open Types ;;
open Tools ;;


let rec eval2 t = match t with
  | Apply (Lambda(s,tt),t2) when ( (v t2) ) -> sub s t2 tt
  | Apply (t1,t2) when (v t1) -> Apply(t1, eval2 t2)
  | Apply (t1 ,t2) -> Apply(eval2 t1, t2)
  | _ -> t
;;

let rec eval1 t =
  match eval2 t with
     | tt when ( (v tt) or t = tt ) -> tt
     | tt -> eval1 tt
;;

let eval t =
  match t with
    Let(s,tt) -> let r = (eval1 tt) in alias := StringMap.add s r !alias ; Let(s,r)
    | _ -> eval1 t
;;