my $GLOBAL-BINARY = False; grammar Foo { regex TOP { :my Bool $*BINARY; <ab>+ { $GLOBAL-BINARY = $*BINARY with $*BINARY } } token ab { <a>+ (<b>+)? } token a { 'a' {$*BINARY = True} } token b { 'b' {$*BINARY = False} } } my $f = Foo.parse('a'); say $GLOBAL-BINARY; $f = Foo.parse('ab'); say $GLOBAL-BINARY; $f = Foo.parse('aba'); say $GLOBAL-BINARY; $f = Foo.parse('abac'); say $GLOBAL-BINARY; $f = Foo.parse('abbbbbbb'); say $GLOBAL-BINARY;