Ambiguous call to Where method on Fin<A> type due to multiple extension methods

[hhko]

Description

When calling the Where method on a Fin<A> type, the compiler throws a CS0121 error due to an ambiguous call between two extension methods with the same signature.

Background

The Fin<A> type implements multiple interfaces:

• IEnumerable<A> - enables System.Linq.Enumerable.Where extension method
• MonoidK<Fin> - enables LanguageExt.MonoidKExtensions.Where extension method

This creates a conflict when trying to call Where directly on a Fin<A> instance.

Steps to Reproduce

1. Create a new .NET project with LanguageExt.Core 5.0.0-beta-54
2. Write the following code:

using LanguageExt;
using static LanguageExt.Prelude;

var fin = Fin<int>.Succ(2025);
var result = fin.Where(x => x > 20); // CS0121 error occurs here

3. Compile the project

Expected Behavior

The code should compile successfully, allowing one of the Where methods to be called unambiguously.

Actual Behavior

Compiler error CS0121:

I would appreciate any feedback if my understanding of the Fin type is inaccurate or incomplete.

[micmarsh]

This seems like it could potentially mean some of those extension or object methods need to be dropped (in the absence of some kind of compiler-hinting attribute to aid resolution?), since I imagine this kind of thing is very hard to test for in "the wild", but will let @louthy chime in on that especially since there are a lot of library design philosophy questions related to that.

I am curious if Filter has the same problem though? I imagine Where is just there to support LINQ syntax and Filter is preferred in regular method call cases.

[louthy]

I had similar issues with the foldable extensions for IEnumerable (which is why I created Iterable). I'll need to think about the best approach here.

Use Filter anyway, it's the 'more functional' name. Although as stated, it may have the same issue.

[louthy]

Should be fixed in v5.0.0-beta-55