title: How is structure sharing broken in Standard ML?
body: <p>In a 2013 <a href="http://www.cs.cmu.edu/~rwh/talks/mlw13.pdf" rel="noreferrer">presentation about the future of Standard ML</a>, Bob Harper says, on slide 9, that "structure sharing is broken". Can someone give more detail on that? I don't have enough experience with sharing to understand what he meant.</p>