src/HOL/HOLCF/Tools/cpodef.ML

clarified class/locale reasoning: avoid side-stepping constraints;

(*  Title:      HOL/HOLCF/Tools/cpodef.ML
    Author:     Brian Huffman

Primitive domain definitions for HOLCF, similar to Gordon/HOL-style
typedef (see also ~~/src/HOL/Tools/typedef.ML).
*)

signature CPODEF =
sig
  type cpo_info =
    { below_def: thm, adm: thm, cont_Rep: thm, cont_Abs: thm,
      lub: thm, compact: thm }
  type pcpo_info =
    { Rep_strict: thm, Abs_strict: thm,
      Rep_bottom_iff: thm, Abs_bottom_iff: thm }

  val add_podef: binding * (string * sort) list * mixfix ->
    term -> Typedef.bindings option -> (Proof.context -> tactic) -> theory ->
    (Typedef.info * thm) * theory
  val add_cpodef: binding * (string * sort) list * mixfix ->
    term -> Typedef.bindings option -> (Proof.context -> tactic) * (Proof.context -> tactic) ->
    theory -> (Typedef.info * cpo_info) * theory
  val add_pcpodef: binding * (string * sort) list * mixfix ->
    term -> Typedef.bindings option -> (Proof.context -> tactic) * (Proof.context -> tactic) ->
    theory -> (Typedef.info * cpo_info * pcpo_info) * theory

  val cpodef_proof:
    (binding * (string * sort) list * mixfix) * term
    * Typedef.bindings option -> theory -> Proof.state
  val cpodef_proof_cmd:
    (binding * (string * string option) list * mixfix) * string
    * Typedef.bindings option -> theory -> Proof.state
  val pcpodef_proof:
    (binding * (string * sort) list * mixfix) * term
    * Typedef.bindings option -> theory -> Proof.state
  val pcpodef_proof_cmd:
    (binding * (string * string option) list * mixfix) * string
    * Typedef.bindings option -> theory -> Proof.state
end

structure Cpodef : CPODEF =
struct

(** type definitions **)

type cpo_info =
  { below_def: thm, adm: thm, cont_Rep: thm, cont_Abs: thm,
    lub: thm, compact: thm }

type pcpo_info =
  { Rep_strict: thm, Abs_strict: thm,
    Rep_bottom_iff: thm, Abs_bottom_iff: thm }

(* building terms *)

fun adm_const T = \<^Const>\<open>adm T\<close>
fun mk_adm (x, T, P) = adm_const T $ absfree (x, T) P

fun below_const T = \<^Const>\<open>below T\<close>

(* proving class instances *)

fun prove_cpo
      (name: binding)
      (newT: typ)
      opt_bindings
      (type_definition: thm)  (* type_definition Rep Abs A *)
      (below_def: thm)        (* op << == %x y. Rep x << Rep y *)
      (admissible: thm)       (* adm (%x. x : set) *)
      (thy: theory)
    =
  let
    val {Rep_name, Abs_name, ...} = Typedef.make_bindings name opt_bindings;
    val cpo_thms = map (Thm.transfer thy) [type_definition, below_def, admissible]
    val (full_tname, Ts) = dest_Type newT
    val lhs_sorts = map (snd o dest_TFree) Ts
    fun tac ctxt = resolve_tac ctxt [@{thm typedef_cpo} OF cpo_thms] 1
    val thy = Axclass.prove_arity (full_tname, lhs_sorts, \<^sort>\<open>cpo\<close>) tac thy
    (* transfer thms so that they will know about the new cpo instance *)
    val cpo_thms' = map (Thm.transfer thy) cpo_thms
    fun make thm = Drule.zero_var_indexes (thm OF cpo_thms')
    val cont_Rep = make @{thm typedef_cont_Rep}
    val cont_Abs = make @{thm typedef_cont_Abs}
    val lub = make @{thm typedef_lub}
    val compact = make @{thm typedef_compact}
    val (_, thy) =
      thy
      |> Sign.add_path (Binding.name_of name)
      |> Global_Theory.add_thms
        ([((Binding.prefix_name "adm_"      name, admissible), []),
          ((Binding.prefix_name "cont_" Rep_name, cont_Rep  ), []),
          ((Binding.prefix_name "cont_" Abs_name, cont_Abs  ), []),
          ((Binding.prefix_name "lub_"      name, lub       ), []),
          ((Binding.prefix_name "compact_"  name, compact   ), [])])
      ||> Sign.parent_path
    val cpo_info : cpo_info =
      { below_def = below_def, adm = admissible, cont_Rep = cont_Rep,
        cont_Abs = cont_Abs, lub = lub, compact = compact }
  in
    (cpo_info, thy)
  end

