Bill Atkins wrote:
Conal Elliott wrote:
And the IO monad is what Jerzy asked about. I'm pointing out that the state monad does not capture concurrency, and the "EDSL model" does not capture FFI. (Really, it depends which "EDSL model". I haven't seen one that can capture FFI. And maybe not concurrency either.)
So which model captures the way the IO monad works?
This is thoroughly discussed in section 3 of Simon Peyton Jones. Tackling the awkward squad: monadic input/output, concurrency, exceptions, and foreign-language calls in Haskell http://tinyurl.com/spj-marktoberdorf In particular, the World -> (a,World) model is unsuitable even without concurrency because it cannot distinguish loop, loop' :: IO () loop = loop loop' = putStr "c" >> loop' I interpret the "EDSL model" to be the operational semantics presented in the tutorial paper. Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com