haskell-simple-webpage-reader-monad.hs

main :: IO ()
main =
  putStrLn "what is your email address?" >>
    getLine >>= \email ->
      putStrLn . show $ runReader view email

view :: Reader Email Html
view =
  page >>= \page' ->
    return $ div
      [ page'
      ]

page :: Reader Email Html
page =
  content >>= \content' ->
    return $ div
      [ topNav
      , content'
      ]

topNav :: Html
topNav =
  div
    [ h1 [ "OurSite.com" ]
    ]

content :: Reader Email Html
content =
  ask >>= \email ->
    right >>= \right' ->
      return $ div
        [ h1 [ "Custom Content for " ++ email ]
        , left
        , right'
        ]

left :: Html
left =
  div
    [ p [ "this is the left side" ]
    ]

right :: Reader Email Html
right =
  article >>= \article' ->
    return $ div
      [ article'
      ]

article :: Reader Email Html
article =
  widget >>= \widget' ->
    return $ div
      [ p [ "this is an article" ]
      , widget'
      ]

widget :: Reader Email Html
widget =
  ask >>= \email ->
    return $ div
      [ p [ "Hey " ++ email ++ ", we've got a great offer for you!" ]
      ]