File res_skolem_function.ML (Isabelle2005: October 2005)

# File res_skolem_function.ML

    (*  Author: Jia Meng, Cambridge University Computer Laboratory
        ID: $Id: res_skolem_function.ML,v 1.2 2005/07/13 14:07:24 wenzelm Exp $
        Copyright 2004 University of Cambridge

    Generation of unique Skolem functions (with types) as term.
    *)

    signature RES_SKOLEM_FUNCTION =
    sig
      val gen_skolem: term list -> typ -> term
    end;

    structure ResSkolemFunction: RES_SKOLEM_FUNCTION  =
    struct

    val skolem_prefix = "sk_";
    val skolem_id = ref 0;

    fun gen_skolem_name () =
      let val sk_fun = skolem_prefix ^ string_of_int (! skolem_id);
      in inc skolem_id; sk_fun end;

    fun gen_skolem univ_vars tp =
      let
        val skolem_type = map Term.fastype_of univ_vars ---> tp
        val skolem_term = Const (gen_skolem_name (), skolem_type)
      in Term.list_comb (skolem_term, univ_vars) end;

    end;