[Ur] Maybe Monad ( option monad) or list monad in Ur

[Adam Chlipala]

austin seipp wrote:
> It's there in basis but there is no function with which you can
> construct an instance of 'monad a'. The type class is closed and the
> only instances are for 'transaction' and 'signal'.
>    

That's right.  Due to a slightly embarrassing compiler implementation 
choice, there is no way now to create other [monad] instances.  You 
could certainly redefine the class on your own in a way which allows 
defining new instances.

Or I could change the compiler at some point. :)