fun prove_pcpo
      (name: binding)
      (newT: typ)
      opt_bindings
      (type_definition: thm)  (* type_definition Rep Abs A *)
      (below_def: thm)        (* op << == %x y. Rep x << Rep y *)
      (bottom_mem: thm)       (* bottom : set *)
      (thy: theory)
    =
  let
    val {Rep_name, Abs_name, ...} = Typedef.make_bindings name opt_bindings;
    val pcpo_thms = map (Thm.transfer thy) [type_definition, below_def, bottom_mem]
    val (full_tname, Ts) = dest_Type newT
    val lhs_sorts = map (snd o dest_TFree) Ts
    fun tac ctxt = resolve_tac ctxt [@{thm typedef_pcpo} OF pcpo_thms] 1
    val thy = Axclass.prove_arity (full_tname, lhs_sorts, \<^sort>\<open>pcpo\<close>) tac thy
    val pcpo_thms' = map (Thm.transfer thy) pcpo_thms
    fun make thm = Drule.zero_var_indexes (thm OF pcpo_thms')
    val Rep_strict = make @{thm typedef_Rep_strict}
    val Abs_strict = make @{thm typedef_Abs_strict}
    val Rep_bottom_iff = make @{thm typedef_Rep_bottom_iff}
    val Abs_bottom_iff = make @{thm typedef_Abs_bottom_iff}
    val (_, thy) =
      thy
      |> Sign.add_path (Binding.name_of name)
      |> Global_Theory.add_thms
        ([((Binding.suffix_name "_strict"     Rep_name, Rep_strict), []),
          ((Binding.suffix_name "_strict"     Abs_name, Abs_strict), []),
          ((Binding.suffix_name "_bottom_iff" Rep_name, Rep_bottom_iff), []),
          ((Binding.suffix_name "_bottom_iff" Abs_name, Abs_bottom_iff), [])])
      ||> Sign.parent_path
    val pcpo_info =
      { Rep_strict = Rep_strict, Abs_strict = Abs_strict,
        Rep_bottom_iff = Rep_bottom_iff, Abs_bottom_iff = Abs_bottom_iff }
  in
    (pcpo_info, thy)
  end

(* prepare_cpodef *)

fun prepare prep_term name (tname, raw_args, _) raw_set thy =
  let
    (*rhs*)
    val tmp_ctxt =
      Proof_Context.init_global thy
      |> fold (Variable.declare_typ o TFree) raw_args
    val set = prep_term tmp_ctxt raw_set
    val tmp_ctxt' = tmp_ctxt |> Variable.declare_term set

    val setT = Term.fastype_of set
    val oldT = HOLogic.dest_setT setT handle TYPE _ =>
      error ("Not a set type: " ^ quote (Syntax.string_of_typ tmp_ctxt setT))

    (*lhs*)
    val lhs_tfrees = map (Proof_Context.check_tfree tmp_ctxt') raw_args
    val full_tname = Sign.full_name thy tname
    val newT = Type (full_tname, map TFree lhs_tfrees)
  in
    (newT, oldT, set)
  end

fun add_podef typ set opt_bindings tac thy =
  let
    val name = #1 typ
    val ((full_tname, info as ({Rep_name, ...}, {type_definition, ...})), thy) =
      thy
      |> Named_Target.theory_map_result (apsnd o Typedef.transform_info)
           (Typedef.add_typedef {overloaded = false} typ set opt_bindings tac)
    val oldT = #rep_type (#1 info)
    val newT = #abs_type (#1 info)
    val lhs_tfrees = map dest_TFree (dest_Type_args newT)

