What's new in F# 10 (#49649)

* What's new in F# 10

* Add ai-usage metadata

* Add link in .net 10 overview to F#

* Apply suggestions from code review

Co-authored-by: Adam Boniecki <20281641+abonie@users.noreply.github.com>

* Add links to language reference

* Add entries about *Final methods to CE reference

* Update parameters page with voption for optional param info

* Apply review feedback

* Add type cache section

* Add Whats New F#10 to the ToC

---------

Co-authored-by: Bill Wagner <wiwagn@microsoft.com>

Author: abonie

docs/core/whats-new/dotnet-10/overview.md

@@ -75,7 +75,7 @@ The F# updates in .NET 10 include several new features and improvements across t
 
   General improvements and bug fixes in the compiler implementation.
 
-For more information, see the [F# release notes](https://fsharp.github.io/fsharp-compiler-docs/release-notes/About.html).
+For more information, see [What's new in F# 10](../../../fsharp/whats-new/fsharp-10.md) or the [F# release notes](https://fsharp.github.io/fsharp-compiler-docs/release-notes/About.html).
 
 ## Visual Basic
 

docs/fsharp/index.yml

@@ -120,6 +120,8 @@ landingContent:
     linkLists:
       - linkListType: whats-new
         links:
+          - text: "What's new in F# 10"
+            url: whats-new/fsharp-10.md
           - text: "What's new in F# 9"
             url: whats-new/fsharp-9.md
           - text: "What's new in F# 8"

docs/fsharp/language-reference/computation-expressions.md

@@ -264,6 +264,7 @@ The following table describes methods that can be used in a workflow builder cla
 |`Delay`|`(unit -> M<'T>) -> Delayed<'T>`|Wraps a computation expression as a function. `Delayed<'T>` can be any type, commonly `M<'T>` or `unit -> M<'T>` are used. The default implementation returns a `M<'T>`.|
 |`Return`|`'T -> M<'T>`|Called for `return` in computation expressions.|
 |`ReturnFrom`|`M<'T> -> M<'T>`|Called for `return!` in computation expressions.|
+|`ReturnFromFinal`|`M<'T> -> M<'T>`|If present, called for `return!` and `do!` when in tail-call position.|
 |`BindReturn`|`(M<'T1> * ('T1 -> 'T2)) -> M<'T2>`|Called for an efficient `let! ... return` in computation expressions.|
 |`BindNReturn`|`(M<'T1> * M<'T2> * ... * M<'TN> * ('T1 * 'T2 ... * 'TN -> M<'U>)) -> M<'U>`|Called for efficient `let! ... and! ... return` in computation expressions without merging inputs.<br /><br />for example, `Bind3Return`, `Bind4Return`.|
 |`MergeSources`|`(M<'T1> * M<'T2>) -> M<'T1 * 'T2>`|Called for `and!` in computation expressions.|
@@ -277,6 +278,7 @@ The following table describes methods that can be used in a workflow builder cla
 |`While`|`(unit -> bool) * Delayed<'T> -> M<'T>`or<br /><br />`(unit -> bool) * Delayed<unit> -> M<unit>`|Called for `while...do` expressions in computation expressions.|
 |`Yield`|`'T -> M<'T>`|Called for `yield` expressions in computation expressions.|
 |`YieldFrom`|`M<'T> -> M<'T>`|Called for `yield!` expressions in computation expressions.|
+|`YieldFromFinal`|`M<'T> -> M<'T>`|If present, called for `yield!` when in tail-call position and in case of `do!` in tail-call position as a fallback for `ReturnFromFinal`|
 |`Zero`|`unit -> M<'T>`|Called for empty `else` branches of `if...then` expressions in computation expressions.|
 |`Quote`|`Quotations.Expr<'T> -> Quotations.Expr<'T>`|Indicates that the computation expression is passed to the `Run` member as a quotation. It translates all instances of a computation into a quotation.|
 

docs/fsharp/language-reference/parameters-and-arguments.md

@@ -150,6 +150,18 @@ Baud Rate: 9600 Duplex: Full Parity: false
 Baud Rate: 4800 Duplex: Half Parity: false
 ```
 
+You can also specify an optional parameter to be a [Value Option](./value-options.md) type by applying a `[<Struct>]` attribute to it.
+
+```fsharp
+type T() =
+    static member M([<Struct>] ?p : string) =
+        match p with
+        | ValueSome s -> printfn "%s" s
+        | ValueNone -> printfn "None"
+```
+
+When using struct-backed optional parameter, as seen above, you would use `defaultValueArg` instead of `defaultArg` to set the default value of the parameter.
+
 ### Optional parameters (C# interop)
 
 For the purposes of C# interop, you can use the attributes `[<Optional; DefaultParameterValue<(...)>]` in F#, so that callers will see an argument as optional. This is equivalent to defining the argument as optional in C# as in `MyMethod(int i = 3)`. This form was introduced in F# 4.1 to help facilitate interoperation with C# code.

docs/fsharp/toc.yml

@@ -292,6 +292,8 @@ items:
     href: tutorials/using-functions.md
 - name: What's new
   items:
+  - name: F# 10
+    href: whats-new/fsharp-10.md
   - name: F# 9
     href: whats-new/fsharp-9.md
   - name: F# 8