gistfile1.txt

    No instance for (Functor f0) arising from a use of ‘creatures’
    The type variable ‘f0’ is ambiguous
    Relevant bindings include
      player :: (Creature -> f0 Creature) -> GameState -> f0 GameState
        (bound at src/GameState.hs:76:1)
    Note: there are several potential instances:
      instance Functor Data.Complex.Complex
        -- Defined in ‘base-orphans-0.5.4:Data.Orphans’
      instance Functor Identity -- Defined in ‘Data.Functor.Identity’
      instance Functor f => Functor (Data.Monoid.Alt f)
        -- Defined in ‘Data.Monoid’
      ...plus 33 others
    In the first argument of ‘(.)’, namely ‘creatures’
    In the expression: creatures . _head
    In an equation for ‘player’: player = creatures . _head