Add rnfFoldableLTR and rnfFoldableRTL #18
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If a type has a `Foldable` instance, then we can force it from left to right or from right to left. Fixes haskell#17
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For context: Haskell libraries mailing list discussion: https://mail.haskell.org/pipermail/libraries/2016-July/027164.html |
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This should carry a huge warning that it is normally not a sensible definition for |
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It has such a warning, specifically mentioning On Jul 27, 2016 5:03 PM, "Reid Barton" [email protected] wrote:
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Oh, so it does. There is such a lot of noise in the diff that I missed it. |
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| instance Monoid UnitLTR where | ||
| mempty = UnitLTR () | ||
| UnitLTR () `mappend` y = y |
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To avoid invoking the wrath of -Wnoncanonical-monoid-instances in later GHCs, it'd be prudent to define mappend like this:
instance Monoid UnitLTR where
mempty = UnitLTR ()
#if MIN_VERSION_base(4,9,0)
mappend = (<>)
#else
UnitLTR () `mappend` y = y
#endifAnd similarly for UnitRTL.
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This seems useful, can this be worked in to the modern deepseq? |
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Perhaps I’m overlooking something obvious : but can’t we tease out
assoxiativity of a structure from its foldmap?
…On Fri, May 3, 2019 at 6:56 PM chessai ***@***.***> wrote:
This seems useful, can this be worked in to the modern deepseq?
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Are we worried at all about the loss of |
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If a type has a
Foldableinstance, then we can force it fromleft to right or from right to left.
Fixes #17