GHC.Generics offers a bunch of data types which have valid instances of various type classes in base, such as Functor. There's no good reason not to have these instances, so they should be added. <details><summary>Trac metadata</summary> | Trac field | Value | | ---------------------- | -------------- | | Version | 7.8.2 | | Type | FeatureRequest | | TypeOfFailure | OtherFailure | | Priority | normal | | Resolution | Unresolved | | Component | libraries/base | | Test case | | | Differential revisions | | | BlockedBy | | | Related | | | Blocking | | | CC | ekmett, hvr | | Operating system | | | Architecture | | </details> <!-- {"blocked_by":[],"summary":"Add missing type class instances for data types in GHC.Generics","status":"New","operating_system":"","component":"libraries/base","related":[],"milestone":"","resolution":"Unresolved","owner":{"tag":"Unowned"},"version":"7.8.2","keywords":[],"differentials":[],"test_case":"","architecture":"","cc":["ekmett","hvr"],"type":"FeatureRequest","description":"GHC.Generics offers a bunch of data types which have valid instances of various type classes in base, such as Functor. There's no good reason not to have these instances, so they should be added.","type_of_failure":"OtherFailure","blocking":[]} -->