title: Haskell thread doesn't die
body: <p>I'm using <a href="https://hackage.haskell.org/package/gloss" rel="nofollow">gloss</a> to display something, while at the same time using <code>forkOS $ system "mpg123 foo.mp3" &gt;&gt; return ()</code> to play some audio in the background. When I close the gloss window, the program exits, but the audio keeps playing. All resources show that this thread is supposed to die, what's going on? It doesn't die even when I use <code>killThread</code> to kill it explicitly.</p>