ocaml5-tutorial VS reagents

The 1978 paper proposes a reasonable set of primitives and then walks through prose examples with them. The book proposes roughly the same primitives (channels are the big change, but stop is barely in the paper) and describes them in a formal notation for state machines. It's the difference between a sketch of a plausible idea and writing down the mathematics.

Related though much later, ocaml https://github.com/ocaml-multicore/reagents observed that the send/recv primitives make less sense than a swap primitive. Between occam and the current ocaml effort, concurrent ML is the same sort of model with the details really well thought through (e.g. a thread executing stop gets garbage collected).

Still early days, but I had done some exploratory work in the past on Reagents, a composable lock-free library [1]. Now that OCaml 5 is released, we're reviving this work.

It's semantics is weaker than STM -- unlike STM, it doesn't provide serializability but Reagents can compile down to multi-word compare and swap operations, which can be implemented with the help of hardware transactions (when present) or efficient software implementations of it [2]. Hence, Reagent programs should be faster than STM.

[1] https://github.com/ocaml-multicore/reagents