Safe Haskell | None |
---|---|
Language | Haskell2010 |
- 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
- Integers
- Floating point
- read helpers
- IO-ish utilities
- Filenames and paths
- Utils for defining Data instances
- Utils for printing C code
- Hashing
- Call stacks
- Utils for flags
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])
- zipWithLazy :: (a -> b -> c) -> [a] -> [b] -> [c]
- zipWith3Lazy :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d]
- filterByList :: [Bool] -> [a] -> [a]
- filterByLists :: [Bool] -> [a] -> [a] -> [a]
- partitionByList :: [Bool] -> [a] -> ([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]
- spanEnd :: (a -> Bool) -> [a] -> ([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) -> 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
- chunkList :: Int -> [a] -> [[a]]
- changeLast :: [a] -> a -> [a]
- fstOf3 :: (a, b, c) -> a
- sndOf3 :: (a, b, c) -> b
- thdOf3 :: (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)
- fst3 :: (a -> d) -> (a, b, c) -> (d, b, c)
- snd3 :: (b -> d) -> (a, b, c) -> (a, d, c)
- third3 :: (c -> d) -> (a, b, c) -> (a, b, d)
- uncurry3 :: (a -> b -> c -> d) -> (a, b, c) -> d
- liftFst :: (a -> b) -> (a, c) -> (b, c)
- liftSnd :: (a -> b) -> (c, a) -> (c, b)
- takeList :: [b] -> [a] -> [a]
- dropList :: [b] -> [a] -> [a]
- splitAtList :: [b] -> [a] -> ([a], [a])
- split :: Char -> String -> [String]
- dropTail :: Int -> [a] -> [a]
- capitalise :: String -> String
- 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
- looksLikePackageName :: String -> Bool
- getCmd :: String -> Either String (String, String)
- toCmdArgs :: String -> Either String (String, [String])
- toArgs :: String -> Either String [String]
- exactLog2 :: Integer -> Maybe Integer
- 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)
- hSetTranslit :: Handle -> IO ()
- global :: a -> IORef a
- consIORef :: IORef [a] -> a -> IO ()
- globalM :: IO a -> IORef a
- sharedGlobal :: a -> (Ptr (IORef a) -> IO (Ptr (IORef a))) -> IORef a
- sharedGlobalM :: IO a -> (Ptr (IORef a) -> IO (Ptr (IORef 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
- data CallStack :: *
- type HasCallStack = HasCallStack
- type HasDebugCallStack = (() :: Constraint)
- prettyCurrentCallStack :: HasCallStack => String
- data OverridingBool
- overrideWith :: Bool -> OverridingBool -> Bool
Flags dependent on the compiler build
ghciSupported :: Bool Source #
ncgDebugIsOn :: Bool Source #
isWindowsHost :: Bool Source #
isDarwinHost :: Bool Source #
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 #
zipWithLazy :: (a -> b -> c) -> [a] -> [b] -> [c] Source #
zipWithLazy
is like zipWith
but is lazy in the second list.
The length of the output is always the same as the length of the first
list.
zipWith3Lazy :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d] Source #
zipWith3Lazy
is like zipWith3
but is lazy in the second and third lists.
The length of the output is always the same as the length of the first
list.
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.
filterByLists :: [Bool] -> [a] -> [a] -> [a] Source #
filterByLists
takes a list of Bools and two lists as input, and
outputs a new list consisting of elements from the last two input lists. For
each Bool in the list, if it is True
, then it takes an element from the
former list. If it is False
, it takes an element from the latter list.
The elements taken correspond to the index of the Bool in its list.
For example:
filterByLists [True, False, True, False] "abcd" "wxyz" = "axcz"
This function does not check whether the lists have equal length.
partitionByList :: [Bool] -> [a] -> ([a], [a]) Source #
partitionByList
takes a list of Bools and a list of some elements and
partitions the list according to the list of Bools. Elements corresponding
to True
go to the left; elements corresponding to False
go to the right.
