rio-0.1.22.0: A standard library for Haskell

Safe Haskell | Safe-Inferred
Language | Haskell2010

RIO.NonEmpty

Contents

- The type of non-empty streams
- Non-empty stream transformations
- Basic functions
- Building streams
- Extracting sublists
- Sublist predicates
- Set-like operations
- Zipping and unzipping streams
- Converting to and from a list

Description

`NonEmpty` list. Import as:

    import qualified RIO.NonEmpty as NE

This module does not export any partial functions. For those, see RIO.NonEmpty.Partial

Synopsis

- data NonEmpty a = a :| [a]
- map :: (a -> b) -> NonEmpty a -> NonEmpty b
- intersperse :: a -> NonEmpty a -> NonEmpty a
- scanl :: Foldable f => (b -> a -> b) -> b -> f a -> NonEmpty b
- scanr :: Foldable f => (a -> b -> b) -> b -> f a -> NonEmpty b
- scanl1 :: (a -> a -> a) -> NonEmpty a -> NonEmpty a
- scanr1 :: (a -> a -> a) -> NonEmpty a -> NonEmpty a
- transpose :: NonEmpty (NonEmpty a) -> NonEmpty (NonEmpty a)
- sortBy :: (a -> a -> Ordering) -> NonEmpty a -> NonEmpty a
- sortWith :: Ord o => (a -> o) -> NonEmpty a -> NonEmpty a
- length :: NonEmpty a -> Int
- head :: NonEmpty a -> a
- tail :: NonEmpty a -> [a]
- last :: NonEmpty a -> a
- init :: NonEmpty a -> [a]
- (<|) :: a -> NonEmpty a -> NonEmpty a
- cons :: a -> NonEmpty a -> NonEmpty a
- uncons :: NonEmpty a -> (a, Maybe (NonEmpty a))
- unfoldr :: (a -> (b, Maybe a)) -> a -> NonEmpty b
- sort :: Ord a => NonEmpty a -> NonEmpty a
- reverse :: NonEmpty a -> NonEmpty a
- inits :: Foldable f => f a -> NonEmpty [a]
- tails :: Foldable f => f a -> NonEmpty [a]
- iterate :: (a -> a) -> a -> NonEmpty a
- repeat :: a -> NonEmpty a
- cycle :: NonEmpty a -> NonEmpty a
- insert :: (Foldable f, Ord a) => a -> f a -> NonEmpty a
- some1 :: Alternative f => f a -> f (NonEmpty a)
- take :: Int -> NonEmpty a -> [a]
- drop :: Int -> NonEmpty a -> [a]
- splitAt :: Int -> NonEmpty a -> ([a], [a])
- takeWhile :: (a -> Bool) -> NonEmpty a -> [a]
- dropWhile :: (a -> Bool) -> NonEmpty a -> [a]
- span :: (a -> Bool) -> NonEmpty a -> ([a], [a])
- break :: (a -> Bool) -> NonEmpty a -> ([a], [a])
- filter :: (a -> Bool) -> NonEmpty a -> [a]
- partition :: (a -> Bool) -> NonEmpty a -> ([a], [a])
- group :: (Foldable f, Eq a) => f a -> [NonEmpty a]
- groupBy :: Foldable f => (a -> a -> Bool) -> f a -> [NonEmpty a]
- groupWith :: (Foldable f, Eq b) => (a -> b) -> f a -> [NonEmpty a]
- groupAllWith :: Ord b => (a -> b) -> [a] -> [NonEmpty a]
- group1 :: Eq a => NonEmpty a -> NonEmpty (NonEmpty a)
- groupBy1 :: (a -> a -> Bool) -> NonEmpty a -> NonEmpty (NonEmpty a)
- groupWith1 :: Eq b => (a -> b) -> NonEmpty a -> NonEmpty (NonEmpty a)
- groupAllWith1 :: Ord b => (a -> b) -> NonEmpty a -> NonEmpty (NonEmpty a)
- isPrefixOf :: Eq a => [a] -> NonEmpty a -> Bool
- nub :: Eq a => NonEmpty a -> NonEmpty a
- nubBy :: (a -> a -> Bool) -> NonEmpty a -> NonEmpty a
- zip :: NonEmpty a -> NonEmpty b -> NonEmpty (a, b)
- zipWith :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c
- unzip :: Functor f => f (a, b) -> (f a, f b)
- nonEmpty :: [a] -> Maybe (NonEmpty a)
- toList :: NonEmpty a -> [a]
- xor :: NonEmpty Bool -> Bool

# The type of non-empty streams

data NonEmpty a #

Non-empty (and non-strict) list type.

