Я ☞ Operators ☞ ya

Precedence: 8

`ya` - [Y]oneda contr[A]variant

How to read: modify argument contravariantly.

Looks like a circle with a white bullet point inside. This white bullet point represents contravariant position of a parameter we are going to map.

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

You are not going to use it often though.