Extra

Control.Concurrent.Extra

withNumCapabilities :: Int -> IO a -> IO a

On GHC 7.6 and above with the -threaded flag, brackets a call to setNumCapabilities. On lower versions (which lack setNumCapabilities) this function just runs the argument action.

setNumCapabilities :: Int -> IO ()

A version of setNumCapabilities that works on all versions of GHC, but has no effect before GHC 7.6.

Control.Exception.Extra

retry :: Int -> IO a -> IO a

showException :: SomeException -> IO String

Print an exception, but if that exception itself contains exceptions, simply print <NestedException>. Since Haskell is a lazy language it is possible to throw exceptions that are themselves undefined. This function is useful to report them to users.

ignore :: IO () -> IO ()

Ignore any exceptions thrown by the action and continue as normal.

catch_ :: IO a -> (SomeException -> IO a) -> IO a

handle_ :: (SomeException -> IO a) -> IO a -> IO a

try_ :: IO a -> IO (Either SomeException a)

catchJust_ :: (SomeException -> Maybe b) -> IO a -> (b -> IO a) -> IO a

handleJust_ :: (SomeException -> Maybe b) -> (b -> IO a) -> IO a -> IO a

tryJust_ :: (SomeException -> Maybe b) -> IO a -> IO (Either b a)

catchBool :: Exception e => (e -> Bool) -> IO a -> (e -> IO a) -> IO a

handleBool :: Exception e => (e -> Bool) -> (e -> IO a) -> IO a -> IO a

tryBool :: Exception e => (e -> Bool) -> IO a -> IO (Either e a)

Control.Monad.Extra

whenJust :: Applicative m => Maybe a -> (a -> m ()) -> m ()

unit :: m () -> m ()

partitionM :: Monad m => (a -> m Bool) -> [a] -> m ([a], [a])

concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b]

loopM :: Monad m => (a -> m (Either a b)) -> a -> m b

whileM :: Monad m => m Bool -> m ()

ifM :: Monad m => m Bool -> m a -> m a -> m a

notM :: Functor m => m Bool -> m Bool

orM :: Monad m => [m Bool] -> m Bool

andM :: Monad m => [m Bool] -> m Bool

anyM :: Monad m => (a -> m Bool) -> [a] -> m Bool

allM :: Monad m => (a -> m Bool) -> [a] -> m Bool

findM :: Monad m => (a -> m Bool) -> [a] -> m (Maybe a)

firstJustM :: Monad m => (a -> m (Maybe b)) -> [a] -> m (Maybe b)

Data.Either.Extra

isLeft :: Either t t1 -> Bool

isRight :: Either t t1 -> Bool

fromLeft :: Either t t1 -> t

fromRight :: Either t t1 -> t1

fromEither :: Either a a -> a

Data.IORef.Extra

modifyIORef' :: IORef a -> (a -> a) -> IO ()

Strict version of modifyIORef

writeIORef' :: IORef a -> a -> IO ()

atomicModifyIORef' :: IORef a -> (a -> (a, b)) -> IO b

Strict version of atomicModifyIORef. This forces both the value stored in the IORef as well as the value returned.

atomicWriteIORef :: IORef a -> a -> IO ()

Variant of writeIORef with the "barrier to reordering" property that atomicModifyIORef has.

atomicWriteIORef' :: IORef a -> a -> IO ()

Data.List.Extra

lower :: String -> String

upper :: String -> String

trim :: String -> String

trimLeft :: String -> String

trimRight :: String -> String

trimBy :: (a -> Bool) -> [a] -> [a]

word1 :: String -> (String, String)

list :: b -> (a -> [a] -> b) -> [a] -> b

uncons :: [a] -> (a, [a])

unsnoc :: [a] -> ([a], a)

groupSort :: Ord k => [(k, v)] -> [(k, [v])]

groupSortOn :: Ord a => (k -> a) -> [(k, v)] -> [(k, [v])]

nubOn :: Eq b => (a -> b) -> [a] -> [a]

groupOn :: Eq b => (a -> b) -> [a] -> [[a]]

sortOn :: Ord b => (a -> b) -> [a] -> [a]

chop :: ([a] -> (b, [a])) -> [a] -> [b]

for :: [a] -> (a -> b) -> [b]

rep :: Eq a => a -> a -> a -> a

reps :: Eq a => a -> a -> [a] -> [a]

disjoint :: Eq a => [a] -> [a] -> Bool

distinct :: Eq a => [a] -> Bool

dropEnd :: Int -> [a] -> [a]

takeEnd :: Int -> [a] -> [a]

breakEnd :: (a -> Bool) -> [a] -> ([a], [a])

spanEnd :: (a -> Bool) -> [a] -> ([a], [a])

dropWhileEnd :: (a -> Bool) -> [a] -> [a]

The dropWhileEnd function drops the largest suffix of a list in which the given predicate holds for all elements. For example:

 dropWhileEnd isSpace "foo\n" == "foo"
 dropWhileEnd isSpace "foo bar" == "foo bar"
 dropWhileEnd isSpace ("foo\n" ++ undefined) == "foo" ++ undefined

takeWhileEnd :: (a -> Bool) -> [a] -> [a]

stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]

Return the prefix of the second string if its suffix matches the entire first string.

