I'm running AMPPS on OS X Yosemite. Everything is working fine.
I ran the script to install Piwik (log analyzer) to it's own domain at root level. Installation completed without errors, however when I try to access either the default page or the admin page, I get this error:
Fatal error: Call to undefined function Piwik\ctype_alnum() in /Applications/AMPPS/www/log.dev/core/FrontController.php on line 469