>perl -le
"use Tk;
 Mainloop;
"

>perl -w -le
"use Tk;
 Mainloop;
"
Useless use of a constant (Mainloop) in void context at ...

>perl -wMstrict -le
"use Tk;
 Mainloop;
"
Bareword "Mainloop" not allowed while "strict subs" in use at ...
Execution of -e aborted due to compilation errors.