You could use the perl built-in debugger, to do simple stuff:

>perl -d -E ""

Loading DB routines from perl5db.pl version 1.33
Editor support available.

Enter h or `h h' for help, or `perldoc perldebug' for more help.

Debugged program terminated.  Use q to quit or R to restart,
  use o inhibit_exit to avoid stopping after program termination,
  h q, h R or h o to get additional info.

  DB<4> chomp (($n,$a,$b,$c)=<>)
Bob Jones
23
45
67
^Z


  DB<5> print join(",",$n,$a,$b,$c)
Bob Jones,23,45,67

  DB<6> print $a+$b-$c
1
[download]