update.elm

type Action = NoOp
            | UpdateModel Model
            | Selected String Bool
            | ShowMap String Bool

update : Action -> Model -> Model
update action model =
  case action of
    NoOp ->
      model
    UpdateModel m ->
      m
    Selected id isSelected ->
      let updateItem m = if m.id == id then { m | selected = isSelected } else m
      in
        { model | items = List.map updateItem model.items }
    ShowMap id showMap ->
      let updateItem m = if m.id == id then { m | showmap = showMap } else m
      in
        { model | items = List.map updateItem model.items }