Well, in the case of functors - yes, that's basically it. Except it's also "apply a function to every object in a tree", "apply a function to an optional object

Well, in the case of functors - yes, that's basically it. Except it's also "apply a function to every object in a tree", "apply a function to an optional object (if it's there)", and so on (there's a list of ones built into Haskell's standard library here [1]). And then the real kicker is - very often stuff can use that general functor idea ("apply a function to whatever objects are inside this wrapping object, whatever it is") instead of being written against a specific, concrete kind of thing. And then you can use that stuff in all kinds of unexpected places, and combine it with other stuff written in the same way, and it all composes together and works harmoniously. [1] https://hackage.haskell.org/package/base-4.12.0.0/docs/Prelude.html#t:Functor https://hackage.haskell.org/package/base-4.12.0.0/docs/Prelu...