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Show, Read, Eq, Ord instances for Control.Applicative.Const

As mentioned in https://www.haskell.org/pipermail/libraries/2013-October/021531.html, the following instances can be derived clearly:

  • Show a => Show (Const a b)
  • Read a => Read (Const a b)
  • Eq a => Eq (Const a b)
  • Ord a => Ord (Const a b)

The absence of these instances makes debugging harder.

I suggest handcrafted Show/Read instances for neat representation.

Trac metadata
Trac field Value
Version 7.8.4
Type FeatureRequest
TypeOfFailure OtherFailure
Priority low
Resolution Unresolved
Component libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC ekmett, hvr
Operating system
Architecture
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