delicious.hs

{-# LANGUAGE ScopedTypeVariables #-}
module Main where
import Network.HTTP
import Text.JSON
import System.IO.UTF8 as U

data Feed = Feed (JSObject JSValue)

stringFromObj :: String -> JSObject JSValue -> String
stringFromObj s obj = let Ok (v::JSString) = valFromObj s obj in fromJSString v

urlFromFeed :: Feed -> String
urlFromFeed (Feed obj) = stringFromObj "u" obj

titleFromFeed :: Feed -> String
titleFromFeed (Feed obj) = stringFromObj "d" obj

dtFromFeed :: Feed -> String
dtFromFeed (Feed obj) = stringFromObj "dt" obj

tagsFromFeed :: Feed -> [String]
tagsFromFeed (Feed obj) = stringArrayFromObj "t" obj
  where
    stringArrayFromObj :: String -> JSObject JSValue -> [String]
    stringArrayFromObj s obj = let Ok (v::[JSString]) = valFromObj s obj in map fromJSString v

feedToHumanReadable :: Feed -> String
feedToHumanReadable feed =
    "url: " ++ urlFromFeed feed ++ "\n"
    ++ "title: " ++ titleFromFeed feed ++ "\n"
    ++ "tags: " ++ (show $ tagsFromFeed feed) ++ "\n"
    ++ "dt: " ++ dtFromFeed feed ++ "\n"

getDeliciousFeed :: Int -> IO [Feed]
getDeliciousFeed count =
  simpleHTTP (getRequest (baseUrl ++ show count)) >>= getResponseBody >>= return . toFeed
  where
    baseUrl = "http://feeds.delicious.com/v2/json?count="
    toFeed :: String -> [Feed]
    toFeed str = let Ok feeds = decodeStrict str in map Feed feeds

main = getDeliciousFeed 5 >>= mapM_ (U.putStrLn . feedToHumanReadable)