include Monad.Def with type +'a t = evar_map -> evar_map * 'a
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
val (>>) : unit t -> 'a t -> 'a t
val map : ('a -> 'b) -> 'a t -> 'b t
The monadic laws must hold:
(x>>=f)>>=g
= x>>=fun x' -> (f x'>>=g)
return a >>= f
= f a
x>>=return
= x
As well as the following identities:
x >> y
= x >>= fun () -> y
map f x
= x >>= fun x' -> f x'