include Soteria_std.Monad.Syntax with type 'a t := 'a option
val (let*) : 'a option -> ('a -> 'b option) -> 'b optionval (let+) : 'a option -> ('a -> 'b) -> 'b optionval (let/) : 'a option -> (unit -> 'a option) -> 'a optionval (let-) : 'a option -> (unit -> 'a) -> 'a