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] #

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 #

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.

`>>>`

*** Exception: die CallStack (from HasCallStack): errorWithCallStack, called at <interactive>:2:1 in interactive:Ghci1`errorWithCallStack "die"`

GHC solves `HasCallStack`

constraints in three steps:

- If there is a
`CallStack`

in scope -- i.e. the enclosing function has a`HasCallStack`

constraint -- GHC will append the new call-site to the existing`CallStack`

. - 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 a`HasCallStack`

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 the`HasCallStack`

constraint for the singleton`CallStack`

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 #