In Perl 6 it extends to the . operator that allows the call of methods on objects. Consider the following example. The subst method can substitude one substring by another one but instead of changing the original string, by default it returns the changed string.
If you'd like to change the original string you can write $str = $str.subst('B', 'X'); or you can write its shortcut version.examples/arrays/assignment_operators.p6
#!/usr/bin/env perl6 use v6; my $str = 'ABBA'; say $str.subst('B', 'X'); # AXBA say $str; # ABBA say $str .= subst('B', 'X'); # AXBA say $str; # AXBA