#!/usr/bin/env stack
-- stack script --resolver lts-20.15 --package xml

import Data.Maybe            (catMaybes)
import System.Environment    (getArgs)
import Text.XML.Light.Input
import Text.XML.Light.Output
import Text.XML.Light.Types

main :: IO ()
main = do
  filename <- head <$> getArgs
  xml <- parseXML <$> readFile filename
  mapM_ (putStrLn . showContent) . catMaybes $ filterHR <$> xml

filterHR :: Content -> Maybe Content
filterHR (Elem e) | qName (elName e) == "HeartRateBpm" = Nothing
filterHR (Elem e) | otherwise = Just . Elem $ e { elContent = catMaybes (filterHR <$> elContent e) }
filterHR x = Just x