Stdune.Either
Left or right
type ('a, 'b) t =
| Left of 'a
| Right of 'b
val map : ('a, 'b) t -> l:('a -> 'c) -> r:('b -> 'c) -> 'c
val left : 'a -> ('a, _) t
val right : 'b -> (_, 'b) t
val to_dyn : ('a -> Dyn.t) -> ('b -> Dyn.t) -> ('a, 'b) t -> Dyn.t