Copyright	(c) 2006-2007 Roman Leshchinskiy
License	BSD-style (see the file LICENSE)
Maintainer	Roman Leshchinskiy <rl@cse.unsw.edu.au>
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Data.Strict.Maybe

Description

Strict Maybe.

Same as the standard Haskell Maybe, but Just _|_ = _|_

Note that strict Maybe is not a monad since return _|_ >>= f = _|_ which is not necessarily the same as f _|_.

Synopsis

data Maybe a
- = Nothing
- | Just !a
isJust :: Maybe a -> Bool
isNothing :: Maybe a -> Bool
fromJust :: Maybe a -> a
fromMaybe :: a -> Maybe a -> a
maybe :: b -> (a -> b) -> Maybe a -> b

Documentation

data Maybe a Source #

The type of strict optional values.

Constructors

Nothing
Just !a

Instances

Functor Maybe Source #
Instance details Defined in Data.Strict.Maybe Methods fmap :: (a -> b) -> Maybe a -> Maybe b Source # (<$) :: a -> Maybe b -> Maybe a Source #
Eq a => Eq (Maybe a) Source #
Instance details Defined in Data.Strict.Maybe Methods (==) :: Maybe a -> Maybe a -> Bool Source # (/=) :: Maybe a -> Maybe a -> Bool Source #
Ord a => Ord (Maybe a) Source #
Instance details Defined in Data.Strict.Maybe Methods compare :: Maybe a -> Maybe a -> Ordering Source # (<) :: Maybe a -> Maybe a -> Bool Source # (<=) :: Maybe a -> Maybe a -> Bool Source # (>) :: Maybe a -> Maybe a -> Bool Source # (>=) :: Maybe a -> Maybe a -> Bool Source # max :: Maybe a -> Maybe a -> Maybe a Source # min :: Maybe a -> Maybe a -> Maybe a Source #
Read a => Read (Maybe a) Source #
Instance details Defined in Data.Strict.Maybe Methods readsPrec :: Int -> ReadS (Maybe a) Source # readList :: ReadS [Maybe a] Source # readPrec :: ReadPrec (Maybe a) Source # readListPrec :: ReadPrec [Maybe a] Source #
Show a => Show (Maybe a) Source #
Instance details Defined in Data.Strict.Maybe Methods showsPrec :: Int -> Maybe a -> ShowS Source # show :: Maybe a -> String Source # showList :: [Maybe a] -> ShowS Source #

isJust :: Maybe a -> Bool Source #

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

isNothing :: Maybe a -> Bool Source #

Yields True iff the argument is Nothing.

fromJust :: Maybe a -> a Source #

Extracts the element out of a Just and throws an error if the argument is Nothing.

fromMaybe :: a -> Maybe a -> a Source #

Given a default value and a Maybe, yield the default value if the Maybe argument is Nothing and extract the value out of the Just otherwise.

maybe :: b -> (a -> b) -> Maybe a -> b Source #

Given a default value, a function and a Maybe value, yields the default value if the Maybe value is Nothing and applies the function to the value stored in the Just otherwise.