Component tags and sums

[dpwiz]

This allows types like Map Entity (Map WorldTag WorldSum) and IntMap (IntMap a) for #146

The story so far (an excerpt from my patched shmup used to

type WorldComps = [''Position, ''Velocity, ''Player, ''Target, ''Bullet, ''Score, ''Time, ''Particle, ''Camera]

-- vanilla makeWorld
makeWorld "World" WorldComps

-- new tagged stuff generators
makeTaggedComponents "World" WorldComps -- same component list (requires it to be defined elsewhere, or a fused generator)

{- generated:

data WorldTag = TPosition | TVelocity | ...
  deriving (Eq, Ord, Show, Enum, Bounded)

data WorldSum
  = SPosition Position
  | SVelocity Velocity
  | ...
  deriving (Show)

tagWorldSum :: WorldSum -> WorldTag -- don't like the name

type instance WTag World = WorldTag

instance Monad m => HasTags World m where
  entityTags = getWorldTags
-}

-- all live entities (already in main)
worldEntityIds :: System World IS.IntSet
worldEntityIds = do
  s :: Storage WorldEnumerable <- getStore
  explMemberSet s

-- count your archetypes
census :: System World (M.Map (S.Set WorldTag) Int)
census = do
  live <- worldEntityIds -- using raw intset
  countCombinations live -- new helper that 

-- alternatives:
-- [WorldSum] -- the wrapper is its own tag (a forgetting map is available)
-- Maybify WorldEnumerable -- type fun to quickly hack (A, B, ...) into (Maybe A, Maybe B, ...)
-- making a record of maybe fields (HKD much?)
type Dump = M.Map WorldTag WorldSum

dump :: Entity -> System World Dump
dump e = do
  tags <- entityTags e -- check explExists
  fmap M.fromList . forM tags $ \t -> (t,) <$> getWorldTag e t -- unsafe get over every found tag

type Megadump = M.Map Entity Dump

-- dump literally every thing in the world
megadump :: System World Megadump
megadump = do
  live <- map Entity . IS.toList <$> worldEntityIds
  fmap M.fromList . forM live $ \e -> fmap (e,) $ dump e

-- dump only some specific entities
dumpPlayer :: System World Megadump
dumpPlayer = do
  players <- collect (\(Player, ety) -> Just ety)
  fmap M.fromList . forM players $ \e -> fmap (e,) $ dump e

step dT = do
  ...
  triggerEvery dT 3 0 $ census >>= liftIO . print
  triggerEvery dT 5 0 $ dumpPlayer >>= liftIO . print
  triggerEvery dT 7 0 $ megadump >>= liftIO . print