Safe Haskell | None |
---|---|
Language | Haskell2010 |
Util
Contents
- Flags dependent on the compiler build
- General list processing
- Tuples
- List operations controlled by another list
- For loop
- Sorting
- Comparisons
- Edit distance
- Transitive closures
- Strictness
- Module names
- Argument processing
- Floating point
- read helpers
- IO-ish utilities
- Filenames and paths
- Utils for defining Data instances
- Utils for printing C code
- Hashing
Description
Highly random utility functions
- ghciSupported :: Bool
- debugIsOn :: Bool
- ncgDebugIsOn :: Bool
- ghciTablesNextToCode :: Bool
- isWindowsHost :: Bool
- isDarwinHost :: Bool
- zipEqual :: String -> [a] -> [b] -> [(a, b)]
- zipWithEqual :: String -> (a -> b -> c) -> [a] -> [b] -> [c]
- zipWith3Equal :: String -> (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
- zipWith4Equal :: String -> (a -> b -> c -> d -> e) -> [a] -> [b] -> [c] -> [d] -> [e]
- zipLazy :: [a] -> [b] -> [(a, b)]
- stretchZipWith :: (a -> Bool) -> b -> (a -> b -> c) -> [a] -> [b] -> [c]
- zipWithAndUnzip :: (a -> b -> (c, d)) -> [a] -> [b] -> ([c], [d])
- filterByList :: [Bool] -> [a] -> [a]
- unzipWith :: (a -> b -> c) -> [(a, b)] -> [c]
- mapFst :: (a -> c) -> [(a, b)] -> [(c, b)]
- mapSnd :: (b -> c) -> [(a, b)] -> [(a, c)]
- chkAppend :: [a] -> [a] -> [a]
- mapAndUnzip :: (a -> (b, c)) -> [a] -> ([b], [c])
- mapAndUnzip3 :: (a -> (b, c, d)) -> [a] -> ([b], [c], [d])
- mapAccumL2 :: (s1 -> s2 -> a -> (s1, s2, b)) -> s1 -> s2 -> [a] -> (s1, s2, [b])
- nOfThem :: Int -> a -> [a]
- filterOut :: (a -> Bool) -> [a] -> [a]
- partitionWith :: (a -> Either b c) -> [a] -> ([b], [c])
- splitEithers :: [Either a b] -> ([a], [b])
- dropWhileEndLE :: (a -> Bool) -> [a] -> [a]
- foldl1' :: (a -> a -> a) -> [a] -> a
- foldl2 :: (acc -> a -> b -> acc) -> acc -> [a] -> [b] -> acc
- count :: (a -> Bool) -> [a] -> Int
- all2 :: (a -> b -> Bool) -> [a] -> [b] -> Bool
- lengthExceeds :: [a] -> Int -> Bool
- lengthIs :: [a] -> Int -> Bool
- lengthAtLeast :: [a] -> Int -> Bool
- listLengthCmp :: [a] -> Int -> Ordering
- atLength :: ([a] -> b) -> (Int -> b) -> [a] -> Int -> b
- equalLength :: [a] -> [b] -> Bool
- compareLength :: [a] -> [b] -> Ordering
- leLength :: [a] -> [b] -> Bool
- isSingleton :: [a] -> Bool
- only :: [a] -> a
- singleton :: a -> [a]
- notNull :: [a] -> Bool
- snocView :: [a] -> Maybe ([a], a)
- isIn :: Eq a => String -> a -> [a] -> Bool
- isn'tIn :: Eq a => String -> a -> [a] -> Bool
- fstOf3 :: (a, b, c) -> a
- sndOf3 :: (a, b, c) -> b
- thirdOf3 :: (a, b, c) -> c
- firstM :: Monad m => (a -> m c) -> (a, b) -> m (c, b)
- first3M :: Monad m => (a -> m d) -> (a, b, c) -> m (d, b, c)
- third3 :: (c -> d) -> (a, b, c) -> (a, b, d)
- uncurry3 :: (a -> b -> c -> d) -> (a, b, c) -> d
- takeList :: [b] -> [a] -> [a]
- dropList :: [b] -> [a] -> [a]
- splitAtList :: [b] -> [a] -> ([a], [a])
- split :: Char -> String -> [String]
- dropTail :: Int -> [a] -> [a]
- nTimes :: Int -> (a -> a) -> a -> a
- sortWith :: Ord b => (a -> b) -> [a] -> [a]
- minWith :: Ord b => (a -> b) -> [a] -> a
- nubSort :: Ord a => [a] -> [a]
- isEqual :: Ordering -> Bool
- eqListBy :: (a -> a -> Bool) -> [a] -> [a] -> Bool
- eqMaybeBy :: (a -> a -> Bool) -> Maybe a -> Maybe a -> Bool
- thenCmp :: Ordering -> Ordering -> Ordering
- cmpList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
- removeSpaces :: String -> String
- (<&&>) :: Applicative f => f Bool -> f Bool -> f Bool
- (<||>) :: Applicative f => f Bool -> f Bool -> f Bool
- fuzzyMatch :: String -> [String] -> [String]
- fuzzyLookup :: String -> [(String, a)] -> [a]
- transitiveClosure :: (a -> [a]) -> (a -> a -> Bool) -> [a] -> [a]
- seqList :: [a] -> b -> b
- looksLikeModuleName :: String -> Bool
- getCmd :: String -> Either String (String, String)
- toCmdArgs :: String -> Either String (String, [String])
- toArgs :: String -> Either String [String]
- readRational :: String -> Rational
- maybeRead :: Read a => String -> Maybe a
- maybeReadFuzzy :: Read a => String -> Maybe a
- doesDirNameExist :: FilePath -> IO Bool
- getModificationUTCTime :: FilePath -> IO UTCTime
- modificationTimeIfExists :: FilePath -> IO (Maybe UTCTime)
- global :: a -> IORef a
- consIORef :: IORef [a] -> a -> IO ()
- globalM :: IO a -> IORef a
- type Suffix = String
- splitLongestPrefix :: String -> (Char -> Bool) -> (String, String)
- escapeSpaces :: String -> String
- data Direction
- reslash :: Direction -> FilePath -> FilePath
