F# 4.1 brings improvements to the language. It is distributed trough the Microsoft tools for F#, which are stated to ship later this year. This version enables support for struct tuples, interoperation with C# 7 and by-ref returns.
Tuples are commonly used in F#, as the syntax and type inference make them easy to use. They are reference types, stored on the heap. F# 4.1 brings struct tuples, stored on the stack. This have performance benefits for certain scenarios, such as allocating a large number of small tuples.
To support the ValueTuple type, tuple types, tuple expressions and tuple patterns can now be annotated with the struct keyword.
