Error_or.Make
IO : IO
module IO : IO
val return : 'a -> ('a, 'b) Stdlib.result IO.t
val fail : 'b -> ('a, 'b) Stdlib.result IO.t
val (>>=?) : ('a, 'b) Stdlib.result IO.t -> ('a -> ('c, 'b) Stdlib.result IO.t) -> ('c, 'b) Stdlib.result IO.t