    {-# LANGUAGE CPP #-}
    {-# LANGUAGE BangPatterns #-}
    {-# LANGUAGE PatternGuards #-}
    #ifdef __GLASGOW_HASKELL__
    {-# LANGUAGE DeriveLift #-}
    {-# LANGUAGE MagicHash #-}
    {-# LANGUAGE StandaloneDeriving #-}
    {-# LANGUAGE TypeFamilies #-}
    #endif
    #if !defined(TESTING) && defined(__GLASGOW_HASKELL__)
    {-# LANGUAGE Trustworthy #-}
    #endif

    {-# OPTIONS_HADDOCK not-home #-}

    #include "containers.h"

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Data.IntSet.Internal
    -- Copyright   :  (c) Daan Leijen 2002
    --                (c) Joachim Breitner 2011
    -- License     :  BSD-style
    -- Maintainer  :  libraries@haskell.org
    -- Portability :  portable
    --
    -- = WARNING
    --
    -- This module is considered __internal__.
    --
    -- The Package Versioning Policy __does not apply__.
    --
    -- The contents of this module may change __in any way whatsoever__
    -- and __without any warning__ between minor versions of this package.
    --
    -- Authors importing this module are expected to track development
    -- closely.
    --
    -- = Description
    --
    -- An efficient implementation of integer sets.
    --
    -- These modules are intended to be imported qualified, to avoid name
    -- clashes with Prelude functions, e.g.
    --
    -- >  import Data.IntSet (IntSet)
    -- >  import qualified Data.IntSet as IntSet
    --
    -- The implementation is based on /big-endian patricia trees/.  This data
    -- structure performs especially well on binary operations like 'union'
    -- and 'intersection'.  However, my benchmarks show that it is also
    -- (much) faster on insertions and deletions when compared to a generic
    -- size-balanced set implementation (see "Data.Set").
    --
    --    * Chris Okasaki and Andy Gill,  \"/Fast Mergeable Integer Maps/\",
    --      Workshop on ML, September 1998, pages 77-86,
    --      <http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.37.5452>
    --
    --    * D.R. Morrison, \"/PATRICIA -- Practical Algorithm To Retrieve Information Coded In Alphanumeric/\",
    --      Journal of the ACM, 15(4), October 1968, pages 514-534.
    --
    -- Additionally, this implementation places bitmaps in the leaves of the tree.
    -- Their size is the natural size of a machine word (32 or 64 bits) and greatly
    -- reduce memory footprint and execution times for dense sets, e.g. sets where
    -- it is likely that many values lie close to each other. The asymptotics are
    -- not affected by this optimization.
    --
    -- Many operations have a worst-case complexity of \(O(\min(n,W))\).
    -- This means that the operation can become linear in the number of
    -- elements with a maximum of \(W\) -- the number of bits in an 'Int'
    -- (32 or 64).
    --
    -- @since 0.5.9
    -----------------------------------------------------------------------------

    -- [Note: INLINE bit fiddling]
    -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    -- It is essential that the bit fiddling functions like mask, zero, branchMask
    -- etc are inlined. If they do not, the memory allocation skyrockets. The GHC
    -- usually gets it right, but it is disastrous if it does not. Therefore we
    -- explicitly mark these functions INLINE.

    -- [Note: Local 'go' functions and capturing]
    -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    -- Care must be taken when using 'go' function which captures an argument.
    -- Sometimes (for example when the argument is passed to a data constructor,
    -- as in insert), GHC heap-allocates more than necessary. Therefore C-- code
    -- must be checked for increased allocation when creating and modifying such
    -- functions.

    -- [Note: Order of constructors]
    -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    -- The order of constructors of IntSet matters when considering performance.
    -- Currently in GHC 7.0, when type has 3 constructors, they are matched from
    -- the first to the last -- the best performance is achieved when the
    -- constructors are ordered by frequency.
    -- On GHC 7.0, reordering constructors from Nil | Tip | Bin to Bin | Tip | Nil
    -- improves the benchmark by circa 10%.

    module Data.IntSet.Internal (
        -- * Set type
          IntSet(..), Key -- instance Eq,Show
        , Prefix, Mask, BitMap

        -- * Operators
        , (\\)

        -- * Query
        , null
        , size
        , member
        , notMember
        , lookupLT
        , lookupGT
        , lookupLE
        , lookupGE
        , isSubsetOf
        , isProperSubsetOf
        , disjoint

        -- * Construction
        , empty
        , singleton
        , insert
        , delete
        , alterF

        -- * Combine
        , union
        , unions
        , difference
        , intersection

        -- * Filter
        , filter
        , partition

        , takeWhileAntitone
        , dropWhileAntitone
        , spanAntitone

        , split
        , splitMember
        , splitRoot

        -- * Map
        , map
        , mapMonotonic

        -- * Folds
        , foldr
        , foldl
        -- ** Strict folds
        , foldr'
        , foldl'
        -- ** Legacy folds
        , fold

        -- * Min\/Max
        , findMin
        , findMax
        , deleteMin
        , deleteMax
        , deleteFindMin
        , deleteFindMax
        , maxView
        , minView

        -- * Conversion

        -- ** List
        , elems
        , toList
        , fromList

        -- ** Ordered list
        , toAscList
        , toDescList
        , fromAscList
        , fromDistinctAscList

        -- * Debugging
        , showTree
        , showTreeWith

        -- * Internals
        , match
        , suffixBitMask
        , prefixBitMask
        , bitmapOf
        , zero
        ) where

    import Control.Applicative (Const(..))
    import Control.DeepSeq (NFData(rnf))
    import Data.Bits
    import qualified Data.List as List
    import Data.Maybe (fromMaybe)
    import Data.Semigroup (Semigroup(stimes))
    #if !(MIN_VERSION_base(4,11,0))
    import Data.Semigroup (Semigroup((<>)))
    #endif
    import Data.Semigroup (stimesIdempotentMonoid)
    import Utils.Containers.Internal.Prelude hiding
      (filter, foldr, foldl, null, map)
    import Prelude ()

    import Utils.Containers.Internal.BitUtil
    import Utils.Containers.Internal.StrictPair

    #if __GLASGOW_HASKELL__
    import Data.Data (Data(..), Constr, mkConstr, constrIndex, DataType, mkDataType)
    import qualified Data.Data
    import Text.Read
    #endif

    #if __GLASGOW_HASKELL__
    import qualified GHC.Exts
    #  if !(WORD_SIZE_IN_BITS==64)
    import qualified GHC.Int
    #  endif
    import Language.Haskell.TH.Syntax (Lift)
    -- See Note [ Template Haskell Dependencies ]
    import Language.Haskell.TH ()
    #endif

    import qualified Data.Foldable as Foldable
    import Data.Functor.Identity (Identity(..))

    infixl 9 \\{-This comment teaches CPP correct behaviour -}

    -- A "Nat" is a natural machine word (an unsigned Int)
    type Nat = Word

    natFromInt :: Int -> Nat
    natFromInt :: Mask -> Word
    natFromInt Mask
    i = Mask -> Word
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral Mask
    i
    {-# INLINE natFromInt #-}

    intFromNat :: Nat -> Int
    intFromNat :: Word -> Mask
    intFromNat Word
    w = Word -> Mask
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral Word
    w
    {-# INLINE intFromNat #-}

    {--------------------------------------------------------------------
      Operators
    --------------------------------------------------------------------}
    -- | \(O(n+m)\). See 'difference'.
    (\\) :: IntSet -> IntSet -> IntSet
    IntSet
    m1 \\ :: IntSet -> IntSet -> IntSet
    \\ IntSet
    m2 = IntSet -> IntSet -> IntSet
    difference IntSet
    m1 IntSet
    m2

    {--------------------------------------------------------------------
      Types
    --------------------------------------------------------------------}

    -- | A set of integers.

    -- See Note: Order of constructors
    data IntSet = Bin {-# UNPACK #-} !Prefix {-# UNPACK #-} !Mask !IntSet !IntSet
    -- Invariant: Nil is never found as a child of Bin.
    -- Invariant: The Mask is a power of 2.  It is the largest bit position at which
    --            two elements of the set differ.
    -- Invariant: Prefix is the common high-order bits that all elements share to
    --            the left of the Mask bit.
    -- Invariant: In Bin prefix mask left right, left consists of the elements that
    --            don't have the mask bit set; right is all the elements that do.
                | Tip {-# UNPACK #-} !Prefix {-# UNPACK #-} !BitMap
    -- Invariant: The Prefix is zero for the last 5 (on 32 bit arches) or 6 bits
    --            (on 64 bit arches). The values of the set represented by a tip
    --            are the prefix plus the indices of the set bits in the bit map.
                | Nil

    -- A number stored in a set is stored as
    -- * Prefix (all but last 5-6 bits) and
    -- * BitMap (last 5-6 bits stored as a bitmask)
    --   Last 5-6 bits are called a Suffix.

    type Prefix = Int
    type Mask   = Int
    type BitMap = Word
    type Key    = Int

    #ifdef __GLASGOW_HASKELL__
    -- | @since 0.6.6
    deriving instance Lift IntSet
    #endif

    instance Monoid IntSet where
        mempty :: IntSet
    mempty  = IntSet
    empty
        mconcat :: [IntSet] -> IntSet
    mconcat = [IntSet] -> IntSet
    forall (f :: * -> *). Foldable f => f IntSet -> IntSet
    unions
        mappend :: IntSet -> IntSet -> IntSet
    mappend = IntSet -> IntSet -> IntSet
    forall a. Semigroup a => a -> a -> a
    (<>)

    -- | @since 0.5.7
    instance Semigroup IntSet where
        <> :: IntSet -> IntSet -> IntSet
    (<>)    = IntSet -> IntSet -> IntSet
    union
        stimes :: forall b. Integral b => b -> IntSet -> IntSet
    stimes  = b -> IntSet -> IntSet
    forall b a. (Integral b, Monoid a) => b -> a -> a
    stimesIdempotentMonoid

    #if __GLASGOW_HASKELL__

    {--------------------------------------------------------------------
      A Data instance
    --------------------------------------------------------------------}

    -- This instance preserves data abstraction at the cost of inefficiency.
    -- We provide limited reflection services for the sake of data abstraction.

    instance Data IntSet where
      gfoldl :: forall (c :: * -> *).
    (forall d b. Data d => c (d -> b) -> d -> c b)
    -> (forall g. g -> c g) -> IntSet -> c IntSet
    gfoldl forall d b. Data d => c (d -> b) -> d -> c b
    f forall g. g -> c g
    z IntSet
    is = ([Mask] -> IntSet) -> c ([Mask] -> IntSet)
    forall g. g -> c g
    z [Mask] -> IntSet
    fromList c ([Mask] -> IntSet) -> [Mask] -> c IntSet
    forall d b. Data d => c (d -> b) -> d -> c b
    `f` (IntSet -> [Mask]
    toList IntSet
    is)
      toConstr :: IntSet -> Constr
    toConstr IntSet
    _     = Constr
    fromListConstr
      gunfold :: forall (c :: * -> *).
    (forall b r. Data b => c (b -> r) -> c r)
    -> (forall r. r -> c r) -> Constr -> c IntSet
    gunfold forall b r. Data b => c (b -> r) -> c r
    k forall r. r -> c r
    z Constr
    c  = case Constr -> Mask
    constrIndex Constr
    c of
        Mask
    1 -> c ([Mask] -> IntSet) -> c IntSet
    forall b r. Data b => c (b -> r) -> c r
    k (([Mask] -> IntSet) -> c ([Mask] -> IntSet)
    forall r. r -> c r
    z [Mask] -> IntSet
    fromList)
        Mask
    _ -> [Char] -> c IntSet
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "gunfold"
      dataTypeOf :: IntSet -> DataType
    dataTypeOf IntSet
    _   = DataType
    intSetDataType

    fromListConstr :: Constr
    fromListConstr :: Constr
    fromListConstr = DataType -> [Char] -> [[Char]] -> Fixity -> Constr
    mkConstr DataType
    intSetDataType [Char]
    "fromList" [] Fixity
    Data.Data.Prefix

    intSetDataType :: DataType
    intSetDataType :: DataType
    intSetDataType = [Char] -> [Constr] -> DataType
    mkDataType [Char]
    "Data.IntSet.Internal.IntSet" [Constr
    fromListConstr]

    #endif

    {--------------------------------------------------------------------
      Query
    --------------------------------------------------------------------}
    -- | \(O(1)\). Is the set empty?
    null :: IntSet -> Bool
    null :: IntSet -> Bool
    null IntSet
    Nil = Bool
    True
    null IntSet
    _   = Bool
    False
    {-# INLINE null #-}

    -- | \(O(n)\). Cardinality of the set.
    size :: IntSet -> Int
    size :: IntSet -> Mask
    size = Mask -> IntSet -> Mask
    go Mask
    0
      where
        go :: Mask -> IntSet -> Mask
    go !Mask
    acc (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    r) = Mask -> IntSet -> Mask
    go (Mask -> IntSet -> Mask
    go Mask
    acc IntSet
    l) IntSet
    r
        go Mask
    acc (Tip Mask
    _ Word
    bm) = Mask
    acc Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Mask -> Word -> Mask
    bitcount Mask
    0 Word
    bm
        go Mask
    acc IntSet
    Nil = Mask
    acc

    -- | \(O(\min(n,W))\). Is the value a member of the set?

    -- See Note: Local 'go' functions and capturing.
    member :: Key -> IntSet -> Bool
    member :: Mask -> IntSet -> Bool
    member !Mask
    x = IntSet -> Bool
    go
      where
        go :: IntSet -> Bool
    go (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
          | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x Mask
    p Mask
    m = Bool
    False
          | Mask -> Mask -> Bool
    zero Mask
    x Mask
    m      = IntSet -> Bool
    go IntSet
    l
          | Bool
    otherwise     = IntSet -> Bool
    go IntSet
    r
        go (Tip Mask
    y Word
    bm) = Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    y Bool -> Bool -> Bool
    && Mask -> Word
    bitmapOf Mask
    x Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0
        go IntSet
    Nil = Bool
    False

    -- | \(O(\min(n,W))\). Is the element not in the set?
    notMember :: Key -> IntSet -> Bool
    notMember :: Mask -> IntSet -> Bool
    notMember Mask
    k = Bool -> Bool
    not (Bool -> Bool) -> (IntSet -> Bool) -> IntSet -> Bool
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Mask -> IntSet -> Bool
    member Mask
    k

    -- | \(O(\min(n,W))\). Find largest element smaller than the given one.
    --
    -- > lookupLT 3 (fromList [3, 5]) == Nothing
    -- > lookupLT 5 (fromList [3, 5]) == Just 3

    -- See Note: Local 'go' functions and capturing.
    lookupLT :: Key -> IntSet -> Maybe Key
    lookupLT :: Mask -> IntSet -> Maybe Mask
    lookupLT !Mask
    x IntSet
    t = case IntSet
    t of
        Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0 then IntSet -> IntSet -> Maybe Mask
    go IntSet
    r IntSet
    l else IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    r
        IntSet
    _ -> IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    t
      where
        go :: IntSet -> IntSet -> Maybe Mask
    go IntSet
    def (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x Mask
    p Mask
    m = if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def else IntSet -> Maybe Mask
    unsafeFindMax IntSet
    r
                             | Mask -> Mask -> Bool
    zero Mask
    x Mask
    m  = IntSet -> IntSet -> Maybe Mask
    go IntSet
    def IntSet
    l
                             | Bool
    otherwise = IntSet -> IntSet -> Maybe Mask
    go IntSet
    l IntSet
    r
        go IntSet
    def (Tip Mask
    kx Word
    bm) | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    > Mask
    kx = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    bm
                           | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx Bool -> Bool -> Bool
    && Word
    maskLT Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    maskLT
                           | Bool
    otherwise = IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def
                           where maskLT :: Word
    maskLT = (Mask -> Word
    bitmapOf Mask
    x Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm
        go IntSet
    def IntSet
    Nil = IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def

