Perl script that will budget a given dollar amount for after-expenses-and-retirement uses.

budget.bat

@echo off

perl %~dp0\budget %*

budget.pl

#!/usr/bin/env perl

# Given x dollars, how would you like to apportion it into 
# savings/investments/retirement/fun?

use strict;
use warnings;

use List::Util qw( sum );

my %portions = (
  'savings'          => 0.1,
  'play money'       => 0.3,
  'safe investments' => 0.35,
  'fun'              => 0.25,
);

my $sum = sum values %portions;
die "Portions must total <= 1.0\n" unless $sum <= 1.0;

my $remainder = 1.0 - $sum;

my $amount = $ARGV[0] or die "Please provide a dollar amount to portion out\n";

# get longest of categories to horizontally align dollar amounts in print_category
my $longest = 0;
foreach my $cat (keys %portions) {
  $longest = length $cat if length $cat > $longest;
}

# sort into array of hashrefs, descending order by dollars allocated to that category
my @totals = sort { $$b{'allocated'} <=> $$a{'allocated'} } map { {
  'category'  => $_,
  'allocated' => $amount * $portions{$_}
} } keys %portions;

# Print them out
foreach my $hashref (@totals) {
  print_category($$hashref{'category'}, $$hashref{'allocated'});
}

# Prints a category
sub print_category {
  my $category  = shift;
  my $allocated = shift;
  die 'argument undef' unless defined $category;
  die 'argument undef' unless defined $allocated;

  print "$category:";
  print ' ' for length $category .. $longest;
  printf("\$%.2f\n", $allocated);
}