from permchain import InMemoryPubSubConnection, PubSub, Topic

topic_one = Topic("one")
chain_one = Topic.IN.subscribe() | (lambda x: x + 'b') | topic_one.publish()
chain_two = topic_one.subscribe() | (lambda x: x + 'c') | Topic.OUT.publish()

conn = InMemoryPubSubConnection()
pubsub = PubSub(processes=(chain_one, chain_two), connection=conn)

assert pubsub.invoke('a') == ['abc']

Check tests and examples for more examples.

Near-term Roadmap

Add initial retry support (pending changes in langchain)
Implement OUT as regular topic
Implement IN as regular topic
Add Connection.peek() to monitor past messages from all topics
Enable resuming PubSub from the "middle" of the computation
Add test for .peek()
Move tracking of inflight processes/messages to Connection
- Use this to build retry mechanism, where any inflight messages are moved back to the respective topics when restarting
Detect cycles (aka. infinite loops) and throw an error
- Allow user to catch that error (by subcribing to an error topic?)
Add "human in the loop" pattern
Add "wait until topic X is done" pattern, aka. Topic.reduce()
Add Redis-backed Connection implementation