static IEnumerable<Transaction> Filter(IEnumerable<Transaction> transactions, Period period)
{
var beginOfMonth = new DateTime(period.Year, period.Month, 01);
var endOfMonth = new DateTime(period.Year, period.Month, 01).AddMonths(1);
return from t in transactions
where (beginOfMonth <= t.Date && t.Date < endOfMonth)
select t;
}
static void Run(IEnumerable<Transaction> transactions, Period period)
{
var filteredTransactions = Filter(transactions, period);
var categorizer = new Categorizer();
var categorized = categorizer.Categorize(filteredTransactions);
Reporter.Report(categorized, period);
}