my $mainVar1 = ...;
my $mainVar2 = ...;

while( something ) {
   if( isSomething() ) {
       my $result = doSomething();
       doSomethingElse() if $result eq somthing;
   }
}

exit;

sub isSomething {
    ...;
}

sub doSomething {
    ...;
}

sub doSomethingElse {
    ...;
}