What is F#?


F# is an open-source, cross-platform programming language that makes it easy to write succinct, performant, robust, and practical code.

F# runs anywhere .NET runs and in cases where your application needs to run in a JavaScript environment, there are various libraries you can use to convert your F# code into JavaScript.

F# has numerous features that include:

  • Lightweight syntax: Write low-ceremony code and focus on the core logic of your application.
  • Type inference and automatic generalization: Leverage the compiler to get the benefits of a statically typed language without explicitly defining your types.
  • Immutable by default: Apply predictable & repeatable transformations to your data without worrying about side-effects.
  • Powerful data types: Represent complex data & model domains using tuples, records, and discriminated unions.
  • Pattern matching: Enforce correctness in your application's behavior using the compiler.
  • Asynchronous programming: Support for asynchronous workflows out of the box.

Why F#?

There are many language features and aspects of the F# language that make it easy to be productive when writing code:

  • Succinct: You write less code with F# that's also expressed in a clear manner.
  • Performant: F# comes with built-in parallelism and concurrency. It also uses the fact that it's part of the .NET runtime to speed things up.
  • Robust: There are language constructs that make the code fault tolerant and robust like immutable by default, null value management and more.
  • Supports multiple programming paradigms: F# lets you choose the patterns and practices most effective for solving problems by providing strong support for functional and object programming paradigms.


Writing less code not only cuts down on your development time, but it also makes your code easier to read and test.

  • Type inference: As a result of its strong type system, the F# compiler is able to analyze your code and infer the data types you're working with without explicitly defining them.
  • Lightweight syntax: F# lets you be productive without writing too much boilerplate code. Its lightweight syntax lets you focus on the core components of your application.


As the demands on your application grow, writing scalable code to meet those demands is hard. F# simplifies the process of writing scalable code by building on top of a performant runtime and having parallelism and concurrency built into the language.

  • Built-in parallelism & concurrency: F# has language features like async expressions that simplify the process of writing concurrent code to safely make the most of your compute resources.
  • Leverage the performance of the .NET Runtime: The .NET runtime is able to efficiently handle large workloads across a wide range of deployment targets.


Writing code that's unreliable can be costly. When you develop applications, you want to make sure that they stand the test of time. F# helps you write robust code by making the expected outcomes predictable and reproducible. Using world-class tooling and libraries you can catch and handle those edge-cases before your users do.

  • Immutable by default: Having immutability by default means you can process your data without changing the original data throughout the execution of your program. Therefore when applying changes to your data you have a high degree of certainty of the expected outcome making code simpler to reason about and test.
  • Null value handling: Errors in an application due to null values can be costly. As a result, code bases can often be riddled with code to check for and handle null values. In F#, you can use the Option type to safely handle scenarios where null values may arise.
  • Professional-grade tooling: Use lightweight text editors such as Visual Studio Code or an IDE like Visual Studio.
  • Works with .NET libraries: The .NET ecosystem has a rich ecosystem of libraries. As a .NET language, F# can take advantage of those libraries and use them inside your applications.

Supports multiple programming paradigms

F# is about getting things done. With strong functional & object programming support, F# lets you choose which patterns and practices best solve your problem. Using its interactive programming & scripting environments, you can begin validating your ideas instantly.

  • Strong functional & object programming support: Regardless of the patterns you implement in your applications, with F# you don't have to choose because it provides strong support for both functional and object programming.
  • Interactive programming: F# via F# Interactive provides scripting capabilities. Instead of compiling your code inside an F# project, you can get started writing and evaluating your code logic interactively via the console or through script files. For more visual environments such as when building visualizations, you can use tools like .NET notebooks via .NET Interactive.