diff options
| -rw-r--r-- | libraries/base/GHC/List.hs | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/libraries/base/GHC/List.hs b/libraries/base/GHC/List.hs index 4427d1af1b..edbe535f76 100644 --- a/libraries/base/GHC/List.hs +++ b/libraries/base/GHC/List.hs @@ -34,8 +34,8 @@ module GHC.List ( head, last, tail, init, uncons, (!?), (!!), scanl, scanl1, scanl', scanr, scanr1, iterate, iterate', repeat, replicate, cycle, - take, drop, splitAt, takeWhile, dropWhile, span, break, reverse, - zip, zip3, zipWith, zipWith3, unzip, unzip3, + take, drop, splitAt, takeWhile, dropWhile, span, span', break, break', + reverse, zip, zip3, zipWith, zipWith3, unzip, unzip3, errorEmptyList, -- * GHC List fusion @@ -1082,6 +1082,15 @@ span p xs@(x:xs') | p x = let (ys,zs) = span p xs' in (x:ys,zs) | otherwise = ([],xs) +-- | span' is equivalent to span, but is strict on the recursive tuple +span' :: (a -> Bool) -> [a] -> ([a],[a]) +span' _ xs@[] = (xs, xs) +span' p xs@(x:xs') + | p x = let !(ys,zs) = span' p xs' in (x:ys,zs) + | otherwise = ([],xs) + + + -- | 'break', applied to a predicate @p@ and a list @xs@, returns a tuple where -- first element is longest prefix (possibly empty) of @xs@ of elements that -- /do not satisfy/ @p@ and second element is the remainder of the list: @@ -1105,6 +1114,14 @@ break p xs@(x:xs') | otherwise = let (ys,zs) = break p xs' in (x:ys,zs) #endif +-- | break' is equivalent to break, but is strict on the recursive tuple +break' :: (a -> Bool) -> [a] -> ([a],[a]) +break' _ xs@[] = (xs, xs) +break' p xs@(x:xs') + | p x = ([],xs) + | otherwise = let !(ys,zs) = break' p xs' in (x:ys,zs) + + -- | 'reverse' @xs@ returns the elements of @xs@ in reverse order. -- @xs@ must be finite. -- |