@since base-4.9.0.0

Constructors

a :| [a] infixr 5 |

#### Instances

Instances details

MonadZip NonEmpty | Since: base-4.9.0.0
Instance details Defined in Control.Monad.Zip Methods mzip :: NonEmpty a -> NonEmpty b -> NonEmpty (a, b) # mzipWith :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c # munzip :: NonEmpty (a, b) -> (NonEmpty a, NonEmpty b) #
Foldable1 NonEmpty | Since: base-4.18.0.0

Instance details

Defined in Data.Foldable1

Methods

fold1 :: Semigroup m => NonEmpty m -> m #

foldMap1 :: Semigroup m => (a -> m) -> NonEmpty a -> m #

foldMap1' :: Semigroup m => (a -> m) -> NonEmpty a -> m #

toNonEmpty :: NonEmpty a -> NonEmpty a #

maximum :: Ord a => NonEmpty a -> a #

minimum :: Ord a => NonEmpty a -> a #

head :: NonEmpty a -> a #

last :: NonEmpty a -> a #

foldrMap1 :: (a -> b) -> (a -> b -> b) -> NonEmpty a -> b #

foldlMap1' :: (a -> b) -> (b -> a -> b) -> NonEmpty a -> b #

foldlMap1 :: (a -> b) -> (b -> a -> b) -> NonEmpty a -> b #

foldrMap1' :: (a -> b) -> (a -> b -> b) -> NonEmpty a -> b #

Eq1 NonEmpty | Since: base-4.10.0.0
Instance details Defined in Data.Functor.Classes Methods liftEq :: (a -> b -> Bool) -> NonEmpty a -> NonEmpty b -> Bool #
Ord1 NonEmpty | Since: base-4.10.0.0
Instance details Defined in Data.Functor.Classes Methods liftCompare :: (a -> b -> Ordering) -> NonEmpty a -> NonEmpty b -> Ordering #
Read1 NonEmpty | Since: base-4.10.0.0
Instance details Defined in Data.Functor.Classes Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (NonEmpty a) # liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [NonEmpty a] # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (NonEmpty a) # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [NonEmpty a] #
Show1 NonEmpty | Since: base-4.10.0.0
Instance details Defined in Data.Functor.Classes Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> NonEmpty a -> ShowS # liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [NonEmpty a] -> ShowS #
NFData1 NonEmpty | Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf :: (a -> ()) -> NonEmpty a -> () #
Applicative NonEmpty | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods pure :: a -> NonEmpty a # (<*>) :: NonEmpty (a -> b) -> NonEmpty a -> NonEmpty b # liftA2 :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c # (*>) :: NonEmpty a -> NonEmpty b -> NonEmpty b # (<*) :: NonEmpty a -> NonEmpty b -> NonEmpty a #
Functor NonEmpty | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods fmap :: (a -> b) -> NonEmpty a -> NonEmpty b # (<$) :: a -> NonEmpty b -> NonEmpty a #
Monad NonEmpty | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods (>>=) :: NonEmpty a -> (a -> NonEmpty b) -> NonEmpty b # (>>) :: NonEmpty a -> NonEmpty b -> NonEmpty b # return :: a -> NonEmpty a #
Foldable NonEmpty | @since base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Foldable

Methods

fold :: Monoid m => NonEmpty m -> m #

foldMap :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldMap' :: Monoid m => (a -> m) -> NonEmpty a -> m #

foldr :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldr' :: (a -> b -> b) -> b -> NonEmpty a -> b #

foldl :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldl' :: (b -> a -> b) -> b -> NonEmpty a -> b #

