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Simon Jakobi pushed to branch wip/sjakobi/set-ops at Glasgow Haskell Compiler / GHC

Commits:

092fcbbe

by Simon Jakobi at 2026-05-25T09:06:36+02:00

Ensure that SetOps.{minusList,unionListsOrd} can be specialized

...by marking them INLINABLE. Haddock allocates 0.1–0.3% less as a
result.

This also removes some redundant constraints on unionListsOrd.

1 changed file:

compiler/GHC/Data/List/SetOps.hs

Changes:

compiler/GHC/Data/List/SetOps.hs

@@ -60,12 +60,13 @@ getNth xs n = assertPpr (xs `lengthExceeds` n) (ppr n $$ ppr xs) $
  --
  -- Uses a set internally to record duplicates. This makes it slightly slower for
  -- very small lists but avoids quadratic behaviour for large lists.
 -unionListsOrd :: (HasDebugCallStack, Outputable a, Ord a) => [a] -> [a] -> [a]
 +unionListsOrd :: Ord a => [a] -> [a] -> [a]
  unionListsOrd xs ys
 -  -- Since both arguments don't have internal duplicates we can just take all of xs
 -  -- and every element of ys that's not already in xs.
 +  -- Since both arguments don't have internal duplicates we can just take all of ys
 +  -- and every element of xs that's not already in ys.
    = let set_ys = S.fromList ys
      in (filter (\e -> not $ S.member e set_ys) xs) ++ ys
 +{-# INLINABLE unionListsOrd #-} -- Ensure the function can be specialized.
  -- | Assumes that the arguments contain no duplicates
  unionLists :: (HasDebugCallStack, Outputable a, Eq a) => [a] -> [a] -> [a]
@@ -108,6 +109,7 @@ minusList xs [y] = filter (/= y) xs
  minusList xs ys = filter (`S.notMember` yss) xs
    where
      yss = S.fromList ys
 +{-# INLINABLE minusList #-} -- Ensure the function can be specialized.
  {-
  ************************************************************************