    -- | \(O(\min(n,W))\). Find smallest element greater than the given one.
    --
    -- > lookupGT 4 (fromList [3, 5]) == Just 5
    -- > lookupGT 5 (fromList [3, 5]) == Nothing

    -- See Note: Local 'go' functions and capturing.
    lookupGT :: Key -> IntSet -> Maybe Key
    lookupGT :: Mask -> IntSet -> Maybe Mask
    lookupGT !Mask
    x IntSet
    t = case IntSet
    t of
        Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0 then IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    l else IntSet -> IntSet -> Maybe Mask
    go IntSet
    l IntSet
    r
        IntSet
    _ -> IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    t
      where
        go :: IntSet -> IntSet -> Maybe Mask
    go IntSet
    def (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x Mask
    p Mask
    m = if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then IntSet -> Maybe Mask
    unsafeFindMin IntSet
    l else IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def
                             | Mask -> Mask -> Bool
    zero Mask
    x Mask
    m  = IntSet -> IntSet -> Maybe Mask
    go IntSet
    r IntSet
    l
                             | Bool
    otherwise = IntSet -> IntSet -> Maybe Mask
    go IntSet
    def IntSet
    r
        go IntSet
    def (Tip Mask
    kx Word
    bm) | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    kx = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    bm
                           | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx Bool -> Bool -> Bool
    && Word
    maskGT Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    maskGT
                           | Bool
    otherwise = IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def
                           where maskGT :: Word
    maskGT = (- ((Mask -> Word
    bitmapOf Mask
    x) Word -> Mask -> Word
    `shiftLL` Mask
    1)) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm
        go IntSet
    def IntSet
    Nil = IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def

    -- | \(O(\min(n,W))\). Find largest element smaller or equal to the given one.
    --
    -- > lookupLE 2 (fromList [3, 5]) == Nothing
    -- > lookupLE 4 (fromList [3, 5]) == Just 3
    -- > lookupLE 5 (fromList [3, 5]) == Just 5

    -- See Note: Local 'go' functions and capturing.
    lookupLE :: Key -> IntSet -> Maybe Key
    lookupLE :: Mask -> IntSet -> Maybe Mask
    lookupLE !Mask
    x IntSet
    t = case IntSet
    t of
        Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0 then IntSet -> IntSet -> Maybe Mask
    go IntSet
    r IntSet
    l else IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    r
        IntSet
    _ -> IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    t
      where
        go :: IntSet -> IntSet -> Maybe Mask
    go IntSet
    def (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x Mask
    p Mask
    m = if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def else IntSet -> Maybe Mask
    unsafeFindMax IntSet
    r
                             | Mask -> Mask -> Bool
    zero Mask
    x Mask
    m  = IntSet -> IntSet -> Maybe Mask
    go IntSet
    def IntSet
    l
                             | Bool
    otherwise = IntSet -> IntSet -> Maybe Mask
    go IntSet
    l IntSet
    r
        go IntSet
    def (Tip Mask
    kx Word
    bm) | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    > Mask
    kx = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    bm
                           | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx Bool -> Bool -> Bool
    && Word
    maskLE Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    maskLE
                           | Bool
    otherwise = IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def
                           where maskLE :: Word
    maskLE = (((Mask -> Word
    bitmapOf Mask
    x) Word -> Mask -> Word
    `shiftLL` Mask
    1) Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm
        go IntSet
    def IntSet
    Nil = IntSet -> Maybe Mask
    unsafeFindMax IntSet
    def

    -- | \(O(\min(n,W))\). Find smallest element greater or equal to the given one.
    --
    -- > lookupGE 3 (fromList [3, 5]) == Just 3
    -- > lookupGE 4 (fromList [3, 5]) == Just 5
    -- > lookupGE 6 (fromList [3, 5]) == Nothing

    -- See Note: Local 'go' functions and capturing.
    lookupGE :: Key -> IntSet -> Maybe Key
    lookupGE :: Mask -> IntSet -> Maybe Mask
    lookupGE !Mask
    x IntSet
    t = case IntSet
    t of
        Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0 then IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    l else IntSet -> IntSet -> Maybe Mask
    go IntSet
    l IntSet
    r
        IntSet
    _ -> IntSet -> IntSet -> Maybe Mask
    go IntSet
    Nil IntSet
    t
      where
        go :: IntSet -> IntSet -> Maybe Mask
    go IntSet
    def (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x Mask
    p Mask
    m = if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then IntSet -> Maybe Mask
    unsafeFindMin IntSet
    l else IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def
                             | Mask -> Mask -> Bool
    zero Mask
    x Mask
    m  = IntSet -> IntSet -> Maybe Mask
    go IntSet
    r IntSet
    l
                             | Bool
    otherwise = IntSet -> IntSet -> Maybe Mask
    go IntSet
    def IntSet
    r
        go IntSet
    def (Tip Mask
    kx Word
    bm) | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    kx = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    bm
                           | Mask -> Mask
    prefixOf Mask
    x Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx Bool -> Bool -> Bool
    && Word
    maskGE Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    maskGE
                           | Bool
    otherwise = IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def
                           where maskGE :: Word
    maskGE = (- (Mask -> Word
    bitmapOf Mask
    x)) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm
        go IntSet
    def IntSet
    Nil = IntSet -> Maybe Mask
    unsafeFindMin IntSet
    def

    -- Helper function for lookupGE and lookupGT. It assumes that if a Bin node is
    -- given, it has m > 0.
    unsafeFindMin :: IntSet -> Maybe Key
    unsafeFindMin :: IntSet -> Maybe Mask
    unsafeFindMin IntSet
    Nil = Maybe Mask
    forall a. Maybe a
    Nothing
    unsafeFindMin (Tip Mask
    kx Word
    bm) = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    bm
    unsafeFindMin (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    _) = IntSet -> Maybe Mask
    unsafeFindMin IntSet
    l

    -- Helper function for lookupLE and lookupLT. It assumes that if a Bin node is
    -- given, it has m > 0.
    unsafeFindMax :: IntSet -> Maybe Key
    unsafeFindMax :: IntSet -> Maybe Mask
    unsafeFindMax IntSet
    Nil = Maybe Mask
    forall a. Maybe a
    Nothing
    unsafeFindMax (Tip Mask
    kx Word
    bm) = Mask -> Maybe Mask
    forall a. a -> Maybe a
    Just (Mask -> Maybe Mask) -> Mask -> Maybe Mask
    forall a b. (a -> b) -> a -> b
    $ Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    bm
    unsafeFindMax (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    r) = IntSet -> Maybe Mask
    unsafeFindMax IntSet
    r

    {--------------------------------------------------------------------
      Construction
    --------------------------------------------------------------------}
    -- | \(O(1)\). The empty set.
    empty :: IntSet
    empty :: IntSet
    empty
      = IntSet
    Nil
    {-# INLINE empty #-}

    -- | \(O(1)\). A set of one element.
    singleton :: Key -> IntSet
    singleton :: Mask -> IntSet
    singleton Mask
    x
      = Mask -> Word -> IntSet
    Tip (Mask -> Mask
    prefixOf Mask
    x) (Mask -> Word
    bitmapOf Mask
    x)
    {-# INLINE singleton #-}

    {--------------------------------------------------------------------
      Insert
    --------------------------------------------------------------------}
    -- | \(O(\min(n,W))\). Add a value to the set. There is no left- or right bias for
    -- IntSets.
    insert :: Key -> IntSet -> IntSet
    insert :: Mask -> IntSet -> IntSet
    insert !Mask
    x = Mask -> Word -> IntSet -> IntSet
    insertBM (Mask -> Mask
    prefixOf Mask
    x) (Mask -> Word
    bitmapOf Mask
    x)

    -- Helper function for insert and union.
    insertBM :: Prefix -> BitMap -> IntSet -> IntSet
    insertBM :: Mask -> Word -> IntSet -> IntSet
    insertBM !Mask
    kx !Word
    bm t :: IntSet
    t@(Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
      | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx Mask
    p Mask
    m = Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    kx (Mask -> Word -> IntSet
    Tip Mask
    kx Word
    bm) Mask
    p IntSet
    t
      | Mask -> Mask -> Bool
    zero Mask
    kx Mask
    m      = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p Mask
    m (Mask -> Word -> IntSet -> IntSet
    insertBM Mask
    kx Word
    bm IntSet
    l) IntSet
    r
      | Bool
    otherwise      = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p Mask
    m IntSet
    l (Mask -> Word -> IntSet -> IntSet
    insertBM Mask
    kx Word
    bm IntSet
    r)
    insertBM Mask
    kx Word
    bm t :: IntSet
    t@(Tip Mask
    kx' Word
    bm')
      | Mask
    kx' Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx = Mask -> Word -> IntSet
    Tip Mask
    kx' (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. Word
    bm')
      | Bool
    otherwise = Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    kx (Mask -> Word -> IntSet
    Tip Mask
    kx Word
    bm) Mask
    kx' IntSet
    t
    insertBM Mask
    kx Word
    bm IntSet
    Nil = Mask -> Word -> IntSet
    Tip Mask
    kx Word
    bm

    -- | \(O(\min(n,W))\). Delete a value in the set. Returns the
    -- original set when the value was not present.
    delete :: Key -> IntSet -> IntSet
    delete :: Mask -> IntSet -> IntSet
    delete !Mask
    x = Mask -> Word -> IntSet -> IntSet
    deleteBM (Mask -> Mask
    prefixOf Mask
    x) (Mask -> Word
    bitmapOf Mask
    x)

    -- Deletes all values mentioned in the BitMap from the set.
    -- Helper function for delete and difference.
    deleteBM :: Prefix -> BitMap -> IntSet -> IntSet
    deleteBM :: Mask -> Word -> IntSet -> IntSet
    deleteBM !Mask
    kx !Word
    bm t :: IntSet
    t@(Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
      | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx Mask
    p Mask
    m = IntSet
    t
      | Mask -> Mask -> Bool
    zero Mask
    kx Mask
    m      = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m (Mask -> Word -> IntSet -> IntSet
    deleteBM Mask
    kx Word
    bm IntSet
    l) IntSet
    r
      | Bool
    otherwise      = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l (Mask -> Word -> IntSet -> IntSet
    deleteBM Mask
    kx Word
    bm IntSet
    r)
    deleteBM Mask
    kx Word
    bm t :: IntSet
    t@(Tip Mask
    kx' Word
    bm')
      | Mask
    kx' Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx = Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm' Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement Word
    bm)
      | Bool
    otherwise = IntSet
    t
    deleteBM Mask
    _ Word
    _ IntSet
    Nil = IntSet
    Nil

    -- | \(O(\min(n,W))\). @('alterF' f x s)@ can delete or insert @x@ in @s@ depending
    -- on whether it is already present in @s@.
    --
    -- In short:
    --
    -- @
    -- 'member' x \<$\> 'alterF' f x s = f ('member' x s)
    -- @
    --
    -- Note: 'alterF' is a variant of the @at@ combinator from "Control.Lens.At".
    --
    -- @since 0.6.3.1
    alterF :: Functor f => (Bool -> f Bool) -> Key -> IntSet -> f IntSet
    alterF :: forall (f :: * -> *).
    Functor f =>
    (Bool -> f Bool) -> Mask -> IntSet -> f IntSet
    alterF Bool -> f Bool
    f Mask
    k IntSet
    s = (Bool -> IntSet) -> f Bool -> f IntSet
    forall a b. (a -> b) -> f a -> f b
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap Bool -> IntSet
    choose (Bool -> f Bool
    f Bool
    member_)
      where
        member_ :: Bool
    member_ = Mask -> IntSet -> Bool
    member Mask
    k IntSet
    s

        (IntSet
    inserted, IntSet
    deleted)
          | Bool
    member_   = (IntSet
    s         , Mask -> IntSet -> IntSet
    delete Mask
    k IntSet
    s)
          | Bool
    otherwise = (Mask -> IntSet -> IntSet
    insert Mask
    k IntSet
    s, IntSet
    s         )

        choose :: Bool -> IntSet
    choose Bool
    True  = IntSet
    inserted
        choose Bool
    False = IntSet
    deleted
    #ifndef __GLASGOW_HASKELL__
    {-# INLINE alterF #-}
    #else
    {-# INLINABLE [2] alterF #-}

    {-# RULES
    "alterF/Const" forall k (f :: Bool -> Const a Bool) . alterF f k = \s -> Const . getConst . f $ member k s
     #-}
    #endif

    {-# SPECIALIZE alterF :: (Bool -> Identity Bool) -> Key -> IntSet -> Identity IntSet #-}

    {--------------------------------------------------------------------
      Union
    --------------------------------------------------------------------}
    -- | The union of a list of sets.
    unions :: Foldable f => f IntSet -> IntSet
    unions :: forall (f :: * -> *). Foldable f => f IntSet -> IntSet
    unions f IntSet
    xs
      = (IntSet -> IntSet -> IntSet) -> IntSet -> f IntSet -> IntSet
    forall b a. (b -> a -> b) -> b -> f a -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    Foldable.foldl' IntSet -> IntSet -> IntSet
    union IntSet
    empty f IntSet
    xs

    -- | \(O(n+m)\). The union of two sets.
    union :: IntSet -> IntSet -> IntSet
    union :: IntSet -> IntSet -> IntSet
    union t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) t2 :: IntSet
    t2@(Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = IntSet
    union1
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = IntSet
    union2
      | Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2       = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p1 Mask
    m1 (IntSet -> IntSet -> IntSet
    union IntSet
    l1 IntSet
    l2) (IntSet -> IntSet -> IntSet
    union IntSet
    r1 IntSet
    r2)
      | Bool
    otherwise      = Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    p1 IntSet
    t1 Mask
    p2 IntSet
    t2
      where
        union1 :: IntSet
    union1  | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p2 Mask
    p1 Mask
    m1  = Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    p1 IntSet
    t1 Mask
    p2 IntSet
    t2
                | Mask -> Mask -> Bool
    zero Mask
    p2 Mask
    m1        = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p1 Mask
    m1 (IntSet -> IntSet -> IntSet
    union IntSet
    l1 IntSet
    t2) IntSet
    r1
                | Bool
    otherwise         = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p1 Mask
    m1 IntSet
    l1 (IntSet -> IntSet -> IntSet
    union IntSet
    r1 IntSet
    t2)

        union2 :: IntSet
    union2  | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p1 Mask
    p2 Mask
    m2  = Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    p1 IntSet
    t1 Mask
    p2 IntSet
    t2
                | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2        = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p2 Mask
    m2 (IntSet -> IntSet -> IntSet
    union IntSet
    t1 IntSet
    l2) IntSet
    r2
                | Bool
    otherwise         = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p2 Mask
    m2 IntSet
    l2 (IntSet -> IntSet -> IntSet
    union IntSet
    t1 IntSet
    r2)

    union t :: IntSet
    t@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) (Tip Mask
    kx Word
    bm) = Mask -> Word -> IntSet -> IntSet
    insertBM Mask
    kx Word
    bm IntSet
    t
    union t :: IntSet
    t@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    Nil = IntSet
    t
    union (Tip Mask
    kx Word
    bm) IntSet
    t = Mask -> Word -> IntSet -> IntSet
    insertBM Mask
    kx Word
    bm IntSet
    t
    union IntSet
    Nil IntSet
    t = IntSet
    t

