[#30] Rewrite fromSortedList to use arrays #51
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src/Data/TypeRepMap/Internal.hs
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| let arrOrigin = fromList l | ||
| arrResult <- thawArray arrOrigin 0 n | ||
| _ <- go n 0 0 arrResult arrOrigin | ||
| toList <$> freezeArray arrResult 0 n |
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Looks like you can use unsafeFreezeArray here:
Both thawArray and freezeArray functions create a copy of an array by cloning, as I can see from the documentation. So in most cases one of the two (freeze or thaw) can be unsafe to make implementation even more efficient. In our case we can't use unsafeThaw because we actually use arrOrigin after thaw.
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yes, same goes for the adjust patch (I wanted to comment but it was merged already)
src/Data/TypeRepMap/Internal.hs
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| let n = length l | ||
| let arrOrigin = fromList l | ||
| arrResult <- thawArray arrOrigin 0 n | ||
| _ <- go n 0 0 arrResult arrOrigin |
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it's called void (from Control.Monad)
src/Data/TypeRepMap/Internal.hs
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| fromSortedList l = IM.elems $ fst $ go 0 0 mempty (IM.fromList $ zip [0..] l) | ||
| fromSortedList l = runST $ do | ||
| let n = length l | ||
| let arrOrigin = fromList l |
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Since you've precalculated length of the array, you can use fromListN function to create arrOrigin. This will be more efficient:
src/Data/TypeRepMap/Internal.hs
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| if i >= IM.size vector | ||
| then (result, first) | ||
| go :: Int -> Int -> Int -> MutableArray s a -> Array a -> ST s Int | ||
| go n i first result vector = |
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I see that arguments n, result and vector are always passed to go function without changes. So it makes sense to me to rearrange and rename argument and introduce one more where function to make implementation more clean and robust and efficient:
go len result origin = loop -- or destination/source (dst/src) instead of `result/vector`
where
loop = ...
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