(* Pretty-normal form (PNF) subset of core-calculus, explicitly typed, with subtyping *)

module Pnf = 
struct
  type id = Tcore.id

  type label = Tcore.label

  type var = Tcore.var * Tcore.typ

  and typ = Tcore.typ
    = IntT
    | ArrowT of typ * typ
    | RecordT of rtyp 
    | SumT of rtyp    


  and rtyp = (label * typ) list  (* labels are sorted and unique *)

  type trexp = 
      Var of var
    | Abs of var * exp
    | Int of int

  and exp  =
      Triv of trexp
    | Let of var * exp * exp
    | App of trexp * trexp
    | Fix of (var * trexp) list * exp 
    | Record of row
    | Select of label * trexp
    | Variant of label * trexp
    | Switch of trexp * row 

  and row = (label * trexp) list

  let gensym (t:typ) : var = (Tcore.gensym(),t)

end