Sqlam.hs

--     InFor n -> for (g $ InFor f) $ \y -> for (runForFor (f $ ForFor $ \_ -> y) NotInFor) $ \x ->
-- _


data ForFor r t a where
  For :: r (t a) -> (r a -> r (t b)) -> ForFor r t (t b)
  Other :: r a -> ForFor r t a

unForFor :: Sqlam r t => ForFor r t a -> r a
unForFor (For m n) = for m n
unForFor (Other x) = x

instance Sqlam repr t => Sqlam (ForFor repr t) t where
  for (For l m) n = For l $ \x -> for (m x) $ \y -> unForFor $ n $ Other y
  for (Other m) n = For m $ \x -> unForFor $ n $ Other x
  lam f = Other $ lam $ \x -> unForFor $ f $ Other x
  f $$ x = Other $ (unForFor f) $$ (unForFor x)
  table s = Other $ table s
  yeild x = Other $ yeild $ unForFor x

newtype S a = S { runS :: [String] -> String }
instance Sqlam S [] where
  for (S m) n = S $ \(v:vs) ->
    "for (" ++ v ++ " <- " ++ m vs ++ ") " ++ runS (n $ S $ const v) vs
  lam b = S $ \(v:vs) ->
    "\\" ++ v ++ " -> " ++ runS (b $ S $ const v) vs
  f $$ x = S $ \vs -> "(" ++ runS f vs ++ ") (" ++ runS x vs ++ ")"
  table x = S $ \_ -> "table " ++ show x
  yeild x = S $ \vs -> "yeild " ++ runS x vs