#| Filter incoming messages according to predicate. sub filter(&logger, &pred) { -> $msg { logger($msg) if pred($msg) }; } #| Transform incoming messages, e.g. censor passwords, add timestamp, etc. sub transform(&logger, &func) { -> $msg { logger(func($msg)) }; } my &logger = &say; my &timed-logger = transform(&logger, { "{now} {$_}" }); logger("hello world"); timed-logger("hello world");