Advanced
Variance and covariance, nominal typing with brands, type-level arithmetic, const type parameters, NoInfer, builder pattern, type-state pattern, higher-kinded types, variadic tuples, monorepos with project references, React advanced patterns, performance optimization, inference tricks, dependency injection, Compiler API, and testing patterns.
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Type System Mastery
Variance: Covariance & Contravariance
Understand how types relate to each other through their type parameters, and why function parameters are checked differently from return types.
Nominal Typing Patterns
Simulate nominal (name-based) typing in TypeScript's structural system using branding, opaque types, and unique symbols to prevent value confusion.
Type-Level Arithmetic & String Parsing
Compute with types at compile time: count tuple lengths, do numeric comparisons, parse string patterns, and build type-safe DSLs.
`const` Type Parameters & NoInfer
Use TypeScript 5.0's const type parameters to preserve literal types in generic functions, and NoInfer to control where TypeScript deduces types.
Advanced Design Patterns
The Typed Builder Pattern
Build fluent, step-by-step construction APIs where TypeScript tracks which fields have been set and prevents calling build() until all required fields are provided.
Type-State Pattern (Phantom Types)
Encode object lifecycle states into the type system so that calling the wrong method in the wrong state is a compile error, not a runtime exception.
Simulating Higher-Kinded Types
Simulate HKT (type constructors as first-class values) in TypeScript using interface lookup maps, enabling truly generic abstractions like Functor and Monad patterns.
Variadic Tuple Types
Use rest elements and spread in tuple types to model typed `compose`, `pipe`, `concat`, and argument-forwarding functions with full type inference.
Advanced Integration
Monorepos & TypeScript Project References
Structure large codebases with TypeScript project references for incremental builds, proper cross-package type checking, and monorepo tooling integration.
TypeScript with React - Advanced Patterns
Master advanced TypeScript patterns for React: polymorphic components, generic components, discriminated union props, forward refs, and typed context.
TypeScript Performance Optimization
Identify and fix slow TypeScript compilation: simplify complex types, avoid distributive inference traps, use `interface` over `type` for merging, and structure projects for incremental builds.
Advanced Type Inference Tricks
Deep-dive into TypeScript's inference engine: infer in conditional types, return type inference, contextual typing, generic defaults, and satisfies vs as.
Expert Patterns
Dependency Injection Patterns in TypeScript
Implement type-safe dependency injection using interfaces, factory functions, and manual containers - without decorators or runtime metadata.
TypeScript Compiler API
Use the TypeScript Compiler API to build code generators, linters, codemods, and documentation tools that work directly with the TypeScript AST.
TypeScript Testing Patterns
Write type-safe tests with typed mocks, test doubles, utility types for testing, type assertion tests, and patterns for testing TypeScript-specific features.