#!/usr/bin/perl

use strict;
use Text::RewriteRules;

use Data::Dumper;
my $a;

sub lines{ my $a=shift;
  my $l;
  open(F,"<",$a) or die("Error: cant find $a\n");
  while(<F>){chomp; s/[ \t\r]+\n/\n/g; push(@$l,$_) if /\S/}
  $l;
}

sub myeval{ my $exp=shift;
 my $v=eval($exp);
 print STDERR "Error: $@ in calculation of ($exp)\n" if $@;
 $v
}

print Dumper(myeval('lines("x.lines")'));