Explore a gentle introduction to functional programming with dependent types in this 36-minute DevConf.IN 2025 talk by Jens Petersen. Learn how dependent types enhance program precision and safety, providing higher assurance guarantees for software design. Discover various practical examples demonstrating Dependent Type Theory using the Lean4 programming language and theorem prover. Understand Lean4's powerful features including interactive evaluation and native code compilation, and see why this elegant modern language, though primarily used for formalizing mathematics, is also becoming a formidable programming tool. Access accompanying slides and resources through the provided link to enhance your learning experience.