x.map(f) doesnt mean "apply function f to each element in this list that we called x"

x.map(f) means "apply the function f to the value within x, where x is a container of some sort"

[].map(f) would do nothing, because there is nothing to pull out.

['adam', 'bill'].map(f) takes 'adam' out of the array, applies f to it, and puts it back in the array, then does the same with 'bill'.

Just(5).map(f) takes 5 out of the Maybe, applies f to it, and puts it back in

nothing.map(f) returns nothing.

So we can map functions to values in Arrays, map functions to values in Maybes and even map functions to values in Eithers. Each time the function doesnt care that the value is in a Maybe or an Array or an Either.

Brian Lonsdorf has a fun course where he explains these things: https://egghead.io/courses/professor-frisby-introduces-compo...

Because of the mathematical "map" [0] perhaps?

[0]: https://en.wikipedia.org/wiki/Map_(mathematics)

Because the Result and Maybe types in the examples are functors: https://en.wikipedia.org/wiki/Functor_(functional_programmin...

Are you thinking about Maybe.map in particular? It's the same name because it does the same thing: run this function on the value inside if there is one. It's a Functor :)

A Maybe is effectively isomorphic to an immutable list whose cardinality can only be zero or one.

The only requirement for something to be mappable is that it be iterable