ghc-6.10.2: The GHC APIContentsIndex
Maybes
Synopsis
module Data.Maybe
data MaybeErr err val
= Succeeded val
| Failed err
failME :: err -> MaybeErr err val
isSuccess :: MaybeErr err val -> Bool
orElse :: Maybe a -> a -> a
mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
allMaybes :: [Maybe a] -> Maybe [a]
firstJust :: [Maybe a] -> Maybe a
expectJust :: String -> Maybe a -> a
maybeToBool :: Maybe a -> Bool
newtype MaybeT m a = MaybeT {
runMaybeT :: m (Maybe a)
}
Documentation
module Data.Maybe
data MaybeErr err val
Constructors
Succeeded val
Failed err
show/hide Instances
failME :: err -> MaybeErr err val
isSuccess :: MaybeErr err val -> Bool
orElse :: Maybe a -> a -> a
mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
allMaybes :: [Maybe a] -> Maybe [a]
Collects a list of Justs into a single Just, returning Nothing if there are any Nothings.
firstJust :: [Maybe a] -> Maybe a
Takes a list of Maybes and returns the first Just if there is one, or Nothing otherwise.
expectJust :: String -> Maybe a -> a
maybeToBool :: Maybe a -> Bool
newtype MaybeT m a
Constructors
MaybeT
runMaybeT :: m (Maybe a)
show/hide Instances
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