    val RepC = Const (Rep_name, newT --> oldT)
    val below_eqn = Logic.mk_equals (below_const newT,
      Abs ("x", newT, Abs ("y", newT, below_const oldT $ (RepC $ Bound 1) $ (RepC $ Bound 0))))
    val ((_, (_, below_ldef)), lthy) = thy
      |> Class.instantiation ([full_tname], lhs_tfrees, \<^sort>\<open>po\<close>)
      |> Specification.definition NONE [] []
          ((Binding.prefix_name "below_" (Thm.def_binding name), []), below_eqn)
    val ctxt_thy = Proof_Context.init_global (Proof_Context.theory_of lthy)
    val below_def = singleton (Proof_Context.export lthy ctxt_thy) below_ldef
    val thy = lthy
      |> Class.prove_instantiation_exit
          (fn ctxt => resolve_tac ctxt [@{thm typedef_po_class} OF [type_definition, below_def]] 1)
  in ((info, below_def), thy) end

fun prepare_cpodef
      (prep_term: Proof.context -> 'a -> term)
      (typ: binding * (string * sort) list * mixfix)
      (raw_set: 'a)
      opt_bindings
      (thy: theory)
    : term * term * (thm -> thm -> theory -> (Typedef.info * cpo_info) * theory) =
  let
    val name = #1 typ
    val (newT, oldT, set) = prepare prep_term name typ raw_set thy

    val goal_nonempty =
      HOLogic.mk_Trueprop (HOLogic.mk_exists ("x", oldT, HOLogic.mk_mem (Free ("x", oldT), set)))
    val goal_admissible =
      HOLogic.mk_Trueprop (mk_adm ("x", oldT, HOLogic.mk_mem (Free ("x", oldT), set)))

    fun cpodef_result nonempty admissible thy =
      let
        val ((info as (_, {type_definition, ...}), below_def), thy) = thy
          |> add_podef typ set opt_bindings (fn ctxt => resolve_tac ctxt [nonempty] 1)
        val (cpo_info, thy) = thy
          |> prove_cpo name newT opt_bindings type_definition below_def admissible
      in
        ((info, cpo_info), thy)
      end
  in
    (goal_nonempty, goal_admissible, cpodef_result)
  end
  handle ERROR msg =>
    cat_error msg ("The error(s) above occurred in cpodef " ^ Binding.print (#1 typ))

fun prepare_pcpodef
      (prep_term: Proof.context -> 'a -> term)
      (typ: binding * (string * sort) list * mixfix)
      (raw_set: 'a)
      opt_bindings
      (thy: theory)
    : term * term * (thm -> thm -> theory -> (Typedef.info * cpo_info * pcpo_info) * theory) =
  let
    val name = #1 typ
    val (newT, oldT, set) = prepare prep_term name typ raw_set thy

    val goal_bottom_mem =
      HOLogic.mk_Trueprop (HOLogic.mk_mem (\<^Const>\<open>bottom oldT\<close>, set))

    val goal_admissible =
      HOLogic.mk_Trueprop (mk_adm ("x", oldT, HOLogic.mk_mem (Free ("x", oldT), set)))

    fun pcpodef_result bottom_mem admissible thy =
      let
        fun tac ctxt = resolve_tac ctxt [exI] 1 THEN resolve_tac ctxt [bottom_mem] 1
        val ((info as (_, {type_definition, ...}), below_def), thy) = thy
          |> add_podef typ set opt_bindings tac
        val (cpo_info, thy) = thy
          |> prove_cpo name newT opt_bindings type_definition below_def admissible
        val (pcpo_info, thy) = thy
          |> prove_pcpo name newT opt_bindings type_definition below_def bottom_mem
      in
        ((info, cpo_info, pcpo_info), thy)
      end
  in
    (goal_bottom_mem, goal_admissible, pcpodef_result)
  end
  handle ERROR msg =>
    cat_error msg ("The error(s) above occurred in pcpodef " ^ Binding.print (#1 typ))


(* tactic interface *)

fun add_cpodef typ set opt_bindings (tac1, tac2) thy =
  let
    val (goal1, goal2, cpodef_result) =
      prepare_cpodef Syntax.check_term typ set opt_bindings thy
    val thm1 = Goal.prove_global thy [] [] goal1 (tac1 o #context)
      handle ERROR msg => cat_error msg
        ("Failed to prove non-emptiness of " ^ quote (Syntax.string_of_term_global thy set))
    val thm2 = Goal.prove_global thy [] [] goal2 (tac2 o #context)
      handle ERROR msg => cat_error msg
        ("Failed to prove admissibility of " ^ quote (Syntax.string_of_term_global thy set))
  in cpodef_result thm1 thm2 thy end

fun add_pcpodef typ set opt_bindings (tac1, tac2) thy =
  let
    val (goal1, goal2, pcpodef_result) =
      prepare_pcpodef Syntax.check_term typ set opt_bindings thy
    val thm1 = Goal.prove_global thy [] [] goal1 (tac1 o #context)
      handle ERROR msg => cat_error msg
        ("Failed to prove non-emptiness of " ^ quote (Syntax.string_of_term_global thy set))
    val thm2 = Goal.prove_global thy [] [] goal2 (tac2 o #context)
      handle ERROR msg => cat_error msg
        ("Failed to prove admissibility of " ^ quote (Syntax.string_of_term_global thy set))
  in pcpodef_result thm1 thm2 thy end


(* proof interface *)

local

fun gen_cpodef_proof prep_term prep_constraint
    ((b, raw_args, mx), set, opt_bindings) thy =
  let
    val ctxt = Proof_Context.init_global thy
    val args = map (apsnd (prep_constraint ctxt)) raw_args
    val (goal1, goal2, make_result) =
      prepare_cpodef prep_term (b, args, mx) set opt_bindings thy
    fun after_qed [[th1, th2]] = Proof_Context.background_theory (snd o make_result th1 th2)
      | after_qed _ = raise Fail "cpodef_proof"
  in Proof.theorem NONE after_qed [[(goal1, []), (goal2, [])]] ctxt end

fun gen_pcpodef_proof prep_term prep_constraint
    ((b, raw_args, mx), set, opt_bindings) thy =
  let
    val ctxt = Proof_Context.init_global thy
    val args = map (apsnd (prep_constraint ctxt)) raw_args
    val (goal1, goal2, make_result) =
      prepare_pcpodef prep_term (b, args, mx) set opt_bindings thy
    fun after_qed [[th1, th2]] = Proof_Context.background_theory (snd o make_result th1 th2)
      | after_qed _ = raise Fail "pcpodef_proof"
  in Proof.theorem NONE after_qed [[(goal1, []), (goal2, [])]] ctxt end

in

fun cpodef_proof x = gen_cpodef_proof Syntax.check_term (K I) x
fun cpodef_proof_cmd x = gen_cpodef_proof Syntax.read_term Typedecl.read_constraint x

fun pcpodef_proof x = gen_pcpodef_proof Syntax.check_term (K I) x
fun pcpodef_proof_cmd x = gen_pcpodef_proof Syntax.read_term Typedecl.read_constraint x

end



(** outer syntax **)

local

fun cpodef pcpo =
  (Parse.type_args_constrained -- Parse.binding) -- Parse.opt_mixfix --
  (\<^keyword>\<open>=\<close> |-- Parse.term) --
  Scan.option
    (\<^keyword>\<open>morphisms\<close> |-- Parse.!!! (Parse.binding -- Parse.binding))
  >> (fn ((((args, t), mx), A), morphs) =>
      Toplevel.theory_to_proof
        ((if pcpo then pcpodef_proof_cmd else cpodef_proof_cmd)
          ((t, args, mx), A, SOME (Typedef.make_morphisms t morphs))))

in

val _ =
  Outer_Syntax.command \<^command_keyword>\<open>pcpodef\<close>
    "HOLCF type definition (requires admissibility proof)"
    (cpodef true)

val _ =
  Outer_Syntax.command \<^command_keyword>\<open>cpodef\<close>
    "HOLCF type definition (requires admissibility proof)"
    (cpodef false)

end

end