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| author | Bodigrim <andrew.lelechenko@gmail.com> | 2022-10-09 13:45:31 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-10-11 18:02:59 -0400 |
| commit | da679f2eda0f920afa522ce9c4b9ad50cdec7d74 (patch) | |
| tree | e602e88d1d81566934b4beb19b602b50b9962411 /libraries/base/GHC | |
| parent | dce9f320ce7275fa97f49abef604abbc3b0f9a9c (diff) | |
| download | haskell-da679f2eda0f920afa522ce9c4b9ad50cdec7d74.tar.gz | |
Extend documentation for Data.List, mostly wrt infinite lists
Diffstat (limited to 'libraries/base/GHC')
| -rw-r--r-- | libraries/base/GHC/List.hs | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/libraries/base/GHC/List.hs b/libraries/base/GHC/List.hs index 6b1a94fafe..b96c16cfab 100644 --- a/libraries/base/GHC/List.hs +++ b/libraries/base/GHC/List.hs @@ -801,8 +801,8 @@ iterate'FB c f x0 = go x0 -- | 'repeat' @x@ is an infinite list, with @x@ the value of every element. -- --- >>> take 20 $ repeat 17 ---[17,17,17,17,17,17,17,17,17... +-- >>> repeat 17 +-- [17,17,17,17,17,17,17,17,17... repeat :: a -> [a] {-# INLINE [0] repeat #-} -- The pragma just gives the rules more chance to fire @@ -839,9 +839,9 @@ replicate n x = take n (repeat x) -- -- >>> cycle [] -- *** Exception: Prelude.cycle: empty list --- >>> take 20 $ cycle [42] +-- >>> cycle [42] -- [42,42,42,42,42,42,42,42,42,42... --- >>> take 20 $ cycle [2, 5, 7] +-- >>> cycle [2, 5, 7] -- [2,5,7,2,5,7,2,5,7,2,5,7... cycle :: HasCallStack => [a] -> [a] cycle [] = errorEmptyList "cycle" @@ -1284,6 +1284,7 @@ notElem x (y:ys)= x /= y && notElem x ys -- | \(\mathcal{O}(n)\). 'lookup' @key assocs@ looks up a key in an association -- list. +-- For the result to be 'Nothing', the list must be finite. -- -- >>> lookup 2 [] -- Nothing @@ -1291,6 +1292,7 @@ notElem x (y:ys)= x /= y && notElem x ys -- Nothing -- >>> lookup 2 [(1, "first"), (2, "second"), (3, "third")] -- Just "second" +-- lookup :: (Eq a) => a -> [(a,b)] -> Maybe b lookup _key [] = Nothing lookup key ((x,y):xys) @@ -1349,8 +1351,8 @@ concat = foldr (++) [] -- >>> ['a', 'b', 'c'] !! (-1) -- *** Exception: Prelude.!!: negative index -- --- WARNING: This function is partial. You can use <'atMay' --- https://hackage.haskell.org/package/safe-0.3.19/docs/Safe.html#v:atMay> +-- WARNING: This function is partial. You can use +-- <https://hackage.haskell.org/package/safe/docs/Safe.html#v:atMay atMay> -- instead. #if defined(USE_REPORT_PRELUDE) (!!) :: [a] -> Int -> a |