ComponentFramework.elm

type alias Component state action view 
  =  { initial : (state, action)
     , view    : Address action -> state -> view
     , address : Address action 
     , history : Signal (List (state, action))
     }


makeComponent 
  :  state 
  -> action 
  -> (action -> state -> state) 
  -> (Address action -> state -> view) 
  -> Component state action view
makeComponent initialState initialAction update view = 
  let
      componentMailbox = 
        mailbox initialAction
      
      address = 
        componentMailbox.address
        
      actions = 
        componentMailbox.signal
        
      state = Signal.foldp update initialState actions  
        
      history = 
        Signal.foldp (\a b -> a :: b) [] 
          (Signal.map2 (,) state actions)
        
      
  in
      { initial = (initialState, initialAction)
      , view    = view
      , address = address 
      , history = history
      }
      
      
view : Component state action view -> Signal view
view component = 
  Signal.map (component.view component.address) (getCurrentState component)
  
  
getCurrentState : Component state action view -> Signal state
getCurrentState component = 
  let
      getState initial history = 
        case history of 
          [] -> initial
          x :: xs -> fst x
          
  in
      Signal.map (getState (fst component.initial)) component.history
  


send : action -> Component state action view -> Task error ()
send action component = 
  Signal.send component.address action