data Food = Apple | Orange | Carrot | Potato

sumCond :: Food -> (Int, Int) -> (Int, Int)
{-
sumCond Apple   (f, v) = (f + 1, v)
sumCond Orange  (f, v) = (f + 1, v)
sumCond Carrot  (f, v) = (f, v + 1)
sumCond Potato (f, v) = (f, v + 1)
-}
sumCond food (f, v) = case food of Apple -> (f + 1, v)
                                   Orange -> (f + 1, v)
                                   Carrot -> (f, v + 1)
                                   Potato -> (f, v + 1)

sumFood :: [Food] -> (Int, Int)
sumFood xs = foldl (\x y -> sumCond y x) (0, 0) xs