Don Syme has announced the release of a new version of F# that replaces the old F# September 2008 CTP. This new release brings F# much more into alignment with the rest of .NET 4, in preparation for the first full product release of F# in Visual Studio 2010. The release is available either as part of the latest Visual Studio 2010 beta or as a separate F# May 2009 CTP that works with Visual Studio 2008.
Many of the improvements in the new version of F# are breaking changes that require existing software to be updated, such as the renaming of basic functions. For example, the List.fold_right function from OCaml has been renamed List.foldBack. We are in the process of bringing our F# for Visualization and F# for Numerics libraries up to date with respect to the latest F# CTP. Our forthcoming book F# for Technical Computing will not only cover the latest version of F# but also all of the latest library versions and new techniques for integration and interoperability.