Applicative.Basic2
type ('a, 'e) t
val return : 'a -> ( 'a, _ ) t
val apply : ( 'a -> 'b, 'e ) t -> ( 'a, 'e ) t -> ( 'b, 'e ) t
val map : [ `Define_using_apply | `Custom of ( 'a, 'e ) t -> f:( 'a -> 'b ) -> ( 'b, 'e ) t ]