module Make(T : Utils.Functor) : sig
  module Untyped := Untyped.Make(T)
  module Constraint := Constraint.Make(T)

  type err =
    | Clash of STLC.ty Utils.clash
    | Cycle of Constraint.variable Utils.cycle

  type 'a constraint_ = ('a, err) Constraint.t

  val eq : Constraint.variable -> Constraint.variable -> unit constraint_
  val decode : Constraint.variable -> STLC.ty constraint_

  type env = Constraint.variable Untyped.Var.Map.t

  val has_type : env ->
    Untyped.term -> Constraint.variable -> STLC.term constraint_
end