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Within LTS Haskell 24.4 (ghc-9.10.2)
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maybeType :: DataType be a -> DataType be (Maybe a)beam-core Database.Beam.Query.DataTypes Haskell requires DataTypes to match exactly. Use this function to convert a DataType that expects a concrete value to one expecting a Maybe
maybeGen :: Gen a -> Gen (Maybe a)checkers Test.QuickCheck.Instances.Maybe No documentation available.
maybeBlank :: BPState (m :: Type -> Type) il bl -> !Boolcommonmark Commonmark.Blocks No documentation available.
maybeLazy :: BPState (m :: Type -> Type) il bl -> !Boolcommonmark Commonmark.Blocks No documentation available.
maybeName :: a -> Bool -> Maybe adbus DBus.Generation No documentation available.
maybeParseString :: Parser a -> String -> Maybe adbus DBus.Internal.Address No documentation available.
maybeParseString :: MonadThrow m => Parser a -> String -> m adbus DBus.Internal.Types No documentation available.
maybeEndOfExecutable :: String -> IO (Maybe String)end-of-exe EndOfExe2 Can be used instead of os to check whether the executable ends in ".exe". The function returns IO Nothing if there is neither ys nor (ys ++ ".exe") names for executables in the search path. It can also search in other locations and its behaviour is OS dependent. For more information, please, refer to the link: https://hackage.haskell.org/package/directory-1.3.4.0/docs/System-Directory.html#v:findExecutable For more information, how the executable is searched, see also the following address: https://hackage.haskell.org/package/process-1.6.18.0/docs/System-Process.html#t:CmdSpec
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foundation Foundation The maybeToList function returns an empty list when given Nothing or a singleton list when given Just.
Examples
Basic usage:>>> maybeToList (Just 7) [7]
>>> maybeToList Nothing []
One can use maybeToList to avoid pattern matching when combined with a function that (safely) works on lists:>>> import GHC.Internal.Text.Read ( readMaybe ) >>> sum $ maybeToList (readMaybe "3") 3 >>> sum $ maybeToList (readMaybe "") 0
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persistable-record Database.Record.FromSql Derivation rule of RecordFromSql parser function object for Haskell Maybe type.