| Portability | portable | 
|---|---|
| Stability | stable | 
| Maintainer | libraries@haskell.org | 
| Safe Haskell | Trustworthy | 
Data.Maybe
Description
The Maybe type, and associated operations.
Documentation
data Maybe a
The Maybe type encapsulates an optional value.  A value of type
 Maybe aa (represented as Just aNothing).  Using Maybe is a good way to 
 deal with errors or exceptional cases without resorting to drastic
 measures such as error.
The Maybe type is also a monad.  It is a simple kind of error
 monad, where all errors are represented by Nothing.  A richer
 error monad can be built using the Either type.
Instances
| Monad Maybe | |
| Functor Maybe | |
| Typeable1 Maybe | |
| MonadFix Maybe | |
| MonadPlus Maybe | |
| Applicative Maybe | |
| Foldable Maybe | |
| Traversable Maybe | |
| Generic1 Maybe | |
| Alternative Maybe | |
| Eq a => Eq (Maybe a) | |
| Data a => Data (Maybe a) | |
| Ord a => Ord (Maybe a) | |
| Read a => Read (Maybe a) | |
| Show a => Show (Maybe a) | |
| Generic (Maybe a) | |
| Monoid a => Monoid (Maybe a) | Lift a semigroup into  | 
listToMaybe :: [a] -> Maybe a
The listToMaybe function returns Nothing on an empty list
 or Just aa is the first element of the list.
maybeToList :: Maybe a -> [a]
The maybeToList function returns an empty list when given
 Nothing or a singleton list when not given Nothing.