Module Data.Maybe

Exported Functions

isJust :: Maybe a -> Bool   

Return True iff the argument is of the form Just _.

Further infos:

• solution complete, i.e., able to compute all solutions

isNothing :: Maybe a -> Bool   

Return True iff the argument is of the form Nothing.

Further infos:

• solution complete, i.e., able to compute all solutions

fromJust :: Maybe a -> a   

Extract the argument from the Just constructor and throw an error if the argument is Nothing.

fromMaybe :: a -> Maybe a -> a   

Extract the argument from the Just constructor or return the provided default value if the argument is Nothing.

Further infos:

• solution complete, i.e., able to compute all solutions

listToMaybe :: [a] -> Maybe a   

Return Nothing on an empty list or Just x where x is the first list element.

Further infos:

• solution complete, i.e., able to compute all solutions

maybeToList :: Maybe a -> [a]   

Return an empty list for Nothing or a singleton list for Just x.

Further infos:

• solution complete, i.e., able to compute all solutions

catMaybes :: [Maybe a] -> [a]   

Return the list of all Just values.

mapMaybe :: (a -> Maybe b) -> [a] -> [b]   

Apply a function which may throw out elements using the Nothing constructor to a list of elements.