Portability | portable |
---|---|
Stability | provisional |
Maintainer | libraries@haskell.org |
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, Data.Maybe.Maybe
and System.IO.IO
satisfy these laws.
Functor [] | |
Functor IO | |
Functor [::] | |
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) | |
Monad m => Functor (WrappedMonad m) | |
Functor (Const m) | |
Functor (StateR s) | |
Functor (StateL s) | |
Functor (ST s) | |
Arrow a => Functor (WrappedArrow a b) |