Infix Typed Holes

InfixHoles.hs

*Infix* typed holes!

>>> "suggest" `_` "concat" :: String

<interactive>:1:11: error:
    • Found hole: _ :: [Char] -> [Char] -> String
      Valid hole fits include
        showString :: String -> ShowS
        (++) :: forall a. [a] -> [a] -> [a]
        showList :: forall a. Show a => [a] -> ShowS
        seq :: forall a b. a -> b -> b
        (>>) :: forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
        (<>) :: forall a. Semigroup a => a -> a -> a

Even *kinda* works with lenses if you add enough type annotations!
>>> let x = ("abc", 1) :: (String, Int)
>>> x & (_1 `_` "thing") :: (String, Int)

    • Found hole:
        _ :: ((a0 -> f0 b0) -> s0 -> f0 t0)
             -> [Char] -> (String, Int) -> (String, Int)
      Valid hole fits include
        (#~) :: forall s t a b. ALens s t a b -> b -> s -> t
        storing :: forall s t a b. ALens s t a b -> b -> s -> t
        (.~) :: forall s t a b. ASetter s t a b -> b -> s -> t
        (<>~) :: forall a s t. Monoid a => ASetter s t a a -> a -> s -> t
        set :: forall s t a b. ASetter s t a b -> b -> s -> t
        set' :: forall s a. ASetter' s a -> a -> s -> s