type-system

🔍 RUST TYPE SYSTEM BEST PRACTICES

TL;DR: Leverage Rust's powerful type system for safety, performance, and expressiveness through newtype patterns, phantom types, and zero-cost abstractions.

🔍 TYPE SYSTEM DESIGN STRATEGY

graph TD
    Start["Type Design"] --> DomainCheck{"Domain-Specific<br>Types Needed?"}

    DomainCheck -->|Yes| NewtypePattern["Newtype Pattern"]
    DomainCheck -->|No| PrimitiveCheck{"Primitive<br>Obsession?"}

    NewtypePattern --> StateTracking{"State Tracking<br>Required?"}
    PrimitiveCheck -->|Yes| NewtypePattern
    PrimitiveCheck -->|No| TraitDesign["Trait Design"]

    StateTracking -->|Yes| PhantomTypes["Phantom Types"]
    StateTracking -->|No| ValidatedTypes["Validated Types"]

    PhantomTypes --> CompileTimeCheck["Compile-Time Validation"]
    ValidatedTypes --> RuntimeCheck["Runtime Validation"]

    CompileTimeCheck --> ZeroCost["Zero-Cost Abstractions"]
    RuntimeCheck --> ZeroCost
    TraitDesign --> ZeroCost

    ZeroCost --> ErrorModeling["Error Modeling"]
    ErrorModeling --> SafetyPatterns["Safety Patterns"]
    SafetyPatterns --> Performance["Performance Optimization"]

    style Start fill:#4da6ff,stroke:#0066cc,color:white
    style NewtypePattern fill:#4dbb5f,stroke:#36873f,color:white
    style PhantomTypes fill:#ffa64d,stroke:#cc7a30,color:white
    style ZeroCost fill:#d94dbb,stroke:#a3378a,color:white

🎯 TYPE SAFETY PRINCIPLES

Newtype Pattern for Domain Modeling

use derive_more::{Constructor, Display, From, Into};
use serde::{Deserialize, Serialize};
use std::fmt;

// ✅ Strong typing for domain concepts
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, Constructor, Display, From, Into)]
pub struct UserId(uuid::Uuid);

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, Constructor, Display, From, Into)]
pub struct ProductId(uuid::Uuid);

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, Constructor, Display, From, Into)]
pub struct OrderId(uuid::Uuid);

// ✅ Prevents mixing up IDs at compile time
fn process_order(user_id: UserId, product_id: ProductId) -> OrderId {
    // Compiler prevents: process_order(product_id, user_id)
    OrderId(uuid::Uuid::new_v4())
}

// ❌ Weak typing - prone to errors
// fn process_order(user_id: String, product_id: String) -> String