src/HOL/Datatype.thy
author nipkow
Wed Mar 04 10:47:20 2009 +0100 (2009-03-04)
changeset 30235 58d147683393
parent 29609 a010aab5bed0
child 33633 9f7280e0c231
permissions -rw-r--r--
Made Option a separate theory and renamed option_map to Option.map
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(*  Title:      HOL/Datatype.thy
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Author:     Stefan Berghofer and Markus Wenzel, TU Muenchen
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Could <*> be generalized to a general summation (Sigma)?
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*)
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header {* Analogues of the Cartesian Product and Disjoint Sum for Datatypes *}
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theory Datatype
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imports Nat Product_Type
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begin
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typedef (Node)
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  ('a,'b) node = "{p. EX f x k. p = (f::nat=>'b+nat, x::'a+nat) & f k = Inr 0}"
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    --{*it is a subtype of @{text "(nat=>'b+nat) * ('a+nat)"}*}
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  by auto
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text{*Datatypes will be represented by sets of type @{text node}*}
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types 'a item        = "('a, unit) node set"
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      ('a, 'b) dtree = "('a, 'b) node set"
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consts
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  Push      :: "[('b + nat), nat => ('b + nat)] => (nat => ('b + nat))"
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  Push_Node :: "[('b + nat), ('a, 'b) node] => ('a, 'b) node"
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  ndepth    :: "('a, 'b) node => nat"
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  Atom      :: "('a + nat) => ('a, 'b) dtree"
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  Leaf      :: "'a => ('a, 'b) dtree"
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  Numb      :: "nat => ('a, 'b) dtree"
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  Scons     :: "[('a, 'b) dtree, ('a, 'b) dtree] => ('a, 'b) dtree"
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  In0       :: "('a, 'b) dtree => ('a, 'b) dtree"
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  In1       :: "('a, 'b) dtree => ('a, 'b) dtree"
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  Lim       :: "('b => ('a, 'b) dtree) => ('a, 'b) dtree"
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  ntrunc    :: "[nat, ('a, 'b) dtree] => ('a, 'b) dtree"
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  uprod     :: "[('a, 'b) dtree set, ('a, 'b) dtree set]=> ('a, 'b) dtree set"
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  usum      :: "[('a, 'b) dtree set, ('a, 'b) dtree set]=> ('a, 'b) dtree set"
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  Split     :: "[[('a, 'b) dtree, ('a, 'b) dtree]=>'c, ('a, 'b) dtree] => 'c"
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  Case      :: "[[('a, 'b) dtree]=>'c, [('a, 'b) dtree]=>'c, ('a, 'b) dtree] => 'c"
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  dprod     :: "[(('a, 'b) dtree * ('a, 'b) dtree)set, (('a, 'b) dtree * ('a, 'b) dtree)set]
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                => (('a, 'b) dtree * ('a, 'b) dtree)set"
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  dsum      :: "[(('a, 'b) dtree * ('a, 'b) dtree)set, (('a, 'b) dtree * ('a, 'b) dtree)set]
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                => (('a, 'b) dtree * ('a, 'b) dtree)set"
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defs
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  Push_Node_def:  "Push_Node == (%n x. Abs_Node (apfst (Push n) (Rep_Node x)))"
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  (*crude "lists" of nats -- needed for the constructions*)
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  Push_def:   "Push == (%b h. nat_case b h)"
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  (** operations on S-expressions -- sets of nodes **)
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  (*S-expression constructors*)
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  Atom_def:   "Atom == (%x. {Abs_Node((%k. Inr 0, x))})"
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  Scons_def:  "Scons M N == (Push_Node (Inr 1) ` M) Un (Push_Node (Inr (Suc 1)) ` N)"
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  (*Leaf nodes, with arbitrary or nat labels*)
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  Leaf_def:   "Leaf == Atom o Inl"
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  Numb_def:   "Numb == Atom o Inr"
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  (*Injections of the "disjoint sum"*)
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  In0_def:    "In0(M) == Scons (Numb 0) M"
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  In1_def:    "In1(M) == Scons (Numb 1) M"
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  (*Function spaces*)
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  Lim_def: "Lim f == Union {z. ? x. z = Push_Node (Inl x) ` (f x)}"
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  (*the set of nodes with depth less than k*)
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  ndepth_def: "ndepth(n) == (%(f,x). LEAST k. f k = Inr 0) (Rep_Node n)"
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  ntrunc_def: "ntrunc k N == {n. n:N & ndepth(n)<k}"
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  (*products and sums for the "universe"*)
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  uprod_def:  "uprod A B == UN x:A. UN y:B. { Scons x y }"
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  usum_def:   "usum A B == In0`A Un In1`B"
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  (*the corresponding eliminators*)
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  Split_def:  "Split c M == THE u. EX x y. M = Scons x y & u = c x y"
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  Case_def:   "Case c d M == THE u.  (EX x . M = In0(x) & u = c(x))
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                                  | (EX y . M = In1(y) & u = d(y))"
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  (** equality for the "universe" **)
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  dprod_def:  "dprod r s == UN (x,x'):r. UN (y,y'):s. {(Scons x y, Scons x' y')}"
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  dsum_def:   "dsum r s == (UN (x,x'):r. {(In0(x),In0(x'))}) Un
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                          (UN (y,y'):s. {(In1(y),In1(y'))})"
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lemma apfst_convE: 
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    "[| q = apfst f p;  !!x y. [| p = (x,y);  q = (f(x),y) |] ==> R  
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     |] ==> R"
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by (force simp add: apfst_def)
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(** Push -- an injection, analogous to Cons on lists **)
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lemma Push_inject1: "Push i f = Push j g  ==> i=j"
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apply (simp add: Push_def expand_fun_eq) 
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apply (drule_tac x=0 in spec, simp) 
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done
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lemma Push_inject2: "Push i f = Push j g  ==> f=g"
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apply (auto simp add: Push_def expand_fun_eq) 
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apply (drule_tac x="Suc x" in spec, simp) 
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done
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lemma Push_inject:
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    "[| Push i f =Push j g;  [| i=j;  f=g |] ==> P |] ==> P"
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by (blast dest: Push_inject1 Push_inject2) 
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lemma Push_neq_K0: "Push (Inr (Suc k)) f = (%z. Inr 0) ==> P"
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by (auto simp add: Push_def expand_fun_eq split: nat.split_asm)
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lemmas Abs_Node_inj = Abs_Node_inject [THEN [2] rev_iffD1, standard]
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(*** Introduction rules for Node ***)
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lemma Node_K0_I: "(%k. Inr 0, a) : Node"
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by (simp add: Node_def)
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lemma Node_Push_I: "p: Node ==> apfst (Push i) p : Node"
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apply (simp add: Node_def Push_def) 
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apply (fast intro!: apfst_conv nat_case_Suc [THEN trans])
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done
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subsection{*Freeness: Distinctness of Constructors*}
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(** Scons vs Atom **)
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lemma Scons_not_Atom [iff]: "Scons M N \<noteq> Atom(a)"
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apply (simp add: Atom_def Scons_def Push_Node_def One_nat_def)
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apply (blast intro: Node_K0_I Rep_Node [THEN Node_Push_I] 
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         dest!: Abs_Node_inj 
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         elim!: apfst_convE sym [THEN Push_neq_K0])  
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done
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lemmas Atom_not_Scons [iff] = Scons_not_Atom [THEN not_sym, standard]
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(*** Injectiveness ***)
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(** Atomic nodes **)
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lemma inj_Atom: "inj(Atom)"
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apply (simp add: Atom_def)
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apply (blast intro!: inj_onI Node_K0_I dest!: Abs_Node_inj)
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done
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lemmas Atom_inject = inj_Atom [THEN injD, standard]
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lemma Atom_Atom_eq [iff]: "(Atom(a)=Atom(b)) = (a=b)"
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by (blast dest!: Atom_inject)
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lemma inj_Leaf: "inj(Leaf)"
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apply (simp add: Leaf_def o_def)
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apply (rule inj_onI)
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apply (erule Atom_inject [THEN Inl_inject])
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done
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lemmas Leaf_inject [dest!] = inj_Leaf [THEN injD, standard]
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lemma inj_Numb: "inj(Numb)"
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apply (simp add: Numb_def o_def)
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apply (rule inj_onI)
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apply (erule Atom_inject [THEN Inr_inject])
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done
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lemmas Numb_inject [dest!] = inj_Numb [THEN injD, standard]
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(** Injectiveness of Push_Node **)
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lemma Push_Node_inject:
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    "[| Push_Node i m =Push_Node j n;  [| i=j;  m=n |] ==> P  
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     |] ==> P"
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apply (simp add: Push_Node_def)
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apply (erule Abs_Node_inj [THEN apfst_convE])
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apply (rule Rep_Node [THEN Node_Push_I])+
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apply (erule sym [THEN apfst_convE]) 
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apply (blast intro: Rep_Node_inject [THEN iffD1] trans sym elim!: Push_inject)
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done
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(** Injectiveness of Scons **)
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lemma Scons_inject_lemma1: "Scons M N <= Scons M' N' ==> M<=M'"
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apply (simp add: Scons_def One_nat_def)
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apply (blast dest!: Push_Node_inject)
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done
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lemma Scons_inject_lemma2: "Scons M N <= Scons M' N' ==> N<=N'"
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apply (simp add: Scons_def One_nat_def)
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apply (blast dest!: Push_Node_inject)
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done
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lemma Scons_inject1: "Scons M N = Scons M' N' ==> M=M'"
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apply (erule equalityE)
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apply (iprover intro: equalityI Scons_inject_lemma1)
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done
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lemma Scons_inject2: "Scons M N = Scons M' N' ==> N=N'"
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apply (erule equalityE)
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apply (iprover intro: equalityI Scons_inject_lemma2)
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done
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lemma Scons_inject:
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    "[| Scons M N = Scons M' N';  [| M=M';  N=N' |] ==> P |] ==> P"
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by (iprover dest: Scons_inject1 Scons_inject2)
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lemma Scons_Scons_eq [iff]: "(Scons M N = Scons M' N') = (M=M' & N=N')"
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by (blast elim!: Scons_inject)
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(*** Distinctness involving Leaf and Numb ***)
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(** Scons vs Leaf **)
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lemma Scons_not_Leaf [iff]: "Scons M N \<noteq> Leaf(a)"
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by (simp add: Leaf_def o_def Scons_not_Atom)
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lemmas Leaf_not_Scons  [iff] = Scons_not_Leaf [THEN not_sym, standard]
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(** Scons vs Numb **)
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lemma Scons_not_Numb [iff]: "Scons M N \<noteq> Numb(k)"
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by (simp add: Numb_def o_def Scons_not_Atom)
