##### λ Tony's Blog λ

## Lifting (Haskell addendum)

Posted on August 19, 2011A follow-on from Lifting. A port of the Scala code to Haskell follows.

```
class Lift f where
lift0 ::
a -> f a
lift1 ::
(a -> b) -> f a -> f b
lift1 =
ap . lift0
lift2 ::
(a -> b -> c) -> f a -> f b -> f c
lift2 f =
ap . lift1 f
lift3 ::
(a -> b -> c -> d) -> f a -> f b -> f c -> f d
lift3 f a =
ap . lift2 f a
ap ::
f (a -> b) -> f a -> f b
-- scala.List
instance Lift [] where
lift0 =
error "todo"
ap =
error "todo"
-- scala.Option
instance Lift Maybe where
lift0 =
error "todo"
ap =
error "todo"
-- scala.Either[R, _]
instance Lift (Either r) where
lift0 =
error "todo"
ap =
error "todo"
-- scala.Functior1[R, _]
instance Lift ((->) r) where
lift0 =
error "todo"
ap =
error "todo"
```