Module type Gvars.VARS

module type VARS = sig .. end

Constrains variables needed for the inference

module TVar: sig .. end

module LSVar: sig .. end 
   with type elm = LSet.t

module PrVar: sig .. end

module ObjectType: sig .. end

module OTVar: MapVar.S  
   with type I.img = TVar.t
   and type I.key = Syntax.label

module LEVar: sig .. end 
   with type I.img = OTVar.t
   and type I.key = Loc.t
   and type domain_var = LSVar.t