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Commit 1060462

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Add (Int, +) finger trees
* Export a type for `(Int,+)` finger trees. * Export more `Data.Sequence` internals. * Offer a module of `Data.Sequence` internals intended for external use, that should obey the PVP.
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‎containers/changelog.md

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# Changelog for [`containers` package](http://github.com/haskell/containers)
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3-
## [0.6.4.1]
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## 0.6.5.1
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* Add support for finger trees with measurements in the `(Int, +)`
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monoid.
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* Export more `Data.Sequence` internals.
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* Add a `Data.Sequence.StableInternal` module exporting functions
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intended for use by external packages.
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* Remove the `Functor` and `Traversable` instances from the
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heretofore "internal" `FingerTree` and `Node` types, in favor
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of type-specific mapping functions. These instances could
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break data structure invariants.
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* Remove the `Generic1 FingerTree` instance, which can no longer
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be derived.
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## 0.6.4.1
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### Bug fixes
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‎containers/containers.cabal

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exposed-modules:
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Data.Containers.ListUtils
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Data.FingerTree.IntPlus
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Data.FingerTree.IntPlus.Unsafe
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Data.IntMap
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Data.IntMap.Lazy
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Data.IntMap.Strict
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Data.Sequence
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Data.Sequence.Internal
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Data.Sequence.Internal.Sorting
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Data.Sequence.StableInternal
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Data.Tree
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Utils.Containers.Internal.BitUtil
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Utils.Containers.Internal.BitQueue
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{-# LANGUAGE CPP #-}
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#include "containers.h"
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{-# LANGUAGE BangPatterns #-}
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#ifdef DEFINE_PATTERN_SYNONYMS
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{-# LANGUAGE PatternSynonyms #-}
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{-# LANGUAGE ViewPatterns #-}
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#endif
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-- | This module exports a type of finger trees with measurements ("sizes") in
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-- the @(Int, +)@ monoid. This type is used to implement sequences in
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-- "Data.Sequence". It may occasionally be useful for other purposes.
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--
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-- Caution: splitting and lookup functions assume that the size of the tree is
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-- at most @'maxBound' :: Int@. If this is not the case, then they may produce
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-- errors and/or utter nonsense.
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module Data.FingerTree.IntPlus
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(
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#ifdef DEFINE_PATTERN_SYNONYMS
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FingerTree (Empty, (:<|), (:|>), Singleton)
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#else
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FingerTree
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#endif
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, Elem (..)
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, Sized (..)
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, Split (..)
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, UncheckedSplit (..)
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, ViewL (..)
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, ViewR (..)
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, (<|)
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, (|>)
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, (><)
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, fromList
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, viewl
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, viewr
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, split
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, uncheckedSplit
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) where
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import Data.Sequence.Internal
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( FingerTree (..), Sized (..), Elem (..) )
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import qualified Data.Sequence.Internal as S
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#if !MIN_VERSION_base(4,8,0)
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import Data.Word (Word)
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#endif
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infixr 5 ><
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infixr 5 <|, :<
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infixl 5 |>, :>
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(<|) :: Sized a => a -> FingerTree a -> FingerTree a
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(<|) = S.consTree
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(|>) :: Sized a => FingerTree a -> a -> FingerTree a
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(|>) = S.snocTree
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(><) :: Sized a => FingerTree a -> FingerTree a -> FingerTree a
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(><) = S.appendTree
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fromList :: Sized a => [a] -> FingerTree a
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fromList = S.fromListFT
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data ViewL a = a :< FingerTree a | EmptyL
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data ViewR a = FingerTree a :> a | EmptyR
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{-# INLINE viewl #-}
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viewl :: Sized a => FingerTree a -> ViewL a
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viewl t = case S.viewLTree t of
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S.ConsLTree a as -> a :< as
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S.EmptyLTree -> EmptyL
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{-# INLINE viewr #-}
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viewr :: Sized a => FingerTree a -> ViewR a
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viewr t = case S.viewRTree t of
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S.SnocRTree as a -> as :> a
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S.EmptyRTree -> EmptyR
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#ifdef DEFINE_PATTERN_SYNONYMS
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infixr 5 :<|
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infixl 5 :|>
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#if __GLASGOW_HASKELL__ >= 801
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{-# COMPLETE (:<|), Empty #-}
