I think it's possible by including the return-type in the argument list and using inline operators. You really have to jump through hoops though to make it work and the resulting code is damn ugly. Take a look at the source for FsControl[1]. It implements what they call 'type methods'. So there's types for Monad.Bind, Functor.Map, Applicative.Pure, etc.
I'm still trying to get my head around it; I thought I'd try to do so by implementing the core types and functions in Haskell's Pipes. So far I've managed to convince the F# compiler to take well over an hour to compile 70 lines of code!
The main argument against them has been lack of CLR support. But it seems that there's already the FsControl way, so I think some syntactic sugar would go a long way.
So yeah, until there's language support for type-classes I think it's probably not worth it.
