A minimal Kruskal MST implementation in Ocaml

kruskal.ml

type  edge = ( int * int * int ) list
module type EDGECOMPARE = sig
  type t
  val compare :  'a  list -> 'a list ->bool 
end

module EDGECOMPARE_weight : EDGECOMPARE with type t = edge = struct
             type t = edge
             let compare l r =  ( List.nth l ( List.length l/ 2 )) ==  ( List.nth r (List.length r/2))
end