decimal-money

Money types for Rust — CurrencyAmount with Decimal precision, multi-currency support, FX conversion, and formatting.

Features

• Decimal precision — Uses rust_decimal for exact arithmetic
• 36+ currencies — Fiat and crypto (USD, EUR, GBP, JPY, BTC, ETH, ...)
• FX conversion — Pluggable FxProvider trait with in-memory implementation
• Formatting — Configurable symbol position, separators, ISO codes
• Type-safe — Currency mismatch errors at runtime, not panics

Quick Start

use money::{CurrencyAmount, Currency, FormatConfig};

let price = CurrencyAmount::new(rust_decimal_macros::dec!(19.99), Currency::USD);
let tax = CurrencyAmount::new(rust_decimal_macros::dec!(1.60), Currency::USD);
let total = (price + tax).unwrap();

assert_eq!(total.amount, rust_decimal_macros::dec!(21.59));
assert_eq!(format!("{total}"), "$21.59");

Formatting

use money::{CurrencyAmount, Currency, FormatConfig};

let amount = CurrencyAmount::new(rust_decimal_macros::dec!(1234.56), Currency::EUR);

// US style: $1,234.56
let us = FormatConfig::us();

// European style: 1.234,56 €
let eu = FormatConfig::european();
assert_eq!(eu.format(&amount), "1.234,56 \u{20AC}");

FX Conversion

use money::{CurrencyAmount, Currency, InMemoryFxProvider};
use rust_decimal::Decimal;

let mut provider = InMemoryFxProvider::new();
provider.set_rate(Currency::USD, Currency::EUR, Decimal::try_from("0.85").unwrap());

let dollars = CurrencyAmount::new(rust_decimal_macros::dec!(100), Currency::USD);
let euros = money::convert(&dollars, &provider).unwrap();

Comparison with Manual rust_decimal Usage

Without money, you'd track currency manually:

use rust_decimal::Decimal;

let amount = Decimal::from(1999); // cents
let currency = "USD";
// ... hope you don't mix up currencies

With money, you get:

• CurrencyAmount bundles amount + currency
• Arithmetic checks currency compatibility
• Formatting handles symbols and decimal places
• No "stringly-typed" currency codes in your business logic

License

Licensed under either of MIT or Apache-2.0 at your option.