[delusional]

> Immutable code platforms (like Lambda) make things much more tractable

My job is admittedly very old-school, but is that actually doable? I dont think my stakeholders would accept a version of "well we can't fix this bug for our current customers, but the new ones wont have it". That just seems like a chaos nobody wants to deal with.

[p10jkle]

I don't personally believe this immutability property should be used for handlers that run for more than say 5 minutes. Any longer than that, I'd suggest the use of delayed calls, which explicitly will serialise the handler arguments instead of saving the whole journal. I agree executing code that is even just an hour old is unacceptable in almost all cases.

Obviously you can still sleep for a month, but I really see no way to make such a handler safely updatable without editing the code to branch on versions, which can become a mess really quick (but good for getting out of a jam!)