foldr1 :: (a -> a -> a) -> NonEmpty a -> a #

foldl1 :: (a -> a -> a) -> NonEmpty a -> a #

toList :: NonEmpty a -> [a] #

null :: NonEmpty a -> Bool #

length :: NonEmpty a -> Int #

elem :: Eq a => a -> NonEmpty a -> Bool #

maximum :: Ord a => NonEmpty a -> a #

minimum :: Ord a => NonEmpty a -> a #

sum :: Num a => NonEmpty a -> a #

product :: Num a => NonEmpty a -> a #

Traversable NonEmpty | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Data.Traversable Methods traverse :: Applicative f => (a -> f b) -> NonEmpty a -> f (NonEmpty b) # sequenceA :: Applicative f => NonEmpty (f a) -> f (NonEmpty a) # mapM :: Monad m => (a -> m b) -> NonEmpty a -> m (NonEmpty b) # sequence :: Monad m => NonEmpty (m a) -> m (NonEmpty a) #
Hashable1 NonEmpty | Since: hashable-1.3.1.0
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt :: (Int -> a -> Int) -> Int -> NonEmpty a -> Int #
Generic1 NonEmpty |

Instance details

Defined in GHC.Internal.Generics

Associated Types

type Rep1 NonEmpty | @since base-4.6.0.0

Instance details

Defined in GHC.Internal.Generics

type Rep1 NonEmpty = D1 ('MetaData "NonEmpty" "GHC.Internal.Base" "ghc-internal" 'False) (C1 ('MetaCons ":|" ('InfixI 'RightAssociative 5) 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1 :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 [])))

Methods

from1 :: NonEmpty a -> Rep1 NonEmpty a #

to1 :: Rep1 NonEmpty a -> NonEmpty a #

Lift a => Lift (NonEmpty a :: Type) | Since: template-haskell-2.15.0.0
Instance details Defined in Language.Haskell.TH.Syntax Methods lift :: Quote m => NonEmpty a -> m Exp # liftTyped :: forall (m :: Type -> Type). Quote m => NonEmpty a -> Code m (NonEmpty a) #
NFData a => NFData (NonEmpty a) | Since: deepseq-1.4.2.0
Instance details Defined in Control.DeepSeq Methods rnf :: NonEmpty a -> () #
Semigroup (NonEmpty a) | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods (<>) :: NonEmpty a -> NonEmpty a -> NonEmpty a # sconcat :: NonEmpty (NonEmpty a) -> NonEmpty a # stimes :: Integral b => b -> NonEmpty a -> NonEmpty a #
Data a => Data (NonEmpty a) | @since base-4.9.0.0

Instance details

Defined in GHC.Internal.Data.Data

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> NonEmpty a -> c (NonEmpty a) #

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (NonEmpty a) #

toConstr :: NonEmpty a -> Constr #

dataTypeOf :: NonEmpty a -> DataType #

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (NonEmpty a)) #

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (NonEmpty a)) #

gmapT :: (forall b. Data b => b -> b) -> NonEmpty a -> NonEmpty a #

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> NonEmpty a -> r #

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> NonEmpty a -> r #

gmapQ :: (forall d. Data d => d -> u) -> NonEmpty a -> [u] #

gmapQi :: Int -> (forall d. Data d => d -> u) -> NonEmpty a -> u #

gmapM :: Monad m => (forall d. Data d => d -> m d) -> NonEmpty a -> m (NonEmpty a) #

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> NonEmpty a -> m (NonEmpty a) #

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> NonEmpty a -> m (NonEmpty a) #

Generic (NonEmpty a) |

Instance details

Defined in GHC.Internal.Generics

Associated Types

type Rep (NonEmpty a) | @since base-4.6.0.0

Instance details

Defined in GHC.Internal.Generics

type Rep (NonEmpty a) = D1 ('MetaData "NonEmpty" "GHC.Internal.Base" "ghc-internal" 'False) (C1 ('MetaCons ":|" ('InfixI 'RightAssociative 5) 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [a])))

Methods

from :: NonEmpty a -> Rep (NonEmpty a) x #

to :: Rep (NonEmpty a) x -> NonEmpty a #

IsList (NonEmpty a) | @since base-4.9.0.0

Instance details

Defined in GHC.Internal.IsList

Associated Types

type Item (NonEmpty a) |
Instance details Defined in GHC.Internal.IsList type Item (NonEmpty a) = a

