functor
(G : G) (W : sig
type edge = G.E.t
type t
val weight : edge -> t
val compare : t -> t -> int
val add : t -> t -> t
val zero : t
end) ->
sig
val spanningtree : Prim.G.t -> Prim.G.E.t list
val spanningtree_from : Prim.G.t -> G.V.t -> Prim.G.E.t list
end