    {--------------------------------------------------------------------
      Difference
    --------------------------------------------------------------------}
    -- | \(O(n+m)\). Difference between two sets.
    difference :: IntSet -> IntSet -> IntSet
    difference :: IntSet -> IntSet -> IntSet
    difference t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) t2 :: IntSet
    t2@(Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = IntSet
    difference1
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = IntSet
    difference2
      | Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2       = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p1 Mask
    m1 (IntSet -> IntSet -> IntSet
    difference IntSet
    l1 IntSet
    l2) (IntSet -> IntSet -> IntSet
    difference IntSet
    r1 IntSet
    r2)
      | Bool
    otherwise      = IntSet
    t1
      where
        difference1 :: IntSet
    difference1 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p2 Mask
    p1 Mask
    m1  = IntSet
    t1
                    | Mask -> Mask -> Bool
    zero Mask
    p2 Mask
    m1        = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p1 Mask
    m1 (IntSet -> IntSet -> IntSet
    difference IntSet
    l1 IntSet
    t2) IntSet
    r1
                    | Bool
    otherwise         = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p1 Mask
    m1 IntSet
    l1 (IntSet -> IntSet -> IntSet
    difference IntSet
    r1 IntSet
    t2)

        difference2 :: IntSet
    difference2 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p1 Mask
    p2 Mask
    m2  = IntSet
    t1
                    | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2        = IntSet -> IntSet -> IntSet
    difference IntSet
    t1 IntSet
    l2
                    | Bool
    otherwise         = IntSet -> IntSet -> IntSet
    difference IntSet
    t1 IntSet
    r2

    difference t :: IntSet
    t@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) (Tip Mask
    kx Word
    bm) = Mask -> Word -> IntSet -> IntSet
    deleteBM Mask
    kx Word
    bm IntSet
    t
    difference t :: IntSet
    t@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    Nil = IntSet
    t

    difference t1 :: IntSet
    t1@(Tip Mask
    kx Word
    bm) IntSet
    t2 = IntSet -> IntSet
    differenceTip IntSet
    t2
      where differenceTip :: IntSet -> IntSet
    differenceTip (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx Mask
    p2 Mask
    m2 = IntSet
    t1
                                            | Mask -> Mask -> Bool
    zero Mask
    kx Mask
    m2 = IntSet -> IntSet
    differenceTip IntSet
    l2
                                            | Bool
    otherwise = IntSet -> IntSet
    differenceTip IntSet
    r2
            differenceTip (Tip Mask
    kx2 Word
    bm2) | Mask
    kx Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 = Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement Word
    bm2)
                                        | Bool
    otherwise = IntSet
    t1
            differenceTip IntSet
    Nil = IntSet
    t1

    difference IntSet
    Nil IntSet
    _     = IntSet
    Nil

    {--------------------------------------------------------------------
      Intersection
    --------------------------------------------------------------------}
    -- | \(O(n+m)\). The intersection of two sets.
    intersection :: IntSet -> IntSet -> IntSet
    intersection :: IntSet -> IntSet -> IntSet
    intersection t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) t2 :: IntSet
    t2@(Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = IntSet
    intersection1
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = IntSet
    intersection2
      | Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2       = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p1 Mask
    m1 (IntSet -> IntSet -> IntSet
    intersection IntSet
    l1 IntSet
    l2) (IntSet -> IntSet -> IntSet
    intersection IntSet
    r1 IntSet
    r2)
      | Bool
    otherwise      = IntSet
    Nil
      where
        intersection1 :: IntSet
    intersection1 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p2 Mask
    p1 Mask
    m1  = IntSet
    Nil
                      | Mask -> Mask -> Bool
    zero Mask
    p2 Mask
    m1        = IntSet -> IntSet -> IntSet
    intersection IntSet
    l1 IntSet
    t2
                      | Bool
    otherwise         = IntSet -> IntSet -> IntSet
    intersection IntSet
    r1 IntSet
    t2

        intersection2 :: IntSet
    intersection2 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p1 Mask
    p2 Mask
    m2  = IntSet
    Nil
                      | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2        = IntSet -> IntSet -> IntSet
    intersection IntSet
    t1 IntSet
    l2
                      | Bool
    otherwise         = IntSet -> IntSet -> IntSet
    intersection IntSet
    t1 IntSet
    r2

    intersection t1 :: IntSet
    t1@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) (Tip Mask
    kx2 Word
    bm2) = IntSet -> IntSet
    intersectBM IntSet
    t1
      where intersectBM :: IntSet -> IntSet
    intersectBM (Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx2 Mask
    p1 Mask
    m1 = IntSet
    Nil
                                          | Mask -> Mask -> Bool
    zero Mask
    kx2 Mask
    m1       = IntSet -> IntSet
    intersectBM IntSet
    l1
                                          | Bool
    otherwise         = IntSet -> IntSet
    intersectBM IntSet
    r1
            intersectBM (Tip Mask
    kx1 Word
    bm1) | Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 = Mask -> Word -> IntSet
    tip Mask
    kx1 (Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm2)
                                      | Bool
    otherwise = IntSet
    Nil
            intersectBM IntSet
    Nil = IntSet
    Nil

    intersection (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    Nil = IntSet
    Nil

    intersection (Tip Mask
    kx1 Word
    bm1) IntSet
    t2 = IntSet -> IntSet
    intersectBM IntSet
    t2
      where intersectBM :: IntSet -> IntSet
    intersectBM (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx1 Mask
    p2 Mask
    m2 = IntSet
    Nil
                                          | Mask -> Mask -> Bool
    zero Mask
    kx1 Mask
    m2       = IntSet -> IntSet
    intersectBM IntSet
    l2
                                          | Bool
    otherwise         = IntSet -> IntSet
    intersectBM IntSet
    r2
            intersectBM (Tip Mask
    kx2 Word
    bm2) | Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 = Mask -> Word -> IntSet
    tip Mask
    kx1 (Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm2)
                                      | Bool
    otherwise = IntSet
    Nil
            intersectBM IntSet
    Nil = IntSet
    Nil

    intersection IntSet
    Nil IntSet
    _ = IntSet
    Nil

    {--------------------------------------------------------------------
      Subset
    --------------------------------------------------------------------}
    -- | \(O(n+m)\). Is this a proper subset? (ie. a subset but not equal).
    isProperSubsetOf :: IntSet -> IntSet -> Bool
    isProperSubsetOf :: IntSet -> IntSet -> Bool
    isProperSubsetOf IntSet
    t1 IntSet
    t2
      = case IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    t1 IntSet
    t2 of
          Ordering
    LT -> Bool
    True
          Ordering
    _  -> Bool
    False

    subsetCmp :: IntSet -> IntSet -> Ordering
    subsetCmp :: IntSet -> IntSet -> Ordering
    subsetCmp t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = Ordering
    GT
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = case Ordering
    subsetCmpLt of
                           Ordering
    GT -> Ordering
    GT
                           Ordering
    _  -> Ordering
    LT
      | Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2       = Ordering
    subsetCmpEq
      | Bool
    otherwise      = Ordering
    GT  -- disjoint
      where
        subsetCmpLt :: Ordering
    subsetCmpLt | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p1 Mask
    p2 Mask
    m2  = Ordering
    GT
                    | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2        = IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    t1 IntSet
    l2
                    | Bool
    otherwise         = IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    t1 IntSet
    r2
        subsetCmpEq :: Ordering
    subsetCmpEq = case (IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    l1 IntSet
    l2, IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    r1 IntSet
    r2) of
                        (Ordering
    GT,Ordering
    _ ) -> Ordering
    GT
                        (Ordering
    _ ,Ordering
    GT) -> Ordering
    GT
                        (Ordering
    EQ,Ordering
    EQ) -> Ordering
    EQ
                        (Ordering, Ordering)
    _       -> Ordering
    LT

    subsetCmp (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    _  = Ordering
    GT
    subsetCmp (Tip Mask
    kx1 Word
    bm1) (Tip Mask
    kx2 Word
    bm2)
      | Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    kx2                  = Ordering
    GT -- disjoint
      | Word
    bm1 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    bm2                  = Ordering
    EQ
      | Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement Word
    bm2 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    0 = Ordering
    LT
      | Bool
    otherwise                   = Ordering
    GT
    subsetCmp t1 :: IntSet
    t1@(Tip Mask
    kx Word
    _) (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
      | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx Mask
    p Mask
    m = Ordering
    GT
      | Mask -> Mask -> Bool
    zero Mask
    kx Mask
    m      = case IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    t1 IntSet
    l of Ordering
    GT -> Ordering
    GT ; Ordering
    _ -> Ordering
    LT
      | Bool
    otherwise      = case IntSet -> IntSet -> Ordering
    subsetCmp IntSet
    t1 IntSet
    r of Ordering
    GT -> Ordering
    GT ; Ordering
    _ -> Ordering
    LT
    subsetCmp (Tip Mask
    _ Word
    _) IntSet
    Nil = Ordering
    GT -- disjoint
    subsetCmp IntSet
    Nil IntSet
    Nil = Ordering
    EQ
    subsetCmp IntSet
    Nil IntSet
    _   = Ordering
    LT

    -- | \(O(n+m)\). Is this a subset?
    -- @(s1 \`isSubsetOf\` s2)@ tells whether @s1@ is a subset of @s2@.

    isSubsetOf :: IntSet -> IntSet -> Bool
    isSubsetOf :: IntSet -> IntSet -> Bool
    isSubsetOf t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = Bool
    False
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = Mask -> Mask -> Mask -> Bool
    match Mask
    p1 Mask
    p2 Mask
    m2 Bool -> Bool -> Bool
    && (if Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2 then IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    t1 IntSet
    l2
                                                          else IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    t1 IntSet
    r2)
      | Bool
    otherwise      = (Mask
    p1Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    ==Mask
    p2) Bool -> Bool -> Bool
    && IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    l1 IntSet
    l2 Bool -> Bool -> Bool
    && IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    r1 IntSet
    r2
    isSubsetOf (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    _  = Bool
    False
    isSubsetOf (Tip Mask
    kx1 Word
    bm1) (Tip Mask
    kx2 Word
    bm2) = Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 Bool -> Bool -> Bool
    && Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement Word
    bm2 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    0
    isSubsetOf t1 :: IntSet
    t1@(Tip Mask
    kx Word
    _) (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
      | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx Mask
    p Mask
    m = Bool
    False
      | Mask -> Mask -> Bool
    zero Mask
    kx Mask
    m      = IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    t1 IntSet
    l
      | Bool
    otherwise      = IntSet -> IntSet -> Bool
    isSubsetOf IntSet
    t1 IntSet
    r
    isSubsetOf (Tip Mask
    _ Word
    _) IntSet
    Nil = Bool
    False
    isSubsetOf IntSet
    Nil IntSet
    _         = Bool
    True

    {--------------------------------------------------------------------
      Disjoint
    --------------------------------------------------------------------}
    -- | \(O(n+m)\). Check whether two sets are disjoint (i.e. their intersection
    --   is empty).
    --
    -- > disjoint (fromList [2,4,6])   (fromList [1,3])     == True
    -- > disjoint (fromList [2,4,6,8]) (fromList [2,3,5,7]) == False
    -- > disjoint (fromList [1,2])     (fromList [1,2,3,4]) == False
    -- > disjoint (fromList [])        (fromList [])        == True
    --
    -- @since 0.5.11
    disjoint :: IntSet -> IntSet -> Bool
    disjoint :: IntSet -> IntSet -> Bool
    disjoint t1 :: IntSet
    t1@(Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) t2 :: IntSet
    t2@(Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      | Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2  = Bool
    disjoint1
      | Mask -> Mask -> Bool
    shorter Mask
    m2 Mask
    m1  = Bool
    disjoint2
      | Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2       = IntSet -> IntSet -> Bool
    disjoint IntSet
    l1 IntSet
    l2 Bool -> Bool -> Bool
    && IntSet -> IntSet -> Bool
    disjoint IntSet
    r1 IntSet
    r2
      | Bool
    otherwise      = Bool
    True
      where
        disjoint1 :: Bool
    disjoint1 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p2 Mask
    p1 Mask
    m1  = Bool
    True
                  | Mask -> Mask -> Bool
    zero Mask
    p2 Mask
    m1        = IntSet -> IntSet -> Bool
    disjoint IntSet
    l1 IntSet
    t2
                  | Bool
    otherwise         = IntSet -> IntSet -> Bool
    disjoint IntSet
    r1 IntSet
    t2

        disjoint2 :: Bool
    disjoint2 | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    p1 Mask
    p2 Mask
    m2  = Bool
    True
                  | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m2        = IntSet -> IntSet -> Bool
    disjoint IntSet
    t1 IntSet
    l2
                  | Bool
    otherwise         = IntSet -> IntSet -> Bool
    disjoint IntSet
    t1 IntSet
    r2

    disjoint t1 :: IntSet
    t1@(Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) (Tip Mask
    kx2 Word
    bm2) = IntSet -> Bool
    disjointBM IntSet
    t1
      where disjointBM :: IntSet -> Bool
    disjointBM (Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx2 Mask
    p1 Mask
    m1 = Bool
    True
                                         | Mask -> Mask -> Bool
    zero Mask
    kx2 Mask
    m1       = IntSet -> Bool
    disjointBM IntSet
    l1
                                         | Bool
    otherwise         = IntSet -> Bool
    disjointBM IntSet
    r1
            disjointBM (Tip Mask
    kx1 Word
    bm1) | Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 = (Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm2) Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    0
                                     | Bool
    otherwise = Bool
    True
            disjointBM IntSet
    Nil = Bool
    True

    disjoint (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    _) IntSet
    Nil = Bool
    True

    disjoint (Tip Mask
    kx1 Word
    bm1) IntSet
    t2 = IntSet -> Bool
    disjointBM IntSet
    t2
      where disjointBM :: IntSet -> Bool
    disjointBM (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2) | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    kx1 Mask
    p2 Mask
    m2 = Bool
    True
                                         | Mask -> Mask -> Bool
    zero Mask
    kx1 Mask
    m2       = IntSet -> Bool
    disjointBM IntSet
    l2
                                         | Bool
    otherwise         = IntSet -> Bool
    disjointBM IntSet
    r2
            disjointBM (Tip Mask
    kx2 Word
    bm2) | Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 = (Word
    bm1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bm2) Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    0
                                     | Bool
    otherwise = Bool
    True
            disjointBM IntSet
    Nil = Bool
    True

    disjoint IntSet
    Nil IntSet
    _ = Bool
    True

    {--------------------------------------------------------------------
      Filter
    --------------------------------------------------------------------}
    -- | \(O(n)\). Filter all elements that satisfy some predicate.
    filter :: (Key -> Bool) -> IntSet -> IntSet
    filter :: (Mask -> Bool) -> IntSet -> IntSet
    filter Mask -> Bool
    predicate IntSet
    t
      = case IntSet
    t of
          Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
            -> Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m ((Mask -> Bool) -> IntSet -> IntSet
    filter Mask -> Bool
    predicate IntSet
    l) ((Mask -> Bool) -> IntSet -> IntSet
    filter Mask -> Bool
    predicate IntSet
    r)
          Tip Mask
    kx Word
    bm
            -> Mask -> Word -> IntSet
    tip Mask
    kx (Mask -> (Word -> Mask -> Word) -> Word -> Word -> Word
    forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldl'Bits Mask
    0 (Mask -> Word -> Mask -> Word
    bitPred Mask
    kx) Word
    0 Word
    bm)
          IntSet
    Nil -> IntSet
    Nil
      where bitPred :: Mask -> Word -> Mask -> Word
    bitPred Mask
    kx Word
    bm Mask
    bi | Mask -> Bool
    predicate (Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Mask
    bi) = Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. Mask -> Word
    bitmapOfSuffix Mask
    bi
                             | Bool
    otherwise           = Word
    bm
            {-# INLINE bitPred #-}

