FSharp.HSM
Hierarchical State Machine library in F#
Inspired by http://code.google.com/p/stateless/, http://accu.org/index.php/journals/252
Features:
- Hierarchical states
- Entry/Exit actions
- Guards
- Auto transitions
- Event handlers with optional transitions
- Output events for states and transitions
- Introspection of available events
Examples:
Phone call:
[ configure OffHook
|> on CallDialed Ringing
configure Ringing
|> on CallConnected Connected
|> on HungUp OffHook
configure Connected
|> onEntry startTimer
|> onExit stopTimer
|> transitionTo InCall
|> on HungUp OffHook
configure InCall
|> substateOf Connected
|> on PlacedOnHold OnHold
configure OnHold
|> substateOf Connected
|> onEntry startHoldMusic
|> onExit endHoldMusic
|> on TakenOffHold InCall ]
|> HSM.create
Pelican Signal HSM:
[ configure State.Off
|> onEntry shutdown
configure Operational
|> onEntry (fun () -> printfn "Operational %A" DateTime.Now)
|> on Event.Off State.Off
|> transitionTo VehiclesEnabled
configure VehiclesEnabled
|> substateOf Operational
|> onEntry dontWalk
|> transitionTo VehiclesGreen
configure VehiclesGreen
|> substateOf VehiclesEnabled
|> onEntry (setTimer 10.)
|> onEntry green
|> handle PedestrianWaiting handleWaitingOnGreen
|> handle Timeout handleTimeoutOnGreen
configure VehiclesGreenInt
|> substateOf VehiclesEnabled
|> on PedestrianWaiting VehiclesYellow
configure VehiclesYellow
|> substateOf VehiclesEnabled
|> onEntry (setTimer 4.)
|> onEntry yellow
|> on Timeout PedestriansEnabled
configure PedestriansEnabled
|> substateOf Operational
|> transitionTo PedestriansWalk
|> onEntry red
configure PedestriansWalk
|> substateOf PedestriansEnabled
|> onEntry (setTimer 10.)
|> onEntry walk
|> onExit setFlashCount
|> on Timeout PedestriansFlash
configure PedestriansFlash
|> substateOf PedestriansEnabled
|> onEntry (setTimer 0.5)
|> handle Timeout timeoutFlashing ]
|> HSM.create
