lazy-signals 0.1.0

running effects on value updates with dependency discovery - conceptually inspired by Signal in JavaScript

Lazy Signals 🪢

lazysignals is a python library to run effects on state changes. It employs dependency discovery and is lazy. It is conceptually inspired by Signal in JavaScript.

Example

The framework runs relevant effects whenever some state changes:

define a new signal s, holding the initial value 1

s = Signal(1)

derive a signal that checks the parity of s

p = derived(lambda: s.value % 2 == 0)

log the parity of s to the console

effect(lambda: print(f"parity:", "even" if p.value else "odd"))

perform some updates to s

s.value = 1  # no change, no output
s.value = 2  # output: "parity: even"
s.value = 3  # output: "parity: odd"
s.value = 5  # no change, no output
s.value = 6  # output: "parity: even"

Have a look at example.py for more; run with pipenv install (to locally install this library) and pipenv run example.