    -- | \(O(n)\). partition the set according to some predicate.
    partition :: (Key -> Bool) -> IntSet -> (IntSet,IntSet)
    partition :: (Mask -> Bool) -> IntSet -> (IntSet, IntSet)
    partition Mask -> Bool
    predicate0 IntSet
    t0 = StrictPair IntSet IntSet -> (IntSet, IntSet)
    forall a b. StrictPair a b -> (a, b)
    toPair (StrictPair IntSet IntSet -> (IntSet, IntSet))
    -> StrictPair IntSet IntSet -> (IntSet, IntSet)
    forall a b. (a -> b) -> a -> b
    $ (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate0 IntSet
    t0
      where
        go :: (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    t
          = case IntSet
    t of
              Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
                -> let (IntSet
    l1 :*: IntSet
    l2) = (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    l
                       (IntSet
    r1 :*: IntSet
    r2) = (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    r
                   in Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l1 IntSet
    r1 IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l2 IntSet
    r2
              Tip Mask
    kx Word
    bm
                -> let bm1 :: Word
    bm1 = Mask -> (Word -> Mask -> Word) -> Word -> Word -> Word
    forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldl'Bits Mask
    0 (Mask -> Word -> Mask -> Word
    bitPred Mask
    kx) Word
    0 Word
    bm
                   in  Mask -> Word -> IntSet
    tip Mask
    kx Word
    bm1 IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bm1)
              IntSet
    Nil -> (IntSet
    Nil IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    Nil)
          where bitPred :: Mask -> Word -> Mask -> Word
    bitPred Mask
    kx Word
    bm Mask
    bi | Mask -> Bool
    predicate (Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Mask
    bi) = Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. Mask -> Word
    bitmapOfSuffix Mask
    bi
                                 | Bool
    otherwise           = Word
    bm
                {-# INLINE bitPred #-}

    -- | \(O(\min(n,W))\). Take while a predicate on the elements holds.
    -- The user is responsible for ensuring that for all @Int@s, @j \< k ==\> p j \>= p k@.
    -- See note at 'spanAntitone'.
    --
    -- @
    -- takeWhileAntitone p = 'fromDistinctAscList' . 'Data.List.takeWhile' p . 'toList'
    -- takeWhileAntitone p = 'filter' p
    -- @
    --
    -- @since 0.6.7
    takeWhileAntitone :: (Key -> Bool) -> IntSet -> IntSet
    takeWhileAntitone :: (Mask -> Bool) -> IntSet -> IntSet
    takeWhileAntitone Mask -> Bool
    predicate IntSet
    t =
      case IntSet
    t of
        Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
          | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 ->
            if Mask -> Bool
    predicate Mask
    0 -- handle negative numbers.
            then Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m ((Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    l) IntSet
    r
            else (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    r
        IntSet
    _ -> (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    t
      where
        go :: (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
          | Mask -> Bool
    predicate' (Mask -> Bool) -> Mask -> Bool
    forall a b. (a -> b) -> a -> b
    $! Mask
    pMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    m = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l ((Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' IntSet
    r)
          | Bool
    otherwise         = (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' IntSet
    l
        go Mask -> Bool
    predicate' (Tip Mask
    kx Word
    bm) = Mask -> Word -> IntSet
    tip Mask
    kx (Mask -> (Mask -> Bool) -> Word -> Word
    takeWhileAntitoneBits Mask
    kx Mask -> Bool
    predicate' Word
    bm)
        go Mask -> Bool
    _ IntSet
    Nil = IntSet
    Nil

    -- | \(O(\min(n,W))\). Drop while a predicate on the elements holds.
    -- The user is responsible for ensuring that for all @Int@s, @j \< k ==\> p j \>= p k@.
    -- See note at 'spanAntitone'.
    --
    -- @
    -- dropWhileAntitone p = 'fromDistinctAscList' . 'Data.List.dropWhile' p . 'toList'
    -- dropWhileAntitone p = 'filter' (not . p)
    -- @
    --
    -- @since 0.6.7
    dropWhileAntitone :: (Key -> Bool) -> IntSet -> IntSet
    dropWhileAntitone :: (Mask -> Bool) -> IntSet -> IntSet
    dropWhileAntitone Mask -> Bool
    predicate IntSet
    t =
      case IntSet
    t of
        Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
          | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 ->
            if Mask -> Bool
    predicate Mask
    0 -- handle negative numbers.
            then (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    l
            else Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l ((Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    r)
        IntSet
    _ -> (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate IntSet
    t
      where
        go :: (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
          | Mask -> Bool
    predicate' (Mask -> Bool) -> Mask -> Bool
    forall a b. (a -> b) -> a -> b
    $! Mask
    pMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    m = (Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' IntSet
    r
          | Bool
    otherwise         = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m ((Mask -> Bool) -> IntSet -> IntSet
    go Mask -> Bool
    predicate' IntSet
    l) IntSet
    r
        go Mask -> Bool
    predicate' (Tip Mask
    kx Word
    bm) = Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Mask -> (Mask -> Bool) -> Word -> Word
    takeWhileAntitoneBits Mask
    kx Mask -> Bool
    predicate' Word
    bm)
        go Mask -> Bool
    _ IntSet
    Nil = IntSet
    Nil

    -- | \(O(\min(n,W))\). Divide a set at the point where a predicate on the elements stops holding.
    -- The user is responsible for ensuring that for all @Int@s, @j \< k ==\> p j \>= p k@.
    --
    -- @
    -- spanAntitone p xs = ('takeWhileAntitone' p xs, 'dropWhileAntitone' p xs)
    -- spanAntitone p xs = 'partition' p xs
    -- @
    --
    -- Note: if @p@ is not actually antitone, then @spanAntitone@ will split the set
    -- at some /unspecified/ point.
    --
    -- @since 0.6.7
    spanAntitone :: (Key -> Bool) -> IntSet -> (IntSet, IntSet)
    spanAntitone :: (Mask -> Bool) -> IntSet -> (IntSet, IntSet)
    spanAntitone Mask -> Bool
    predicate IntSet
    t =
      case IntSet
    t of
        Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
          | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 ->
            if Mask -> Bool
    predicate Mask
    0 -- handle negative numbers.
            then
              case (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    l of
                (IntSet
    lt :*: IntSet
    gt) ->
                  let !lt' :: IntSet
    lt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    lt IntSet
    r
                  in (IntSet
    lt', IntSet
    gt)
            else
              case (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    r of
                (IntSet
    lt :*: IntSet
    gt) ->
                  let !gt' :: IntSet
    gt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    gt
                  in (IntSet
    lt, IntSet
    gt')
        IntSet
    _ -> case (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate IntSet
    t of
              (IntSet
    lt :*: IntSet
    gt) -> (IntSet
    lt, IntSet
    gt)
      where
        go :: (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate' (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
          | Mask -> Bool
    predicate' (Mask -> Bool) -> Mask -> Bool
    forall a b. (a -> b) -> a -> b
    $! Mask
    pMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    m = case (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate' IntSet
    r of (IntSet
    lt :*: IntSet
    gt) -> Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    lt IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    gt
          | Bool
    otherwise         = case (Mask -> Bool) -> IntSet -> StrictPair IntSet IntSet
    go Mask -> Bool
    predicate' IntSet
    l of (IntSet
    lt :*: IntSet
    gt) -> IntSet
    lt IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    gt IntSet
    r
        go Mask -> Bool
    predicate' (Tip Mask
    kx Word
    bm) = let bm' :: Word
    bm' = Mask -> (Mask -> Bool) -> Word -> Word
    takeWhileAntitoneBits Mask
    kx Mask -> Bool
    predicate' Word
    bm
                                    in (Mask -> Word -> IntSet
    tip Mask
    kx Word
    bm' IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bm'))
        go Mask -> Bool
    _ IntSet
    Nil = (IntSet
    Nil IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    Nil)

    -- | \(O(\min(n,W))\). The expression (@'split' x set@) is a pair @(set1,set2)@
    -- where @set1@ comprises the elements of @set@ less than @x@ and @set2@
    -- comprises the elements of @set@ greater than @x@.
    --
    -- > split 3 (fromList [1..5]) == (fromList [1,2], fromList [4,5])
    split :: Key -> IntSet -> (IntSet,IntSet)
    split :: Mask -> IntSet -> (IntSet, IntSet)
    split Mask
    x IntSet
    t =
      case IntSet
    t of
        Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
          | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 ->
            if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0  -- handle negative numbers.
            then
              case Mask -> IntSet -> StrictPair IntSet IntSet
    go Mask
    x IntSet
    l of
                (IntSet
    lt :*: IntSet
    gt) ->
                  let !lt' :: IntSet
    lt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    lt IntSet
    r
                  in (IntSet
    lt', IntSet
    gt)
            else
              case Mask -> IntSet -> StrictPair IntSet IntSet
    go Mask
    x IntSet
    r of
                (IntSet
    lt :*: IntSet
    gt) ->
                  let !gt' :: IntSet
    gt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    gt
                  in (IntSet
    lt, IntSet
    gt')
        IntSet
    _ -> case Mask -> IntSet -> StrictPair IntSet IntSet
    go Mask
    x IntSet
    t of
              (IntSet
    lt :*: IntSet
    gt) -> (IntSet
    lt, IntSet
    gt)
      where
        go :: Mask -> IntSet -> StrictPair IntSet IntSet
    go !Mask
    x' t' :: IntSet
    t'@(Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
            | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x' Mask
    p Mask
    m = if Mask
    x' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then (IntSet
    Nil IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    t') else (IntSet
    t' IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    Nil)
            | Mask -> Mask -> Bool
    zero Mask
    x' Mask
    m      = case Mask -> IntSet -> StrictPair IntSet IntSet
    go Mask
    x' IntSet
    l of (IntSet
    lt :*: IntSet
    gt) -> IntSet
    lt IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    gt IntSet
    r
            | Bool
    otherwise      = case Mask -> IntSet -> StrictPair IntSet IntSet
    go Mask
    x' IntSet
    r of (IntSet
    lt :*: IntSet
    gt) -> Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    lt IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    gt
        go Mask
    x' t' :: IntSet
    t'@(Tip Mask
    kx' Word
    bm)
            | Mask
    kx' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    > Mask
    x'          = (IntSet
    Nil IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    t')
              -- equivalent to kx' > prefixOf x'
            | Mask
    kx' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask -> Mask
    prefixOf Mask
    x' = (IntSet
    t' IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    Nil)
            | Bool
    otherwise = Mask -> Word -> IntSet
    tip Mask
    kx' (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    lowerBitmap) IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: Mask -> Word -> IntSet
    tip Mask
    kx' (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    higherBitmap)
                where lowerBitmap :: Word
    lowerBitmap = Mask -> Word
    bitmapOf Mask
    x' Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1
                      higherBitmap :: Word
    higherBitmap = Word -> Word
    forall a. Bits a => a -> a
    complement (Word
    lowerBitmap Word -> Word -> Word
    forall a. Num a => a -> a -> a
    + Mask -> Word
    bitmapOf Mask
    x')
        go Mask
    _ IntSet
    Nil = (IntSet
    Nil IntSet -> IntSet -> StrictPair IntSet IntSet
    forall a b. a -> b -> StrictPair a b
    :*: IntSet
    Nil)

    -- | \(O(\min(n,W))\). Performs a 'split' but also returns whether the pivot
    -- element was found in the original set.
    splitMember :: Key -> IntSet -> (IntSet,Bool,IntSet)
    splitMember :: Mask -> IntSet -> (IntSet, Bool, IntSet)
    splitMember Mask
    x IntSet
    t =
      case IntSet
    t of
        Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
          | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 ->
            if Mask
    x Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Mask
    0 -- handle negative numbers.
            then
              case Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x IntSet
    l of
                (IntSet
    lt, Bool
    fnd, IntSet
    gt) ->
                  let !lt' :: IntSet
    lt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    lt IntSet
    r
                  in (IntSet
    lt', Bool
    fnd, IntSet
    gt)
            else
              case Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x IntSet
    r of
                (IntSet
    lt, Bool
    fnd, IntSet
    gt) ->
                  let !gt' :: IntSet
    gt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    gt
                  in (IntSet
    lt, Bool
    fnd, IntSet
    gt')
        IntSet
    _ -> Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x IntSet
    t
      where
        go :: Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x' t' :: IntSet
    t'@(Bin Mask
    p Mask
    m IntSet
    l IntSet
    r)
            | Mask -> Mask -> Mask -> Bool
    nomatch Mask
    x' Mask
    p Mask
    m = if Mask
    x' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    p then (IntSet
    Nil, Bool
    False, IntSet
    t') else (IntSet
    t', Bool
    False, IntSet
    Nil)
            | Mask -> Mask -> Bool
    zero Mask
    x' Mask
    m =
              case Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x' IntSet
    l of
                (IntSet
    lt, Bool
    fnd, IntSet
    gt) ->
                  let !gt' :: IntSet
    gt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    gt IntSet
    r
                  in (IntSet
    lt, Bool
    fnd, IntSet
    gt')
            | Bool
    otherwise =
              case Mask -> IntSet -> (IntSet, Bool, IntSet)
    go Mask
    x' IntSet
    r of
                (IntSet
    lt, Bool
    fnd, IntSet
    gt) ->
                  let !lt' :: IntSet
    lt' = Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    lt
                  in (IntSet
    lt', Bool
    fnd, IntSet
    gt)
        go Mask
    x' t' :: IntSet
    t'@(Tip Mask
    kx' Word
    bm)
            | Mask
    kx' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    > Mask
    x'          = (IntSet
    Nil, Bool
    False, IntSet
    t')
              -- equivalent to kx' > prefixOf x'
            | Mask
    kx' Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask -> Mask
    prefixOf Mask
    x' = (IntSet
    t', Bool
    False, IntSet
    Nil)
            | Bool
    otherwise = let !lt :: IntSet
    lt = Mask -> Word -> IntSet
    tip Mask
    kx' (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    lowerBitmap)
                              !found :: Bool
    found = (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    bitmapOfx') Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0
                              !gt :: IntSet
    gt = Mask -> Word -> IntSet
    tip Mask
    kx' (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    higherBitmap)
                          in (IntSet
    lt, Bool
    found, IntSet
    gt)
                where bitmapOfx' :: Word
    bitmapOfx' = Mask -> Word
    bitmapOf Mask
    x'
                      lowerBitmap :: Word
    lowerBitmap = Word
    bitmapOfx' Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1
                      higherBitmap :: Word
    higherBitmap = Word -> Word
    forall a. Bits a => a -> a
    complement (Word
    lowerBitmap Word -> Word -> Word
    forall a. Num a => a -> a -> a
    + Word
    bitmapOfx')
        go Mask
    _ IntSet
    Nil = (IntSet
    Nil, Bool
    False, IntSet
    Nil)

    {----------------------------------------------------------------------
      Min/Max
    ----------------------------------------------------------------------}

    -- | \(O(\min(n,W))\). Retrieves the maximal key of the set, and the set
    -- stripped of that element, or 'Nothing' if passed an empty set.
    maxView :: IntSet -> Maybe (Key, IntSet)
    maxView :: IntSet -> Maybe (Mask, IntSet)
    maxView IntSet
    t =
      case IntSet
    t of IntSet
    Nil -> Maybe (Mask, IntSet)
    forall a. Maybe a
    Nothing
                Bin Mask
    p Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> case IntSet -> (Mask, IntSet)
    go IntSet
    l of (Mask
    result, IntSet
    l') -> (Mask, IntSet) -> Maybe (Mask, IntSet)
    forall a. a -> Maybe a
    Just (Mask
    result, Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l' IntSet
    r)
                IntSet
    _ -> (Mask, IntSet) -> Maybe (Mask, IntSet)
    forall a. a -> Maybe a
    Just (IntSet -> (Mask, IntSet)
    go IntSet
    t)
      where
        go :: IntSet -> (Mask, IntSet)
    go (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) = case IntSet -> (Mask, IntSet)
    go IntSet
    r of (Mask
    result, IntSet
    r') -> (Mask
    result, Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    r')
        go (Tip Mask
    kx Word
    bm) = case Word -> Mask
    highestBitSet Word
    bm of Mask
    bi -> (Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Mask
    bi, Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement (Mask -> Word
    bitmapOfSuffix Mask
    bi)))
        go IntSet
    Nil = [Char] -> (Mask, IntSet)
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "maxView Nil"

