On Thu, May 29, 2003 at 11:57:00AM -0700, Iavor Diatchki wrote:
[...] and don't you think the code bellow is better? not to mention that moving the library to a new localtion would be practically for free (as far as the library is concerned, the users may still have to adjust their imports)
module State (State,runState,runStateS,module Trans) where
import Identity import StateT import Trans
type State s = StateT s Identity
runState :: s -> State s a -> a runState s m = runIdentity (StateT.runState s m)
runStateS :: s -> State s a -> (a,s) runStateS s m = runIdentity (StateT.runStateS s m)
I believe you need a qualified on the import of StateT to avoid ambiguity. But you would get the same effect with a variant of Malcolm's version: module Control.Monad.State ( State,runState,runStateS,module Trans) where import Control.Monad.Identity as Identity import qualified Control.Monad.StateT as StateT import Control.Monad.Trans as Trans with the rest of the module unchanged. Further changes would be required only (1) to export the whole of the current module (2) if names needed to be qualified with the name of the current module to avoid ambiguity (quite rare -- only one module does it in fptools/{libraries,hslibs}, and that unnecessarily) In both cases you'd need to specify the module name with or without your extension, the only difference is its length. Even that could be fixed in Haskell 98, where you could write import Control.Monad.State as State but none of the implementations would like it. The current setup is cumbersome, but the verbosity can be confined to the module header and the imports, except in the rare case (2) above. And it is simple: the name mentioned in the import is the real module name.