| License | GPL-3.0-or-later |
|---|---|
| Safe Haskell | None |
| Language | Haskell2010 |
CabalFmt.Prelude
Contents
Description
Copyright: Oleg Grenrus
Fat-prelude.
Synopsis
- (&&&) :: Arrow a => a b c -> a b c' -> a b (c, c')
- when :: Applicative f => Bool -> f () -> f ()
- unless :: Applicative f => Bool -> f () -> f ()
- void :: Functor f => f a -> f ()
- bimap :: Bifunctor p => (a -> b) -> (c -> d) -> p a c -> p b d
- toLower :: Char -> Char
- partitionEithers :: [Either a b] -> ([a], [b])
- toList :: Foldable t => t a -> [a]
- traverse_ :: (Foldable t, Applicative f) => (a -> f b) -> t a -> f ()
- asum :: (Foldable t, Alternative f) => t (f a) -> f a
- on :: (b -> b -> c) -> (a -> b) -> a -> a -> c
- (&) :: a -> (a -> b) -> b
- intercalate :: [a] -> [[a]] -> [a]
- sortOn :: Ord b => (a -> b) -> [a] -> [a]
- sortBy :: (a -> a -> Ordering) -> [a] -> [a]
- nub :: Eq a => [a] -> [a]
- catMaybes :: [Maybe a] -> [a]
- fromMaybe :: a -> Maybe a -> a
- isJust :: Maybe a -> Bool
- isNothing :: Maybe a -> Bool
- data ByteString
- fromUTF8BS :: ByteString -> String
- toUTF8BS :: String -> ByteString
- pack' :: Newtype o n => (o -> n) -> o -> n
- unpack' :: Newtype o n => (o -> n) -> n -> o
- data Set a
- dropExtension :: FilePath -> FilePath
- splitDirectories :: FilePath -> [FilePath]
- catchError :: MonadError e m => m a -> (e -> m a) -> m a
- throwError :: MonadError e m => e -> m a
- traverseOf :: Applicative f => ((a -> f b) -> s -> f t) -> (a -> f b) -> s -> f t
- over :: ASetter s t a b -> (a -> b) -> s -> t
- view :: Getting a s a -> s -> a
- _1 :: Functor f => (a -> f b) -> (a, c) -> f (b, c)
Control.Arrow
(&&&) :: Arrow a => a b c -> a b c' -> a b (c, c') infixr 3 #
Fanout: send the input to both argument arrows and combine their output.
The default definition may be overridden with a more efficient version if desired.
Control.Monad
when :: Applicative f => Bool -> f () -> f () #
Conditional execution of Applicative expressions. For example,
when debug (putStrLn "Debugging")
will output the string Debugging if the Boolean value debug
is True, and otherwise do nothing.
unless :: Applicative f => Bool -> f () -> f () #
The reverse of when.
void :: Functor f => f a -> f () #
void valueIO action.
Examples
Replace the contents of a Maybe Int
>>>void NothingNothing>>>void (Just 3)Just ()
Replace the contents of an Either Int IntEither Int '()'
>>>void (Left 8675309)Left 8675309>>>void (Right 8675309)Right ()
Replace every element of a list with unit:
>>>void [1,2,3][(),(),()]
Replace the second element of a pair with unit:
>>>void (1,2)(1,())
Discard the result of an IO action:
>>>mapM print [1,2]1 2 [(),()]>>>void $ mapM print [1,2]1 2
Data.Bifunctor
Data.Char
Convert a letter to the corresponding lower-case letter, if any. Any other character is returned unchanged.
Data.Either
partitionEithers :: [Either a b] -> ([a], [b]) #
Partitions a list of Either into two lists.
All the Left elements are extracted, in order, to the first
component of the output. Similarly the Right elements are extracted
to the second component of the output.
Examples
Basic usage:
>>>let list = [ Left "foo", Right 3, Left "bar", Right 7, Left "baz" ]>>>partitionEithers list(["foo","bar","baz"],[3,7])
The pair returned by partitionEithers x(:lefts x, rights x)
>>>let list = [ Left "foo", Right 3, Left "bar", Right 7, Left "baz" ]>>>partitionEithers list == (lefts list, rights list)True
Data.Foldable
traverse_ :: (Foldable t, Applicative f) => (a -> f b) -> t a -> f () #
Map each element of a structure to an action, evaluate these
actions from left to right, and ignore the results. For a version
that doesn't ignore the results see traverse.
asum :: (Foldable t, Alternative f) => t (f a) -> f a #
Data.Function
Data.List
intercalate :: [a] -> [[a]] -> [a] #
intercalate xs xss is equivalent to (.
It inserts the list concat (intersperse xs xss))xs in between the lists in xss and concatenates the
result.
>>>intercalate ", " ["Lorem", "ipsum", "dolor"]"Lorem, ipsum, dolor"
sortOn :: Ord b => (a -> b) -> [a] -> [a] #
Sort a list by comparing the results of a key function applied to each
element. sortOn f is equivalent to sortBy (comparing f), but has the
performance advantage of only evaluating f once for each element in the
input list. This is called the decorate-sort-undecorate paradigm, or
Schwartzian transform.
Elements are arranged from from lowest to highest, keeping duplicates in the order they appeared in the input.
>>>sortOn fst [(2, "world"), (4, "!"), (1, "Hello")][(1,"Hello"),(2,"world"),(4,"!")]
Since: base-4.8.0.0
O(n^2). The nub function removes duplicate elements from a list.
