[Feature]: Make assertions with Action<_> more friendly to F# by adding Func<_, _> and ignoring the result

[cmeeren]

Background and motivation

I love FluentAssertions and use it for F#. However, F#'s overload resolution and type inference means that some parts of FluentAssertions are more difficult or verbose to use than with C#.

One thing that is annoying is that I want to be able to do this (note that I'm ignoring the because limitation mentioned in #2225 to make this point more clear):

elements.Should().AllSatisfy(fun e -> e.Should.Be(expected))

This fails to compile because AllSatisfy takes an Action, which means there must be no return value. But e.Should.Be(expected) returns a value of type AndConstraint<...Assertions>, and therefore compilation fails.

The ad-hoc, verbose workaround is to insert |> ignore in these places:

elements.Should().AllSatisfy(fun e -> e.Should.Be(expected) |> ignore)

The above compiles. But I have verified that if I add an extension like the below, the first example also compiles:

type GenericCollectionAssertions<'T> with

    member this.AllSatisfy(expected: Func<'T, 'TIgnored>) =
        this.AllSatisfy(fun x -> expected.Invoke(x) |> ignore)

My proposal is to change all relevant Action<T>-based overloads to instead use Func<T, TIgnored>, so that the "clean" F# code will compile as is. (Alternatively, new overloads could be added alongside existing ones.)

Alternative Concerns

No response

[cmeeren]

For what it's worth, I am no longer interested in this. As detailed in #2225 (comment), I am creating a brand new F# assertions library inspired by FluentAssertions. Feel free to close.