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| author | jwaldmann <johannes.waldmann@htwk-leipzig.de> | 2022-10-11 17:51:56 +0000 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-10-11 18:02:59 -0400 |
| commit | 9c099387ae82b7bf91232b714a3d35f429d6ffe3 (patch) | |
| tree | 783ebbf4b6a6d98880ad6739cc86ba407ec61cb4 /libraries | |
| parent | da679f2eda0f920afa522ce9c4b9ad50cdec7d74 (diff) | |
| download | haskell-9c099387ae82b7bf91232b714a3d35f429d6ffe3.tar.gz | |
Expand comment for Data.List.permutations
Diffstat (limited to 'libraries')
| -rw-r--r-- | libraries/base/Data/OldList.hs | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/libraries/base/Data/OldList.hs b/libraries/base/Data/OldList.hs index 4ba0a8e4df..240292f95b 100644 --- a/libraries/base/Data/OldList.hs +++ b/libraries/base/Data/OldList.hs @@ -1246,6 +1246,9 @@ nonEmptySubsequences (x:xs) = [x] : foldr f [] (nonEmptySubsequences xs) -- >>> permutations "abc" -- ["abc","bac","cba","bca","cab","acb"] -- +-- The 'permutations' function is maximally lazy: +-- for each @n@, the value of @'permutations' xs@ starts with those permutations +-- that permute @'take' n xs@ and keep @'drop' n xs@. -- This function is productive on infinite inputs: -- -- >>> take 6 $ map (take 3) $ permutations ['a'..] |