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{-# COMPLETE (:|>), Empty #-}
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#endif
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-- | A bidirectional pattern synonym matching an empty finger tree.
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pattern Empty :: S.FingerTree a
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pattern Empty = S.EmptyT
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-- | A bidirectional pattern synonym viewing the front of a non-empty
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-- finger tree.
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pattern (:<|) :: Sized a => a -> FingerTree a -> FingerTree a
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pattern x :<| xs <- (viewl -> x :< xs)
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where
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x :<| xs = x <| xs
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-- | A bidirectional pattern synonym viewing the rear of a non-empty
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-- finger tree.
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pattern (:|>) :: Sized a => FingerTree a -> a -> FingerTree a
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pattern xs :|> x <- (viewr -> xs :> x)
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where
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xs :|> x = xs |> x
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-- | A bidirectional pattern synonym for a singleton
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-- sequence. @Singleton xs@ is equivalent to @xs :< Empty@.
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pattern Singleton :: a -> FingerTree a
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pattern Singleton x <- S.Single x
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where
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Singleton = S.Single
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#endif
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data Split a
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= Split !(FingerTree a) a !(FingerTree a)
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| EmptySplit
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data UncheckedSplit a
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= UncheckedSplit !(FingerTree a) a !(FingerTree a)
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-- | Split a finger tree around a measurement.
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--
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-- @split i xs = EmptySplit@ if and only if @xs = Empty@. Given that
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--
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-- @
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-- split i xs = 'Split' l x r
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-- @
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--
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-- it's guaranteed that
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--
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-- 1. @ xs = l <> (x <| r) @
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-- 2. @i >= size l@ or @l = Empty@
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-- 3. @i < size l + size x@ or @r = Empty@
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split :: Sized a => Int -> FingerTree a -> Split a
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split !_i S.EmptyT = EmptySplit
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split i ft
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| S.Split l m r <- S.splitTree i ft
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= Split l m r
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-- | Split a nonempty finger tree around a measurement. Given that
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--
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-- @
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-- uncheckedSplit i xs = 'UncheckedSplit' l x r
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-- @
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--
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-- it's guaranteed that
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--
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-- 1. @ xs = l <> (x <| r) @
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-- 2. @i >= size l@ or @l = Empty@
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-- 3. @i < size l + size x@ or @r = Empty@
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uncheckedSplit :: Sized a => Int -> FingerTree a -> UncheckedSplit a
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uncheckedSplit i ft
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| S.Split l m r <- S.splitTree i ft
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= UncheckedSplit l m r
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{-# LANGUAGE CPP #-}
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#include "containers.h"
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-- | This module exports functions that can easily
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-- produce finger trees violating the annotation invariants.
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-- Trees violating these invariants will produce garbage
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-- when split.
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module Data.FingerTree.IntPlus.Unsafe
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( unsafeMap
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, unsafeTraverse
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) where
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import Data.Sequence.Internal
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( FingerTree (..), Node (..) )
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import qualified Data.Sequence.Internal as S
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import Control.Applicative (liftA2, liftA3)
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-- | Map over a 'FingerTree'. The following precondition
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-- is assumed but not checked:
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--
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-- For each @a@ in the @FingerTree@, @size (f a) = size a@.
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unsafeMap :: (a -> b) -> FingerTree a -> FingerTree b
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unsafeMap = S.unsafeMapFT
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-- | Traverse a 'FingerTree'. The following precondition is required
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-- but not checked:
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--
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-- For each element @a@ in the 'FingerTree',
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-- @size <$> f a = size a <$ f a@
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unsafeTraverse :: Applicative f => (a -> f b) -> FingerTree a -> f (FingerTree b)
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unsafeTraverse _ EmptyT = pure EmptyT
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unsafeTraverse f (Single x) = Single <$> f x
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unsafeTraverse f (Deep v pr m sf) =
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liftA3 (Deep v) (traverse f pr) (unsafeTraverse (unsafeTraverseNode f) m) (traverse f sf)
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-- | Traverse a 'Node'. The following precondition is required
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-- but not checked:
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--
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-- For each element @a@ in the 'Node',
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-- @size <$> f a = size a <$ f a@
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unsafeTraverseNode :: Applicative f => (a -> f b) -> Node a -> f (Node b)
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unsafeTraverseNode f (Node2 v a b) = liftA2 (Node2 v) (f a) (f b)
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unsafeTraverseNode f (Node3 v a b c) = liftA3 (Node3 v) (f a) (f b) (f c)

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