Optionals are also "applicative", but Haskellers used them for a long time before applicative functors became popular. A concept can support a certain way of thinking about it without everyone needing to think that way :)

you don't need to think that way, no, but i was pretty sure that rust optionals were modeled after the maybe monad. perhaps not.

oh ok i misread your original, you were only referring to type inference. i thought you were saying none of the languages mentioned had monads.