Sundown is a fast, robust Markdown parsing library for PHP5 Formula was removed
Last version was
php53-sundown requires the following formula to be installed:
autoconf 2.69 Automatic configure script builder

Recent formula history

Mike McQuaid Deprecate tap.
Andreas Braun Add description for sundown formula
Andy Blyler php53-sundown: convert from sha1 to sha256
Andy Blyler fix style issues
Andy Blyler Update URLs to use HTTPS

Formula code at GitHub