- makeRelativeTo :: FilePath -> FilePath -> FilePath
- abstractConstr :: String -> Constr
- abstractDataType :: String -> DataType
- mkNoRepType :: String -> DataType
- charToC :: Word8 -> String
- hashString :: String -> Int32
Flags dependent on the compiler build
General list processing
zipWithEqual :: String -> (a -> b -> c) -> [a] -> [b] -> [c] Source
zipWith3Equal :: String -> (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d] Source
zipWith4Equal :: String -> (a -> b -> c -> d -> e) -> [a] -> [b] -> [c] -> [d] -> [e] Source
stretchZipWith :: (a -> Bool) -> b -> (a -> b -> c) -> [a] -> [b] -> [c] Source
stretchZipWith p z f xs ys
stretches ys
by inserting z
in
the places where p
returns True
zipWithAndUnzip :: (a -> b -> (c, d)) -> [a] -> [b] -> ([c], [d]) Source
filterByList :: [Bool] -> [a] -> [a] Source
filterByList
takes a list of Bools and a list of some elements and
filters out these elements for which the corresponding value in the list of
Bools is False. This function does not check whether the lists have equal
length.
mapAndUnzip :: (a -> (b, c)) -> [a] -> ([b], [c]) Source
mapAndUnzip3 :: (a -> (b, c, d)) -> [a] -> ([b], [c], [d]) Source
mapAccumL2 :: (s1 -> s2 -> a -> (s1, s2, b)) -> s1 -> s2 -> [a] -> (s1, s2, [b]) Source
partitionWith :: (a -> Either b c) -> [a] -> ([b], [c]) Source
Uses a function to determine which of two output lists an input element should join
splitEithers :: [Either a b] -> ([a], [b]) Source
Teases a list of Either
s apart into two lists
dropWhileEndLE :: (a -> Bool) -> [a] -> [a] Source
lengthExceeds :: [a] -> Int -> Bool Source
(lengthExceeds xs n) = (length xs > n)
lengthAtLeast :: [a] -> Int -> Bool Source
listLengthCmp :: [a] -> Int -> Ordering Source
atLength :: ([a] -> b) -> (Int -> b) -> [a] -> Int -> b Source
atLength atLen atEnd ls n
unravels list ls
to position n
. Precisely:
atLength atLenPred atEndPred ls n | n < 0 = atLenPred n | length ls < n = atEndPred (n - length ls) | otherwise = atLenPred (drop n ls)
equalLength :: [a] -> [b] -> Bool Source
compareLength :: [a] -> [b] -> Ordering Source
isSingleton :: [a] -> Bool Source
Tuples
List operations controlled by another list
splitAtList :: [b] -> [a] -> ([a], [a]) Source
For loop
nTimes :: Int -> (a -> a) -> a -> a Source
Compose a function with itself n times. (nth rather than twice)
Sorting
Comparisons
removeSpaces :: String -> String Source
Edit distance
fuzzyMatch :: String -> [String] -> [String] Source
fuzzyLookup :: String -> [(String, a)] -> [a] Source
Search for possible matches to the users input in the given list, returning a small number of ranked results
Transitive closures
transitiveClosure :: (a -> [a]) -> (a -> a -> Bool) -> [a] -> [a] Source
Strictness
Module names
looksLikeModuleName :: String -> Bool Source
Argument processing
Floating point
readRational :: String -> Rational Source
read helpers
maybeReadFuzzy :: Read a => String -> Maybe a Source
IO-ish utilities
doesDirNameExist :: FilePath -> IO Bool Source
Filenames and paths
escapeSpaces :: String -> String Source
makeRelativeTo :: FilePath -> FilePath -> FilePath Source
Utils for defining Data instances
abstractConstr :: String -> Constr Source
abstractDataType :: String -> DataType Source
mkNoRepType :: String -> DataType Source
Constructs a non-representation for a non-representable type
Utils for printing C code
Hashing
hashString :: String -> Int32 Source
A sample hash function for Strings. We keep multiplying by the golden ratio and adding. The implementation is:
hashString = foldl' f golden where f m c = fromIntegral (ord c) * magic + hashInt32 m magic = 0xdeadbeef
Where hashInt32 works just as hashInt shown above.
Knuth argues that repeated multiplication by the golden ratio will minimize gaps in the hash space, and thus it's a good choice for combining together multiple keys to form one.
Here we know that individual characters c are often small, and this produces frequent collisions if we use ord c alone. A particular problem are the shorter low ASCII and ISO-8859-1 character strings. We pre-multiply by a magic twiddle factor to obtain a good distribution. In fact, given the following test:
testp :: Int32 -> Int testp k = (n - ) . length . group . sort . map hs . take n $ ls where ls = [] : [c : l | l <- ls, c <- ['\0'..'\xff']] hs = foldl' f golden f m c = fromIntegral (ord c) * k + hashInt32 m n = 100000
We discover that testp magic = 0.