main.elm

import Html exposing (..)
import Html.Events exposing (onClick)

type alias F = Int -> Int

mailbox = Signal.mailbox identity

view address value = div [] [ text <| toString value
                            , button [onClick address ((+) 1)] [text "+"]
                            , button [onClick address ((-) 1)] [text "-"]
                            ]
                            
updates = Signal.foldp (<|) 0 mailbox.signal

main = Signal.map (view mailbox.address) updates