module Main where
import Database 
import Nondeterminism
import Classes
import Terms
import Binding

demoProgram :: Database
demoProgram = Database
  { clauses =
    -- act(sam, 'goes to law school')
    [ return $ Clause (Compound "act" [Compound "Sam" [], Compound "goes to law school" []]) []
    , return $ Clause (Compound "vampire_behavior" [Compound "drinks blood" []]) []
    , return $ Clause (Compound "vampire_behavior" [Compound "spits venom" []]) []
    , do
      -- act(Who, Action) :- is_vampire(Who), vampire_behavior(Action).
      who <- newVar "Who"
      action <- newVar "Action"
      return $ Clause (Compound "act" [Var who, Var action])
        [ Compound "is_vampire" [Var who]
        , Compound "vampire_behavior" [Var action]
        ]
    , do
      -- is_vampire(Progeny) :- has_progenitor(Progenitor, Progeny), is_vampire(Progenitor)>
      progenitor <- newVar "Progenitor"
      progeny <- newVar "Progeny"
      return $ Clause (Compound "is_vampire" [Var progeny])
        [ Compound "has_progenitor" [Var progenitor, Var progeny]
        , Compound "is_vampire" [Var progenitor]
        ]
    , return $ Clause (Compound "is_vampire" [Compound "Nyeogmi" []]) []
    , return $ Clause (Compound "has_progenitor" [Compound "Sam" [], Compound "Alex" []]) []
    , return $ Clause (Compound "is_vampire" [Compound "Sam" []]) []
    ]
  }

main :: IO ()
main = do
  thread <- newThread runDemoProgram
  _ <- takeAllRemainingSolutions thread
  return ()
  where
  runDemoProgram :: PrologStream ()
  runDemoProgram = do
    who <- newVar "who"
    what <- newVar "what"
    let goal = Compound "act" [Var who, Var what]
    goal' <- seekAndInstantiate goal demoProgram
    liftIO $ putStrLn ("Got " ++ show goal')