Examples:

 stripSuffix "bar" "foobar" == Just "foo"
 stripSuffix ""    "baz"    == Just "baz"
 stripSuffix "foo" "quux"   == Nothing

concatUnzip :: [([a], [b])] -> ([a], [b])

merge :: Ord a => [a] -> [a] -> [a]

mergeBy :: (a -> a -> Ordering) -> [a] -> [a] -> [a]

replace :: String -> String -> String -> String

wordsBy :: (a -> Bool) -> [a] -> [[a]]

linesBy :: (a -> Bool) -> [a] -> [[a]]

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

breakOn :: Eq a => [a] -> [a] -> ([a], [a])

Find the first instance of needle in haystack. The first element of the returned tuple is the prefix of haystack before needle is matched. The second is the remainder of haystack, starting with the match.

Examples:

 breakOn "::" "a::b::c" == ("a", "::b::c")
 breakOn "/" "foobar"   == ("foobar", "")

Laws:

 \needle haystack -> let (prefix,match) = breakOn needle haystack in prefix ++ match == haystack

breakOnEnd :: Eq a => [a] -> [a] -> ([a], [a])

Similar to breakOn, but searches from the end of the string.

The first element of the returned tuple is the prefix of haystack up to and including the last match of needle. The second is the remainder of haystack, following the match.

 breakOnEnd "::" "a::b::c" == ("a::b::", "c")

splitOn :: Eq a => [a] -> [a] -> [[a]]

Break a list into pieces separated by the first list argument, consuming the delimiter. An empty delimiter is invalid, and will cause an error to be raised.

Examples:

 splitOn "\r\n" "a\r\nb\r\nd\r\ne" == ["a","b","d","e"]
 splitOn "aaa"  "aaaXaaaXaaaXaaa"  == ["","X","X","X",""]
 splitOn "x"    "x"                == ["",""]
 splitOn "x"    ""                 == [""]

and

 \s x -> s /= "" ==> intercalate s (splitOn s x) == x
 \c x -> splitOn [c] x                           == split (==c) x

split :: (a -> Bool) -> [a] -> [[a]]

Splits a list into components delimited by separators, where the predicate returns True for a separator element. The resulting components do not contain the separators. Two adjacent separators result in an empty component in the output. eg.

 split (=='a') "aabbaca" == ["","","bb","c",""]
 split (=='a') ""        == [""]

chunksOf :: Int -> [a] -> [[a]]

Data.Tuple.Extra

dupe :: a -> (a, a)

fst3 :: (a, b, c) -> a

snd3 :: (a, b, c) -> b

thd3 :: (a, b, c) -> c

concat2 :: [([a], [b])] -> ([a], [b])

concat3 :: [([a], [b], [c])] -> ([a], [b], [c])

Numeric.Extra

showDP :: RealFloat a => Int -> a -> String

intToDouble :: Int -> Double

intToFloat :: Int -> Float

floatToDouble :: Float -> Double

doubleToFloat :: Double -> Float

System.Directory.Extra

withCurrentDirectory :: FilePath -> IO a -> IO a

getDirectoryContentsRecursive :: FilePath -> IO [FilePath]

System.Environment.Extra

getExecutablePath :: IO FilePath

Returns the absolute pathname of the current executable.

Note that for scripts and interactive sessions, this is the path to the interpreter (e.g. ghci.)

lookupEnv :: String -> IO (Maybe String)

Return the value of the environment variable var, or Nothing if there is no such value.

For POSIX users, this is equivalent to getEnv.

System.Info.Extra

isWindows :: Bool

getProcessorCount :: IO Int

System.IO.Extra

readFileEncoding :: TextEncoding -> FilePath -> IO String

readFileUTF8 :: FilePath -> IO String

readFileBinary :: FilePath -> IO String

readFile' :: FilePath -> IO String

readFileEncoding' :: TextEncoding -> FilePath -> IO String

readFileUTF8' :: FilePath -> IO String

readFileBinary' :: FilePath -> IO String

writeFileEncoding :: TextEncoding -> FilePath -> String -> IO ()

writeFileUTF8 :: FilePath -> String -> IO ()

writeFileBinary :: FilePath -> String -> IO ()

withTemporaryFile :: String -> (FilePath -> IO a) -> IO a

captureOutput :: IO () -> IO String

withBuffering :: Handle -> BufferMode -> IO a -> IO a

System.Time.Extra

sleep :: Double -> IO ()

subtractTime :: UTCTime -> UTCTime -> Double

showTime :: Double -> String

offsetTime :: IO (IO Double)

Call once at the start, then call repeatedly to get Time values out

offsetTimeIncrease :: IO (IO Double)

Like offsetTime, but results will never decrease (though they may stay the same)

duration :: IO a -> IO (Double, a)