componentstandard.elm

import Signal exposing (Address)
import Html exposing (Html, div, button, text, span)
import Html.Events exposing (onClick)

type alias Init options state effect   = options ->          (state, List effect)
type alias Update action state effect  = action  -> state -> (state, List effect)
type alias View state view             =            state -> view


type alias Component options action state effect view = 
  { init   : Init options state effect
  , update : Update action state effect
  , view   : View state view
  }

type alias HtmlComponent options action state effect = 
  Component options action state effect (Address action -> Html)
  
  
  
  
  
  
  

---------------
-- COUNTER ----
---------------

type Action 
  = Increment
  | Decrement 
  
counter : HtmlComponent Void Action Int Never
counter = 
  let 
      init = 0
      
      update action state = 
        case action of 
          Increment ->
            state + 1
            
          Decrement ->
            state - 1
            
      view state address = 
        div 
          []
          [ button
              [ onClick address Increment ]
              [ text "+" ]
          , button 
              [ onClick address Decrement ]
              [ text "-" ]
          , span 
              []
              [ text (toString state) ]
          ]
  in 
      sealed 
        { init   = init
        , update = update
        , view   = view
        }


main = 
  run Void counter
  |> .views
---------------




 
sealed : { init   : state
         , update : action -> state -> state
         , view   : state -> view
         }
      -> Component Void action state Never view
sealed { init , update , view } = 
  { init   = always (init, [])
  , update = (\a s -> (update a s, []))
  , view   = view
  }
  
  
simple : { init : state
         , view : state -> view
         }
      -> Component Void action state Never view
simple {init, view} = 
  { init   = always (init, [])
  , update = (\_ s -> (s, []))
  , view   = view
  }
  
  
  

  
  
type alias Output action state effect = 
  { actions : Signal (Maybe action)
  , states  : Signal state
  , effects : Signal (List effect)
  , views   : Signal Html
  }
  
  
run : options 
   -> HtmlComponent options action state effect
   -> Output action state effect
run options component = 
  let
      appMailbox = 
        Signal.mailbox Nothing
        
      actions = 
        appMailbox.signal
        
      address = 
        Signal.forwardTo appMailbox.address Just
        
      update maybeAction (state, effects) = 
        case maybeAction of 
          Nothing ->
            (state, effects)
          Just action ->
            component.update action state
            
            
      view = 
        flip component.view address
        
      initial = 
        component.init options
        
      transitions = 
        Signal.foldp update initial actions
        
      states = 
        Signal.map fst transitions
        
      effects = 
        Signal.map snd transitions
        
      views = 
        Signal.map view states
        
  in 
      { actions = actions
      , states  = states
      , effects = effects
      , views   = views
      }
    
type Never = Never Never
      
type Void = Void