> Functions allow shared state, they don't isolate errors.
So why not use Haskell (or other pure language)? It's pure, so functions don't share state. And you don't have to replace function call with network call.
You'll never achieve the level of operational stability of an air gap that you would without a strictly in process system.
Shared state is part of it. Isolation of failure is another. Your Haskell code can still blow up.
Immutability makes that way easier to recover from, but it's just one part.
Of course, microservices are much more than processes over a network, they're a discipline. And I think one can go much further than microservices as well - microservice architecture doesn't tell you how processes should communicate, it's more focused on how they're split up, and leaves the protocol to you. Good protocol design is critical.
Shared state is part of it. Isolation of failure is another. Your Haskell code can still blow up.
Immutability makes that way easier to recover from, but it's just one part.
Of course, microservices are much more than processes over a network, they're a discipline. And I think one can go much further than microservices as well - microservice architecture doesn't tell you how processes should communicate, it's more focused on how they're split up, and leaves the protocol to you. Good protocol design is critical.