Serious Data.Data dataTypeName breakage
Summary
Under GHC 8.0.2 and earlier, Data.Data.dataTypeName
behaved as documented:
Data.Data> dataTypeName (dataTypeOf (Just ""))
"Prelude.Maybe"
Under GHC 8.2.2 and 9.0.1 (and presumably the versions in between), the module name is omitted:
Data.Data> dataTypeName (dataTypeOf (Just ""))
"Maybe"
Whoops!
Environment
- GHC version used: 8.2.2, 9.0.1
Optional:
- Operating System:
- System Architecture: