routerNix

Some notes for haskell

(==) :: (Eq a) => a -> a -> Bool

=>符号: 它左边的部分叫做类型约束。我们可以这样阅读这段类型声明：

    “相等函数取两个相同类型的值作为参数并返回一个布尔值，而这两个参数的类型同在Eq类之中（即类型约束）”

removeNonUppercase :: [Char] -> [Char]   

::读作“它的类型为”。凡是明确的类型，其首字母必为大写。

ghci> [1,2,3] <> [4,5,6]
[1,2,3,4,5,6]

It's an alias for mappend, from the Data.Monoid module.

GHCi> (+) (Just 3) <*> Just 4
Just 7

. and $

putStrLn (show (1 + 1))

putStrLn $ show $ 1 + 1

putStrLn . show $ 1 + 1

f ( g x ) = (f . g) x

Some notes for Miso and Servant

Steps:

main: run port app (Servant module)

main = do
    IO.hPutStrLn IO.stderr ("Running on port " ++ show port ++ "...")
    run port $ logStdout (compress app)
  where
    port     = 3001 :: Port
    compress = gzip def { gzipFiles = GzipCompress }

app: composed of routes and handlers

app :: Application
app =
    Servant.serve (Proxy @ServerAPI)
        (    static
        :<|> serverHandlers
        :<|> Tagged page404
        )

routes: static routes and serverRoutes

-- The server serves static files besides the ServerRoutes, among which is the
-- javascript file of the client.
type ServerAPI =
       StaticAPI
  :<|> (ServerRoutes
  :<|> Raw) -- This will show the 404 page for any unknown route

type StaticAPI = "static" :> Raw
-- Raw is another app::application

type ServerRoutes
= Miso.ToServerRoutes Common.ViewRoutes HtmlPage Common.Action

static handler

static :: Servant.Server StaticAPI
static = Servant.serveDirectoryFileServer "static"

server Handler (import qualified Common)

serverHandlers :: Servant.Server ServerRoutes
serverHandlers = homeServer :<|> flippedServer

-- Alternative type:
-- Servant.Server (ToServerRoutes Common.Home HtmlPage Common.Action)
-- Handles the route for the home page, rendering Common.homeView.
homeServer :: Servant.Handler (HtmlPage (View Common.Action))
homeServer =
    pure $ HtmlPage $
      Common.viewModel $
      Common.initialModel Common.homeLink

viewModel

-- Checks which URI is open and shows the appropriate view
viewModel :: Model -> View Action
viewModel m =
    case Miso.runRoute (Proxy @ViewRoutes) viewTree _uri m of
      Left _routingError -> page404View
      Right v -> v
      
-- Servant tree of view functions
-- Should follow the structure of ViewRoutes
viewTree
    ::      (Model -> View Action)
       :<|> (Model -> View Action)
viewTree = homeView :<|> flippedView

initialModel

initialModel :: Network.URI -> Model
initialModel uri =
    Model
    { _uri = uri
    , _counterValue = 0
    }

homeLink (import qualified Network.URI as Network)

homeLink :: Network.URI
homeLink =
#if MIN_VERSION_servant(0,10,0)
    Servant.linkURI $ Servant.safeLink (Proxy @ViewRoutes) (Proxy @Home)
#else
    safeLink (Proxy @ViewRoutes) (Proxy @Home)
#endif

ViewRoutes

-- Holds a servant route tree of `View action`
type ViewRoutes = Home :<|> Flipped

-- Home route, contains two buttons and a field
type Home = View Action

-- Flipped route, same as Home, but with the buttons flipped
type Flipped = "flipped" :> View Action

404 Handler

-- The 404 page is a Wai application because the endpoint is Raw.
-- It just renders the page404View and sends it to the client.
page404 :: Wai.Application
page404 _ respond = respond $ Wai.responseLBS
    HTTP.status404 [("Content-Type", "text/html")] $
    L.renderBS $ L.toHtml Common.page404View

page404View :: View Action
page404View =
    text "Yo, 404, page unknown. Go to / or /flipped. Shoo!"

yitaozh/routerNix

routerNix

Some notes for haskell

Some notes for Miso and Servant

Steps: