(*  Title:      nominal_library.ML

    Author:     Christian Urban

  Basic functions for nominal.

*)

signature NOMINAL_LIBRARY =

sig

  val dest_listT: typ -> typ

  val mk_minus: term -> term

  val mk_plus: term -> term -> term

  val perm_ty: typ -> typ 

  val mk_perm_ty: typ -> term -> term -> term

  val mk_perm: term -> term -> term

  val dest_perm: term -> term * term

  val mk_sort_of: term -> term

  val atom_ty: typ -> typ

  val mk_atom_ty: typ -> term -> term

  val mk_atom: term -> term

  val supp_ty: typ -> typ

  val mk_supp_ty: typ -> term -> term

  val mk_supp: term -> term

  val mk_equiv: thm -> thm

  val safe_mk_equiv: thm -> thm

  val mk_diff: term * term -> term

  val mk_union: term * term -> term

  val fold_union: term list -> term

  (* datatype operations *)

  val nth_dtyp: Datatype_Aux.descr -> (string * sort) list -> int -> typ

  val all_dtyp_constrs_types: Datatype_Aux.descr -> (string * sort) list -> 

  val nth_dtyp_constrs_types: Datatype_Aux.descr -> (string * sort) list -> int -> 

  val prefix_dt_names: Datatype_Aux.descr -> (string * sort) list -> string -> string list

end

structure Nominal_Library: NOMINAL_LIBRARY =

struct

(* this function should be in hologic.ML *)

fun dest_listT (Type (@{type_name list}, [T])) = T

  | dest_listT T = raise TYPE ("dest_listT: list type expected", [T], [])

fun mk_minus p = @{term "uminus::perm => perm"} $ p;

fun mk_plus p q = @{term "plus::perm => perm => perm"} $ p $ q;

fun perm_ty ty = @{typ "perm"} --> ty --> ty; 

fun mk_perm_ty ty p trm = Const (@{const_name "permute"}, perm_ty ty) $ p $ trm;

fun mk_perm p trm = mk_perm_ty (fastype_of trm) p trm;

fun dest_perm (Const (@{const_name "permute"}, _) $ p $ t) = (p, t)

  | dest_perm t = raise TERM ("dest_perm", [t]);

fun mk_sort_of t = @{term "sort_of"} $ t;

fun atom_ty ty = ty --> @{typ "atom"};

fun mk_atom_ty ty t = Const (@{const_name "atom"}, atom_ty ty) $ t;

fun mk_atom t = mk_atom_ty (fastype_of t) t;

fun supp_ty ty = ty --> @{typ "atom set"};

fun mk_supp t = mk_supp_ty (fastype_of t) t;

fun mk_equiv r = r RS @{thm eq_reflection};

fun safe_mk_equiv r = mk_equiv r handle Thm.THM _ => r;

fun mk_diff (@{term "{}::atom set"}, _) = @{term "{}::atom set"}

  | mk_diff (t1, @{term "{}::atom set"}) = t1

  | mk_diff (t1, t2) = HOLogic.mk_binop @{const_name minus} (t1, t2)

fun mk_union (@{term "{}::atom set"}, @{term "{}::atom set"}) = @{term "{}::atom set"}

  | mk_union (t1 , @{term "{}::atom set"}) = t1

  | mk_union (@{term "{}::atom set"}, t2) = t2

fun fold_union trms = fold (curry mk_union) trms @{term "{}::atom set"}

(** datatypes **)

(* returns the type of the nth datatype *)

fun nth_dtyp descr sorts n = 

  Datatype_Aux.typ_of_dtyp descr sorts (Datatype_Aux.DtRec n);

(* returns info about constructors in a datatype *)

fun all_dtyp_constrs_info descr = 

  map (fn (_, (ty, vs, constrs)) => map (pair (ty, vs)) constrs) descr

(* returns the constants of the constructors plus the 

   corresponding type and types of arguments *)

fun all_dtyp_constrs_types descr sorts = 

let

  fun aux ((ty_name, vs), (cname, args)) =

  let

    val vs_tys = map (Datatype_Aux.typ_of_dtyp descr sorts) vs

    val ty = Type (ty_name, vs_tys)

    val arg_tys = map (Datatype_Aux.typ_of_dtyp descr sorts) args

  in

  end

in

  map (map aux) (all_dtyp_constrs_info descr)

end

fun nth_dtyp_constrs_types descr sorts n =

  nth (all_dtyp_constrs_types descr sorts) n

(* generates for every datatype a name str ^ dt_name 

   plus and index for multiple occurences of a string *)

fun prefix_dt_names descr sorts str = 

let

  fun get_nth_name (i, _) = 

    Datatype_Aux.name_of_typ (nth_dtyp descr sorts i) 

in

  Datatype_Prop.indexify_names 

    (map (prefix str o get_nth_name) descr)

end

end (* structure *)

open Nominal_Library;