regex [ ]
Documentation for regex [ ], assembled from the following types:
The parentheses in regexes perform a double role: they group the regex elements inside and they capture what is matched by the sub-regex inside.
To get only the grouping behavior, you can use square brackets
[ ... ] instead.
if 'abc' ~~ / [a||b] (c) /
If you do not need the captures, using non-capturing groups provides three benefits: they more cleanly communicate the regex intent; they make it easier to count the capturing groups that you do care about; and matching is bit faster.