header {* Local theory specifications *}

theory Ex1
imports Main
begin

section {* Target context *}

locale NAT =
  fixes zero :: 'n
    and succ :: "'n \<Rightarrow> 'n"
  assumes succ_inject: "(succ m = succ n) \<longleftrightarrow> (m = n)"
    and succ_neq_zero: "succ m \<noteq> zero"
    and induct "P zero \<Longrightarrow> (\<And>n. P n \<Longrightarrow> P (succ n)) \<Longrightarrow> P n"
begin


section {* Some definitions *}

ML {* val lthy = @{context} *}

ML {* val ((one, (_, one_def)), lthy1) = lthy |> LocalTheory.define ""
  ((@{binding one}, NoSyn), (Attrib.empty_binding, @{term "succ zero"})) *}

ML {* val ((two, (_, two_def)), lthy2) = lthy1 |> LocalTheory.define ""
  ((@{binding two}, NoSyn), (Attrib.empty_binding, @{term "succ one"})) *}

ML {* val export = singleton (ProofContext.export lthy2 (LocalTheory.target_of lthy2)) *}
ML {* export one_def *}
ML {* export two_def *}

ML {* val global_export =
  singleton (ProofContext.export lthy2 (ProofContext.init (ProofContext.theory_of lthy2))) *}
ML {* global_export one_def *}
ML {* global_export two_def *}


definition "one = succ zero"
definition "two = succ one"


section {* Proofs *}

lemma "succ one = two" by (simp add: one_def two_def)

ML {*
  val lthy = @{context};

  val th =
    Goal.prove lthy [] [] @{prop "succ one = two"}
      (fn _ => asm_full_simp_tac
        (local_simpset_of lthy addsimps [@{thm one_def}, @{thm two_def}]) 1);

  LocalTheory.note "" ((@{binding ex1}, []), [th]) lthy;
*}

local_setup {* fn lthy =>
  let
    val th =
      Goal.prove lthy [] [] @{prop "succ one = two"}
        (fn _ => asm_full_simp_tac
          (local_simpset_of lthy addsimps [@{thm one_def}, @{thm two_def}]) 1);
  in lthy |> LocalTheory.note "" ((@{binding ex1}, []), [th]) |> #2 end
*}

thm ex1


section {* Derived definitional mechamisms *}

inductive
  Rec :: "'a \<Rightarrow> ('n \<Rightarrow> 'a \<Rightarrow> 'a) \<Rightarrow> 'n \<Rightarrow> 'a \<Rightarrow> bool"
  for e :: 'a and r :: "'n \<Rightarrow> 'a \<Rightarrow> 'a"
where
    Rec_zero: "Rec e r zero e"
  | Rec_succ: "Rec e r m n \<Longrightarrow> Rec e r (succ m) (r m n)"

thm Rec_def Rec.induct

end

thm NAT.Rec_def NAT.Rec.induct

end