OS.U
type !'a result = ('a, [ `Unix of Unix.error ]) result
val pp_error : Format.formatter -> [ `Unix of Unix.error ] -> unit
val open_error : 'a result -> ('a, [> `Unix of Unix.error ]) result
val error_to_msg : 'a result -> ('a, [> Rresult.R.msg ]) result
val call : ('a -> 'b) -> 'a -> 'b result
val mkdir : Fpath.t -> Unix.file_perm -> unit result
val stat : Fpath.t -> Unix.stats result
val lstat : Fpath.t -> Unix.stats result