I think you are right about STM being roughly equivalent to snapshot isolation. What STM offers is an easy way to invent "containers for snapshotted values" ak

I think you are right about STM being roughly equivalent to snapshot isolation. What STM offers is an easy way to invent "containers for snapshotted values" aka TVars. Using them carefully may result in better scaling: https://hackage.haskell.org/package/stm-containers https://hackage.haskell.org/package/stm-containers