Weird syntax error in State's Applicative instance

[paul-snively]

instance Applicative (State s) where
  pure ::
    a
    -> State s a
  pure a = State (\s -> (a, s))
  (<*>) ::
    State s (a -> b)
    -> State s a
    -> State s b 
  State f <*> State a =
    State (\s -> let (g, t) = f s
                    (z, u) = a t
                in (g z, u))

This is copied straight out of State.hs, but haskell-ide-engine complains of a syntax error on the ( of Iz, u). So does ghci when I try to load it (unsurprisingly).

[tonymorris]

What's the error?

[vaibhavsagar]

It looks like the last two lines of the code sample need to be indented by one further space, but State.hs looks fine to me:

instance Applicative (State s) where
  pure ::
    a
    -> State s a
  pure a = State (\s -> (a, s))
  (<*>) ::
    State s (a -> b)
    -> State s a
    -> State s b 
  State f <*> State a =
    State (\s -> let (g, t) = f s
                     (z, u) = a t
                 in (g z, u))

[paul-snively]

I went back to significant whitespace but can't reproduce the issue now, so I'm closing this. Thanks, guys!