation is disposed on unmount.

Example::

doubled = create_memo(lambda: count() * 2)
print(doubled())  # reactive read

on_mount(fn)

Register a callback to run once after the component mounts.

Must be called during a component's setup phase (the body of a @component function, before the return).

on_cleanup(fn)

Register a cleanup callback.

• Inside create_effect: runs before each re-execution and on disposal.
• Inside a component's setup phase: runs when the component unmounts.

get_props()

Return a reactive getter for the current component's props.

Useful in stateful components that need to react to parent prop changes::

props = get_props()
create_effect(lambda: print("query changed:", props()["query"]))