Show all XML tags

tags.hs

#!/usr/bin/env stack
-- stack --resolver lts-12.21 script --package hexpat --package bytestring --package text

{-

dependency: install libexpat1-dev

      sudo apt install libexpat1-dev


Pipe in the XML input, outputs a list of tag names as it encounters them. Use unix
tools `sort` and `uniq -c` to tally the tag frequency.

-}

{-# LANGUAGE ScopedTypeVariables #-}
import qualified Data.ByteString.Lazy.Char8 as BL8
import           Data.Text                  (Text)
import qualified Data.Text.IO               as T
import           Text.XML.Expat.SAX

main :: IO ()
main = do
    lbs <- BL8.getContents
    mapM_ T.putStrLn $ [ t | (StartElement t _) :: SAXEvent Text Text <- parse (ParseOptions Nothing Nothing) lbs ]