The type Cofree (Either t) e is isomorphic to a non-empty version of List t e On Wednesday, November 25, 2015 at 8:00:40 PM UTC+1, Silvio Frischknecht wrote:
Hello,
I'm interested in learning more about a list-like structure with a terminal element. I.e.
data List t e = Cons e (List t e) | Null t
or maybe
data List t e = Cons e (List t e) | Null | Terminal t
An practical application could be lazy reading from a file readFile :: String -> List Error String
Obviously there is a Functor instance. There is even a Monad instance. However, it is not defined as obviously because it's not clear what the terminal element should be. There is a straight forward fold like structure.
My questions are.
Are there more interesting generalizations of List? What rules do they follow? How should the Monad work? Why?
I know this is related to the whole Iteratee discussion (I'm not completely familiar with it).
Cheers
Silvio _______________________________________________ Haskell-Cafe mailing list Haskel...@haskell.org javascript: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe