Add Down newtype wrapper for reversing orderings
In the same spirit as the newtypes in Data.Monoid, we can also add a newtype for reversing the ordering of a type:
newtype Down a = Down { getDown :: a }
instance Ord a => Ord (Down a) where
Down x < Down y = y < x
-- etc.
This newtype is especially useful in combination with sortOn
(ticket #2629 (closed)).
Trac metadata
Trac field | Value |
---|---|
Version | 6.8.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | libraries/base |
Test case | |
Differential revisions | |
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Blocking | |
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Operating system | |
Architecture |