vperl.tcl is a tiny program I wrote on 16.8.2000
It allows you rapidly to create, test, and modify perl programs. One window contains an input document; another contains the program; a third contains the output (and a fourth contains stderr's output). Whenever you make a change to the program or the input, the result is instantly reflected in the output windows.
If your normal way of writing and testing small perl programs is alternately to edit the perl in emacs and apply the program to a file in a shell, then you may find vperl speeds your life up.
vperl.tcl does not waste time giving warning messages like "are you sure you want to overwrite this file?" so take care.
vperl.tcl is horribly written.
vperl was inspired by the (much fancier) program vdiff, and by conversations with Alan Blackwell, who works on truly visual alternatives to perl.