- tyvars = tyConTyVars tycon -- [a, b, c]
- datacons = tyConDataConsIfAvailable tycon -- [C, D]
- tycon_ty = mkTyConApp tycon tyvar_tys -- T a b c
- tyvar_tys = mkTyVarTys tyvars
+ maybe_datacons = tyConDataCons_maybe tycon
+ Just datacons = maybe_datacons -- [C, D]
+
+ tyvars = tyConTyVars tycon -- [a, b, c]
+ tycon_ty = mkTyConApp tycon tyvar_tys -- T a b c
+ tyvar_tys = mkTyVarTys tyvars