Markdown compiler for simple variable substitution

compile.pl

#!/usr/bin/perl
use warnings;
use strict;
use Caaz::Prompt;

if($ARGV[0]) {
  my (@lines, %map);
  open FILE, "<$ARGV[0]";
  chomp(@lines = <FILE>);
  close FILE;
  for my $line (@lines){
    while($line =~ /\{(\w+?)\}/) {
      my $key = $1;
      unless($map{$key}) {
        echo($line);
        $map{$key} = ask($key);
      }
      $line =~ s/\{$key\}/$map{$key}/gs;
    }
  }
  open EXPORT, ">$ARGV[1]";
  print EXPORT join "\n", @lines;
  close EXPORT;
}