title: What is it about a single namespace that leads to unhygienic macros? (in LISP)
body: <p>Some claim that a single namespace in LISP leads to unhygienic macros. 
  <a href="http://community.schemewiki.org/?hygiene-versus-gensym" rel="nofollow noreferrer">http://community.schemewiki.org/?hygiene-versus-gensym</a></p>
  
  <p><a href="http://www.nhplace.com/kent/Papers/Technical-Issues.html" rel="nofollow noreferrer">http://www.nhplace.com/kent/Papers/Technical-Issues.html</a></p>
  
  <p>What precisely is it about having single, dual or multiple namespaces that leads to macro hygiene? </p>