my $text = read_file( 'filename' );
Yeah, that's a whole day's work.
I submit that finding the documentation on such a method is substantially easier than finding the documentation (for lack of a better word) for the snippet you gave.
The "cost" of useing the module is amortized over all the calls you make to any of its methods (of which File::Slurp has several useful ones).
And the cost of downloading a module is amortized over all of the times you ever use it (at least on that machine).