[Git][ghc/ghc][master] 2 commits: Add permutations for non-empty lists.
Marge Bot (@marge-bot)
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Fri Nov 17 01:54:05 UTC 2023
Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
9bc0dd1f by Ignat Insarov at 2023-11-16T20:53:34-05:00
Add permutations for non-empty lists.
Approved by CLC in https://github.com/haskell/core-libraries-committee/issues/68#issuecomment-1221409837
- - - - -
5643ecf9 by Andrew Lelechenko at 2023-11-16T20:53:34-05:00
Update changelog and since annotations for Data.List.NonEmpty.permutations
Approved by CLC in https://github.com/haskell/core-libraries-committee/issues/68#issuecomment-1221409837
- - - - -
6 changed files:
- libraries/base/changelog.md
- libraries/base/src/Data/List/NonEmpty.hs
- testsuite/tests/interface-stability/base-exports.stdout
- testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs
- testsuite/tests/interface-stability/base-exports.stdout-mingw32
- testsuite/tests/interface-stability/base-exports.stdout-ws-32
Changes:
=====================================
libraries/base/changelog.md
=====================================
@@ -2,6 +2,7 @@
## 4.20.0.0 *TBA*
* Export `foldl'` from `Prelude` ([CLC proposal #167](https://github.com/haskell/core-libraries-committee/issues/167))
+ * Add `permutations` and `permutations1` to `Data.List.NonEmpty` ([CLC proposal #68](https://github.com/haskell/core-libraries-committee/issues/68))
* Add a `RULE` to `Prelude.lookup`, allowing it to participate in list fusion ([CLC proposal #174](https://github.com/haskell/core-libraries-committee/issues/175))
* The `Enum Int64` and `Enum Word64` instances now use native operations on 32-bit platforms, increasing performance by up to 1.5x on i386 and up to 5.6x with the JavaScript backend. ([CLC proposal #187](https://github.com/haskell/core-libraries-committee/issues/187))
* Update to [Unicode 15.1.0](https://www.unicode.org/versions/Unicode15.1.0/).
=====================================
libraries/base/src/Data/List/NonEmpty.hs
=====================================
@@ -78,6 +78,8 @@ module Data.List.NonEmpty (
, groupBy1 -- :: (a -> a -> Bool) -> NonEmpty a -> NonEmpty (NonEmpty a)
, groupWith1 -- :: (Foldable f, Eq b) => (a -> b) -> f a -> NonEmpty (NonEmpty a)
, groupAllWith1 -- :: (Foldable f, Ord b) => (a -> b) -> f a -> NonEmpty (NonEmpty a)
+ , permutations
+ , permutations1
-- * Sublist predicates
, isPrefixOf -- :: Foldable f => f a -> NonEmpty a -> Bool
-- * \"Set\" operations
@@ -441,6 +443,30 @@ groupWith1 f = groupBy1 ((==) `on` f)
groupAllWith1 :: (Ord b) => (a -> b) -> NonEmpty a -> NonEmpty (NonEmpty a)
groupAllWith1 f = groupWith1 f . sortWith f
+-- | The 'permutations' function returns the list of all permutations of the argument.
+--
+-- @since 4.20.0.0
+permutations :: [a] -> NonEmpty [a]
+permutations xs0 = xs0 :| perms xs0 []
+ where
+ perms [] _ = []
+ perms (t:ts) is = foldr interleave (perms ts (t:is)) (permutations is)
+ where interleave xs r = let (_,zs) = interleave' id xs r in zs
+ interleave' _ [] r = (ts, r)
+ interleave' f (y:ys) r = let (us,zs) = interleave' (f . (y:)) ys r
+ in (y:us, f (t:y:us) : zs)
+-- The implementation of 'permutations' is adopted from 'Data.List.permutations',
+-- see there for discussion and explanations.
+
+-- | 'permutations1' operates like 'permutations', but uses the knowledge that its input is
+-- non-empty to produce output where every element is non-empty.
