here's a state machine representing a lock in elm:

  type State = Locked | Unlocked
  type alias Model = State
  
  lock : Model -> Model
  lock model = Locked
  
  unlock : Model -> Model
  unlock model = Unlocked
  
  open : Model -> Bool
  open model =
    if model = Locked then True else False

and here it is in erlang:

  lock(_Lock) -> locked.
  
  unlock(_Lock) -> unlocked.
  
  open(locked) -> false;
  open(unlocked) -> true.

i think working with state machines in imperative languages is messy, mistake prone and hard to reason about. functional languages are just better for managing state