From 72b4588677d32d3e4c003a87f985652e11adb847 Mon Sep 17 00:00:00 2001
From: meooow <soumiksarkar.3120@gmail.com>
Date: Thu, 15 Jun 2023 09:56:20 +0000
Subject: [PATCH] Update note [Inlining and fusion]
---
Data/Array/Base.hs | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/Data/Array/Base.hs b/Data/Array/Base.hs
index aef7aa73..5c561558 100644
--- a/Data/Array/Base.hs
+++ b/Data/Array/Base.hs
@@ -194,7 +194,7 @@ listArray (l,u) es =
let n = safeRangeSize (l,u)
in unsafeArray (l,u) (zip [0 .. n - 1] es)
-{-# INLINE listArrayST #-}
+{-# INLINE listArrayST #-} -- See Note [Inlining and fusion]
listArrayST :: Ix i => (i,i) -> [e] -> ST s (STArray s i e)
listArrayST = newListArray
@@ -203,7 +203,7 @@ listArrayST = newListArray
\lu es -> runST (listArrayST lu es >>= ArrST.unsafeFreezeSTArray)
#-}
-{-# INLINE listUArrayST #-}
+{-# INLINE listUArrayST #-} -- See Note [Inlining and fusion]
listUArrayST :: (MArray (STUArray s) e (ST s), Ix i)
=> (i,i) -> [e] -> ST s (STUArray s i e)
listUArrayST = newListArray
@@ -881,8 +881,7 @@ instance MArray IOArray e IO where
unsafeRead = unsafeReadIOArray
unsafeWrite = unsafeWriteIOArray
--- See Note [Inlining and fusion]
-{-# INLINE newListArray #-}
+{-# INLINE newListArray #-} -- See Note [Inlining and fusion]
-- | Constructs a mutable array from a list of initial elements.
-- The list gives the elements of the array in ascending order
-- beginning with the lowest index.
@@ -1587,6 +1586,8 @@ castSTUArray (STUArray l u n marr#) = return (STUArray l u n marr#)
-- Note [Inlining and fusion]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~
--- In general, functions here are marked INLINE to allow maximum optimization,
--- but for some functions that generate and consume lists it is particularly
--- important to allow list fusion.
+-- Many functions in this module are marked INLINE because they consume their
+-- input with `foldr`. By inlining them, it is possible that the `foldr` will
+-- meet a `build` from the call site, and beneficial fusion will take place.
+-- That is, they become "good consumers". See array issue #8 for data showing
+-- the perf improvement that comes with fusion.
--
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