[Git][ghc/ghc][master] compiler: use fromAscList when applicable

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
1c8e608a by Cheng Shao at 2025-02-21T20:18:41-05:00
compiler: use fromAscList when applicable

This patch uses fromAscList (with O(n) complexity) instead of fromList
(with O(nlogn) complexity) in certain Binary instances. It's safe to
do so since the corresponding serialization logic is based on toList
(same as toAscList).

- - - - -


1 changed file:

- compiler/GHC/Utils/Binary.hs


Changes:

=====================================
compiler/GHC/Utils/Binary.hs
=====================================
@@ -940,8 +940,8 @@ instance Binary a => Binary [a] where
 -- | This instance doesn't rely on the determinism of the keys' 'Ord' instance,
 -- so it works e.g. for 'Name's too.
 instance (Binary a, Ord a) => Binary (Set a) where
-  put_ bh s = put_ bh (Set.toList s)
-  get bh = Set.fromList <$> get bh
+  put_ bh s = put_ bh (Set.toAscList s)
+  get bh = Set.fromAscList <$> get bh
 
 instance Binary a => Binary (NonEmpty a) where
     put_ bh = put_ bh . NonEmpty.toList
@@ -2086,5 +2086,5 @@ source location as part of a larger structure.
 --------------------------------------------------------------------------------
 
 instance (Binary v) => Binary (IntMap v) where
-  put_ bh m = put_ bh (IntMap.toList m)
-  get bh = IntMap.fromList <$> get bh
+  put_ bh m = put_ bh (IntMap.toAscList m)
+  get bh = IntMap.fromAscList <$> get bh



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1c8e608a84b9d54abb352b59a592d4669872517e

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/1c8e608a84b9d54abb352b59a592d4669872517e
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