Module types 

Value types for the trading domain model.

This module provides immutable value types that represent fundamental trading concepts: Price, Quantity, and Money. These types use fixed-point arithmetic internally for deterministic calculations while providing a natural numeric interface.

Immutability

All value types are immutable - once constructed, their values cannot change. Arithmetic operations return new instances rather than modifying existing ones. This design ensures thread safety and predictable behavior in concurrent trading systems.

Arithmetic operations

Value types implement Rust’s standard arithmetic traits (Add, Sub, Mul) for same-type operations. When operating on two values of the same type, the result preserves that type.

Operation	Result	Notes
Quantity + Quantity	Quantity	Precision is max of both operands.
Quantity - Quantity	Quantity	Panics if result would be negative.
Price + Price	Price	Precision is max of both operands.
Price - Price	Price	Precision is max of both operands.
Money + Money	Money	Panics if currencies don’t match.
Money - Money	Money	Panics if currencies don’t match.

For Python bindings with mixed-type operations (e.g., Quantity + int), see the Python API documentation.

Precision

Each value type stores a precision field indicating the number of decimal places. The maximum precision is defined by fixed::FIXED_PRECISION. When performing arithmetic between values with different precisions, the result uses the maximum precision of the operands.

Constraints

• Quantity: Non-negative values only. Subtracting a larger quantity from a smaller one raises an error rather than producing a negative result.
• Price: Signed values allowed (can represent negative prices for spreads, etc.).
• Money: Signed values allowed. Operations between different currencies raise an error.

Re-exports

pub use balance::AccountBalance;

pub use balance::MarginBalance;

pub use currency::Currency;

pub use money::MONEY_MAX;

pub use money::MONEY_MIN;

pub use money::Money;

pub use price::ERROR_PRICE;

pub use price::PRICE_ERROR;

pub use price::PRICE_MAX;

pub use price::PRICE_MIN;

pub use price::PRICE_RAW_MAX;

pub use price::PRICE_RAW_MIN;

pub use price::PRICE_UNDEF;

pub use price::Price;

pub use quantity::QUANTITY_MAX;

pub use quantity::QUANTITY_MIN;

pub use quantity::QUANTITY_UNDEF;

pub use quantity::Quantity;

Modules

balance

Represents an account balance denominated in a particular currency.

currency

Represents a medium of exchange in a specified denomination with a fixed decimal precision.

fixed

Functions for handling fixed-point arithmetic.

money

Represents an amount of money in a specified currency denomination.

price

Represents a price in a market with a specified precision.

quantity

Represents a quantity with a non-negative value and specified precision.

stubs