use ~>

[mlang]

No description provided.

[hdgarrood]

I think it might be best to leave these as they are, since they aren’t really natural transformations, as they violate parametricity, and also Nullable isn’t even a functor.

[hdgarrood]

Thanks for the PR, but I'm going to close this for the above reason. For a less jargon-y explanation, I think using ~> encourages the reader not to worry about what the type a happens to be. However, when you're using Nullable a, you do need to worry about what the type a is, because stuff will break if a happens to allow null as a runtime representation.