Safe Haskell | None |
---|
This module documents all the functions available in this package.
Most users should import the specific modules (e.g. Data.List.Extra
), which
also reexport their non-Extra
modules (e.g. Data.List
).
- withNumCapabilities :: Int -> IO a -> IO a
- setNumCapabilities :: Int -> IO ()
- forkFinally :: IO a -> (Either SomeException a -> IO ()) -> IO ThreadId
- data Lock
- newLock :: IO Lock
- withLock :: Lock -> IO a -> IO a
- withLockTry :: Lock -> IO a -> IO (Maybe a)
- data Var a
- newVar :: a -> IO (Var a)
- readVar :: Var a -> IO a
- modifyVar :: Var a -> (a -> IO (a, b)) -> IO b
- modifyVar_ :: Var a -> (a -> IO a) -> IO ()
- withVar :: Var a -> (a -> IO b) -> IO b
- data Barrier a
- newBarrier :: IO (Barrier a)
- signalBarrier :: Barrier a -> a -> IO ()
- waitBarrier :: Barrier a -> IO a
- waitBarrierMaybe :: Barrier a -> IO (Maybe a)
- retry :: Int -> IO a -> IO a
- showException :: Show e => e -> IO String
- stringException :: String -> IO String
- ignore :: IO () -> IO ()
- 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)
- 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]
- mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]
- loopM :: Monad m => (a -> m (Either a b)) -> a -> m b
- whileM :: Monad m => m Bool -> m ()
- whenM :: Monad m => m Bool -> m () -> m ()
- unlessM :: Monad m => m Bool -> m () -> m ()
- ifM :: Monad m => m Bool -> m a -> m a -> m a
- notM :: Functor m => m Bool -> m Bool
- (||^) :: Monad m => m Bool -> m Bool -> m Bool
- (&&^) :: Monad m => m Bool -> 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)
- isLeft :: Either t t1 -> Bool
- isRight :: Either t t1 -> Bool
- fromLeft :: Either l r -> l
- fromRight :: Either l r -> r
- fromEither :: Either a a -> a
- modifyIORef' :: IORef a -> (a -> a) -> IO ()
- writeIORef' :: IORef a -> a -> IO ()
- atomicModifyIORef' :: IORef a -> (a -> (a, b)) -> IO b
- atomicWriteIORef :: IORef a -> a -> IO ()
- atomicWriteIORef' :: IORef a -> a -> IO ()
- lower :: String -> String
- upper :: String -> String
- trim :: String -> String
- trimStart :: String -> String
- trimEnd :: String -> String
- dropAround :: (a -> Bool) -> [a] -> [a]
- word1 :: String -> (String, String)
- drop1 :: [a] -> [a]
- list :: b -> (a -> [a] -> b) -> [a] -> b
- uncons :: [a] -> Maybe (a, [a])
- unsnoc :: [a] -> Maybe ([a], a)
- cons :: a -> [a] -> [a]
- snoc :: [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]
- repeatedly :: ([a] -> (b, [a])) -> [a] -> [b]
- for :: [a] -> (a -> b) -> [b]
- disjoint :: Eq a => [a] -> [a] -> Bool
- allSame :: Eq a => [a] -> Bool
- anySame :: 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]
- dropWhileEnd' :: (a -> Bool) -> [a] -> [a]
- takeWhileEnd :: (a -> Bool) -> [a] -> [a]
- stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
- concatUnzip :: [([a], [b])] -> ([a], [b])
- concatUnzip3 :: [([a], [b], [c])] -> ([a], [b], [c])
- merge :: Ord a => [a] -> [a] -> [a]
- mergeBy :: (a -> a -> Ordering) -> [a] -> [a] -> [a]
- replace :: Eq a => [a] -> [a] -> [a] -> [a]
- wordsBy :: (a -> Bool) -> [a] -> [[a]]
- linesBy :: (a -> Bool) -> [a] -> [[a]]
- firstJust :: (a -> Maybe b) -> [a] -> Maybe b
- breakOn :: Eq a => [a] -> [a] -> ([a], [a])
- breakOnEnd :: Eq a => [a] -> [a] -> ([a], [a])
- splitOn :: Eq a => [a] -> [a] -> [[a]]
- split :: (a -> Bool) -> [a] -> [[a]]
- chunksOf :: Int -> [a] -> [[a]]
- first :: (a -> a') -> (a, b) -> (a', b)
