module Option: sig .. end
sig
end
Monad instance for an option type
type 'a t = 'a option
'a
'a option
val _None : 'a option
val _Some : 'a -> 'a option
'a -> 'a option
include Monad.S
val fold : ('a -> 'b) -> 'b -> 'a option -> 'b
('a -> 'b) -> 'b -> 'a option -> 'b