How to extract all links and link text from a Markdown file using pandoc

gistfile1.hs

-- adapted from <http://johnmacfarlane.net/pandoc/scripting.html>
import Text.Pandoc
import Text.Pandoc.Shared (stringify)

extractURL :: Inline -> [String]
extractURL (Link txt (u,_)) = [stringify txt ++ " : <" ++ u ++ ">"]
extractURL (Image _ (u,_)) = [u]
extractURL _ = []

extractURLs :: Pandoc -> [String]
extractURLs = queryWith extractURL

readDoc :: String -> Pandoc
readDoc = readMarkdown defaultParserState

main :: IO ()
main = interact (unlines . extractURLs . readDoc)