Ledgertype txn = {date : Civil.date;num : string;payee : string;category : string;memo : string;amount : Money.cents;status : status;}val date_of_string : string -> Civil.date optionval date_to_string : Civil.date -> stringval balances : txn list -> (txn * Money.cents) listval by_category : txn list -> (string * Money.cents) listval next_check : txn list -> string