A first pass at a reflex API for working with local storage.

There is an Obelisk project in example you can use to play around with this.

You should be able to do ob run and then open a few tabs at http://localhost:8000 and watch them interact with each other.

The relevant bits of the code are:

body :: MonadWidget t m => m ()
body = do
  text "Testing storage"
  void . runStorageT LocalStorage $ do
    -- sets the default value for Tag1, only if none is already present
    initializeTag Tag1 0
    counter

counter :: (MonadWidget t m, HasStorage t ExampleTag m) => m ()
counter = el "div" $ do
  -- ask for the current value in local storage under the Tag1 key, defaulting to 0
  dTag1 <- askStorageTagDef Tag1 0

  eAdd <- button "Add"
  eClear <- button "Clear"
  display dTag1

  let
    eChange = mergeWith (.) [
        succ <$ eAdd
      , const 0 <$ eClear
      ]

  -- insert the new value for Tag1 into local storage
  tellStorageInsert Tag1 $ (&) <$> current dTag1 <@> eChange

along with some instances around the ExampleTag so that the keys can be marshalled to and from Text and the values can be marshalled to and from JSON.