gistfile1.txt

zoffix@VirtualBox~$ perl6 -e 'react { whenever $*IN.Supply(:size<1>).lines { .say } }'
line 1
line 1
second line
second line
third line
third line
^C
zoffix@VirtualBox~$ perl6 -e 'react { whenever $*IN.lines.Supply { .say } }'                                                                                                                                                                                   
line 1
line 1
second line
second line
third line
third line
^C
zoffix@VirtualBox~$