Methods

fromList :: [Item (NonEmpty a)] -> NonEmpty a #

fromListN :: Int -> [Item (NonEmpty a)] -> NonEmpty a #

toList :: NonEmpty a -> [Item (NonEmpty a)] #

Read a => Read (NonEmpty a) | @since base-4.11.0.0
Instance details Defined in GHC.Internal.Read Methods readsPrec :: Int -> ReadS (NonEmpty a) # readList :: ReadS [NonEmpty a] # readPrec :: ReadPrec (NonEmpty a) # readListPrec :: ReadPrec [NonEmpty a] #
Show a => Show (NonEmpty a) | @since base-4.11.0.0
Instance details Defined in GHC.Internal.Show Methods showsPrec :: Int -> NonEmpty a -> ShowS # show :: NonEmpty a -> String # showList :: [NonEmpty a] -> ShowS #
Eq a => Eq (NonEmpty a) | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods (==) :: NonEmpty a -> NonEmpty a -> Bool # (/=) :: NonEmpty a -> NonEmpty a -> Bool #
Ord a => Ord (NonEmpty a) | @since base-4.9.0.0
Instance details Defined in GHC.Internal.Base Methods compare :: NonEmpty a -> NonEmpty a -> Ordering # (<) :: NonEmpty a -> NonEmpty a -> Bool # (<=) :: NonEmpty a -> NonEmpty a -> Bool # (>) :: NonEmpty a -> NonEmpty a -> Bool # (>=) :: NonEmpty a -> NonEmpty a -> Bool # max :: NonEmpty a -> NonEmpty a -> NonEmpty a # min :: NonEmpty a -> NonEmpty a -> NonEmpty a #
Hashable a => Hashable (NonEmpty a) |
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> NonEmpty a -> Int # hash :: NonEmpty a -> Int #
Ixed (NonEmpty a) |
Instance details Defined in Lens.Micro.Internal Methods ix :: Index (NonEmpty a) -> Traversal' (NonEmpty a) (IxValue (NonEmpty a)) #
Each (NonEmpty a) (NonEmpty b) a b |
Instance details Defined in Lens.Micro.Internal Methods each :: Traversal (NonEmpty a) (NonEmpty b) a b #
type Rep1 NonEmpty | @since base-4.6.0.0

Instance details

Defined in GHC.Internal.Generics

type Rep1 NonEmpty = D1 ('MetaData "NonEmpty" "GHC.Internal.Base" "ghc-internal" 'False) (C1 ('MetaCons ":|" ('InfixI 'RightAssociative 5) 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1 :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec1 [])))

type Rep (NonEmpty a) | @since base-4.6.0.0

Instance details

Defined in GHC.Internal.Generics

type Rep (NonEmpty a) = D1 ('MetaData "NonEmpty" "GHC.Internal.Base" "ghc-internal" 'False) (C1 ('MetaCons ":|" ('InfixI 'RightAssociative 5) 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [a])))

type Item (NonEmpty a) |
Instance details Defined in GHC.Internal.IsList type Item (NonEmpty a) = a
type Index (NonEmpty a) |
Instance details Defined in Lens.Micro.Internal type Index (NonEmpty a) = Int
type IxValue (NonEmpty a) |
Instance details Defined in Lens.Micro.Internal type IxValue (NonEmpty a) = a

# Non-empty stream transformations

map :: (a -> b) -> NonEmpty a -> NonEmpty b #

Map a function over a `NonEmpty` stream.

intersperse :: a -> NonEmpty a -> NonEmpty a #

'intersperse x xs' alternates elements of the list with copies of `x`.

    intersperse 0 (1 :| [2,3]) == 1 :| [0,2,0,3]

scanl :: Foldable f => (b -> a -> b) -> b -> f a -> NonEmpty b #

`scanl` is similar to `foldl`, but returns a stream of successive reduced values from the left:

    scanl f z [x1, x2, ...] == z :| [z `f` x1, (z `f` x1) `f` x2, ...]

Note that

    last (scanl f z xs) == foldl f z xs.

scanr :: Foldable f => (a -> b -> b) -> b -> f a -> NonEmpty b #

`scanr` is the right-to-left dual of `scanl`. Note that

    head (scanr f z xs) == foldr f z xs.

scanl1 :: (a -> a -> a) -> NonEmpty a -> NonEmpty a #

`scanl1` is a variant of `scanl` that has no starting value argument:

    scanl1 f [x1, x2, ...] == x1 :| [x1 `f` x2, x1 `f` (x2 `f` x3), ...]

scanr1 :: (a -> a -> a) -> NonEmpty a -> NonEmpty a #

`scanr1` is a variant of `scanr` that has no starting value argument.

