Hiring a Functional programming developer can significantly enhance your software development process. They bring in a different approach, focusing on pure functions and avoiding shared state or mutable data. This leads to code that is more predictable, easier to test, and less prone to bugs. It's particularly beneficial for handling complex data transformations, parallel programming, and for systems where predictability and stability are paramount. Moreover, functional programming languages like Haskell, Erlang, and Scala are increasingly being used in data science, machine learning, and distributed systems, making these developers valuable for such advanced applications.