+--
+-- > permutations1 = fmap fromList . permutations . toList
+--
+-- @since 4.20.0.0
+permutations1 :: NonEmpty a -> NonEmpty (NonEmpty a)
+permutations1 xs = fromList <$> permutations (toList xs)
+
-- | The 'isPrefixOf' function returns 'True' if the first argument is
-- a prefix of the second.
isPrefixOf :: Eq a => [a] -> NonEmpty a -> Bool
=====================================
testsuite/tests/interface-stability/base-exports.stdout
=====================================
@@ -1410,6 +1410,8 @@ module Data.List.NonEmpty where
nub :: forall a. GHC.Classes.Eq a => NonEmpty a -> NonEmpty a
nubBy :: forall a. (a -> a -> GHC.Types.Bool) -> NonEmpty a -> NonEmpty a
partition :: forall a. (a -> GHC.Types.Bool) -> NonEmpty a -> ([a], [a])
+ permutations :: forall a. [a] -> NonEmpty [a]
+ permutations1 :: forall a. NonEmpty a -> NonEmpty (NonEmpty a)
prependList :: forall a. [a] -> NonEmpty a -> NonEmpty a
repeat :: forall a. a -> NonEmpty a
reverse :: forall a. NonEmpty a -> NonEmpty a
=====================================
testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs
=====================================
@@ -1410,6 +1410,8 @@ module Data.List.NonEmpty where
nub :: forall a. GHC.Classes.Eq a => NonEmpty a -> NonEmpty a
nubBy :: forall a. (a -> a -> GHC.Types.Bool) -> NonEmpty a -> NonEmpty a
partition :: forall a. (a -> GHC.Types.Bool) -> NonEmpty a -> ([a], [a])
+ permutations :: forall a. [a] -> NonEmpty [a]
+ permutations1 :: forall a. NonEmpty a -> NonEmpty (NonEmpty a)
prependList :: forall a. [a] -> NonEmpty a -> NonEmpty a
repeat :: forall a. a -> NonEmpty a
reverse :: forall a. NonEmpty a -> NonEmpty a
=====================================
testsuite/tests/interface-stability/base-exports.stdout-mingw32
=====================================
@@ -1410,6 +1410,8 @@ module Data.List.NonEmpty where
nub :: forall a. GHC.Classes.Eq a => NonEmpty a -> NonEmpty a
nubBy :: forall a. (a -> a -> GHC.Types.Bool) -> NonEmpty a -> NonEmpty a
partition :: forall a. (a -> GHC.Types.Bool) -> NonEmpty a -> ([a], [a])
+ permutations :: forall a. [a] -> NonEmpty [a]
+ permutations1 :: forall a. NonEmpty a -> NonEmpty (NonEmpty a)
prependList :: forall a. [a] -> NonEmpty a -> NonEmpty a
repeat :: forall a. a -> NonEmpty a
reverse :: forall a. NonEmpty a -> NonEmpty a
=====================================
testsuite/tests/interface-stability/base-exports.stdout-ws-32
=====================================
@@ -1410,6 +1410,8 @@ module Data.List.NonEmpty where
nub :: forall a. GHC.Classes.Eq a => NonEmpty a -> NonEmpty a
nubBy :: forall a. (a -> a -> GHC.Types.Bool) -> NonEmpty a -> NonEmpty a
partition :: forall a. (a -> GHC.Types.Bool) -> NonEmpty a -> ([a], [a])
+ permutations :: forall a. [a] -> NonEmpty [a]
+ permutations1 :: forall a. NonEmpty a -> NonEmpty (NonEmpty a)
prependList :: forall a. [a] -> NonEmpty a -> NonEmpty a
repeat :: forall a. a -> NonEmpty a
reverse :: forall a. NonEmpty a -> NonEmpty a
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b4f84e4bfac3648864d9482b7585a01d44b5eb58...5643ecf97150805032203bd9c8c92b5ded54d724
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b4f84e4bfac3648864d9482b7585a01d44b5eb58...5643ecf97150805032203bd9c8c92b5ded54d724
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