More interestingly you can also go the other way if you use only the lower level F# features (F# being mostly a superset of C# features) and a C# developer won't realise that they are calling F# code - it's all just .NET IL in the end. Did it often when creating libraries at work; it isn't like invoking another language's binary code at all. One of the pro's I guess of working with a VM (JVM/.NET) based language - interop between languages is usually much easier and so niche languages can have a much larger ecosystem than they otherwise would have.
