F# for Fun and Profit
Completeness
In this final set of posts, we will look at some other aspects of F# under the theme of “completeness”.
Programming languages coming from the academic world tend to focus on elegance and purity over real-world usefulness, while more mainstream business languages such as C# and Java are valued precisely because they are pragmatic; they can work in a wide array of situations and have extensive tools and libraries to meet almost every need. In other words, to be useful in the enterprise, a language needs to be complete, not just well-designed.
F# is unusual in that it successfully bridges both worlds. Although all the examples so far have focused on F# as an elegant functional language, it does support an object-oriented paradigm as well, and can integrate easily with other .NET languages and tools. As a result, F# is not a isolated island, but benefits from being part of the whole .NET ecosystem.
The other aspects that make F# “complete” are being an official .NET language (with all the support and documentation that that entails) and being designed to work in Visual Studio (which provides a nice editor with IntelliSense support, a debugger, and so on) and Visual Studio Code. These benefits should be obvious and won’t be discussed here.
So, in this last section, we’ll focus on two particular areas:
- Seamless interoperation with .NET libraries. Obviously, there can be a mismatch between the functional approach of F# and the imperative approach that is designed into the base libraries. We’ll look at some of the features of F# that make this integration easier.
- Full support for classes and other C# style code. F# is designed as a hybrid functional/OO language, so it can do almost everything that C# can do as well. We’ll have a quick tour of the syntax for these other features.
The "Why use F#?" series
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Introduction to the 'Why use F#' series
An overview of the benefits of F# -
F# syntax in 60 seconds
A very quick overview on how to read F# code -
Comparing F# with C#: A simple sum
In which we attempt to sum the squares from 1 to N without using a loop -
Comparing F# with C#: Sorting
In which we see that F# is more declarative than C#, and we are introduced to pattern matching. -
Comparing F# with C#: Downloading a web page
In which we see that F# excels at callbacks, and we are introduced to the 'use' keyword -
Four Key Concepts
The concepts that differentiate F# from a standard imperative language -
Conciseness
Why is conciseness important? -
Type inference
How to avoid getting distracted by complex type syntax -
Low overhead type definitions
No penalty for making new types -
Using functions to extract boilerplate code
The functional approach to the DRY principle -
Using functions as building blocks
Function composition and mini-languages make code more readable -
Pattern matching for conciseness
Pattern matching can match and bind in a single step -
Convenience
Features that reduce programming drudgery and boilerplate code -
Out-of-the-box behavior for types
Immutability and built-in equality with no coding -
Functions as interfaces
OO design patterns can be trivial when functions are used -
Partial Application
How to fix some of a function's parameters -
Active patterns
Dynamic patterns for powerful matching -
Correctness
How to write 'compile time unit tests' -
Immutability
Making your code predictable -
Exhaustive pattern matching
A powerful technique to ensure correctness -
Using the type system to ensure correct code
In F# the type system is your friend, not your enemy -
Worked example: Designing for correctness
How to make illegal states unrepresentable -
Concurrency
The next major revolution in how we write software? -
Asynchronous programming
Encapsulating a background task with the Async class -
Messages and Agents
Making it easier to think about concurrency -
Functional Reactive Programming
Turning events into streams -
Completeness
F# is part of the whole .NET ecosystem -
Seamless interoperation with .NET libraries
Some convenient features for working with .NET libraries -
Anything C# can do...
A whirlwind tour of object-oriented code in F# -
Why use F#: Conclusion
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