transpose :: NonEmpty (NonEmpty a) -> NonEmpty (NonEmpty a) #

`transpose` for `NonEmpty`, behaves the same as `transpose` The rows/columns need not be the same length, in which case > transpose . transpose /= id

sortBy :: (a -> a -> Ordering) -> NonEmpty a -> NonEmpty a #

`sortBy` for `NonEmpty`, behaves the same as `sortBy`

sortWith :: Ord o => (a -> o) -> NonEmpty a -> NonEmpty a #

`sortWith` for `NonEmpty`, behaves the same as:

    sortBy . comparing

# Basic functions

length :: NonEmpty a -> Int #

Number of elements in `NonEmpty` list.

head :: NonEmpty a -> a #

Extract the first element of the stream.

tail :: NonEmpty a -> [a] #

Extract the possibly-empty tail of the stream.

last :: NonEmpty a -> a #

Extract the last element of the stream.

init :: NonEmpty a -> [a] #

Extract everything except the last element of the stream.

(<|) :: a -> NonEmpty a -> NonEmpty a infixr 5 #

Prepend an element to the stream.

cons :: a -> NonEmpty a -> NonEmpty a #

Synonym for `<|`.

uncons :: NonEmpty a -> (a, Maybe (NonEmpty a)) #

`uncons` produces the first element of the stream, and a stream of the remaining elements, if any.

unfoldr :: (a -> (b, Maybe a)) -> a -> NonEmpty b #

The `unfoldr` function is analogous to Data.List's `unfoldr` operation.

sort :: Ord a => NonEmpty a -> NonEmpty a #

Sort a stream.

reverse :: NonEmpty a -> NonEmpty a #

`reverse` a finite NonEmpty stream.

inits :: Foldable f => f a -> NonEmpty [a] #

The `inits` function takes a stream `xs` and returns all the finite prefixes of `xs`, starting with the shortest. The result is `NonEmpty` because the result always contains the empty list as the first element.

    inits [1,2,3] == [] :| [[1], [1,2], [1,2,3]]
    inits [1] == [] :| [[1]]
    inits [] == [] :| []

tails :: Foldable f => f a -> NonEmpty [a] #

The `tails` function takes a stream `xs` and returns all the suffixes of `xs`, starting with the longest. The result is `NonEmpty` because the result always contains the empty list as the last element.

    tails [1,2,3] == [1,2,3] :| [[2,3], [3], []]
    tails [1] == [1] :| [[]]
    tails [] == [] :| []

# Building streams

iterate :: (a -> a) -> a -> NonEmpty a #

``iterate` f x` produces the infinite sequence of repeated applications of `f` to `x`.

    iterate f x = x :| [f x, f (f x), ..]

repeat :: a -> NonEmpty a #

``repeat` x` returns a constant stream, where all elements are equal to `x`.

cycle :: NonEmpty a -> NonEmpty a #

``cycle` xs` returns the infinite repetition of `xs`:

    cycle (1 :| [2,3]) = 1 :| [2,3,1,2,3,...]

insert :: (Foldable f, Ord a) => a -> f a -> NonEmpty a #

``insert` x xs` inserts `x` into the last position in `xs` where it is still less than or equal to the next element. In particular, if the list is sorted beforehand, the result will also be sorted.

some1 :: Alternative f => f a -> f (NonEmpty a) #

``some1` x` sequences `x` one or more times.

# Extracting sublists

take :: Int -> NonEmpty a -> [a] #

``take` n xs` returns the first `n` elements of `xs`.

drop :: Int -> NonEmpty a -> [a] #

``drop` n xs` drops the first `n` elements off the front of the sequence `xs`.

splitAt :: Int -> NonEmpty a -> ([a], [a]) #

``splitAt` n xs` returns a pair consisting of the prefix of `xs` of length `n` and the remaining stream immediately following this prefix.

    'splitAt' n xs == ('take' n xs, 'drop' n xs)
    xs == ys ++ zs where (ys, zs) = 'splitAt' n xs

takeWhile :: (a -> Bool) -> NonEmpty a -> [a] #

``takeWhile` p xs` returns the longest prefix of the stream `xs` for which the predicate `p` holds.

dropWhile :: (a -> Bool) -> NonEmpty a -> [a] #

``dropWhile` p xs` returns the suffix remaining after ``takeWhile` p xs`.

span :: (a -> Bool) -> NonEmpty a -> ([a], [a]) #

``span` p xs` returns the longest prefix of `xs` that satisfies `p`, together with the remainder of the stream.