    -- | \(O(\min(n,W))\). Retrieves the minimal key of the set, and the set
    -- stripped of that element, or 'Nothing' if passed an empty set.
    minView :: IntSet -> Maybe (Key, IntSet)
    minView :: IntSet -> Maybe (Mask, IntSet)
    minView IntSet
    t =
      case IntSet
    t of IntSet
    Nil -> Maybe (Mask, IntSet)
    forall a. Maybe a
    Nothing
                Bin Mask
    p Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> case IntSet -> (Mask, IntSet)
    go IntSet
    r of (Mask
    result, IntSet
    r') -> (Mask, IntSet) -> Maybe (Mask, IntSet)
    forall a. a -> Maybe a
    Just (Mask
    result, Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l IntSet
    r')
                IntSet
    _ -> (Mask, IntSet) -> Maybe (Mask, IntSet)
    forall a. a -> Maybe a
    Just (IntSet -> (Mask, IntSet)
    go IntSet
    t)
      where
        go :: IntSet -> (Mask, IntSet)
    go (Bin Mask
    p Mask
    m IntSet
    l IntSet
    r) = case IntSet -> (Mask, IntSet)
    go IntSet
    l of (Mask
    result, IntSet
    l') -> (Mask
    result, Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    p Mask
    m IntSet
    l' IntSet
    r)
        go (Tip Mask
    kx Word
    bm) = case Word -> Mask
    lowestBitSet Word
    bm of Mask
    bi -> (Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Mask
    bi, Mask -> Word -> IntSet
    tip Mask
    kx (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Bits a => a -> a
    complement (Mask -> Word
    bitmapOfSuffix Mask
    bi)))
        go IntSet
    Nil = [Char] -> (Mask, IntSet)
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "minView Nil"

    -- | \(O(\min(n,W))\). Delete and find the minimal element.
    --
    -- > deleteFindMin set = (findMin set, deleteMin set)
    deleteFindMin :: IntSet -> (Key, IntSet)
    deleteFindMin :: IntSet -> (Mask, IntSet)
    deleteFindMin = (Mask, IntSet) -> Maybe (Mask, IntSet) -> (Mask, IntSet)
    forall a. a -> Maybe a -> a
    fromMaybe ([Char] -> (Mask, IntSet)
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "deleteFindMin: empty set has no minimal element") (Maybe (Mask, IntSet) -> (Mask, IntSet))
    -> (IntSet -> Maybe (Mask, IntSet)) -> IntSet -> (Mask, IntSet)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> Maybe (Mask, IntSet)
    minView

    -- | \(O(\min(n,W))\). Delete and find the maximal element.
    --
    -- > deleteFindMax set = (findMax set, deleteMax set)
    deleteFindMax :: IntSet -> (Key, IntSet)
    deleteFindMax :: IntSet -> (Mask, IntSet)
    deleteFindMax = (Mask, IntSet) -> Maybe (Mask, IntSet) -> (Mask, IntSet)
    forall a. a -> Maybe a -> a
    fromMaybe ([Char] -> (Mask, IntSet)
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "deleteFindMax: empty set has no maximal element") (Maybe (Mask, IntSet) -> (Mask, IntSet))
    -> (IntSet -> Maybe (Mask, IntSet)) -> IntSet -> (Mask, IntSet)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> Maybe (Mask, IntSet)
    maxView

    -- | \(O(\min(n,W))\). The minimal element of the set.
    findMin :: IntSet -> Key
    findMin :: IntSet -> Mask
    findMin IntSet
    Nil = [Char] -> Mask
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "findMin: empty set has no minimal element"
    findMin (Tip Mask
    kx Word
    bm) = Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    bm
    findMin (Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r)
      |   Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0   = IntSet -> Mask
    find IntSet
    r
      | Bool
    otherwise = IntSet -> Mask
    find IntSet
    l
        where find :: IntSet -> Mask
    find (Tip Mask
    kx Word
    bm) = Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    lowestBitSet Word
    bm
              find (Bin Mask
    _ Mask
    _ IntSet
    l' IntSet
    _) = IntSet -> Mask
    find IntSet
    l'
              find IntSet
    Nil            = [Char] -> Mask
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "findMin Nil"

    -- | \(O(\min(n,W))\). The maximal element of a set.
    findMax :: IntSet -> Key
    findMax :: IntSet -> Mask
    findMax IntSet
    Nil = [Char] -> Mask
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "findMax: empty set has no maximal element"
    findMax (Tip Mask
    kx Word
    bm) = Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    bm
    findMax (Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r)
      |   Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0   = IntSet -> Mask
    find IntSet
    l
      | Bool
    otherwise = IntSet -> Mask
    find IntSet
    r
        where find :: IntSet -> Mask
    find (Tip Mask
    kx Word
    bm) = Mask
    kx Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    + Word -> Mask
    highestBitSet Word
    bm
              find (Bin Mask
    _ Mask
    _ IntSet
    _ IntSet
    r') = IntSet -> Mask
    find IntSet
    r'
              find IntSet
    Nil            = [Char] -> Mask
    forall a. HasCallStack => [Char] -> a
    error [Char]
    "findMax Nil"

    -- | \(O(\min(n,W))\). Delete the minimal element. Returns an empty set if the set is empty.
    --
    -- Note that this is a change of behaviour for consistency with 'Data.Set.Set' &#8211;
    -- versions prior to 0.5 threw an error if the 'IntSet' was already empty.
    deleteMin :: IntSet -> IntSet
    deleteMin :: IntSet -> IntSet
    deleteMin = IntSet
    -> ((Mask, IntSet) -> IntSet) -> Maybe (Mask, IntSet) -> IntSet
    forall b a. b -> (a -> b) -> Maybe a -> b
    maybe IntSet
    Nil (Mask, IntSet) -> IntSet
    forall a b. (a, b) -> b
    snd (Maybe (Mask, IntSet) -> IntSet)
    -> (IntSet -> Maybe (Mask, IntSet)) -> IntSet -> IntSet
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> Maybe (Mask, IntSet)
    minView

    -- | \(O(\min(n,W))\). Delete the maximal element. Returns an empty set if the set is empty.
    --
    -- Note that this is a change of behaviour for consistency with 'Data.Set.Set' &#8211;
    -- versions prior to 0.5 threw an error if the 'IntSet' was already empty.
    deleteMax :: IntSet -> IntSet
    deleteMax :: IntSet -> IntSet
    deleteMax = IntSet
    -> ((Mask, IntSet) -> IntSet) -> Maybe (Mask, IntSet) -> IntSet
    forall b a. b -> (a -> b) -> Maybe a -> b
    maybe IntSet
    Nil (Mask, IntSet) -> IntSet
    forall a b. (a, b) -> b
    snd (Maybe (Mask, IntSet) -> IntSet)
    -> (IntSet -> Maybe (Mask, IntSet)) -> IntSet -> IntSet
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> Maybe (Mask, IntSet)
    maxView

    {----------------------------------------------------------------------
      Map
    ----------------------------------------------------------------------}

    -- | \(O(n \min(n,W))\).
    -- @'map' f s@ is the set obtained by applying @f@ to each element of @s@.
    --
    -- It's worth noting that the size of the result may be smaller if,
    -- for some @(x,y)@, @x \/= y && f x == f y@

    map :: (Key -> Key) -> IntSet -> IntSet
    map :: (Mask -> Mask) -> IntSet -> IntSet
    map Mask -> Mask
    f = [Mask] -> IntSet
    fromList ([Mask] -> IntSet) -> (IntSet -> [Mask]) -> IntSet -> IntSet
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (Mask -> Mask) -> [Mask] -> [Mask]
    forall a b. (a -> b) -> [a] -> [b]
    List.map Mask -> Mask
    f ([Mask] -> [Mask]) -> (IntSet -> [Mask]) -> IntSet -> [Mask]
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> [Mask]
    toList

    -- | \(O(n)\). The
    --
    -- @'mapMonotonic' f s == 'map' f s@, but works only when @f@ is strictly increasing.
    -- /The precondition is not checked./
    -- Semi-formally, we have:
    --
    -- > and [x < y ==> f x < f y | x <- ls, y <- ls]
    -- >                     ==> mapMonotonic f s == map f s
    -- >     where ls = toList s
    --
    -- @since 0.6.3.1

    -- Note that for now the test is insufficient to support any fancier implementation.
    mapMonotonic :: (Key -> Key) -> IntSet -> IntSet
    mapMonotonic :: (Mask -> Mask) -> IntSet -> IntSet
    mapMonotonic Mask -> Mask
    f = [Mask] -> IntSet
    fromDistinctAscList ([Mask] -> IntSet) -> (IntSet -> [Mask]) -> IntSet -> IntSet
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (Mask -> Mask) -> [Mask] -> [Mask]
    forall a b. (a -> b) -> [a] -> [b]
    List.map Mask -> Mask
    f ([Mask] -> [Mask]) -> (IntSet -> [Mask]) -> IntSet -> [Mask]
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . IntSet -> [Mask]
    toAscList

    {--------------------------------------------------------------------
      Fold
    --------------------------------------------------------------------}
    -- | \(O(n)\). Fold the elements in the set using the given right-associative
    -- binary operator. This function is an equivalent of 'foldr' and is present
    -- for compatibility only.
    --
    -- /Please note that fold will be deprecated in the future and removed./
    fold :: (Key -> b -> b) -> b -> IntSet -> b
    fold :: forall b. (Mask -> b -> b) -> b -> IntSet -> b
    fold = (Mask -> b -> b) -> b -> IntSet -> b
    forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldr
    {-# INLINE fold #-}

    -- | \(O(n)\). Fold the elements in the set using the given right-associative
    -- binary operator, such that @'foldr' f z == 'Prelude.foldr' f z . 'toAscList'@.
    --
    -- For example,
    --
    -- > toAscList set = foldr (:) [] set
    foldr :: (Key -> b -> b) -> b -> IntSet -> b
    foldr :: forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldr Mask -> b -> b
    f b
    z = \IntSet
    t ->      -- Use lambda t to be inlinable with two arguments only.
      case IntSet
    t of Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z IntSet
    l) IntSet
    r -- put negative numbers before
                            | Bool
    otherwise -> b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z IntSet
    r) IntSet
    l
                IntSet
    _ -> b -> IntSet -> b
    go b
    z IntSet
    t
      where
        go :: b -> IntSet -> b
    go b
    z' IntSet
    Nil           = b
    z'
        go b
    z' (Tip Mask
    kx Word
    bm)   = Mask -> (Mask -> b -> b) -> b -> Word -> b
    forall a. Mask -> (Mask -> a -> a) -> a -> Word -> a
    foldrBits Mask
    kx Mask -> b -> b
    f b
    z' Word
    bm
        go b
    z' (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    r) = b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z' IntSet
    r) IntSet
    l
    {-# INLINE foldr #-}

    -- | \(O(n)\). A strict version of 'foldr'. Each application of the operator is
    -- evaluated before using the result in the next application. This
    -- function is strict in the starting value.
    foldr' :: (Key -> b -> b) -> b -> IntSet -> b
    foldr' :: forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldr' Mask -> b -> b
    f b
    z = \IntSet
    t ->      -- Use lambda t to be inlinable with two arguments only.
      case IntSet
    t of Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z IntSet
    l) IntSet
    r -- put negative numbers before
                            | Bool
    otherwise -> b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z IntSet
    r) IntSet
    l
                IntSet
    _ -> b -> IntSet -> b
    go b
    z IntSet
    t
      where
        go :: b -> IntSet -> b
    go !b
    z' IntSet
    Nil           = b
    z'
        go b
    z' (Tip Mask
    kx Word
    bm)   = Mask -> (Mask -> b -> b) -> b -> Word -> b
    forall a. Mask -> (Mask -> a -> a) -> a -> Word -> a
    foldr'Bits Mask
    kx Mask -> b -> b
    f b
    z' Word
    bm
        go b
    z' (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    r) = b -> IntSet -> b
    go (b -> IntSet -> b
    go b
    z' IntSet
    r) IntSet
    l
    {-# INLINE foldr' #-}

    -- | \(O(n)\). Fold the elements in the set using the given left-associative
    -- binary operator, such that @'foldl' f z == 'Prelude.foldl' f z . 'toAscList'@.
    --
    -- For example,
    --
    -- > toDescList set = foldl (flip (:)) [] set
    foldl :: (a -> Key -> a) -> a -> IntSet -> a
    foldl :: forall a. (a -> Mask -> a) -> a -> IntSet -> a
    foldl a -> Mask -> a
    f a
    z = \IntSet
    t ->      -- Use lambda t to be inlinable with two arguments only.
      case IntSet
    t of Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z IntSet
    r) IntSet
    l -- put negative numbers before
                            | Bool
    otherwise -> a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z IntSet
    l) IntSet
    r
                IntSet
    _ -> a -> IntSet -> a
    go a
    z IntSet
    t
      where
        go :: a -> IntSet -> a
    go a
    z' IntSet
    Nil           = a
    z'
        go a
    z' (Tip Mask
    kx Word
    bm)   = Mask -> (a -> Mask -> a) -> a -> Word -> a
    forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldlBits Mask
    kx a -> Mask -> a
    f a
    z' Word
    bm
        go a
    z' (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    r) = a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z' IntSet
    l) IntSet
    r
    {-# INLINE foldl #-}

    -- | \(O(n)\). A strict version of 'foldl'. Each application of the operator is
    -- evaluated before using the result in the next application. This
    -- function is strict in the starting value.
    foldl' :: (a -> Key -> a) -> a -> IntSet -> a
    foldl' :: forall a. (a -> Mask -> a) -> a -> IntSet -> a
    foldl' a -> Mask -> a
    f a
    z = \IntSet
    t ->      -- Use lambda t to be inlinable with two arguments only.
      case IntSet
    t of Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 -> a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z IntSet
    r) IntSet
    l -- put negative numbers before
                            | Bool
    otherwise -> a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z IntSet
    l) IntSet
    r
                IntSet
    _ -> a -> IntSet -> a
    go a
    z IntSet
    t
      where
        go :: a -> IntSet -> a
    go !a
    z' IntSet
    Nil           = a
    z'
        go a
    z' (Tip Mask
    kx Word
    bm)   = Mask -> (a -> Mask -> a) -> a -> Word -> a
    forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldl'Bits Mask
    kx a -> Mask -> a
    f a
    z' Word
    bm
        go a
    z' (Bin Mask
    _ Mask
    _ IntSet
    l IntSet
    r) = a -> IntSet -> a
    go (a -> IntSet -> a
    go a
    z' IntSet
    l) IntSet
    r
    {-# INLINE foldl' #-}

    {--------------------------------------------------------------------
      List variations
    --------------------------------------------------------------------}
    -- | \(O(n)\). An alias of 'toAscList'. The elements of a set in ascending order.
    -- Subject to list fusion.
    elems :: IntSet -> [Key]
    elems :: IntSet -> [Mask]
    elems
      = IntSet -> [Mask]
    toAscList

    {--------------------------------------------------------------------
      Lists
    --------------------------------------------------------------------}

    #ifdef __GLASGOW_HASKELL__
    -- | @since 0.5.6.2
    instance GHC.Exts.IsList IntSet where
      type Item IntSet = Key
      fromList :: [Item IntSet] -> IntSet
    fromList = [Mask] -> IntSet
    [Item IntSet] -> IntSet
    fromList
      toList :: IntSet -> [Item IntSet]
    toList   = IntSet -> [Mask]
    IntSet -> [Item IntSet]
    toList
    #endif

    -- | \(O(n)\). Convert the set to a list of elements. Subject to list fusion.
    toList :: IntSet -> [Key]
    toList :: IntSet -> [Mask]
    toList
      = IntSet -> [Mask]
    toAscList

    -- | \(O(n)\). Convert the set to an ascending list of elements. Subject to list
    -- fusion.
    toAscList :: IntSet -> [Key]
    toAscList :: IntSet -> [Mask]
    toAscList = (Mask -> [Mask] -> [Mask]) -> [Mask] -> IntSet -> [Mask]
    forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldr (:) []

    -- | \(O(n)\). Convert the set to a descending list of elements. Subject to list
    -- fusion.
    toDescList :: IntSet -> [Key]
    toDescList :: IntSet -> [Mask]
    toDescList = ([Mask] -> Mask -> [Mask]) -> [Mask] -> IntSet -> [Mask]
    forall a. (a -> Mask -> a) -> a -> IntSet -> a
    foldl ((Mask -> [Mask] -> [Mask]) -> [Mask] -> Mask -> [Mask]
    forall a b c. (a -> b -> c) -> b -> a -> c
    flip (:)) []

