Crate debtsolver

Track and settle debts between parties with the fewest transactions.

Debtsolver gives you two structs - Transactions, which track payments that have been made or need to be made, and a Ledger which can store and balance the current states of credits and debits between everyone.

Use

Transactions must be initialized with a debtor, creditor and positive amount. For example, if Bob borrows 10 from Alice, you would track that as:

transaction = transaction!("Alice", "Bob", (10, "USD")));

Legders are created empty, and you can add transactions to them to track the current state of debtors and creditors.

ledger = Ledger::new()
ledger.add_transaction(transaction);

You can inspect the state of the ledger at any point by calling to_vector on it to get the list of debtors and creditors as a vector of tuples

for transaction in ledger.to_vector(){
    println!("{}", transaction)
};
// (Alice, Bob, 10 USD)

Once all the debts are tracked, and you want to figure out the fastest way for debtors to pay back creditors, you can simply call settle:

let payments = ledger.settle();

Examples

use debtsolver::Ledger;
use debtsolver::Transaction;
use debtsolver::transaction;

fn main() {
    let mut ledger = Ledger::new();

    // Let's say that:
    // Alice paid 20 for Bob's lunch
    // Bob paid 20 for Charlie's dinner the next day.
    ledger.add_transaction(transaction!("Alice", "Bob", (20, "USD")));
    ledger.add_transaction(transaction!("Bob", "Charlie", (20, "USD")));

    for payment in ledger.settle() {
        println!("{}", payment)
    }
    // Debtsolver will resolve this with one payment:
    // Alice owes Charlie 20.00 USD


    // Now lets say that:
    //   Bob paid for Alice's breakfast (20).
    //   Charlie paid for Bob's lunch (50).
    //   Alice paid for Charlie's dinner (35).
    ledger.add_transaction(transaction!("Alice", "Bob", (20, "USD")));
    ledger.add_transaction(transaction!("Bob", "Charlie", (50, "USD")));
    ledger.add_transaction(transaction!("Charlie", "Alice", (35, "USD")));


    for payment in ledger.settle() {
        println!("{}", payment)
    }
    //Debtsolver will resolve this with just two payments:
    // Bob owes Alice 15.00 USD
    // Bob owes Charlie 15.00 USD

Macros

• transaction

Structs

• Ledger
  Represents a zero-sum ledger which tracks the current state of who owes money, and who is owed money. The sum of all balances must always add up to zero, since each debtor has an equivalent creditor.
• MultiPartyTransaction
  Represents a multi-party transaction where one or more parties (debtors) owes one or more parties (creditors) the amount specified.
• ParseAmountError
• Transaction
  Represents a transaction where one party (debtor) pays another (creditor) the amount specified.