    'span' p xs == ('takeWhile' p xs, 'dropWhile' p xs)
    xs == ys ++ zs where (ys, zs) = 'span' p xs

break :: (a -> Bool) -> NonEmpty a -> ([a], [a]) #

The ``break` p` function is equivalent to ``span` (not . p)`.

filter :: (a -> Bool) -> NonEmpty a -> [a] #

``filter` p xs` removes any elements from `xs` that do not satisfy `p`.

partition :: (a -> Bool) -> NonEmpty a -> ([a], [a]) #

The `partition` function takes a predicate `p` and a stream `xs`, and returns a pair of lists. The first list corresponds to the elements of `xs` for which `p` holds; the second corresponds to the elements of `xs` for which `p` does not hold.

    'partition' p xs = ('filter' p xs, 'filter' (not . p) xs)

group :: (Foldable f, Eq a) => f a -> [NonEmpty a] #

The `group` function takes a stream and returns a list of streams such that flattening the resulting list is equal to the argument. Moreover, each stream in the resulting list contains only equal elements, and consecutive equal elements of the input end up in the same stream of the output list. For example, in list notation:

    >>> group "Mississippi"
    ["M", "i", "ss", "i", "ss", "i", "pp", "i"]

groupBy :: Foldable f => (a -> a -> Bool) -> f a -> [NonEmpty a] #

`groupBy` operates like `group`, but uses the provided equality predicate instead of `==`.

groupWith :: (Foldable f, Eq b) => (a -> b) -> f a -> [NonEmpty a] #

`groupWith` operates like `group`, but uses the provided projection when comparing for equality

groupAllWith :: Ord b => (a -> b) -> [a] -> [NonEmpty a] #

`groupAllWith` operates like `groupWith`, but sorts the list first so that each equivalence class has, at most, one list in the output

group1 :: Eq a => NonEmpty a -> NonEmpty (NonEmpty a) #

`group1` operates like `group`, but uses the knowledge that its input is non-empty to produce guaranteed non-empty output.

groupBy1 :: (a -> a -> Bool) -> NonEmpty a -> NonEmpty (NonEmpty a) #

`groupBy1` is to `group1` as `groupBy` is to `group`.

groupWith1 :: Eq b => (a -> b) -> NonEmpty a -> NonEmpty (NonEmpty a) #

`groupWith1` is to `group1` as `groupWith` is to `group`

groupAllWith1 :: Ord b => (a -> b) -> NonEmpty a -> NonEmpty (NonEmpty a) #

`groupAllWith1` is to `groupWith1` as `groupAllWith` is to `groupWith`

# Sublist predicates

isPrefixOf :: Eq a => [a] -> NonEmpty a -> Bool #

The `isPrefixOf` function returns `True` if the first argument is a prefix of the second.

# Set-like operations

nub :: Eq a => NonEmpty a -> NonEmpty a #

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 inequality test.

nubBy :: (a -> a -> Bool) -> NonEmpty a -> NonEmpty a #

The `nubBy` function behaves just like `nub`, except it uses a user-supplied equality predicate instead of the overloaded `==` function.

# Zipping and unzipping streams

zip :: NonEmpty a -> NonEmpty b -> NonEmpty (a, b) #

The `zip` function takes two streams and returns a stream of corresponding pairs.

zipWith :: (a -> b -> c) -> NonEmpty a -> NonEmpty b -> NonEmpty c #

The `zipWith` function generalizes `zip`. Rather than tupling the elements, the elements are combined using the function passed as the first argument.

unzip :: Functor f => f (a, b) -> (f a, f b) #

The `unzip` function is the inverse of the `zip` function.

# Converting to and from a list

nonEmpty :: [a] -> Maybe (NonEmpty a) #

`nonEmpty` efficiently turns a normal list into a `NonEmpty` stream, producing `Nothing` if the input is empty.

toList :: NonEmpty a -> [a] #

Convert a stream to a normal list efficiently.

xor :: NonEmpty Bool -> Bool #

Compute n-ary logic exclusive OR operation on `NonEmpty` list.