snipplets.dev/code/Crystal/schedule.cr

def every(period : Time::Span, &block : -> T) forall T
  spawn do
    loop do
      block.call
      sleep period
    end
  end
end

every(2.seconds) {
  puts "-@-@-"
}

every(4.seconds) {
  puts "(-.-)Zzz..."
}

sleep