The

@higherkinds

creates the boilerplate to gives

Foo

the ability of work with a

HKT

@higherkind
 class Option<A> : OptionOf<A>

to

class ForOption private constructor() { companion object }
 typealias OptionOf<A> = arrow.Kind<ForOption, A>
 inline fun <A> OptionOf<A>.fix(): Option<A> =
   this as Option<A>