How to use external library (LanguageExt) in Unity?

Unity Engine
1

I have added the DLL to assets and set player to use .NET 4.x. Unfortunately I am getting this error:

error CS0009: Metadata file `/mnt/xxx/test03-lang-ext/Assets/LanguageExt.Core.dll' does not contain valid metadata

The library should be compatible with Mono and this .NET version. Any ideas what might be wrong?

2

Just tested it with Mono and it works, so this seems to be a problem related to Unity. I am using the beta build of Unity - 2018.1.0b8 and testing it on Kubuntu 16.04.