For example, partitionByList [True, False, True] [1,2,3] == ([1,3], [2])
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 #
spanEnd :: (a -> Bool) -> [a] -> ([a], [a]) Source #
spanEnd p l == reverse (span p (reverse l))
. The first list
returns actually comes after the second list (when you look at the
input list).
lengthExceeds :: [a] -> Int -> Bool Source #
(lengthExceeds xs n) = (length xs > n)
lengthAtLeast :: [a] -> Int -> Bool Source #
listLengthCmp :: [a] -> Int -> Ordering Source #
atLength :: ([a] -> b) -> 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 ls | 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 #
changeLast :: [a] -> a -> [a] Source #
Replace the last element of a list with another element.
Tuples
List operations controlled by another list
splitAtList :: [b] -> [a] -> ([a], [a]) Source #
capitalise :: String -> String Source #
Convert a word to title case by capitalising the first letter
For loop
nTimes :: Int -> (a -> a) -> a -> a Source #
Compose a function with itself n times. (nth rather than twice)
Sorting
sortWith :: Ord b => (a -> b) -> [a] -> [a] Source #
The sortWith
function sorts a list of elements using the
user supplied function to project something out of each element
Comparisons
removeSpaces :: String -> String Source #
Edit distance
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 #
looksLikePackageName :: String -> Bool Source #
Argument processing
Integers
Floating point
readRational :: String -> Rational Source #
read helpers
IO-ish utilities
hSetTranslit :: Handle -> IO () Source #
Filenames and paths
escapeSpaces :: String -> String 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.
Call stacks
CallStack
s are a lightweight method of obtaining a
partial call-stack at any point in the program.
A function can request its call-site with the HasCallStack
constraint.
For example, we can define
errorWithCallStack :: HasCallStack => String -> a
as a variant of error
that will get its call-site. We can access the
call-stack inside errorWithCallStack
with callStack
.
errorWithCallStack :: HasCallStack => String -> a errorWithCallStack msg = error (msg ++ "n" ++ prettyCallStack callStack)
Thus, if we call errorWithCallStack
we will get a formatted call-stack
alongside our error message.
>>>
errorWithCallStack "die"
*** Exception: die CallStack (from HasCallStack): errorWithCallStack, called at <interactive>:2:1 in interactive:Ghci1
GHC solves HasCallStack
constraints in three steps:
- If there is a
CallStack
in scope -- i.e. the enclosing function has aHasCallStack
constraint -- GHC will append the new call-site to the existingCallStack
. - If there is no
CallStack
in scope -- e.g. in the GHCi session above -- and the enclosing definition does not have an explicit type signature, GHC will infer aHasCallStack
constraint for the enclosing definition (subject to the monomorphism restriction). - If there is no
CallStack
in scope and the enclosing definition has an explicit type signature, GHC will solve theHasCallStack
constraint for the singletonCallStack
containing just the current call-site.
CallStack
s do not interact with the RTS and do not require compilation
with -prof
. On the other hand, as they are built up explicitly via the
HasCallStack
constraints, they will generally not contain as much
information as the simulated call-stacks maintained by the RTS.
A CallStack
is a [(String, SrcLoc)]
. The String
is the name of
function that was called, the SrcLoc
is the call-site. The list is
ordered with the most recently called function at the head.
NOTE: The intrepid user may notice that HasCallStack
is just an
alias for an implicit parameter ?callStack :: CallStack
. This is an
implementation detail and should not be considered part of the
CallStack
API, we may decide to change the implementation in the
future.
Since: 4.8.1.0
type HasCallStack = HasCallStack Source #
A compatibility wrapper for the GHC.Stack.HasCallStack
constraint.
type HasDebugCallStack = (() :: Constraint) Source #
A call stack constraint, but only when isDebugOn
.
prettyCurrentCallStack :: HasCallStack => String Source #
Pretty-print the current callstack
Utils for flags
overrideWith :: Bool -> OverridingBool -> Bool Source #