Perl 6 Deep Dive

:p (:pos)

A regex the with the :p or :pos adverb matches the string from a position that is given in the argument of the adverb. The behavior is clearly seen from the following example.

By default, a regex starts from the beginning of the string:

'pineapple' ~~ / (\w+) /;say $0; # pineapple

Due to the greedy nature of \w+, the whole string is consumed and matched. Let us try skipping a few characters and apply the regex to the same string:

'pineapple' ~~ m:p(4)/ (\w+) /;say $0; # apple

This time, only the apple substring will be matched.

An index of the :p adverb also behaves like an anchor. Similar to how ^ ties the regex to the beginning of the string, the :p(N) adverb ties it to the given position. Compare the following two matches: