pseudo-haskell

sketch.rb

class Valid a where
  valid :: a -> OkF Errors

class Valid a => Persist m a where
  save :: a -> m (OkF a)  -- or errors

data User = User {name :: String} 
data Organisation = Organisation {name :: String, users :: [User]}

class Url r 
  show :: r -> Url
  edit :: r -> Url
  list :: [r] -> Url    -- ?

instance Restful r => Url r where ... 

-- yank constrs out?
-- responsibility: marshall, save, redirect
-- constr can be (\n -> Org n u), closure
create_ constr args
 = do 
     res <- save (constr args)
     case res of 
       Ok   r      -> redirect (show r)
       Fail "oops" -> render template