    -- List fusion for the list generating functions.
    #if __GLASGOW_HASKELL__
    -- The foldrFB and foldlFB are foldr and foldl equivalents, used for list fusion.
    -- They are important to convert unfused to{Asc,Desc}List back, see mapFB in prelude.
    foldrFB :: (Key -> b -> b) -> b -> IntSet -> b
    foldrFB :: forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldrFB = (Mask -> b -> b) -> b -> IntSet -> b
    forall b. (Mask -> b -> b) -> b -> IntSet -> b
    foldr
    {-# INLINE[0] foldrFB #-}
    foldlFB :: (a -> Key -> a) -> a -> IntSet -> a
    foldlFB :: forall a. (a -> Mask -> a) -> a -> IntSet -> a
    foldlFB = (a -> Mask -> a) -> a -> IntSet -> a
    forall a. (a -> Mask -> a) -> a -> IntSet -> a
    foldl
    {-# INLINE[0] foldlFB #-}

    -- Inline elems and toList, so that we need to fuse only toAscList.
    {-# INLINE elems #-}
    {-# INLINE toList #-}

    -- The fusion is enabled up to phase 2 included. If it does not succeed,
    -- convert in phase 1 the expanded to{Asc,Desc}List calls back to
    -- to{Asc,Desc}List.  In phase 0, we inline fold{lr}FB (which were used in
    -- a list fusion, otherwise it would go away in phase 1), and let compiler do
    -- whatever it wants with to{Asc,Desc}List -- it was forbidden to inline it
    -- before phase 0, otherwise the fusion rules would not fire at all.
    {-# NOINLINE[0] toAscList #-}
    {-# NOINLINE[0] toDescList #-}
    {-# RULES "IntSet.toAscList" [~1] forall s . toAscList s = GHC.Exts.build (\c n -> foldrFB c n s) #-}
    {-# RULES "IntSet.toAscListBack" [1] foldrFB (:) [] = toAscList #-}
    {-# RULES "IntSet.toDescList" [~1] forall s . toDescList s = GHC.Exts.build (\c n -> foldlFB (\xs x -> c x xs) n s) #-}
    {-# RULES "IntSet.toDescListBack" [1] foldlFB (\xs x -> x : xs) [] = toDescList #-}
    #endif

    -- | \(O(n \min(n,W))\). Create a set from a list of integers.
    fromList :: [Key] -> IntSet
    fromList :: [Mask] -> IntSet
    fromList [Mask]
    xs
      = (IntSet -> Mask -> IntSet) -> IntSet -> [Mask] -> IntSet
    forall b a. (b -> a -> b) -> b -> [a] -> b
    forall (t :: * -> *) b a.
    Foldable t =>
    (b -> a -> b) -> b -> t a -> b
    Foldable.foldl' IntSet -> Mask -> IntSet
    ins IntSet
    empty [Mask]
    xs
      where
        ins :: IntSet -> Mask -> IntSet
    ins IntSet
    t Mask
    x  = Mask -> IntSet -> IntSet
    insert Mask
    x IntSet
    t

    -- | \(O(n)\). Build a set from an ascending list of elements.
    -- /The precondition (input list is ascending) is not checked./
    fromAscList :: [Key] -> IntSet
    fromAscList :: [Mask] -> IntSet
    fromAscList = [Mask] -> IntSet
    fromMonoList
    {-# NOINLINE fromAscList #-}

    -- | \(O(n)\). Build a set from an ascending list of distinct elements.
    -- /The precondition (input list is strictly ascending) is not checked./
    fromDistinctAscList :: [Key] -> IntSet
    fromDistinctAscList :: [Mask] -> IntSet
    fromDistinctAscList = [Mask] -> IntSet
    fromAscList
    {-# INLINE fromDistinctAscList #-}

    -- | \(O(n)\). Build a set from a monotonic list of elements.
    --
    -- The precise conditions under which this function works are subtle:
    -- For any branch mask, keys with the same prefix w.r.t. the branch
    -- mask must occur consecutively in the list.
    fromMonoList :: [Key] -> IntSet
    fromMonoList :: [Mask] -> IntSet
    fromMonoList []         = IntSet
    Nil
    fromMonoList (Mask
    kx : [Mask]
    zs1) = Mask -> Word -> [Mask] -> IntSet
    addAll' (Mask -> Mask
    prefixOf Mask
    kx) (Mask -> Word
    bitmapOf Mask
    kx) [Mask]
    zs1
      where
        -- `addAll'` collects all keys with the prefix `px` into a single
        -- bitmap, and then proceeds with `addAll`.
        addAll' :: Mask -> Word -> [Mask] -> IntSet
    addAll' !Mask
    px !Word
    bm []
            = Mask -> Word -> IntSet
    Tip Mask
    px Word
    bm
        addAll' !Mask
    px !Word
    bm (Mask
    ky : [Mask]
    zs)
            | Mask
    px Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask -> Mask
    prefixOf Mask
    ky
            = Mask -> Word -> [Mask] -> IntSet
    addAll' Mask
    px (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            -- inlined: | otherwise = addAll px (Tip px bm) (ky : zs)
            | Mask
    py <- Mask -> Mask
    prefixOf Mask
    ky
            , Mask
    m <- Mask -> Mask -> Mask
    branchMask Mask
    px Mask
    py
            , Inserted IntSet
    ty [Mask]
    zs' <- Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' Mask
    m Mask
    py (Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            = Mask -> IntSet -> [Mask] -> IntSet
    addAll Mask
    px (Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask Mask
    m Mask
    py IntSet
    ty {-px-} (Mask -> Word -> IntSet
    Tip Mask
    px Word
    bm)) [Mask]
    zs'

        -- for `addAll` and `addMany`, px is /a/ prefix inside the tree `tx`
        -- `addAll` consumes the rest of the list, adding to the tree `tx`
        addAll :: Mask -> IntSet -> [Mask] -> IntSet
    addAll !Mask
    _px !IntSet
    tx []
            = IntSet
    tx
        addAll !Mask
    px !IntSet
    tx (Mask
    ky : [Mask]
    zs)
            | Mask
    py <- Mask -> Mask
    prefixOf Mask
    ky
            , Mask
    m <- Mask -> Mask -> Mask
    branchMask Mask
    px Mask
    py
            , Inserted IntSet
    ty [Mask]
    zs' <- Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' Mask
    m Mask
    py (Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            = Mask -> IntSet -> [Mask] -> IntSet
    addAll Mask
    px (Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask Mask
    m Mask
    py IntSet
    ty {-px-} IntSet
    tx) [Mask]
    zs'

        -- `addMany'` is similar to `addAll'`, but proceeds with `addMany'`.
        addMany' :: Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' !Mask
    _m !Mask
    px !Word
    bm []
            = IntSet -> [Mask] -> Inserted
    Inserted (Mask -> Word -> IntSet
    Tip Mask
    px Word
    bm) []
        addMany' !Mask
    m !Mask
    px !Word
    bm zs0 :: [Mask]
    zs0@(Mask
    ky : [Mask]
    zs)
            | Mask
    px Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask -> Mask
    prefixOf Mask
    ky
            = Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' Mask
    m Mask
    px (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            -- inlined: | otherwise = addMany m px (Tip px bm) (ky : zs)
            | Mask -> Mask -> Mask
    mask Mask
    px Mask
    m Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask -> Mask -> Mask
    mask Mask
    ky Mask
    m
            = IntSet -> [Mask] -> Inserted
    Inserted (Mask -> Word -> IntSet
    Tip (Mask -> Mask
    prefixOf Mask
    px) Word
    bm) [Mask]
    zs0
            | Mask
    py <- Mask -> Mask
    prefixOf Mask
    ky
            , Mask
    mxy <- Mask -> Mask -> Mask
    branchMask Mask
    px Mask
    py
            , Inserted IntSet
    ty [Mask]
    zs' <- Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' Mask
    mxy Mask
    py (Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            = Mask -> Mask -> IntSet -> [Mask] -> Inserted
    addMany Mask
    m Mask
    px (Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask Mask
    mxy Mask
    py IntSet
    ty {-px-} (Mask -> Word -> IntSet
    Tip Mask
    px Word
    bm)) [Mask]
    zs'

        -- `addAll` adds to `tx` all keys whose prefix w.r.t. `m` agrees with `px`.
        addMany :: Mask -> Mask -> IntSet -> [Mask] -> Inserted
    addMany !Mask
    _m !Mask
    _px IntSet
    tx []
            = IntSet -> [Mask] -> Inserted
    Inserted IntSet
    tx []
        addMany !Mask
    m !Mask
    px IntSet
    tx zs0 :: [Mask]
    zs0@(Mask
    ky : [Mask]
    zs)
            | Mask -> Mask -> Mask
    mask Mask
    px Mask
    m Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask -> Mask -> Mask
    mask Mask
    ky Mask
    m
            = IntSet -> [Mask] -> Inserted
    Inserted IntSet
    tx [Mask]
    zs0
            | Mask
    py <- Mask -> Mask
    prefixOf Mask
    ky
            , Mask
    mxy <- Mask -> Mask -> Mask
    branchMask Mask
    px Mask
    py
            , Inserted IntSet
    ty [Mask]
    zs' <- Mask -> Mask -> Word -> [Mask] -> Inserted
    addMany' Mask
    mxy Mask
    py (Mask -> Word
    bitmapOf Mask
    ky) [Mask]
    zs
            = Mask -> Mask -> IntSet -> [Mask] -> Inserted
    addMany Mask
    m Mask
    px (Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask Mask
    mxy Mask
    py IntSet
    ty {-px-} IntSet
    tx) [Mask]
    zs'
    {-# INLINE fromMonoList #-}

    data Inserted = Inserted !IntSet ![Key]

    {--------------------------------------------------------------------
      Eq
    --------------------------------------------------------------------}
    instance Eq IntSet where
      IntSet
    t1 == :: IntSet -> IntSet -> Bool
    == IntSet
    t2  = IntSet -> IntSet -> Bool
    equal IntSet
    t1 IntSet
    t2
      IntSet
    t1 /= :: IntSet -> IntSet -> Bool
    /= IntSet
    t2  = IntSet -> IntSet -> Bool
    nequal IntSet
    t1 IntSet
    t2

    equal :: IntSet -> IntSet -> Bool
    equal :: IntSet -> IntSet -> Bool
    equal (Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      = (Mask
    m1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    m2) Bool -> Bool -> Bool
    && (Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p2) Bool -> Bool -> Bool
    && (IntSet -> IntSet -> Bool
    equal IntSet
    l1 IntSet
    l2) Bool -> Bool -> Bool
    && (IntSet -> IntSet -> Bool
    equal IntSet
    r1 IntSet
    r2)
    equal (Tip Mask
    kx1 Word
    bm1) (Tip Mask
    kx2 Word
    bm2)
      = Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    kx2 Bool -> Bool -> Bool
    && Word
    bm1 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    bm2
    equal IntSet
    Nil IntSet
    Nil = Bool
    True
    equal IntSet
    _   IntSet
    _   = Bool
    False

    nequal :: IntSet -> IntSet -> Bool
    nequal :: IntSet -> IntSet -> Bool
    nequal (Bin Mask
    p1 Mask
    m1 IntSet
    l1 IntSet
    r1) (Bin Mask
    p2 Mask
    m2 IntSet
    l2 IntSet
    r2)
      = (Mask
    m1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    m2) Bool -> Bool -> Bool
    || (Mask
    p1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    p2) Bool -> Bool -> Bool
    || (IntSet -> IntSet -> Bool
    nequal IntSet
    l1 IntSet
    l2) Bool -> Bool -> Bool
    || (IntSet -> IntSet -> Bool
    nequal IntSet
    r1 IntSet
    r2)
    nequal (Tip Mask
    kx1 Word
    bm1) (Tip Mask
    kx2 Word
    bm2)
      = Mask
    kx1 Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    kx2 Bool -> Bool -> Bool
    || Word
    bm1 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    bm2
    nequal IntSet
    Nil IntSet
    Nil = Bool
    False
    nequal IntSet
    _   IntSet
    _   = Bool
    True

    {--------------------------------------------------------------------
      Ord
    --------------------------------------------------------------------}

    instance Ord IntSet where
        compare :: IntSet -> IntSet -> Ordering
    compare IntSet
    s1 IntSet
    s2 = [Mask] -> [Mask] -> Ordering
    forall a. Ord a => a -> a -> Ordering
    compare (IntSet -> [Mask]
    toAscList IntSet
    s1) (IntSet -> [Mask]
    toAscList IntSet
    s2)
        -- tentative implementation. See if more efficient exists.

    {--------------------------------------------------------------------
      Show
    --------------------------------------------------------------------}
    instance Show IntSet where
      showsPrec :: Mask -> IntSet -> ShowS
    showsPrec Mask
    p IntSet
    xs = Bool -> ShowS -> ShowS
    showParen (Mask
    p Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    > Mask
    10) (ShowS -> ShowS) -> ShowS -> ShowS
    forall a b. (a -> b) -> a -> b
    $
        [Char] -> ShowS
    showString [Char]
    "fromList " ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Mask] -> ShowS
    forall a. Show a => a -> ShowS
    shows (IntSet -> [Mask]
    toList IntSet
    xs)

    {--------------------------------------------------------------------
      Read
    --------------------------------------------------------------------}
    instance Read IntSet where
    #ifdef __GLASGOW_HASKELL__
      readPrec :: ReadPrec IntSet
    readPrec = ReadPrec IntSet -> ReadPrec IntSet
    forall a. ReadPrec a -> ReadPrec a
    parens (ReadPrec IntSet -> ReadPrec IntSet)
    -> ReadPrec IntSet -> ReadPrec IntSet
    forall a b. (a -> b) -> a -> b
    $ Mask -> ReadPrec IntSet -> ReadPrec IntSet
    forall a. Mask -> ReadPrec a -> ReadPrec a
    prec Mask
    10 (ReadPrec IntSet -> ReadPrec IntSet)
    -> ReadPrec IntSet -> ReadPrec IntSet
    forall a b. (a -> b) -> a -> b
    $ do
        Ident [Char]
    "fromList" <- ReadPrec Lexeme
    lexP
        [Mask]
    xs <- ReadPrec [Mask]
    forall a. Read a => ReadPrec a
    readPrec
        IntSet -> ReadPrec IntSet
    forall a. a -> ReadPrec a
    forall (m :: * -> *) a. Monad m => a -> m a
    return ([Mask] -> IntSet
    fromList [Mask]
    xs)

      readListPrec :: ReadPrec [IntSet]
    readListPrec = ReadPrec [IntSet]
    forall a. Read a => ReadPrec [a]
    readListPrecDefault
    #else
      readsPrec p = readParen (p > 10) $ \ r -> do
        ("fromList",s) <- lex r
        (xs,t) <- reads s
        return (fromList xs,t)
    #endif

    {--------------------------------------------------------------------
      NFData
    --------------------------------------------------------------------}

    -- The IntSet constructors consist only of strict fields of Ints and
    -- IntSets, thus the default NFData instance which evaluates to whnf
    -- should suffice
    instance NFData IntSet where rnf :: IntSet -> ()
    rnf IntSet
    x = IntSet -> () -> ()
    forall a b. a -> b -> b
    seq IntSet
    x ()

    {--------------------------------------------------------------------
      Debugging
    --------------------------------------------------------------------}
    -- | \(O(n \min(n,W))\). Show the tree that implements the set. The tree is shown
    -- in a compressed, hanging format.
    showTree :: IntSet -> String
    showTree :: IntSet -> [Char]
    showTree IntSet
    s
      = Bool -> Bool -> IntSet -> [Char]
    showTreeWith Bool
    True Bool
    False IntSet
    s

