type unify error

[1/1 TypesDoNotUnify] src/Main.purs:20:16

                     v
  20  config state = do
  21    -- | Create a signal of URL changes.
  22    urlSignal <- sampleUrl
      ...
  29      , update: update
  30      , view: view
  31      , inputs: [routeSignal] }
                                  ^
  
  Could not match type
  
    ( dom :: DOM
    , ajax :: AJAX
    , channel :: CHANNEL
    | e1
    )
  
  with type
  
    ( ajax :: AJAX
    , channel :: CHANNEL
    | e0
    )
  
  while trying to match type Aff
                               ( channel :: CHANNEL
                               , ajax :: AJAX
                               , dom :: DOM
                               | e1
                               )
    with type Aff
                ( channel :: CHANNEL
                , ajax :: AJAX
                | e0
                )
  while checking that expression (bind sampleUrl) (\$0 ->
                                                     case $0 of
                                                       urlSignal -> ...
                                                  )
    has type Eff
               ( channel :: CHANNEL
               , err :: EXCEPTION
               , dom :: DOM
               , ajax :: AJAX
               )
               { update :: Action
                           -> { route :: Route
                              , left :: { topic :: String
                                        , gifUrl :: String
                                        , status :: String
                                        }
                              , right :: { topic :: String
                                         , gifUrl :: String
                                         , status :: String
                                         }
                              }
                              -> { state :: { route :: Route
                                            , left :: { topic :: String
                                                      , gifUrl :: String
                                                      , status :: String
                                                      }
                                            , right :: { topic :: String
                                                       , gifUrl :: String
                                                       , status :: String
                                                       }
                                            }
                                 , effects :: Array
                                                (Aff
                                                   ( channel :: CHANNEL
                                                   , ajax :: AJAX
                                                   | e0
                                                   )
                                                   Action
                                                )
                                 }
               , view :: { route :: Route
                         , left :: { topic :: String
                                   , gifUrl :: String
                                   , status :: String
                                   }
                         , right :: { topic :: String
                                    , gifUrl :: String
                                    , status :: String
                                    }
                         }
                         -> Html Action
               , initialState :: { route :: Route
                                 , left :: { topic :: String
                                           , gifUrl :: String
                                           , status :: String
                                           }
                                 , right :: { topic :: String
                                            , gifUrl :: String
                                            , status :: String
                                            }
                                 }
               , inputs :: Array (Signal Action)
               }
  in value declaration config
  
  where e0 is a rigid type variable
          bound at line 20, column 1 - line 34, column 1
        e1 is a rigid type variable