| Portability | portable |
|---|---|
| Stability | provisional |
| Maintainer | libraries@haskell.org |
| Safe Haskell | Trustworthy |
Data.Functor
Description
Functors: uniform action over a parameterized type, generalizing the
map function on lists.
Documentation
The Functor class is used for types that can be mapped over.
Instances of Functor should satisfy the following laws:
fmap id == id fmap (f . g) == fmap f . fmap g
The instances of Functor for lists, Maybe and IO
satisfy these laws.
Instances
| Functor [] | |
| Functor IO | |
| Functor Maybe | |
| Functor ReadP | |
| Functor ReadPrec | |
| Functor STM | |
| Functor ZipList | |
| Functor Id | |
| Functor ((->) r) | |
| Functor (Either a) | |
| Functor ((,) a) | |
| Functor (ST s) | |
| Ix i => Functor (Array i) | |
| Functor (ST s) | |
| Monad m => Functor (WrappedMonad m) | |
| Functor (Const m) | |
| Functor (StateR s) | |
| Functor (StateL s) | |
| Arrow a => Functor (WrappedArrow a b) |