- second :: (b -> b') -> (a, b) -> (a, b')
- (***) :: (a -> a') -> (b -> b') -> (a, b) -> (a', b')
- (&&&) :: (a -> b) -> (a -> c) -> a -> (b, c)
- dupe :: a -> (a, a)
- both :: (a -> b) -> (a, a) -> (b, b)
- fst3 :: (a, b, c) -> a
- snd3 :: (a, b, c) -> b
- thd3 :: (a, b, c) -> c
- first3 :: (a -> a') -> (a, b, c) -> (a', b, c)
- second3 :: (b -> b') -> (a, b, c) -> (a, b', c)
- third3 :: (c -> c') -> (a, b, c) -> (a, b, c')
- dupe3 :: a -> (a, a, a)
- both3 :: (a -> b) -> (a, a, a) -> (b, b, b)
- showDP :: RealFloat a => Int -> a -> String
- intToDouble :: Int -> Double
- intToFloat :: Int -> Float
- floatToDouble :: Float -> Double
- doubleToFloat :: Double -> Float
- withCurrentDirectory :: FilePath -> IO a -> IO a
- getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
- createDirectoryPrivate :: String -> IO ()
- getExecutablePath :: IO FilePath
- lookupEnv :: String -> IO (Maybe String)
- isWindows :: Bool
- getProcessorCount :: IO Int
- 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 ()
- withTempFile :: (FilePath -> IO a) -> IO a
- withTempDir :: (FilePath -> IO a) -> IO a
- newTempFile :: (IO FilePath, FilePath -> IO ())
- newTempDir :: (IO FilePath, FilePath -> IO ())
- captureOutput :: IO a -> IO (String, a)
- withBuffering :: Handle -> BufferMode -> IO a -> IO a
- system_ :: String -> IO ()
- systemOutput :: String -> IO (ExitCode, String)
- systemOutput_ :: String -> IO String
- type Seconds = Double
- sleep :: Seconds -> IO ()
- subtractTime :: UTCTime -> UTCTime -> Seconds
- showDuration :: Seconds -> String
- offsetTime :: IO (IO Seconds)
- offsetTimeIncrease :: IO (IO Seconds)
- duration :: IO a -> IO (Seconds, a)
Control.Concurrent.Extra
Extra functions available in Control.Concurrent.Extra
.
withNumCapabilities :: Int -> IO a -> IO aSource
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 ()
Set the number of Haskell threads that can run truly simultaneously
(on separate physical processors) at any given time. The number
passed to forkOn
is interpreted modulo this value. The initial
value is given by the +RTS -N
runtime flag.
This is also the number of threads that will participate in parallel garbage collection. It is strongly recommended that the number of capabilities is not set larger than the number of physical processor cores, and it may often be beneficial to leave one or more cores free to avoid contention with other processes in the machine.
forkFinally :: IO a -> (Either SomeException a -> IO ()) -> IO ThreadId
fork a thread and call the supplied function when the thread is about to terminate, with an exception or a returned value. The function is called with asynchronous exceptions masked.
forkFinally action and_then = mask $ \restore -> forkIO $ try (restore action) >>= and_then
This function is useful for informing the parent when a child terminates, for example.
modifyVar_ :: Var a -> (a -> IO a) -> IO ()Source
newBarrier :: IO (Barrier a)Source
signalBarrier :: Barrier a -> a -> IO ()Source
waitBarrier :: Barrier a -> IO aSource
waitBarrierMaybe :: Barrier a -> IO (Maybe a)Source
Control.Exception.Extra
Extra functions available in Control.Exception.Extra
.
retry :: Int -> IO a -> IO aSource
Retry an operation at most N times (N must be positive).
retry 1 (print "x") == print "x" retry 3 (fail "die") == fail "die"
showException :: Show e => e -> IO StringSource
Show a value, but if the result contains exceptions, produce
<Exception>
. Defined as
.
