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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 an modified syntax and improved OCalm compatibility compared to the original. JoCalm was used by team Camls 'R Us to implement a distributed ray tracer, earning 2nd place on the ICFP 2000 programming contest. == 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" () "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("Cofee") | 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); ccoin(Dime); Unix.sleep(1); cbutton(BCoffee); Unix.sleep(1); cbutton(BTea); Unix.sleep(1); cbutton(BCancel); Unix.sleep(1) ( * let the last message show up *) ;; execution
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