Syntaxes.Option
val let+ : 'a option -> ('a -> 'b) -> 'b option
val let* : 'a option -> ('a -> 'b option) -> 'b option
val let> : 'a option -> ('a -> unit) -> unit
val let- : 'a option -> (unit -> 'a) -> 'a
val let/ : 'a option -> (unit -> 'a option) -> 'a option