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lemmas Numb_not_Scons [iff] = Scons_not_Numb [THEN not_sym, standard]
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(** Leaf vs Numb **)
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lemma Leaf_not_Numb [iff]: "Leaf(a) \<noteq> Numb(k)"
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by (simp add: Leaf_def Numb_def)
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lemmas Numb_not_Leaf [iff] = Leaf_not_Numb [THEN not_sym, standard]
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(*** ndepth -- the depth of a node ***)
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lemma ndepth_K0: "ndepth (Abs_Node(%k. Inr 0, x)) = 0"
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by (simp add: ndepth_def  Node_K0_I [THEN Abs_Node_inverse] Least_equality)
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lemma ndepth_Push_Node_aux:
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     "nat_case (Inr (Suc i)) f k = Inr 0 --> Suc(LEAST x. f x = Inr 0) <= k"
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apply (induct_tac "k", auto)
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apply (erule Least_le)
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done
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lemma ndepth_Push_Node: 
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    "ndepth (Push_Node (Inr (Suc i)) n) = Suc(ndepth(n))"
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apply (insert Rep_Node [of n, unfolded Node_def])
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apply (auto simp add: ndepth_def Push_Node_def
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                 Rep_Node [THEN Node_Push_I, THEN Abs_Node_inverse])
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apply (rule Least_equality)
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apply (auto simp add: Push_def ndepth_Push_Node_aux)
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apply (erule LeastI)
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done
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(*** ntrunc applied to the various node sets ***)
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lemma ntrunc_0 [simp]: "ntrunc 0 M = {}"
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by (simp add: ntrunc_def)
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lemma ntrunc_Atom [simp]: "ntrunc (Suc k) (Atom a) = Atom(a)"
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by (auto simp add: Atom_def ntrunc_def ndepth_K0)
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lemma ntrunc_Leaf [simp]: "ntrunc (Suc k) (Leaf a) = Leaf(a)"
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by (simp add: Leaf_def o_def ntrunc_Atom)
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lemma ntrunc_Numb [simp]: "ntrunc (Suc k) (Numb i) = Numb(i)"
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by (simp add: Numb_def o_def ntrunc_Atom)
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lemma ntrunc_Scons [simp]: 
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    "ntrunc (Suc k) (Scons M N) = Scons (ntrunc k M) (ntrunc k N)"
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by (auto simp add: Scons_def ntrunc_def One_nat_def ndepth_Push_Node) 
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(** Injection nodes **)
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lemma ntrunc_one_In0 [simp]: "ntrunc (Suc 0) (In0 M) = {}"
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apply (simp add: In0_def)
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apply (simp add: Scons_def)
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done
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lemma ntrunc_In0 [simp]: "ntrunc (Suc(Suc k)) (In0 M) = In0 (ntrunc (Suc k) M)"
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by (simp add: In0_def)
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lemma ntrunc_one_In1 [simp]: "ntrunc (Suc 0) (In1 M) = {}"
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apply (simp add: In1_def)
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apply (simp add: Scons_def)
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done
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lemma ntrunc_In1 [simp]: "ntrunc (Suc(Suc k)) (In1 M) = In1 (ntrunc (Suc k) M)"
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by (simp add: In1_def)
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subsection{*Set Constructions*}
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(*** Cartesian Product ***)
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lemma uprodI [intro!]: "[| M:A;  N:B |] ==> Scons M N : uprod A B"
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by (simp add: uprod_def)
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(*The general elimination rule*)
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lemma uprodE [elim!]:
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    "[| c : uprod A B;   
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   321
        !!x y. [| x:A;  y:B;  c = Scons x y |] ==> P  
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   322
     |] ==> P"
