You can define monadic interfaces for lists because lists are monads. It would therefore be correct (but slightly pedantic) to talk about "the list monad". >

You can define monadic interfaces for lists because lists are monads. It would therefore be correct (but slightly pedantic) to talk about "the list monad". > as you can with (probably all) parametric data types? Actually, you can't. For instance, if you define a predicate type: `data Predicate a = Predicate (a -> Bool)` It is not a monad, it's not even a functor. (If you're interested in what it is you can look into contravariant functors).