Particularly useful for printing exceptions to users, remembering that exceptions
can themselves contain undefined values.
stringException
. show
stringException :: String -> IO StringSource
Fully evaluate an input String. If the String contains embedded exceptions it will produce <Exception>
.
stringException ("test" ++ undefined) == return "test<Exception>" stringException ("test" ++ undefined ++ "hello") == return "test<Exception>" stringException "test" == return "test"
ignore :: IO () -> IO ()Source
Ignore any exceptions thrown by the action.
ignore (print 1) == print 1 ignore (fail "die") == return ()
catch_ :: IO a -> (SomeException -> IO a) -> IO aSource
A version of catch
without the Exception
context, restricted to SomeException
,
so catches all exceptions.
catchJust_ :: (SomeException -> Maybe b) -> IO a -> (b -> IO a) -> IO aSource
handleJust_ :: (SomeException -> Maybe b) -> (b -> IO a) -> IO a -> IO aSource
Like catch_
but for handleJust
catchBool :: Exception e => (e -> Bool) -> IO a -> (e -> IO a) -> IO aSource
Catch an exception if the predicate passes, then call the handler with the original exception. As an example:
> readFileExists x == catchBool isDoesNotExistError (readFile "myfile") (const $ return "")
Control.Monad.Extra
Extra functions available in Control.Monad.Extra
.
whenJust :: Applicative m => Maybe a -> (a -> m ()) -> m ()Source
The identity function which requires the inner argument to be '()'. Useful for functions with overloaded return times.
\(x :: Maybe ()) -> unit x == x
partitionM :: Monad m => (a -> m Bool) -> [a] -> m ([a], [a])Source
A version of partition
that works with a monadic predicate.
partitionM (Just . even) [1,2,3] == Just ([2], [1,3]) partitionM (const Nothing) [1,2,3] == Nothing
concatMapM :: Monad m => (a -> m [b]) -> [a] -> m [b]Source
A version of concatMap
that works with a monadic predicate.
mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]Source
A version of mapMaybe
that works with a monadic predicate.
firstJustM :: Monad m => (a -> m (Maybe b)) -> [a] -> m (Maybe b)Source
Data.Either.Extra
Extra functions available in Data.Either.Extra
.
fromEither :: Either a a -> aSource
Pull the value out of an Either
where both alternatives
have the same type.
Data.IORef.Extra
Extra functions available in Data.IORef.Extra
.
modifyIORef' :: IORef a -> (a -> a) -> IO ()
Strict version of modifyIORef
writeIORef' :: IORef a -> a -> IO ()Source
Evaluates the value before calling writeIORef
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 ()Source
Evaluates the value before calling atomicWriteIORef
Data.List.Extra
Extra functions available in Data.List.Extra
.
lower :: String -> StringSource
Documentation about lowercase
lower "This is A TEST" == "this is a test" lower "" == ""
dropAround :: (a -> Bool) -> [a] -> [a]Source
groupSortOn :: Ord a => (k -> a) -> [(k, v)] -> [(k, [v])]Source
repeatedly :: ([a] -> (b, [a])) -> [a] -> [b]Source
Apply some operation repeatedly, producing an element of output and the remainder of the list.
\xs -> repeatedly (splitAt 3) xs == chunksOf 3 xs \xs -> repeatedly word1 (trim xs) == words xs
disjoint :: Eq a => [a] -> [a] -> BoolSource
Are two lists disjoint, with no elements in common.
disjoint [1,2,3] [4,5] == True disjoint [1,2,3] [4,1] == False
allSame :: Eq a => [a] -> BoolSource
Are all elements the same.
allSame [1,1,2] == False allSame [1,1,1] == True allSame [1] == True allSame [] == True
anySame :: Eq a => [a] -> BoolSource
Is there any element which occurs more than once.
anySame [1,1,2] == True anySame [1,2,3] == False
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
dropWhileEnd' :: (a -> Bool) -> [a] -> [a]Source
A version of dropWhileEnd
but with different strictness properties.
