- 4 (ppBesides [ppStr "when an instance declared in module `", ppPStr inst_mod, ppStr "' has been imported"])
+ 4 (ppBesides [ppStr "when an instance declared in module `", pp_mod, ppStr "' has been imported"])
+ where
+ pp_mod = case inst_mod of
+ Nothing -> ppPStr SLIT("the standard Prelude")
+ Just m -> ppBesides [ppStr "module `", ppPStr m, ppStr "'"]