It's called pattern matching. You see it a lot in functional languages, not so much in others. Haxe mostly borrowed it from ocaml.
> How does this work, do you code and specify a target output?
Indeed. You can specify multiple targets on multiple builds if your code is compatible with all of them (which happens without too much work when working with libs that do the abstraction for you, like openfl or heaps -- and yeah, that's mostly for games).
> How does this work, do you code and specify a target output?
Indeed. You can specify multiple targets on multiple builds if your code is compatible with all of them (which happens without too much work when working with libs that do the abstraction for you, like openfl or heaps -- and yeah, that's mostly for games).