Consistently refer to Raise as an "effect", with nullable, either, recover, etc as Raise "handlers"

[kyay10]

The docs sometimes use the term "builder" to refer to Raise handlers. I think using the terminology of effects and handlers would be great!
"builder" is especially bad since builders have a different connotation; a builder introduces a block of code where the receiver is the object of focus, while Raise is more so a side character (See Alejandro's blog)