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Diffstat (limited to 'ghc/compiler/utils/Util.lhs')
| -rw-r--r-- | ghc/compiler/utils/Util.lhs | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/ghc/compiler/utils/Util.lhs b/ghc/compiler/utils/Util.lhs index 8e2198b050..2bb567db0a 100644 --- a/ghc/compiler/utils/Util.lhs +++ b/ghc/compiler/utils/Util.lhs @@ -28,7 +28,7 @@ module Util ( assoc, assocUsing, assocDefault, assocDefaultUsing, -- duplicate handling - hasNoDups, equivClasses, runs, removeDups, equivClassesByUniq, + hasNoDups, equivClasses, runs, removeDups, removeDupsEq, equivClassesByUniq, -- sorting IF_NOT_GHC(quicksort COMMA stableSortLt COMMA mergesort COMMA) @@ -364,6 +364,17 @@ removeDups cmp xs where collect_dups dups_so_far [x] = (dups_so_far, x) collect_dups dups_so_far dups@(x:xs) = (dups:dups_so_far, x) + +removeDupsEq :: Eq a => [a] -> ([a], [[a]]) +-- Same, but with only equality +-- It's worst case quadratic, but we only use it on short lists +removeDupsEq [] = ([], []) +removeDupsEq (x:xs) | x `elem` xs = (ys, (x : filter (== x) xs) : zs) + where + (ys,zs) = removeDupsEq (filter (/= x) xs) +removeDupsEq (x:xs) | otherwise = (x:ys, zs) + where + (ys,zs) = removeDupsEq xs \end{code} |