cleanup a little bit

newt/Prelude.newt

@@ -185,15 +185,14 @@ instance Traversable List where
   traverse f Nil = return Nil
   traverse f (x :: xs) = return _::_ <*> f x <*> traverse f xs
 
--- something goes madly wrong with erasure in here.
--- traverse_ : ∀ t f a b. {{Traversable t}} {{Applicative f}} → (a → f b) → t a → f Unit
--- traverse_ f xs = return (const MkUnit) <*> traverse f xs
+traverse_ : ∀ t f a b. {{Traversable t}} {{Applicative f}} → (a → f b) → t a → f Unit
+traverse_ f xs = return (const MkUnit) <*> traverse f xs
 
 for : {t : U → U} {f : U → U} → {{Traversable t}} {{appf : Applicative f}} → {a : U} → {b : U} → t a → (a → f b) → f (t b)
 for stuff fun = traverse fun stuff
 
--- for_ : {t : U → U} {f : U → U} → {{Traversable t}} {{appf : Applicative f}} → {a : U} → {b : U} → t a → (a → f b) → f Unit
--- for_ stuff fun = return (const MkUnit) <*> traverse fun stuff
+for_ : {t : U → U} {f : U → U} → {{Traversable t}} {{appf : Applicative f}} → {a : U} → {b : U} → t a → (a → f b) → f Unit
+for_ stuff fun = return (const MkUnit) <*> traverse fun stuff
 
 instance Applicative Maybe where
   return a = Just a