Update: Thanks to everyone for pointing out my <> v. <STDIN> flaw. When building quick/easy scripts for myself I tend to get lax and use <> when the correct way to reference a line from STDIN is <STDIN>. A bad habit I guess.
I voted this down because I see no reason to accuse anyone of having a confused mind. Even just stating that you think that someone may have been confused should be done with some tact.
I assume the personal attack was not intentional, hence I felt it should be brought to your attention.
I also see no reason to tie writing to STDOUT with reading from STDIN. A very standard practice is to "read from @ARGV" and write to STDOUT (one used by many Unix commands and one that Perl has even devoted a command-line option to). Perhaps you meant "if you write a prompt to STDOUT..."?