In particular, it keeps only the first occurrence of each element.
(The name nub means `essence'.)
It is a special case of nubBy, which allows the programmer to supply
their own equality test.
>>>nub [1,2,3,4,3,2,1,2,4,3,5][1,2,3,4,5]
Data.Maybe
catMaybes :: [Maybe a] -> [a] #
The catMaybes function takes a list of Maybes and returns
a list of all the Just values.
Examples
Basic usage:
>>>catMaybes [Just 1, Nothing, Just 3][1,3]
When constructing a list of Maybe values, catMaybes can be used
to return all of the "success" results (if the list is the result
of a map, then mapMaybe would be more appropriate):
>>>import Text.Read ( readMaybe )>>>[readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ][Just 1,Nothing,Just 3]>>>catMaybes $ [readMaybe x :: Maybe Int | x <- ["1", "Foo", "3"] ][1,3]
fromMaybe :: a -> Maybe a -> a #
The fromMaybe function takes a default value and and Maybe
value. If the Maybe is Nothing, it returns the default values;
otherwise, it returns the value contained in the Maybe.
Examples
Basic usage:
>>>fromMaybe "" (Just "Hello, World!")"Hello, World!"
>>>fromMaybe "" Nothing""
Read an integer from a string using readMaybe. If we fail to
parse an integer, we want to return 0 by default:
>>>import Text.Read ( readMaybe )>>>fromMaybe 0 (readMaybe "5")5>>>fromMaybe 0 (readMaybe "")0
Packages
bytestring
data ByteString #
A space-efficient representation of a Word8 vector, supporting many
efficient operations.
A ByteString contains 8-bit bytes, or by using the operations from
Data.ByteString.Char8 it can be interpreted as containing 8-bit
characters.
Instances
Cabal
fromUTF8BS :: ByteString -> String #
Decode String from UTF8-encoded ByteString
Invalid data in the UTF8 stream (this includes code-points U+D800
through U+DFFF) will be decoded as the replacement character (U+FFFD).
toUTF8BS :: String -> ByteString #
Encode String to to UTF8-encoded ByteString
Code-points in the U+D800-U+DFFF range will be encoded
as the replacement character (i.e. U+FFFD).
containers
A set of values a.
Instances
| Foldable Set | |
Defined in Data.Set.Internal Methods fold :: Monoid m => Set m -> m # foldMap :: Monoid m => (a -> m) -> Set a -> m # foldr :: (a -> b -> b) -> b -> Set a -> b # foldr' :: (a -> b -> b) -> b -> Set a -> b # foldl :: (b -> a -> b) -> b -> Set a -> b # foldl' :: (b -> a -> b) -> b -> Set a -> b # foldr1 :: (a -> a -> a) -> Set a -> a # foldl1 :: (a -> a -> a) -> Set a -> a # elem :: Eq a => a -> Set a -> Bool # maximum :: Ord a => Set a -> a # | |
| Eq1 Set | Since: containers-0.5.9 |
| Ord1 Set | Since: containers-0.5.9 |
Defined in Data.Set.Internal | |
| Show1 Set | Since: containers-0.5.9 |
| Ord a => IsList (Set a) | Since: containers-0.5.6.2 |
| Eq a => Eq (Set a) | |
| (Data a, Ord a) => Data (Set a) | |
Defined in Data.Set.Internal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Set a -> c (Set a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Set a) # dataTypeOf :: Set a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Set a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Set a)) # gmapT :: (forall b. Data b => b -> b) -> Set a -> Set a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Set a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Set a -> r # gmapQ :: (forall d. Data d => d -> u) -> Set a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Set a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Set a -> m (Set a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Set a -> m (Set a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Set a -> m (Set a) # | |
| Ord a => Ord (Set a) | |
| (Read a, Ord a) => Read (Set a) | |
| Show a => Show (Set a) | |
| Ord a => Semigroup (Set a) | Since: containers-0.5.7 |
| Ord a => Monoid (Set a) | |
| NFData a => NFData (Set a) | |
Defined in Data.Set.Internal | |
| Newtype (Set a) (Set' sep wrapper a) | |
| type Item (Set a) | |
Defined in Data.Set.Internal | |
directory
dropExtension :: FilePath -> FilePath #
Remove last extension, and the "." preceding it.
dropExtension "/directory/path.ext" == "/directory/path" dropExtension x == fst (splitExtension x)
splitDirectories :: FilePath -> [FilePath] #
Just as splitPath, but don't add the trailing slashes to each element.
splitDirectories "/directory/file.ext" == ["/","directory","file.ext"]
splitDirectories "test/file" == ["test","file"]
splitDirectories "/test/file" == ["/","test","file"]
Windows: splitDirectories "C:\\test\\file" == ["C:\\", "test", "file"]
Valid x => joinPath (splitDirectories x) `equalFilePath` x
splitDirectories "" == []
Windows: splitDirectories "C:\\test\\\\\\file" == ["C:\\", "test", "file"]
splitDirectories "/test///file" == ["/","test","file"]exceptions
catchError :: MonadError e m => m a -> (e -> m a) -> m a #
A handler function to handle previous errors and return to normal execution. A common idiom is:
do { action1; action2; action3 } `catchError` handlerwhere the action functions can call throwError.
Note that handler and the do-block must have the same return type.
throwError :: MonadError e m => e -> m a #
Is used within a monadic computation to begin exception processing.
Extras
Lens
traverseOf :: Applicative f => ((a -> f b) -> s -> f t) -> (a -> f b) -> s -> f t Source #