twitsearch.hs

import Data.Aeson
import Network.HTTP

import System.Environment (getArgs)
import Control.Monad (mapM_, void)
import Control.Monad.Trans.Maybe
import Control.Monad.Trans.Class (lift)

import qualified Data.ByteString.Lazy.Char8 as LBS
import qualified Data.Text as T -- can be traded for OverloadedStrings option
import qualified Data.HashMap.Strict as HM
import qualified Data.Vector as V

main = do
    args <- getArgs
    case args of
        [q] -> fetchTweets q
        _   -> putStrLn "twitsearch <query>"

fetchTweets q = do
    let req = getRequest $ "http://search.twitter.com/search.json?" ++ urlEncodeVars [("q", q)]
    body <- simpleHTTP req >>= getResponseBody
    void $ runMaybeT $ do
        MaybeT (return $ decode (LBS.pack body)) >>=
             \(Object o) -> MaybeT (return $ HM.lookup (T.pack "results") o) >>=
             \(Array l) -> mapM_ printResult (V.toList l)

printResult (Object o) = MaybeT (return $ HM.lookup (T.pack "text") o) >>=
                         \(String t) -> lift $ putStrLn (T.unpack t)