de class="mendoza-code">x</code> inside the macro, which overshadowed the original
binding. This problem is called the
<a href="https://en.wikipedia.org/wiki/Hygienic_macro#The_hygiene_problem">hygiene
problem</a> and is solved in many programming languages
(such as Scheme) by hygienic macros. Hygienic macros prevent such
accidental captures, but usually constrain the kinds of macros that can be written. Janet's macro system does <em>not</em> use hygienic macros as presented in <a href="ftp://jcmc.indiana.e