### INIT pragma
    use strict;
    use warnings;

### PROCESS
    my  @array  = <DATA>;
    map { (0)?()
        : (/good stuff/) ? do{print "DO STUFF\n";}
        : (/[^a-z]+/)    ? do{print "BAD STUFF: -> $_";}
        : do{} ### do nothing
        } @array;

### SAMPLE output
    q^*******************q
    DO STUFF
    BAD STUFF: -> garbage
    DO STUFF
    BAD STUFF: -> unknown
    BAD STUFF: ->
    BAD STUFF: -> the previous line is blank
    DO STUFF
    DO STUFF
    q********************q^if(0);

__DATA__
good stuff
garbage
good stuff
unknown

the previous line is blank
good stuff
good stuff