With the release of Visual Studio 2015 RC (release candidate), F# 4.0 language and tools updates are now provided. There are various new features added in F# 4.0, including constructors such as first-class functions, metaprogramming support, simplified mutable/ref values, inheritance from types with multiple generic interface, and normalized collections API to name a few apart from supporting fractional exponents such as units of measure. You can find the complete list of features at http://blogs.msdn.com/b/dotnet/archive/2015/04/29/rounding-out-visual-f-4-0-in-vs-2015-rc.aspx.

F# 4.0 is also different in another import aspect. As a community-oriented project, three-fourth of contributors are not affiliated with Microsoft. Even the time-honored naming convention of Microsoft.FSharp is now optional. It can be omitted when referring to namespaces, modules, and types from the FSharp.Core runtime.

Although, there are several significant enhancements in the F# 4.0 language...