Я ☞ Operators ☞ yai

Precedence: 7

`yai` - [Y]oneda contr[A]variant [I]dentity

How to read: modify the first argument contravariantly, ignore the second one.

Works the same way as ya but for a 1-nd argument of a functor.

`yai` : t a _ `AR_` into (from o a) (t o _)
`ya`  : t a   `AR_` into (from o a)  (t o)