Extending tcg_fam_inst_env without tcg_fam_insts results in axioms not being exported
isLeft is not in older versions of base
Translate r { foo :: a, bar :: b } syntax to (Has r "foo" a, Has r "bar" b) :: Constraint
More implications: turn on FlexibleContexts and ConstraintKinds
Pretty-print r { foo :: a, bar :: b} syntax