This is a teaching sample intended to illustrate use of mutability and list consing in F#. The structure is intended to be a thread-safe stack structure, which multiple threads can push to/pop from concurrently. Concerns:
- Will this actually be thread safe?
- Are the locks necessary?
- Is there an immutable way to do the same thing? I don't think one can use the traditional immutable method here of having the Push/Pop return a new stack instance because different clients will see divergent views of the stack.
The code looks like this:
type ConcurrentStack<'T>() = let mutable _stack : List<'T> = [] member this.Push value = lock _stack (fun () -> _stack <- value :: _stack) member this.TryPop() = lock _stack (fun () -> match _stack with | result :: newStack -> _stack <- newStack result |> Some | [] -> None )
