Leo White is giving a talk at Jane Street’s NY office on March 7th about adding an effects system to OCaml. This is pretty cool stuff; he shows how to add effects tracking to OCaml seamlessly, so that all existing programs continue to compile as is, and yet, you can track purity quite precisely. It even has region support to let you write pure functions that use mutability locally, like the ST-monad without the monad. He was showing me some of the demos today, and they looked pretty sweet.
Space is limited, so if you’re interested, you should register soon.