generated at
Contravariant型クラス
Contravariant Functor
Functor型クラスの双対




https://www.fpcomplete.com/blog/2016/11/covariance-contravariance/
https://typeclasses.com/contravariance
https://hackage.haskell.org/package/contravariant-1.4/docs/Data-Functor-Contravariant.html
https://stackoverflow.com/questions/38034077/what-is-a-contravariant-functor
https://qiita.com/masaki_shoji/items/b384eed4595df3423e0c
https://runebook.dev/ja/docs/haskell/libraries/base-4.15.0.0/data-functor-contravariant
https://pursuit.purescript.org/packages/purescript-contravariant/5.0.0/docs/Data.Functor.Contravariant
https://medium.com/text-is-saved/functor-contravariant-bifuntor-profunctor-e6b724655725
https://shiatsumat.hatenablog.com/entry/20131203/p1
https://ywatanabevltmathscilogic.hatenablog.com/entry/2018/02/03/235900
https://jordanmartinez.github.io/purescript-jordans-reference-site/content/91-Type-Classes/External-Explanations.html
https://qiita.com/jun0inoue/items/46f5df4abe19c8ad0b2c