The F# programming language is intended to bring the benefits of functional languages to the common language runtime. F# efficiently runs on Windows, Linux, and OS-X, and it can be used to write applications for mobile platforms like Windows Phone, iPhone, and Android.

Here are some of F#’s main advantages:

Data safety and predictability

The most common programming task we all do is editing, fixing, and extending existing code. Unlike other programming languages, F# has pure functions and immutable data structures that make it easier to understand. A pure function returns the same output from every input and has no side effects. Shared data structures can be shared and used by multiple functions with the assurance that they won’t be changed by other functions.

It can be challenging to work with immutable data at first because a shared object can’t be changed in any other references if revised in a function. A railroad track-shaped program flow is a better fit for immutable data than a bumper car rink-shaped program flow. Code that is highly reasonable and testable is produced by this simple succession of functions returning distinct immutable pieces of state.

Modeling domains using algebraic types

F# has an algebraic type system that is powerful. A type can be wrapped in another type, and it is very convenient for domain modeling to combine types algebraically. It may be possible to combine UnverifiedEmailAddress and VerifiedEmailAddress into an EmailAddress type. The emailAddress string and the isVerified Boolean can be null, so this is a safer and more expressive approach.

A few lines of code are all it takes to create a high-level data structure in F# with its record and tuple features. As well as classic C# syntax for creating objects, F# features inheritance, interfaces, attributes, virtual methods, and a whole lot more. You can learn fully-fledged OO programming even in the middle of an F# project.

Thanks to its type system, F# is especially well suited to domain modeling. Scott Wlaschin’s Domain Modeling Made Functional provides comprehensive guidance on combining these powerful sums and multiplicative types. Other languages can benefit from many of the principles and techniques he describes.

An ecosystem based on the .NET framework

.NET Core is an open-source platform that runs F#, and it is built on the .NET framework. The F# language supports quickly consuming C#-based .NET packages. In addition, there is a gateway to the world of object-oriented programming.

It’s always better to use F#

Functional programming languages can feel risky, despite their many benefits. It is often the case that functional languages are poorly supported or can be challenging to use. Despite this pragmatic approach, F# provides the richness of a functional language with accessible portals back into C# when desired. As part of the .NET ecosystem, it is backed by a full range of features and legacy. Several functions are available as first-class objects in F#, as are immutable data by default, algebraic data types, and many other parts of functional programming.

It is beyond the scope of this article to compare F# with all other languages. Despite these unique features, F# is one of the most powerful languages.