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   323
by (auto simp add: uprod_def) 
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   324
wenzelm@20819
   325
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   326
(*Elimination of a pair -- introduces no eigenvariables*)
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   327
lemma uprodE2: "[| Scons M N : uprod A B;  [| M:A;  N:B |] ==> P |] ==> P"
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   328
by (auto simp add: uprod_def)
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   329
wenzelm@20819
   330
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   331
(*** Disjoint Sum ***)
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   332
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   333
lemma usum_In0I [intro]: "M:A ==> In0(M) : usum A B"
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   334
by (simp add: usum_def)
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   335
wenzelm@20819
   336
lemma usum_In1I [intro]: "N:B ==> In1(N) : usum A B"
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   337
by (simp add: usum_def)
wenzelm@20819
   338
wenzelm@20819
   339
lemma usumE [elim!]: 
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   340
    "[| u : usum A B;   
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   341
        !!x. [| x:A;  u=In0(x) |] ==> P;  
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   342
        !!y. [| y:B;  u=In1(y) |] ==> P  
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   343
     |] ==> P"
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   344
by (auto simp add: usum_def)
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   345
wenzelm@20819
   346
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   347
(** Injection **)
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   348
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   349
lemma In0_not_In1 [iff]: "In0(M) \<noteq> In1(N)"
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   350
by (auto simp add: In0_def In1_def One_nat_def)
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   351
haftmann@21407
   352
lemmas In1_not_In0 [iff] = In0_not_In1 [THEN not_sym, standard]
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   353
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   354
lemma In0_inject: "In0(M) = In0(N) ==>  M=N"
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   355
by (simp add: In0_def)
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   356
wenzelm@20819
   357
lemma In1_inject: "In1(M) = In1(N) ==>  M=N"
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   358
by (simp add: In1_def)
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   359
wenzelm@20819
   360
lemma In0_eq [iff]: "(In0 M = In0 N) = (M=N)"
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   361
by (blast dest!: In0_inject)
wenzelm@20819
   362
wenzelm@20819
   363
lemma In1_eq [iff]: "(In1 M = In1 N) = (M=N)"
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   364
by (blast dest!: In1_inject)
wenzelm@20819
   365
wenzelm@20819
   366
lemma inj_In0: "inj In0"
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   367
by (blast intro!: inj_onI)
wenzelm@20819
   368
wenzelm@20819
   369
lemma inj_In1: "inj In1"
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   370
by (blast intro!: inj_onI)
wenzelm@20819
   371
wenzelm@20819
   372
wenzelm@20819
   373
(*** Function spaces ***)
wenzelm@20819
   374
wenzelm@20819
   375
lemma Lim_inject: "Lim f = Lim g ==> f = g"
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   376
apply (simp add: Lim_def)
wenzelm@20819
   377
apply (rule ext)
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   378
apply (blast elim!: Push_Node_inject)
wenzelm@20819
   379
done
wenzelm@20819
   380
wenzelm@20819
   381
wenzelm@20819
   382
(*** proving equality of sets and functions using ntrunc ***)
wenzelm@20819
   383
wenzelm@20819
   384
lemma ntrunc_subsetI: "ntrunc k M <= M"
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   385
by (auto simp add: ntrunc_def)
wenzelm@20819
   386
wenzelm@20819
   387
lemma ntrunc_subsetD: "(!!k. ntrunc k M <= N) ==> M<=N"
wenzelm@20819
   388
by (auto simp add: ntrunc_def)
wenzelm@20819
   389
wenzelm@20819
   390
(*A generalized form of the take-lemma*)
wenzelm@20819
   391
lemma ntrunc_equality: "(!!k. ntrunc k M = ntrunc k N) ==> M=N"
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   392
apply (rule equalityI)
wenzelm@20819
   393
apply (rule_tac [!] ntrunc_subsetD)
wenzelm@20819
   394
apply (rule_tac [!] ntrunc_subsetI [THEN [2] subset_trans], auto) 
wenzelm@20819
   395
done
wenzelm@20819
   396
wenzelm@20819
   397
lemma ntrunc_o_equality: 
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   398
    "[| !!k. (ntrunc(k) o h1) = (ntrunc(k) o h2) |] ==> h1=h2"
wenzelm@20819
   399
apply (rule ntrunc_equality [THEN ext])
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   400
apply (simp add: expand_fun_eq) 
wenzelm@20819
   401
done
wenzelm@20819
   402
wenzelm@20819
   403
wenzelm@20819
   404
(*** Monotonicity ***)
wenzelm@20819
   405
wenzelm@20819
   406
lemma uprod_mono: "[| A<=A';  B<=B' |] ==> uprod A B <= uprod A' B'"
wenzelm@20819
   407
