domain-fintech

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Translation

Chinese

FinTech Domain

金融科技（FinTech）领域

Layer 3: Domain Constraints

第3层：领域约束

Domain Constraints → Design Implications

领域约束 → 设计影响

Domain Rule	Design Constraint	Rust Implication
Audit trail	Immutable records	Arc<T>, no mutation
Precision	No floating point	rust_decimal
Consistency	Transaction boundaries	Clear ownership
Compliance	Complete logging	Structured tracing
Reproducibility	Deterministic execution	No race conditions

领域规则	设计约束	Rust 实现建议
审计追踪	不可变记录	Arc<T>，禁止修改
精度要求	禁止使用浮点数	rust_decimal
一致性	事务边界	清晰的所有权模型
合规性	完整日志记录	结构化追踪（Structured tracing）
可复现性	确定性执行	无竞态条件

Critical Constraints

关键约束

Financial Precision

金融精度

RULE: Never use f64 for money
WHY: Floating point loses precision
RUST: Use rust_decimal::Decimal

RULE: 切勿使用f64处理资金
WHY: 浮点数会丢失精度
RUST: 使用rust_decimal::Decimal

Audit Requirements

审计要求

RULE: All transactions must be immutable and traceable
WHY: Regulatory compliance, dispute resolution
RUST: Arc<T> for sharing, event sourcing pattern

RULE: 所有交易必须是不可变且可追踪的
WHY: 符合监管要求、解决纠纷
RUST: 使用Arc<T>实现共享，采用事件溯源模式

Consistency

一致性

RULE: Money can't disappear or appear
WHY: Double-entry accounting principles
RUST: Transaction types with validated totals

RULE: 资金不能凭空消失或出现
WHY: 遵循复式记账原则
RUST: 采用带总额验证的事务类型

Trace Down ↓

向下追溯 ↓

From constraints to design (Layer 2):

"Need immutable transaction records"
    ↓ m09-domain: Model as Value Objects
    ↓ m01-ownership: Use Arc for shared immutable data

"Need precise decimal math"
    ↓ m05-type-driven: Newtype for Currency/Amount
    ↓ rust_decimal: Use Decimal type

"Need transaction boundaries"
    ↓ m12-lifecycle: RAII for transaction scope
    ↓ m09-domain: Aggregate boundaries

从约束到设计（第2层）：

"需要不可变的交易记录"
    ↓ m09-domain: 建模为值对象
    ↓ m01-ownership: 使用Arc处理共享不可变数据

"需要精确的小数运算"
    ↓ m05-type-driven: 为货币/金额创建Newtype
    ↓ rust_decimal: 使用Decimal类型

"需要事务边界"
    ↓ m12-lifecycle: 用RAII实现事务范围
    ↓ m09-domain: 聚合边界

Key Crates

关键依赖库（Crates）

Purpose	Crate
Decimal math	rust_decimal
Date/time	chrono, time
UUID	uuid
Serialization	serde
Validation	validator

用途	依赖库
小数运算	rust_decimal
日期/时间	chrono, time
UUID	uuid
序列化	serde
验证	validator

Design Patterns

设计模式

Pattern	Purpose	Implementation
Currency newtype	Type safety	`struct Amount(Decimal);`
Transaction	Atomic operations	Event sourcing
Audit log	Traceability	Structured logging with trace IDs
Ledger	Double-entry	Debit/credit balance

模式	用途	实现方式
货币Newtype	类型安全	`struct Amount(Decimal);`
事务	原子操作	事件溯源
审计日志	可追踪性	带追踪ID的结构化日志
分类账	复式记账	借贷平衡

Code Pattern: Currency Type

代码模式：货币类型

rust

use rust_decimal::Decimal;

#[derive(Clone, Debug, PartialEq)]
pub struct Amount {
    value: Decimal,
    currency: Currency,
}

impl Amount {
    pub fn new(value: Decimal, currency: Currency) -> Self {
        Self { value, currency }
    }

    pub fn add(&self, other: &Amount) -> Result<Amount, CurrencyMismatch> {
        if self.currency != other.currency {
            return Err(CurrencyMismatch);
        }
        Ok(Amount::new(self.value + other.value, self.currency))
    }
}

rust

use rust_decimal::Decimal;

#[derive(Clone, Debug, PartialEq)]
pub struct Amount {
    value: Decimal,
    currency: Currency,
}

impl Amount {
    pub fn new(value: Decimal, currency: Currency) -> Self {
        Self { value, currency }
    }

    pub fn add(&self, other: &Amount) -> Result<Amount, CurrencyMismatch> {
        if self.currency != other.currency {
            return Err(CurrencyMismatch);
        }
        Ok(Amount::new(self.value + other.value, self.currency))
    }
}

Common Mistakes

常见错误

Mistake	Domain Violation	Fix
Using f64	Precision loss	rust_decimal
Mutable transaction	Audit trail broken	Immutable + events
String for amount	No validation	Validated newtype
Silent overflow	Money disappears	Checked arithmetic

错误	违反的领域规则	修复方案
使用f64	丢失精度	改用rust_decimal
可变交易记录	破坏审计追踪	不可变设计 + 事件溯源
用字符串存储金额	无验证机制	带验证的Newtype
静默溢出	资金丢失	使用检查型算术运算

Trace to Layer 1

追溯到第1层

Constraint	Layer 2 Pattern	Layer 1 Implementation
Immutable records	Event sourcing	Arc<T>, Clone
Transaction scope	Aggregate	Owned children
Precision	Value Object	rust_decimal newtype
Thread-safe sharing	Shared immutable	Arc (not Rc)

约束	第2层模式	第1层实现
不可变记录	事件溯源	Arc<T>, Clone
事务范围	聚合	拥有所有权的子对象
精度要求	值对象	rust_decimal Newtype
线程安全共享	共享不可变数据	Arc（而非Rc）

When	See
Value Object design	m09-domain
Ownership for immutable	m01-ownership
Arc for sharing	m02-resource
Error handling	m13-domain-error

场景	参考内容
值对象设计	m09-domain
不可变数据的所有权管理	m01-ownership
使用Arc实现共享	m02-resource
错误处理	m13-domain-error

domain-fintech

Original

Translation

FinTech Domain

金融科技（FinTech）领域

Domain Constraints → Design Implications

领域约束 → 设计影响

Critical Constraints

关键约束

Financial Precision

金融精度

Audit Requirements

审计要求

Consistency

一致性

Trace Down ↓

向下追溯 ↓

Key Crates

关键依赖库（Crates）

Design Patterns

设计模式

Code Pattern: Currency Type

代码模式：货币类型

Common Mistakes

常见错误

Trace to Layer 1

追溯到第1层

Related Skills

相关技能