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