in reply to <STDIN> "anticipate" input?

What you are trying to do of "anticipating the input" cannot be done, with the value being editable on the command-line. You can like the others have kindly suggested use a method to give a default value, like Term::UI, which could even give the user(s) a list of option to choose from.

Other than prompting the user on the command-line, the only way to accomplish what you are looking for is using Perl/Tk; where you would create a GUI display with the editable value.