As an experienced C# developer, I've always been comfortable in the world of objects, classes, and imperative programming. LINQ introduced me to the power of functional concepts, but I wanted a deeper understanding. I wanted to master the essence of functional programming, to see the world through a different lens.
So I embarked on a journey, a journey that led me to the world of Haskell and Scala, and ultimately brought me back to C# with a renewed perspective.

Why Haskell?

Haskell, with its pure functional paradigm and strong static typing, offered the perfect environment to immerse myself in functional concepts. No side effects, no mutable state – just pure functions and immutable data. It was a challenging but rewarding experience.

Free resources that helped me:

University of Helsinki: https://haskell.mooc.fi/ – This provided a structured learning path with interactive exercises and projects (NOTE: Course is in English)
UPenn: https://www.cis.upenn.edu/~cis1940/spring13/ – This course is more than 10 years old and contains outdated tool references, but it offered a more academic approach, delving into the theoretical foundations of functional programming. Well worth the effort.

Key Concepts I learned:

• Immutability: Data doesn't change; instead, functions create new data based on the input. This leads to more predictable and easier-to-reason-about code.
• Pure Functions: Given the same input, a pure function always returns the same output, without any side effects. This makes functions easier to test and compose.
• Higher-Order Functions: Functions that take other functions as arguments or return functions as results. This enables powerful abstractions and code reusability.
• Recursion: Solving problems by breaking them down into smaller, self-similar subproblems. This is a fundamental technique in functional programming.
• Pattern Matching: A concise way to express conditional logic based on the structure of data.

Scala: Bridging the Gap

After Haskell, I explored Scala, a language that blends object-oriented and functional programming. This helped me see how functional concepts can be applied in a more pragmatic setting. This https://docs.scala-lang.org/online-courses.html#effective-programming-in-scala is a good resource.

Bringing it Back to C#

Armed with my newfound knowledge, I returned to C# with fresh eyes. I started to appreciate the functional features these languages offer:

• LINQ: I now more clearly understood the underlying principles of LINQ, allowing me to use it more effectively.
• Lambda Expressions: These became powerful tools for expressing concise and reusable functions.
• Immutable Collections: I started leveraging immutable collections to write more robust and thread-safe code.

Benefits I Experienced:

• Improved Code Readability: Functional code tends to be more concise and declarative, making it easier to understand and maintain.
• Reduced Bugs: Immutability and pure functions minimize side effects, leading to fewer errors and easier debugging.
• Increased Code Reusability: Higher-order functions and function composition promote modularity and code reuse.
• Enhanced Concurrency: Immutable data simplifies concurrent programming by eliminating shared mutable state.

My Advice for Fellow C# Developers:

Over the last few releases, C# has embraced and included more and more functional features - e.g. https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/functional/pattern-matching

If you're looking to expand your programming horizons and improve your craft, I highly recommend exploring functional programming. Start with Haskell to grasp the core concepts, then explore languages like Scala to see how these concepts can be applied in the real world. Finally, bring your newfound knowledge back to C# and unlock its full potential.