Strange behavior of minimal api when using it in fsharp

[vshapenko]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hello! I am trying to use minimal api from fsharp, and encountered a following problem:

https://gist.github.com/vshapenko/5c6ae1c0cb005dddd1325caca266ecd4

First method in gist above works as intended, second and third do not pass value to handler.

Can somebody explain this strange behavior?

Expected Behavior

All methods returns input string

Steps To Reproduce

Run the gist above, invoke endpoints

Exceptions (if any)

No response

.NET Version

7.0.100

Anything else?

No response

[captainsafia]

@vshapenko Thanks for filing this issue! We don't have capacity to investigate at the moment and will place it in the backlog. You can try filing it on StackOverflow to see if folks from the F# community might have some insight on this.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[lucasteles]

@vshapenko This happens because of how F# deals with Delegates, an F# function is not the same as a C# lambda/delegate.

So, there is no information about the parameter name when you construct a Func<> using an already existing F# function and ASPNET is unable to bind the parameter correctly

The first case is working because the F# compiler when see you directly calling a lambda on an Expression<Func<>> or Func<> emits a compatible delegate type

More here fsharp/fslang-suggestions#1083
and here fsharp/fslang-suggestions#1131