I think ToddAndMargo was thinking of perl5 regexes, where [.] is a good way of matching a literal dot-- though myself, I'm more inclined to use \.
In Raku, the square brackets just do non-capturing grouping much like (?: ... } in perl5. To do a character class, you need angles around the squares. This would work to match a single dot: <[.]> In Raku regexes a \. would also work to match a literal dot. Until I saw JJ Merelo's post, I don't think I realized that you could quote a meta-character using quotes: "." Which means there's some potential confusion if you really need to match quotes: my $str = 'string_632="The chicken says--", voice="high"'; say $str ~~ m:g{ ( " .*? " ) }; # False say $str ~~ m:g{ ( \" .*? \" ) }; # let's feed another quote: " to an emacs syntax highlighting bug # 「"The chicken says--"」 # 0 => 「"The chicken says--"」 「"high"」 # 0 => 「"high"」)