Description
Apologies if this should be posted to the mustache and twig editions, but it has to do with core and applies to both:
I believe pattern-lab/core now requires PHP 5.5.9 or higher, due to the dependencies introduced in v2.5.0. The PHP package and site documentation do not reflect this change.
If you only have PHP 5.4 (like many OS X users), and try to install Pattern Lab Standard Edition, Composer installs pattern-lab/core v2.4.1 instead of v2.7, due to the requirements of core's dependencies. The symfony ^3.0 packages all require PHP 5.5.9, for starters.
One result of running PL with core 2.4.1 is that the --server --with-watch command, which is likely the first thing a user is going to try, doesn't run the watcher. The server launches but not even a built site is going to be there to show up if you're following the github instructions.
If you've never used Composer you may not have any idea what is going wrong. I don't believe Composer adequately points out to the user that it is falling back on a previous release and nothing else triggers an error message since you're running a stable release (though for me running create-project on PHP 5.4 also resulted in an undocumented prompt to merge or replace ./public when adding the styleguide).
I did briefly run PL using core v2.7 but with the dependencies of v2.4.1, by copying over only the core files, and did not immediately see anything amiss, though I assume the updated core requirements are there for a reason and something would have broken eventually.