    {- | \(O(n \min(n,W))\). The expression (@'showTreeWith' hang wide map@) shows
     the tree that implements the set. If @hang@ is
     'True', a /hanging/ tree is shown otherwise a rotated tree is shown. If
     @wide@ is 'True', an extra wide version is shown.
    -}
    showTreeWith :: Bool -> Bool -> IntSet -> String
    showTreeWith :: Bool -> Bool -> IntSet -> [Char]
    showTreeWith Bool
    hang Bool
    wide IntSet
    t
      | Bool
    hang      = (Bool -> [[Char]] -> IntSet -> ShowS
    showsTreeHang Bool
    wide [] IntSet
    t) [Char]
    ""
      | Bool
    otherwise = (Bool -> [[Char]] -> [[Char]] -> IntSet -> ShowS
    showsTree Bool
    wide [] [] IntSet
    t) [Char]
    ""

    showsTree :: Bool -> [String] -> [String] -> IntSet -> ShowS
    showsTree :: Bool -> [[Char]] -> [[Char]] -> IntSet -> ShowS
    showsTree Bool
    wide [[Char]]
    lbars [[Char]]
    rbars IntSet
    t
      = case IntSet
    t of
          Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
              -> Bool -> [[Char]] -> [[Char]] -> IntSet -> ShowS
    showsTree Bool
    wide ([[Char]] -> [[Char]]
    withBar [[Char]]
    rbars) ([[Char]] -> [[Char]]
    withEmpty [[Char]]
    rbars) IntSet
    r ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> ShowS
    showWide Bool
    wide [[Char]]
    rbars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 [[Char]] -> ShowS
    showsBars [[Char]]
    lbars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString (Mask -> Mask -> [Char]
    showBin Mask
    p Mask
    m) ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "\n" ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> ShowS
    showWide Bool
    wide [[Char]]
    lbars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> [[Char]] -> IntSet -> ShowS
    showsTree Bool
    wide ([[Char]] -> [[Char]]
    withEmpty [[Char]]
    lbars) ([[Char]] -> [[Char]]
    withBar [[Char]]
    lbars) IntSet
    l
          Tip Mask
    kx Word
    bm
              -> [[Char]] -> ShowS
    showsBars [[Char]]
    lbars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    " " ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Mask -> ShowS
    forall a. Show a => a -> ShowS
    shows Mask
    kx ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    " + " ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                                                    Word -> ShowS
    showsBitMap Word
    bm ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "\n"
          IntSet
    Nil -> [[Char]] -> ShowS
    showsBars [[Char]]
    lbars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "|\n"

    showsTreeHang :: Bool -> [String] -> IntSet -> ShowS
    showsTreeHang :: Bool -> [[Char]] -> IntSet -> ShowS
    showsTreeHang Bool
    wide [[Char]]
    bars IntSet
    t
      = case IntSet
    t of
          Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
              -> [[Char]] -> ShowS
    showsBars [[Char]]
    bars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString (Mask -> Mask -> [Char]
    showBin Mask
    p Mask
    m) ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "\n" ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> ShowS
    showWide Bool
    wide [[Char]]
    bars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> IntSet -> ShowS
    showsTreeHang Bool
    wide ([[Char]] -> [[Char]]
    withBar [[Char]]
    bars) IntSet
    l ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> ShowS
    showWide Bool
    wide [[Char]]
    bars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                 Bool -> [[Char]] -> IntSet -> ShowS
    showsTreeHang Bool
    wide ([[Char]] -> [[Char]]
    withEmpty [[Char]]
    bars) IntSet
    r
          Tip Mask
    kx Word
    bm
              -> [[Char]] -> ShowS
    showsBars [[Char]]
    bars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    " " ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Mask -> ShowS
    forall a. Show a => a -> ShowS
    shows Mask
    kx ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    " + " ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    .
                                                   Word -> ShowS
    showsBitMap Word
    bm ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "\n"
          IntSet
    Nil -> [[Char]] -> ShowS
    showsBars [[Char]]
    bars ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "|\n"

    showBin :: Prefix -> Mask -> String
    showBin :: Mask -> Mask -> [Char]
    showBin Mask
    _ Mask
    _
      = [Char]
    "*" -- ++ show (p,m)

    showWide :: Bool -> [String] -> String -> String
    showWide :: Bool -> [[Char]] -> ShowS
    showWide Bool
    wide [[Char]]
    bars
      | Bool
    wide      = [Char] -> ShowS
    showString ([[Char]] -> [Char]
    forall (t :: * -> *) a. Foldable t => t [a] -> [a]
    concat ([[Char]] -> [[Char]]
    forall a. [a] -> [a]
    reverse [[Char]]
    bars)) ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    "|\n"
      | Bool
    otherwise = ShowS
    forall a. a -> a
    id

    showsBars :: [String] -> ShowS
    showsBars :: [[Char]] -> ShowS
    showsBars [] = ShowS
    forall a. a -> a
    id
    showsBars ([Char]
    _ : [[Char]]
    tl) = [Char] -> ShowS
    showString ([[Char]] -> [Char]
    forall (t :: * -> *) a. Foldable t => t [a] -> [a]
    concat ([[Char]] -> [[Char]]
    forall a. [a] -> [a]
    reverse [[Char]]
    tl)) ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . [Char] -> ShowS
    showString [Char]
    node

    showsBitMap :: Word -> ShowS
    showsBitMap :: Word -> ShowS
    showsBitMap = [Char] -> ShowS
    showString ([Char] -> ShowS) -> (Word -> [Char]) -> Word -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Word -> [Char]
    showBitMap

    showBitMap :: Word -> String
    showBitMap :: Word -> [Char]
    showBitMap Word
    w = [Mask] -> [Char]
    forall a. Show a => a -> [Char]
    show ([Mask] -> [Char]) -> [Mask] -> [Char]
    forall a b. (a -> b) -> a -> b
    $ Mask -> (Mask -> [Mask] -> [Mask]) -> [Mask] -> Word -> [Mask]
    forall a. Mask -> (Mask -> a -> a) -> a -> Word -> a
    foldrBits Mask
    0 (:) [] Word
    w

    node :: String
    node :: [Char]
    node           = [Char]
    "+--"

    withBar, withEmpty :: [String] -> [String]
    withBar :: [[Char]] -> [[Char]]
    withBar [[Char]]
    bars   = [Char]
    "|  "[Char] -> [[Char]] -> [[Char]]
    forall a. a -> [a] -> [a]
    :[[Char]]
    bars
    withEmpty :: [[Char]] -> [[Char]]
    withEmpty [[Char]]
    bars = [Char]
    "   "[Char] -> [[Char]] -> [[Char]]
    forall a. a -> [a] -> [a]
    :[[Char]]
    bars

    {--------------------------------------------------------------------
      Helpers
    --------------------------------------------------------------------}
    {--------------------------------------------------------------------
      Link
    --------------------------------------------------------------------}
    link :: Prefix -> IntSet -> Prefix -> IntSet -> IntSet
    link :: Mask -> IntSet -> Mask -> IntSet -> IntSet
    link Mask
    p1 IntSet
    t1 Mask
    p2 IntSet
    t2 = Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask (Mask -> Mask -> Mask
    branchMask Mask
    p1 Mask
    p2) Mask
    p1 IntSet
    t1 {-p2-} IntSet
    t2
    {-# INLINE link #-}

    -- `linkWithMask` is useful when the `branchMask` has already been computed
    linkWithMask :: Mask -> Prefix -> IntSet -> IntSet -> IntSet
    linkWithMask :: Mask -> Mask -> IntSet -> IntSet -> IntSet
    linkWithMask Mask
    m Mask
    p1 IntSet
    t1 {-p2-} IntSet
    t2
      | Mask -> Mask -> Bool
    zero Mask
    p1 Mask
    m = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p Mask
    m IntSet
    t1 IntSet
    t2
      | Bool
    otherwise = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p Mask
    m IntSet
    t2 IntSet
    t1
      where
        p :: Mask
    p = Mask -> Mask -> Mask
    mask Mask
    p1 Mask
    m
    {-# INLINE linkWithMask #-}

    {--------------------------------------------------------------------
      @bin@ assures that we never have empty trees within a tree.
    --------------------------------------------------------------------}
    bin :: Prefix -> Mask -> IntSet -> IntSet -> IntSet
    bin :: Mask -> Mask -> IntSet -> IntSet -> IntSet
    bin Mask
    _ Mask
    _ IntSet
    l IntSet
    Nil = IntSet
    l
    bin Mask
    _ Mask
    _ IntSet
    Nil IntSet
    r = IntSet
    r
    bin Mask
    p Mask
    m IntSet
    l IntSet
    r   = Mask -> Mask -> IntSet -> IntSet -> IntSet
    Bin Mask
    p Mask
    m IntSet
    l IntSet
    r
    {-# INLINE bin #-}

    {--------------------------------------------------------------------
      @tip@ assures that we never have empty bitmaps within a tree.
    --------------------------------------------------------------------}
    tip :: Prefix -> BitMap -> IntSet
    tip :: Mask -> Word -> IntSet
    tip Mask
    _ Word
    0 = IntSet
    Nil
    tip Mask
    kx Word
    bm = Mask -> Word -> IntSet
    Tip Mask
    kx Word
    bm
    {-# INLINE tip #-}

    {----------------------------------------------------------------------
      Functions that generate Prefix and BitMap of a Key or a Suffix.
    ----------------------------------------------------------------------}

    suffixBitMask :: Int
    suffixBitMask :: Mask
    suffixBitMask = Word -> Mask
    forall b. FiniteBits b => b -> Mask
    finiteBitSize (Word
    forall a. HasCallStack => a
    undefined::Word) Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    - Mask
    1
    {-# INLINE suffixBitMask #-}

    prefixBitMask :: Int
    prefixBitMask :: Mask
    prefixBitMask = Mask -> Mask
    forall a. Bits a => a -> a
    complement Mask
    suffixBitMask
    {-# INLINE prefixBitMask #-}

    prefixOf :: Int -> Prefix
    prefixOf :: Mask -> Mask
    prefixOf Mask
    x = Mask
    x Mask -> Mask -> Mask
    forall a. Bits a => a -> a -> a
    .&. Mask
    prefixBitMask
    {-# INLINE prefixOf #-}

    suffixOf :: Int -> Int
    suffixOf :: Mask -> Mask
    suffixOf Mask
    x = Mask
    x Mask -> Mask -> Mask
    forall a. Bits a => a -> a -> a
    .&. Mask
    suffixBitMask
    {-# INLINE suffixOf #-}

    bitmapOfSuffix :: Int -> BitMap
    bitmapOfSuffix :: Mask -> Word
    bitmapOfSuffix Mask
    s = Word
    1 Word -> Mask -> Word
    `shiftLL` Mask
    s
    {-# INLINE bitmapOfSuffix #-}

    bitmapOf :: Int -> BitMap
    bitmapOf :: Mask -> Word
    bitmapOf Mask
    x = Mask -> Word
    bitmapOfSuffix (Mask -> Mask
    suffixOf Mask
    x)
    {-# INLINE bitmapOf #-}

    {--------------------------------------------------------------------
      Endian independent bit twiddling
    --------------------------------------------------------------------}
    -- Returns True iff the bits set in i and the Mask m are disjoint.
    zero :: Int -> Mask -> Bool
    zero :: Mask -> Mask -> Bool
    zero Mask
    i Mask
    m
      = (Mask -> Word
    natFromInt Mask
    i) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. (Mask -> Word
    natFromInt Mask
    m) Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    == Word
    0
    {-# INLINE zero #-}

    nomatch,match :: Int -> Prefix -> Mask -> Bool
    nomatch :: Mask -> Mask -> Mask -> Bool
    nomatch Mask
    i Mask
    p Mask
    m
      = (Mask -> Mask -> Mask
    mask Mask
    i Mask
    m) Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    p
    {-# INLINE nomatch #-}

    match :: Mask -> Mask -> Mask -> Bool
    match Mask
    i Mask
    p Mask
    m
      = (Mask -> Mask -> Mask
    mask Mask
    i Mask
    m) Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    == Mask
    p
    {-# INLINE match #-}

    -- Suppose a is largest such that 2^a divides 2*m.
    -- Then mask i m is i with the low a bits zeroed out.
    mask :: Int -> Mask -> Prefix
    mask :: Mask -> Mask -> Mask
    mask Mask
    i Mask
    m
      = Word -> Word -> Mask
    maskW (Mask -> Word
    natFromInt Mask
    i) (Mask -> Word
    natFromInt Mask
    m)
    {-# INLINE mask #-}

    {--------------------------------------------------------------------
      Big endian operations
    --------------------------------------------------------------------}
    maskW :: Nat -> Nat -> Prefix
    maskW :: Word -> Word -> Mask
    maskW Word
    i Word
    m
      = Word -> Mask
    intFromNat (Word
    i Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. (Word -> Word
    forall a. Bits a => a -> a
    complement (Word
    mWord -> Word -> Word
    forall a. Num a => a -> a -> a
    -Word
    1) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    m))
    {-# INLINE maskW #-}

    shorter :: Mask -> Mask -> Bool
    shorter :: Mask -> Mask -> Bool
    shorter Mask
    m1 Mask
    m2
      = (Mask -> Word
    natFromInt Mask
    m1) Word -> Word -> Bool
    forall a. Ord a => a -> a -> Bool
    > (Mask -> Word
    natFromInt Mask
    m2)
    {-# INLINE shorter #-}

    branchMask :: Prefix -> Prefix -> Mask
    branchMask :: Mask -> Mask -> Mask
    branchMask Mask
    p1 Mask
    p2
      = Word -> Mask
    intFromNat (Word -> Word
    highestBitMask (Mask -> Word
    natFromInt Mask
    p1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Mask -> Word
    natFromInt Mask
    p2))
    {-# INLINE branchMask #-}

    {----------------------------------------------------------------------
      To get best performance, we provide fast implementations of
      lowestBitSet, highestBitSet and fold[lr][l]Bits for GHC.
      If the intel bsf and bsr instructions ever become GHC primops,
      this code should be reimplemented using these.

      Performance of this code is crucial for folds, toList, filter, partition.

      The signatures of methods in question are placed after this comment.
    ----------------------------------------------------------------------}

    lowestBitSet :: Nat -> Int
    highestBitSet :: Nat -> Int
    foldlBits :: Int -> (a -> Int -> a) -> a -> Nat -> a
    foldl'Bits :: Int -> (a -> Int -> a) -> a -> Nat -> a
    foldrBits :: Int -> (Int -> a -> a) -> a -> Nat -> a
    foldr'Bits :: Int -> (Int -> a -> a) -> a -> Nat -> a
    takeWhileAntitoneBits :: Int -> (Int -> Bool) -> Nat -> Nat

    {-# INLINE lowestBitSet #-}
    {-# INLINE highestBitSet #-}
    {-# INLINE foldlBits #-}
    {-# INLINE foldl'Bits #-}
    {-# INLINE foldrBits #-}
    {-# INLINE foldr'Bits #-}
    {-# INLINE takeWhileAntitoneBits #-}

    #if defined(__GLASGOW_HASKELL__) && (WORD_SIZE_IN_BITS==32 || WORD_SIZE_IN_BITS==64)
    indexOfTheOnlyBit :: Nat -> Int
    {-# INLINE indexOfTheOnlyBit #-}
    #if WORD_SIZE_IN_BITS==64
    indexOfTheOnlyBit :: Word -> Mask
    indexOfTheOnlyBit Word
    bitmask = Word -> Mask
    forall b. FiniteBits b => b -> Mask
    countTrailingZeros Word
    bitmask

    lowestBitSet :: Word -> Mask
    lowestBitSet Word
    x = Word -> Mask
    forall b. FiniteBits b => b -> Mask
    countTrailingZeros Word
    x

    highestBitSet :: Word -> Mask
    highestBitSet Word
    x = WORD_SIZE_IN_BITS - 1 - countLeadingZeros x

    #else
    {----------------------------------------------------------------------
      For lowestBitSet we use wordsize-dependant implementation based on
      multiplication and DeBrujn indeces, which was proposed by Edward Kmett
      <http://haskell.org/pipermail/libraries/2011-September/016749.html>

      The core of this implementation is fast indexOfTheOnlyBit,
      which is given a Nat with exactly one bit set, and returns
      its index.

