Improvements on readByteString(') by avoid extra allocation#180
Merged
mchav merged 2 commits intoDataHaskell:mainfrom Mar 8, 2026
Merged
Improvements on readByteString(') by avoid extra allocation#180mchav merged 2 commits intoDataHaskell:mainfrom
mchav merged 2 commits intoDataHaskell:mainfrom
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also: fuse (chr . fromIntegral) in readString (less alloc)
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Good change. The parquet stuff needs more attention and these kinds of changes are really important. Thank you @Eiko-Tokura |
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Two more notes:
moving
chr . fromIntegralfrommapofIOinside replicateM avoids an extra list allocation. (Because IO is strict and IO of list demonstrate no laziness, it is unclear if ghc can fuse the map inside. We can explicitly fuse it)The use of
bracketOnErrorensures the buffer is not leaked. This can happen in case of unlucky async exception. Its overhead should be insignificant compared to malloc. If in doubt one, may try to run benchmarks to determine whether it brings overhead.