Microsoft releases F# under Apache licence
Microsoft has released the sources of the F# programming language as open source code under the Apache 2.0 licence. The compiler and libraries are now available as "code drops" within the F# PowerPack collection on the CodePlex web site, Microsoft's hosting platform for open source projects. Both components were previously already available to download free of charge under Microsoft's Research Shared Source License Agreement, which permits developers to use the code in non-commercial projects. The Apache licence takes things a step further and allows the unrestricted use of the F# libraries and compiler.
However, releasing the sources as code drops prevents developers from making changes to the language itself; Microsoft has, therefore, retained complete control of the F# releases. The binaries continue to be provided by the F# Developer Center. Don Syme, the main developer of the F# language, also announced that future versions are to be synchronised with Microsoft's releases of the Visual Studio development environment.
The programming language derives its functional ideas from ML (Meta Language) as well as its Caml (Categorical Abstract Machine Language) and OCaml (Objective Caml) derivatives which, unlike such languages as Haskell, allow side effects such as the availability of mutable variables. F# is also based on such mechanisms as static typing, type inference, exception handling and pattern recognition. The object-oriented parts of F# are rooted in C#. Since .NET 4, Microsoft has treated the language as a "first class citizen" which became a component of the development environment with Visual Studio 2010.