You mean C#? F# is an ML family language on the CLR.

> James Gosling, who created the Java programming language in 1994, and Bill Joy, a co-founder of Sun Microsystems, the originator of Java, called C# an "imitation" of Java; Gosling further said that "[C# is] sort of Java with reliability, productivity and security deleted."

(Wikipedia)

I thought C# was Microsoft's NIH version of Java?

To be fair Microsoft wanted to adopt Java, and with J++ they added Windows specific base libraries and make it work with COM. One could still compile ordinary Java back then also with J++.

Although they weren't allowed to do that if I remember right, so they basically had to create C# - and C# turned out to be fantastic in my opinion.