Newick grammar in Perl6... the quoted and unquoted tokens fail if you replace unquoted with <[A..Z]>* it works for the example newick string :/

Newick.pm

#!/usr/bin/env perl6

use v6;

grammar BioInfo::Parser::Tree::Newick {
    rule TOP {
        <tree>+
    }

    rule tree {
        <node> ";"
    }

    rule node {
        <children> <label>? <distance>? | <children>? <label> <distance>?
    }

    rule children {
        "(" <node> ("," <node>)* ")"
    }

    rule label {
        <quoted> | <unquoted>
    }

    rule distance {
        ":" <number>
    }

    token quoted { "'" ( <-[']> | "''" )* "'" }
    #token unquoted { <[A..Z]>* }
    token unquoted { <-[\[\]()':\s]>* }
    token number { <[+-]>?\d+"."?\d*<[eE]>?\d* }

}

my $quoted = "(a,('Darwin''s Bulldog (Huxley)',c):-1.92e19)'The ''Root''':5;";
my $unquoted = "(A:0.1,B:0.2,(C:0.3,D:0.4):0.5);";
say "Quoted Newick";
say BioInfo::Parser::Tree::Newick.parse($quoted);
say "Unquoted Newick";
say BioInfo::Parser::Tree::Newick.parse($unquoted);