Pure interface for hakyll dependency analysis

Manager.hs

module Manager where

-- | Yielded values from a manager. The constructor tagging mark the item for the client to act accordingly
data Yield a 
  = Uptodate a -- ^ this item is uptodate
  | Unlink a -- ^ this item must be eliminated
  | Build a -- ^ this item must be built
  | Empty -- ^ the manager has no item to manage

-- | Create method. Index and value associated is given along dependency logic and existential dependency, if present.
type Create b a 
            = b          -- ^ index for the item
            -> a          -- ^ new item
            -> (b -> Bool)-- ^ mask for dependencies
            -> Maybe b    -- ^ existence dependence 
            -> Manager b a
-- | All items indexed as the argument and all existential dependants will be marked to yield an Unlink 
type Delete b a 
            = b  -- ^ index to be deleted
            -> Manager b a
-- | All items indexed as the argument and their logical dependants will be marked to yield a Build. All items existentially depending on the touched items will be marked as Unlink
type Touch b a 
            = b  -- ^ index to be touched
            -> Manager b a

-- | next programmed operation along the updated manager considering the yielded value
type Step b a = (Yield a, Manager b a)
  
-- | Abstract Manager object. A bunch of closures over the internal structure.
data Manager b a = Manager 
  { create  :: Create b a 
  , delete  :: Delete b a
  , touch   :: Touch b a
  , step    :: Step b a
  }