JoCaml is an experimental functional programming language derived from OCaml. It integrates the primitives of the join-calculus to enable flexible, type-checked concurrent and distributed programming. The current version of JoCaml is a re-implementation of the now unmaintained JoCaml made by Fabrice Le Fessant, featuring a modified syntax and improved OCaml compatibility compared to the original. JoCaml was used by team Camls 'R Us to implement a distributed ray tracer, earning 2nd place on the ICFP 2000 programming contest. The name is a reference to Joe Camel, a cartoon camel used in advertisements for Camel-brand cigarettes. Example type coins = Nickel | Dime and drinks = Coffee | Tea and buttons = BCoffee | BTea | BCancel;; (* def defines a Join-pattern alternatives set clause * '&' in the left side of '=' means join (channel synchronism) * '&' in the right hand side is parallel processing * synchronous_reply :== "reply" [x] "to" channel_name * synchronous channels have function-like types (`a -> `b) * while asynchronous ones have type `a Join.chan * only the last statement in a pattern rhs expression can be an asynchronous message * 0 in an asynchronous message position means STOP ("no sent message" in CSP terminology). *) def put(s) = print_endline s ; 0 (* STOP *) ;; (* put: string Join.chan *) def give(d) = match d with Coffee -> put("Coffee") | Tea -> put("Tea") ;; (* give: drink Join.chan *) def refund(v) = let s = Printf.sprintf "Refund %d" v in put(s) ;; (* refund: int Join.chan *) let new_vending give refund = let vend (cost:int) (credit:int) = if credit >= cost then (true, credit - cost) else (false, credit) in def coin(Nickel) & value(v) = value(v+5) & reply to coin or coin(Dime) & value(v) = value(v+10) & reply to coin or button(BCoffee) & value(v) = let should_give, remainder = vend 10 v in (if should_give then give(Coffee) else 0 (* STOP *)) & value(remainder) & reply to button or button(BTea) & value(v) = let should_give, remainder = vend 5 v in (if should_give then give(Tea) else 0 (* STOP *)) & value(remainder) & reply to button or button(BCancel) & value(v) = refund( v) & value(0) & reply to button in spawn value(0) ; coin, button (* coin, button: int -> unit *) ;; (* new_vending: drink Join.chan -> int Join.chan -> (int->unit)*(int->unit) *) let ccoin, cbutton = new_vending give refund in ccoin(Nickel); ccoin(Nickel);