importJava "java.util.Iterator" where
    data Iterator a
    
    hasNext :: Iterator a -> <Proc> Boolean
    next :: Iterator a -> <Proc> a

@inline
iter :: (a -> <e> dummy) -> Iterator a -> <Proc,e> ()
iter f it = loop ()
  where
    loop _ = 
        if hasNext it
        then do
            f (next it)
            loop ()
        else ()

@inline
find :: (a -> <e> Boolean) -> Iterator a -> <Proc,e> Maybe a
find f it = loop ()
  where
    loop _ = 
        if hasNext it 
        then let el = next it
             in if f el
                then Just el
                else loop ()
        else Nothing

@inline
any :: (a -> <e> Boolean) -> Iterator a -> <Proc,e> Boolean
any f it = loop ()
  where
    loop _ = 
        if hasNext it 
        then if f (next it)
             then True
             else loop ()
        else False

@inline
all :: (a -> <e> Boolean) -> Iterator a -> <Proc,e> Boolean
all f it = loop ()
  where
    loop _ = 
        if hasNext it 
        then if f (next it)
             then loop ()
             else False
        else True

@inline
mapFirst :: (a -> <e> Maybe b) -> Iterator a -> <Proc,e> Maybe b
mapFirst f it = loop ()
  where
    loop _ = 
        if hasNext it 
        then match f (next it) with
                 Nothing -> loop ()
                 r -> r
        else Nothing

@inline
foldl :: (a -> b -> <e> a) -> a -> Iterator b -> <Proc,e> a
foldl f init it = loop init
  where
    loop cur =
        if hasNext it
        then loop (f cur (next it))
        else cur

@inline
foldl1 :: (a -> a -> <e> a) -> Iterator a -> <Proc,e> a
foldl1 f it = foldl f (next it) it