Liftin every day
•Download as PPT, PDF•
2 likes•959 views
This document discusses applicative functors in Haskell. It introduces the pure and ap functions that are used to define an applicative functor. It also discusses how applicative functors are closed under composition and how liftA and liftA2 can be defined in terms of fmap. It provides examples of using applicative functors with lists and discusses eventual results like combinators, comprehensions, and parallel computations.
Report
Share
Liftin every day
- 3. pure :: a -> f a ap :: f (a -> b) -> f a -> f b
- 9. liftA :: (a -> b) -> f a -> f b liftA2 :: (a -> b -> c) -> f a -> f b -> f c
- 10. liftA :: (a -> b) -> f a -> f b liftA2 :: (a -> b -> c) -> f a -> f b -> f c Just fmap
- 11. liftA :: (a -> b) -> f a -> f b liftA2 :: (a -> b -> c) -> f a -> f b -> f c Just fmap We can get arity automatically
- 12. ap(pure(f), x, y) == liftA(f, x, y)
- 16. f(g(x), h(x))
- 18. f(g(x), h(x))
- 27. A Quick Word about Comma Overloading
- 29. ZipLists
- 30. ap([f, g], [x,y]) [f(x), f(y), g(x), g(y)] -or- ap([f, g], [x,y]) [f(x), g(y)]
- 31. ap([f, g], [x,y]) [f(x), f(y), g(x), g(y)] -or- ap([f, g], [x,y]) [f(x), g(y)] ZipList
- 35. Eventual Results
- 41. Lots more I didn’t get to...
- 42. • http://looprecur.com • @drboolean • drboolean.tumblr.com • https://github.com/loop-recur/typeclasses THANKS!