Often outperforms if the list is short or the test is expensive.
takeWhileEnd :: (a -> Bool) -> [a] -> [a]Source
stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]Source
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])Source
concatUnzip3 :: [([a], [b], [c])] -> ([a], [b], [c])Source
breakOn :: Eq a => [a] -> [a] -> ([a], [a])Source
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])Source
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]]Source
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]]Source
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]]Source
Split a list into chunks of a given size. The last chunk may contain fewer than n elements. The chunk size must be positive.
chunksOf 3 "my test" == ["my ","tes","t"] chunksOf 3 "mytest" == ["myt","est"] chunksOf 8 "" == [] chunksOf 0 "test" == error
Data.Tuple.Extra
Extra functions available in Data.Tuple.Extra
.
Numeric.Extra
Extra functions available in Numeric.Extra
.
showDP :: RealFloat a => Int -> a -> StringSource
Show a number to a number of decimal places.
showDP 4 pi == "3.1416" showDP 0 pi == "3" showDP 2 3 == "3.00"
intToDouble :: Int -> DoubleSource
Specialised numeric conversion.
intToFloat :: Int -> FloatSource
Specialised numeric conversion.
floatToDouble :: Float -> DoubleSource
Specialised numeric conversion.
doubleToFloat :: Double -> FloatSource
Specialised numeric conversion.
System.Directory.Extra
Extra functions available in System.Directory.Extra
.
withCurrentDirectory :: FilePath -> IO a -> IO aSource
Remember that the current directory is a global variable, so calling this function multithreaded is almost certain to go wrong. Avoid changing the dir if you can.
getDirectoryContentsRecursive :: FilePath -> IO [FilePath]Source
Find all the files within a directory, including recursively.
Looks through all folders, including those beginning with .
.
createDirectoryPrivate :: String -> IO ()Source
Create a directory with permissions so that only the current user can view it.
On Windows this function is equivalent to createDirectory
.
System.Environment.Extra
Extra functions available in 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
Extra functions available in System.Info.Extra
.
System.IO.Extra
Extra functions available in System.IO.Extra
.
readFileEncoding :: TextEncoding -> FilePath -> IO StringSource
readFileUTF8 :: FilePath -> IO StringSource
readFileBinary :: FilePath -> IO StringSource
readFileEncoding' :: TextEncoding -> FilePath -> IO StringSource
readFileUTF8' :: FilePath -> IO StringSource
writeFileEncoding :: TextEncoding -> FilePath -> String -> IO ()Source
writeFileUTF8 :: FilePath -> String -> IO ()Source
writeFileBinary :: FilePath -> String -> IO ()Source
withTempFile :: (FilePath -> IO a) -> IO aSource
withTempDir :: (FilePath -> IO a) -> IO aSource
captureOutput :: IO a -> IO (String, a)Source
withBuffering :: Handle -> BufferMode -> IO a -> IO aSource
System.Process.Extra
Extra functions available in System.Process.Extra
.
systemOutput_ :: String -> IO StringSource
System.Time.Extra
Extra functions available in System.Time.Extra
.
subtractTime :: UTCTime -> UTCTime -> SecondsSource
showDuration :: Seconds -> StringSource
Show a number of seconds, typically a duration, in a suitable manner with responable precision for a human.
showDuration 3.435 == "3.44s" showDuration 623.8 == "10m24s" showDuration 62003.8 == "17h13m" showDuration 1e8 == "27777h47m"
offsetTime :: IO (IO Seconds)Source
Call once at the start, then call repeatedly to get Time values out
offsetTimeIncrease :: IO (IO Seconds)Source
Like offsetTime, but results will never decrease (though they may stay the same)