I'm writing a MUD server in Haskell (MUD = Multi User Dungeon: basically, a multi-user text adventure/role-playing game). The game world data/state is represented in about 15 different IntMaps. My ...

I'm considering using a TVar to store some state in a web application (that can be recreated on restart). However, the contention aspects of TVar concern me. It seems that a frequent short running ...

Is the "else" part of orElse called when a transaction is retried due to another transaction writing to a TVar it had read, or only when retry is explicitly called?

Can one transaction update two different TVars in an atomic way? i.e. can I compose data structures out of lots of TVars to reduce contention? If so, could you provide an example?

How does TVar work? From what I've read it attempts to run all transactions immediately upon receiving them, however, a transaction completing invalidates other currently running transactions, whic...