      Lot of effort was put in these implementations, please benchmark carefully
      before changing this code.
    ----------------------------------------------------------------------}

    indexOfTheOnlyBit bitmask =
      fromIntegral (GHC.Int.I8# (lsbArray `GHC.Exts.indexInt8OffAddr#` unboxInt (intFromNat ((bitmask * magic) `shiftRL` offset))))
      where unboxInt (GHC.Exts.I# i) = i
    #if WORD_SIZE_IN_BITS==32
            magic = 0x077CB531
            offset = 27
            !lsbArray = "\0\1\28\2\29\14\24\3\30\22\20\15\25\17\4\8\31\27\13\23\21\19\16\7\26\12\18\6\11\5\10\9"#
    #else
            magic = 0x07EDD5E59A4E28C2
            offset = 58
            !lsbArray = "\63\0\58\1\59\47\53\2\60\39\48\27\54\33\42\3\61\51\37\40\49\18\28\20\55\30\34\11\43\14\22\4\62\57\46\52\38\26\32\41\50\36\17\19\29\10\13\21\56\45\25\31\35\16\9\12\44\24\15\8\23\7\6\5"#
    #endif
    -- The lsbArray gets inlined to every call site of indexOfTheOnlyBit.
    -- That cannot be easily avoided, as GHC forbids top-level Addr# literal.
    -- One could go around that by supplying getLsbArray :: () -> Addr# marked
    -- as NOINLINE. But the code size of calling it and processing the result
    -- is 48B on 32-bit and 56B on 64-bit architectures -- so the 32B and 64B array
    -- is actually improvement on 32-bit and only a 8B size increase on 64-bit.

    lowestBitSet x = indexOfTheOnlyBit (lowestBitMask x)

    highestBitSet x = indexOfTheOnlyBit (highestBitMask x)

    #endif

    lowestBitMask :: Nat -> Nat
    lowestBitMask :: Word -> Word
    lowestBitMask Word
    x = Word
    x Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word -> Word
    forall a. Num a => a -> a
    negate Word
    x
    {-# INLINE lowestBitMask #-}

    -- Reverse the order of bits in the Nat.
    revNat :: Nat -> Nat
    #if WORD_SIZE_IN_BITS==32
    revNat x1 = case ((x1 `shiftRL` 1) .&. 0x55555555) .|. ((x1 .&. 0x55555555) `shiftLL` 1) of
                  x2 -> case ((x2 `shiftRL` 2) .&. 0x33333333) .|. ((x2 .&. 0x33333333) `shiftLL` 2) of
                     x3 -> case ((x3 `shiftRL` 4) .&. 0x0F0F0F0F) .|. ((x3 .&. 0x0F0F0F0F) `shiftLL` 4) of
                       x4 -> case ((x4 `shiftRL` 8) .&. 0x00FF00FF) .|. ((x4 .&. 0x00FF00FF) `shiftLL` 8) of
                         x5 -> ( x5 `shiftRL` 16             ) .|. ( x5               `shiftLL` 16);
    #else
    revNat :: Word -> Word
    revNat Word
    x1 = case ((Word
    x1 Word -> Mask -> Word
    `shiftRL` Mask
    1) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x5555555555555555) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ((Word
    x1 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x5555555555555555) Word -> Mask -> Word
    `shiftLL` Mask
    1) of
                  Word
    x2 -> case ((Word
    x2 Word -> Mask -> Word
    `shiftRL` Mask
    2) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x3333333333333333) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ((Word
    x2 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x3333333333333333) Word -> Mask -> Word
    `shiftLL` Mask
    2) of
                     Word
    x3 -> case ((Word
    x3 Word -> Mask -> Word
    `shiftRL` Mask
    4) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x0F0F0F0F0F0F0F0F) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ((Word
    x3 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x0F0F0F0F0F0F0F0F) Word -> Mask -> Word
    `shiftLL` Mask
    4) of
                       Word
    x4 -> case ((Word
    x4 Word -> Mask -> Word
    `shiftRL` Mask
    8) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x00FF00FF00FF00FF) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ((Word
    x4 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x00FF00FF00FF00FF) Word -> Mask -> Word
    `shiftLL` Mask
    8) of
                         Word
    x5 -> case ((Word
    x5 Word -> Mask -> Word
    `shiftRL` Mask
    16) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x0000FFFF0000FFFF) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ((Word
    x5 Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x0000FFFF0000FFFF) Word -> Mask -> Word
    `shiftLL` Mask
    16) of
                           Word
    x6 -> ( Word
    x6 Word -> Mask -> Word
    `shiftRL` Mask
    32             ) Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .|. ( Word
    x6               Word -> Mask -> Word
    `shiftLL` Mask
    32);
    #endif

    foldlBits :: forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldlBits Mask
    prefix a -> Mask -> a
    f a
    z Word
    bitmap = Word -> a -> a
    go Word
    bitmap a
    z
      where go :: Word -> a -> a
    go Word
    0 a
    acc = a
    acc
            go Word
    bm a
    acc = Word -> a -> a
    go (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bitmask) ((a -> Mask -> a
    f a
    acc) (Mask -> a) -> Mask -> a
    forall a b. (a -> b) -> a -> b
    $! (Mask
    prefixMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    bi))
              where
                !bitmask :: Word
    bitmask = Word -> Word
    lowestBitMask Word
    bm
                !bi :: Mask
    bi = Word -> Mask
    indexOfTheOnlyBit Word
    bitmask

    foldl'Bits :: forall a. Mask -> (a -> Mask -> a) -> a -> Word -> a
    foldl'Bits Mask
    prefix a -> Mask -> a
    f a
    z Word
    bitmap = Word -> a -> a
    go Word
    bitmap a
    z
      where go :: Word -> a -> a
    go Word
    0 a
    acc = a
    acc
            go Word
    bm !a
    acc = Word -> a -> a
    go (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bitmask) ((a -> Mask -> a
    f a
    acc) (Mask -> a) -> Mask -> a
    forall a b. (a -> b) -> a -> b
    $! (Mask
    prefixMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    bi))
              where !bitmask :: Word
    bitmask = Word -> Word
    lowestBitMask Word
    bm
                    !bi :: Mask
    bi = Word -> Mask
    indexOfTheOnlyBit Word
    bitmask

    foldrBits :: forall a. Mask -> (Mask -> a -> a) -> a -> Word -> a
    foldrBits Mask
    prefix Mask -> a -> a
    f a
    z Word
    bitmap = Word -> a -> a
    go (Word -> Word
    revNat Word
    bitmap) a
    z
      where go :: Word -> a -> a
    go Word
    0 a
    acc = a
    acc
            go Word
    bm a
    acc = Word -> a -> a
    go (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bitmask) ((Mask -> a -> a
    f (Mask -> a -> a) -> Mask -> a -> a
    forall a b. (a -> b) -> a -> b
    $! (Mask
    prefixMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +(WORD_SIZE_IN_BITS-1)-bi)) acc)
              where !bitmask :: Word
    bitmask = Word -> Word
    lowestBitMask Word
    bm
                    !bi :: Mask
    bi = Word -> Mask
    indexOfTheOnlyBit Word
    bitmask

    foldr'Bits :: forall a. Mask -> (Mask -> a -> a) -> a -> Word -> a
    foldr'Bits Mask
    prefix Mask -> a -> a
    f a
    z Word
    bitmap = Word -> a -> a
    go (Word -> Word
    revNat Word
    bitmap) a
    z
      where go :: Word -> a -> a
    go Word
    0 a
    acc = a
    acc
            go Word
    bm !a
    acc = Word -> a -> a
    go (Word
    bm Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    `xor` Word
    bitmask) ((Mask -> a -> a
    f (Mask -> a -> a) -> Mask -> a -> a
    forall a b. (a -> b) -> a -> b
    $! (Mask
    prefixMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +(WORD_SIZE_IN_BITS-1)-bi)) acc)
              where !bitmask :: Word
    bitmask = Word -> Word
    lowestBitMask Word
    bm
                    !bi :: Mask
    bi = Word -> Mask
    indexOfTheOnlyBit Word
    bitmask

    takeWhileAntitoneBits :: Mask -> (Mask -> Bool) -> Word -> Word
    takeWhileAntitoneBits Mask
    prefix Mask -> Bool
    predicate Word
    bitmap =
      -- Binary search for the first index where the predicate returns false, but skip a predicate
      -- call if the high half of the current range is empty. This ensures
      -- min (log2 WORD_SIZE_IN_BITS + 1) (popcount bitmap) predicate calls.
      let next :: Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    d Word
    h (Word
    n',Mask
    b') =
            if Word
    n' Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    h Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 Bool -> Bool -> Bool
    && (Mask -> Bool
    predicate (Mask -> Bool) -> Mask -> Bool
    forall a b. (a -> b) -> a -> b
    $! Mask
    prefixMask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    b'Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    d) then (Word
    n' Word -> Mask -> Word
    `shiftRL` Mask
    d, Mask
    b'Mask -> Mask -> Mask
    forall a. Num a => a -> a -> a
    +Mask
    d) else (Word
    n',Mask
    b')
          {-# INLINE next #-}
          (Word
    _,Mask
    b) = Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    1  Word
    0x2 ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
                  Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    2  Word
    0xC ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
                  Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    4  Word
    0xF0 ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
                  Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    8  Word
    0xFF00 ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
                  Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    16 Word
    0xFFFF0000 ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
    #if WORD_SIZE_IN_BITS==64
                  Mask -> Word -> (Word, Mask) -> (Word, Mask)
    next Mask
    32 Word
    0xFFFFFFFF00000000 ((Word, Mask) -> (Word, Mask)) -> (Word, Mask) -> (Word, Mask)
    forall a b. (a -> b) -> a -> b
    $
    #endif
                  (Word
    bitmap,Mask
    0)
          m :: Word
    m = if Mask
    b Mask -> Mask -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Mask
    0 Bool -> Bool -> Bool
    || (Word
    bitmap Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    0x1 Word -> Word -> Bool
    forall a. Eq a => a -> a -> Bool
    /= Word
    0 Bool -> Bool -> Bool
    && Mask -> Bool
    predicate Mask
    prefix)
              then ((Word
    2 Word -> Mask -> Word
    `shiftLL` Mask
    b) Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1)
              else ((Word
    1 Word -> Mask -> Word
    `shiftLL` Mask
    b) Word -> Word -> Word
    forall a. Num a => a -> a -> a
    - Word
    1)
      in Word
    bitmap Word -> Word -> Word
    forall a. Bits a => a -> a -> a
    .&. Word
    m

    #else
    {----------------------------------------------------------------------
      In general case we use logarithmic implementation of
      lowestBitSet and highestBitSet, which works up to bit sizes of 64.

      Folds are linear scans.
    ----------------------------------------------------------------------}

    lowestBitSet n0 =
        let (n1,b1) = if n0 .&. 0xFFFFFFFF /= 0 then (n0,0)  else (n0 `shiftRL` 32, 32)
            (n2,b2) = if n1 .&. 0xFFFF /= 0     then (n1,b1) else (n1 `shiftRL` 16, 16+b1)
            (n3,b3) = if n2 .&. 0xFF /= 0       then (n2,b2) else (n2 `shiftRL` 8,  8+b2)
            (n4,b4) = if n3 .&. 0xF /= 0        then (n3,b3) else (n3 `shiftRL` 4,  4+b3)
            (n5,b5) = if n4 .&. 0x3 /= 0        then (n4,b4) else (n4 `shiftRL` 2,  2+b4)
            b6      = if n5 .&. 0x1 /= 0        then     b5  else                   1+b5
        in b6

    highestBitSet n0 =
        let (n1,b1) = if n0 .&. 0xFFFFFFFF00000000 /= 0 then (n0 `shiftRL` 32, 32)    else (n0,0)
            (n2,b2) = if n1 .&. 0xFFFF0000 /= 0         then (n1 `shiftRL` 16, 16+b1) else (n1,b1)
            (n3,b3) = if n2 .&. 0xFF00 /= 0             then (n2 `shiftRL` 8,  8+b2)  else (n2,b2)
            (n4,b4) = if n3 .&. 0xF0 /= 0               then (n3 `shiftRL` 4,  4+b3)  else (n3,b3)
            (n5,b5) = if n4 .&. 0xC /= 0                then (n4 `shiftRL` 2,  2+b4)  else (n4,b4)
            b6      = if n5 .&. 0x2 /= 0                then                   1+b5   else     b5
        in b6

    foldlBits prefix f z bm = let lb = lowestBitSet bm
                              in  go (prefix+lb) z (bm `shiftRL` lb)
      where go !_ acc 0 = acc
            go bi acc n | n `testBit` 0 = go (bi + 1) (f acc bi) (n `shiftRL` 1)
                        | otherwise     = go (bi + 1)    acc     (n `shiftRL` 1)

    foldl'Bits prefix f z bm = let lb = lowestBitSet bm
                               in  go (prefix+lb) z (bm `shiftRL` lb)
      where go !_ !acc 0 = acc
            go bi acc n | n `testBit` 0 = go (bi + 1) (f acc bi) (n `shiftRL` 1)
                        | otherwise     = go (bi + 1)    acc     (n `shiftRL` 1)

    foldrBits prefix f z bm = let lb = lowestBitSet bm
                              in  go (prefix+lb) (bm `shiftRL` lb)
      where go !_ 0 = z
            go bi n | n `testBit` 0 = f bi (go (bi + 1) (n `shiftRL` 1))
                    | otherwise     =       go (bi + 1) (n `shiftRL` 1)

    foldr'Bits prefix f z bm = let lb = lowestBitSet bm
                               in  go (prefix+lb) (bm `shiftRL` lb)
      where
            go !_ 0 = z
            go bi n | n `testBit` 0 = f bi $! go (bi + 1) (n `shiftRL` 1)
                    | otherwise     =         go (bi + 1) (n `shiftRL` 1)

    takeWhileAntitoneBits prefix predicate = foldl'Bits prefix f 0 -- Does not use antitone property
      where
        f acc bi | predicate bi = acc .|. bitmapOf bi
                 | otherwise    = acc

    #endif

    {--------------------------------------------------------------------
      Utilities
    --------------------------------------------------------------------}

    -- | \(O(1)\).  Decompose a set into pieces based on the structure of the underlying
    -- tree.  This function is useful for consuming a set in parallel.
    --
    -- No guarantee is made as to the sizes of the pieces; an internal, but
    -- deterministic process determines this.  However, it is guaranteed that the
    -- pieces returned will be in ascending order (all elements in the first submap
    -- less than all elements in the second, and so on).
    --
    -- Examples:
    --
    -- > splitRoot (fromList [1..120]) == [fromList [1..63],fromList [64..120]]
    -- > splitRoot empty == []
    --
    --  Note that the current implementation does not return more than two subsets,
    --  but you should not depend on this behaviour because it can change in the
    --  future without notice. Also, the current version does not continue
    --  splitting all the way to individual singleton sets -- it stops at some
    --  point.
    splitRoot :: IntSet -> [IntSet]
    splitRoot :: IntSet -> [IntSet]
    splitRoot IntSet
    Nil = []
    -- NOTE: we don't currently split below Tip, but we could.
    splitRoot x :: IntSet
    x@(Tip Mask
    _ Word
    _) = [IntSet
    x]
    splitRoot (Bin Mask
    _ Mask
    m IntSet
    l IntSet
    r) | Mask
    m Mask -> Mask -> Bool
    forall a. Ord a => a -> a -> Bool
    < Mask
    0 = [IntSet
    r, IntSet
    l]
                            | Bool
    otherwise = [IntSet
    l, IntSet
    r]
    {-# INLINE splitRoot #-}