Problems of unmatched types between mli and ml

Learning
1

This my first topic here please if I commit a mistake explain me :slight_smile:
Here is the code I try to compile :

module type OrderedStringFloatFloatFloat =
sig
type t
val compare : t -> t -> int
end

(** module pour la représentation d’une tournée )
module type Tour =
sig
(* une ville )
type city
(* map contenant pour noeud le nom des villes et pour transition la distance entre les deux villes représentées par les noeuds de la map *)
type tour

    (** définition d'une map vide *)
    val empty : tour
    (** test de vacuité d'une map *)
    val is_empty : tour -> bool
    (** calcul de la distance entre deux villes *)
    val distance : city -> city -> float
    (** ajout d'une ville dans la map *)
    val add_city : city -> tour -> tour
    (** ajout d'un chemin pour aller d'une ville A Ă  une ville B *)
    val add_road : city -> city -> tour -> tour
end

module OrderedStringFloatFloatFloat =
struct
type t = string * float * float * float

    let compare t1 t2 = compare t1 t2
end

module MakeMap (X : OrderedStringFloatFloatFloat) =
struct
type city = X.t
module SetString = Set.Make(String)
module MyMap = Map.Make (OrderedStringFloatFloatFloat)
type tour = int * string * SetString.t * SetString.t MyMap.t

	let empty = (0, "", SetString.empty, MyMap.empty)

	let is_empty t = t = (0, "", SetString.empty, MyMap.empty)

	let distance c1 c2 = 
		let (_, long1, lat1, _) = c1 in
		let (_, long2, lat2, _) = c2 in
		sqrt ( (long2 -. long1) ** 2. +. (lat2 -. lat1) ** 2. )

	let add_city c t =
		if MyMap.mem c t then t
		else MyMap.add c SetString.empty t

	let next_cities c t = MyMap.find c t

	let add_road c1 c2 t =
		let t1 = add_city c1 t in
		let t2 = add_city c2 t1 in
		let c1_next = next_cities c1 t2 in
		let (s2, _, _, _) = c2 in
		let c1_next' = SetString.add s2 c1_next in
		let c2_next = next_cities c2 t2 in
		let (s1, _, _, _) = c1 in
		let c2_next' = SetString.add s1 c2_next in
		let t2' = MyMap.add c1 c1_next' t2 in
		MyMap.add c2 c2_next' t2'
end

I don’t know how to paste properly my code but there are different problems of unmatching type…
Each time I use a city a problem appears if you know why it will be great to explain it :slight_smile:
Thank you !