Part 5. Designing real-world software

The final part of the book embarks on a comprehensive exploration of advanced topics crucial for the development of robust, functional software systems. We learn about the complexities of multithreading and concurrency, unraveling the challenges and strategies for designing reliable concurrent code. Our focus includes understanding the nuances of IORefs, MVars, and software transactional memory (STM) TVars and their appropriate use in a concurrent environment. This part also explores the potential of free monads as an architectural pattern for constructing versatile application frameworks, with an emphasis on the role of transactional data structures and transactions in behavior modeling.