For instance, C#:

  public static System.Collections.Generic.IEnumerable<TResult> SelectMany<TSource,TCollection,TResult>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,System.Collections.Generic.IEnumerable<TCollection>> collectionSelector, Func<TSource,TCollection,TResult> resultSelector);

  (>>=) :: m a -> (a -> m b) -> m b

In your c# sample full namespaces are unnecessary and will add only noise in this context.