F# resources snippet

gistfile1.fs

module Resources

  [<Measure>] type Or
  [<Measure>] type Bois
  [<Measure>] type Pierre

  type Resources =
    { Or : int<Or> 
      Bois : int<Bois>
      Pierre : int<Pierre> }

    static member (+) (r1:Resources, r2:Resources) =
      { Or = r1.Or + r2.Or
        Bois = r1.Bois + r2.Bois
        Pierre = r1.Pierre + r2.Pierre }

    static member (-) (r1:Resources, r2:Resources) =
      { Or = 
          match r1, r2 with
          | _ when r1.Or - r2.Or < 0<Or> -> failwith "Resources can't have negative values"
          | _ -> r1.Or - r2.Or

        Bois = 
          match r1, r2 with
          | _ when r1.Bois - r2.Bois < 0<Bois> -> failwith "Resources can't have negative values"
          | _ -> r1.Bois - r2.Bois
        
        Pierre = 
          match r1, r2 with
          | _ when r1.Pierre - r2.Pierre < 0<Pierre> -> failwith "Resources can't have negative values"
          | _ -> r1.Pierre - r2.Pierre
      }

    static member Zero =
      { Or = 0<Or>; Bois = 0<Bois>; Pierre = 0<Pierre>; }