I find explicitness to aid in self-documentation, so why not specify which handle you are reading and never rely on the implicit default?

for my $line (<STDIN>) {
    ...
}
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)