F# is a functional programming language. Functional programming treats programs as mathematical expressions. It focuses on functions and constants that don't change, rather than variables and states. F# is a Microsoft programming language for concise and declarative syntax. Let's begin with a brief history of how this language came into existence. The first attempt at functional programming was Haskell .NET. F# development began in 2005 and after that, various versions came along. At the time of writing this chapter, F# 4.1 is the latest version; it was released in March 2017. This comes with Visual Studio 2017 and supports .NET Core.

The F# language can be used for the following tasks:

• To solve mathematical problems
• For graphic design
• For financial modeling
• For compiler programming
• For CPU design

It is also used for CRUD applications, web pages GUI games, and other programs.