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We have no rules for takeWhile and dropWhile, unlike the ones for span and break. #176

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ekmett opened this issue Jun 10, 2019 · 0 comments · Fixed by #275
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We have no rules for takeWhile and dropWhile, unlike the ones for span and break. #176

ekmett opened this issue Jun 10, 2019 · 0 comments · Fixed by #275
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performance
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0.11.0.0

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@ekmett
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ekmett commented Jun 10, 2019

break and span have specialized RULES in terms of breakByte and spanByte that enable them to lean on the power of elemIndex (and hence transitively on the power memchr).

However, there are no equivalent rules in place for takeWhile (x ==), takeWhile (== x), dropWhile (x ==), dropWhile (==x), takeWhile (x /=), takeWhile (/= x), dropWhile (x/=) and dropWhile (/= x), which are in turn implemented on top of findIndexOrEnd, and hence follow a slower path, despite returning less stuff.
@hvr hvr added the blocked: patch-needed somebody needs to write a patch or contribute code label Dec 19, 2019
@Bodigrim Bodigrim mentioned this issue Aug 28, 2020
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@Bodigrim Bodigrim removed the blocked: patch-needed somebody needs to write a patch or contribute code label Aug 28, 2020
@Bodigrim Bodigrim added this to the 0.11.0.0 milestone Sep 10, 2020
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Rules for takeWhile and dropWhile Bodigrim/bytestring
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@hvr @ekmett @Bodigrim @sjakobi