Add foldCopyData helper function#56
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phadej merged 1 commit intohaskellari:masterfrom Nov 25, 2020
stackbuilders:all_copy_data
Merged
Add foldCopyData helper function#56phadej merged 1 commit intohaskellari:masterfrom stackbuilders:all_copy_data
phadej merged 1 commit intohaskellari:masterfrom
stackbuilders:all_copy_data
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phadej
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Nov 24, 2020
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The withCopyData and getAllCopyData are too specific functions.
I'd rather write something like
-- | Fold over @COPY TO STDOUT@ query. ... same notes as for 'getCopyData'.
foldCopyData
:: (a -> ByteString -> IO a) -- ^ Accumulate one row of the result
-> (a -> Int64 -> IO b) -- ^ Post-process accumulator with a count of rows
-> a -- ^ Initial accumulator
-> IO b -- ^ Resultand let people specialise.
Your getAllCopyData has performance issue, ++ is quadratic when used like that.
Check difference lists (i.e. composing [a] -> [a] functions).
It would be a simple instantiation of foldCopyData
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@phadej thank you for the feedback! I completely agree with you, I think both functions could be replaced by a more general function. I'll work on it. |
sestrella
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Good, thanks! |
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This PR introduces a new function called foldCopyData which folds over
COPY TO STDOUTquery.