by (simp add: uprod_def, blast)
wenzelm@20819
   408
wenzelm@20819
   409
lemma usum_mono: "[| A<=A';  B<=B' |] ==> usum A B <= usum A' B'"
wenzelm@20819
   410
by (simp add: usum_def, blast)
wenzelm@20819
   411
wenzelm@20819
   412
lemma Scons_mono: "[| M<=M';  N<=N' |] ==> Scons M N <= Scons M' N'"
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   413
by (simp add: Scons_def, blast)
wenzelm@20819
   414
wenzelm@20819
   415
lemma In0_mono: "M<=N ==> In0(M) <= In0(N)"
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   416
by (simp add: In0_def subset_refl Scons_mono)
wenzelm@20819
   417
wenzelm@20819
   418
lemma In1_mono: "M<=N ==> In1(M) <= In1(N)"
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   419
by (simp add: In1_def subset_refl Scons_mono)
wenzelm@20819
   420
wenzelm@20819
   421
wenzelm@20819
   422
(*** Split and Case ***)
wenzelm@20819
   423
wenzelm@20819
   424
lemma Split [simp]: "Split c (Scons M N) = c M N"
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   425
by (simp add: Split_def)
wenzelm@20819
   426
wenzelm@20819
   427
lemma Case_In0 [simp]: "Case c d (In0 M) = c(M)"
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   428
by (simp add: Case_def)
wenzelm@20819
   429
wenzelm@20819
   430
lemma Case_In1 [simp]: "Case c d (In1 N) = d(N)"
wenzelm@20819
   431
by (simp add: Case_def)
wenzelm@20819
   432
wenzelm@20819
   433
wenzelm@20819
   434
wenzelm@20819
   435
(**** UN x. B(x) rules ****)
wenzelm@20819
   436
wenzelm@20819
   437
lemma ntrunc_UN1: "ntrunc k (UN x. f(x)) = (UN x. ntrunc k (f x))"
wenzelm@20819
   438
by (simp add: ntrunc_def, blast)
wenzelm@20819
   439
wenzelm@20819
   440
lemma Scons_UN1_x: "Scons (UN x. f x) M = (UN x. Scons (f x) M)"
wenzelm@20819
   441
by (simp add: Scons_def, blast)
wenzelm@20819
   442
wenzelm@20819
   443
lemma Scons_UN1_y: "Scons M (UN x. f x) = (UN x. Scons M (f x))"
wenzelm@20819
   444
by (simp add: Scons_def, blast)
wenzelm@20819
   445
wenzelm@20819
   446
lemma In0_UN1: "In0(UN x. f(x)) = (UN x. In0(f(x)))"
wenzelm@20819
   447
by (simp add: In0_def Scons_UN1_y)
wenzelm@20819
   448
wenzelm@20819
   449
lemma In1_UN1: "In1(UN x. f(x)) = (UN x. In1(f(x)))"
wenzelm@20819
   450
by (simp add: In1_def Scons_UN1_y)
wenzelm@20819
   451
wenzelm@20819
   452
wenzelm@20819
   453
(*** Equality for Cartesian Product ***)
wenzelm@20819
   454
wenzelm@20819
   455
lemma dprodI [intro!]: 
wenzelm@20819
   456
    "[| (M,M'):r;  (N,N'):s |] ==> (Scons M N, Scons M' N') : dprod r s"
wenzelm@20819
   457
by (auto simp add: dprod_def)
wenzelm@20819
   458
wenzelm@20819
   459
(*The general elimination rule*)
wenzelm@20819
   460
lemma dprodE [elim!]: 
wenzelm@20819
   461
    "[| c : dprod r s;   
wenzelm@20819
   462
        !!x y x' y'. [| (x,x') : r;  (y,y') : s;  
wenzelm@20819
   463
                        c = (Scons x y, Scons x' y') |] ==> P  
wenzelm@20819
   464
     |] ==> P"
wenzelm@20819
   465
by (auto simp add: dprod_def)
wenzelm@20819
   466
wenzelm@20819
   467
wenzelm@20819
   468
(*** Equality for Disjoint Sum ***)
wenzelm@20819
   469
wenzelm@20819
   470
lemma dsum_In0I [intro]: "(M,M'):r ==> (In0(M), In0(M')) : dsum r s"
wenzelm@20819
   471
by (auto simp add: dsum_def)
wenzelm@20819
   472
wenzelm@20819
   473
lemma dsum_In1I [intro]: "(N,N'):s ==> (In1(N), In1(N')) : dsum r s"
wenzelm@20819
   474
by (auto simp add: dsum_def)
wenzelm@20819
   475
wenzelm@20819
   476
lemma dsumE [elim!]: 
wenzelm@20819
   477
    "[| w : dsum r s;   
wenzelm@20819
   478
        !!x x'. [| (x,x') : r;  w = (In0(x), In0(x')) |] ==> P;  
wenzelm@20819
   479
        !!y y'. [| (y,y') : s;  w = (In1(y), In1(y')) |] ==> P  
wenzelm@20819
   480
     |] ==> P"
wenzelm@20819
   481
by (auto simp add: dsum_def)
wenzelm@20819
   482
wenzelm@20819
   483
wenzelm@20819
   484
(*** Monotonicity ***)
wenzelm@20819
   485
wenzelm@20819
   486
lemma dprod_mono: "[| r<=r';  s<=s' |] ==> dprod r s <= dprod r' s'"
wenzelm@20819
   487
by blast
wenzelm@20819
   488
wenzelm@20819
   489
lemma dsum_mono: "[| r<=r';  s<=s' |] ==> dsum r s <= dsum r' s'"
wenzelm@20819
   490
by blast
wenzelm@20819
   491
wenzelm@20819
   492
wenzelm@20819
   493
(*** Bounding theorems ***)
wenzelm@20819
   494
wenzelm@20819
   495
lemma dprod_Sigma: "(dprod (A <*> B) (C <*> D)) <= (uprod A C) <*> (uprod B D)"
wenzelm@20819
   496
by blast
wenzelm@20819
   497
wenzelm@20819
   498
lemmas dprod_subset_Sigma = subset_trans [OF dprod_mono dprod_Sigma, standard]
wenzelm@20819
   499
wenzelm@20819
   500
(*Dependent version*)
wenzelm@20819
   501
lemma dprod_subset_Sigma2:
wenzelm@20819
   502
     "(dprod (Sigma A B) (Sigma C D)) <= 
wenzelm@20819
   503
      Sigma (uprod A C) (Split (%x y. uprod (B x) (D y)))"
wenzelm@20819
   504
by auto
wenzelm@20819
   505
wenzelm@20819
   506
lemma dsum_Sigma: "(dsum (A <*> B) (C <*> D)) <= (usum A C) <*> (usum B D)"
wenzelm@20819
   507
by blast
wenzelm@20819
   508
wenzelm@20819
   509
lemmas dsum_subset_Sigma = subset_trans [OF dsum_mono dsum_Sigma, standard]
wenzelm@20819
   510
wenzelm@20819
   511
haftmann@24162
   512
text {* hides popular names *}
haftmann@24162
   513
hide (open) type node item
wenzelm@20819
   514
hide (open) const Push Node Atom Leaf Numb Lim Split Case
wenzelm@20819
   515
wenzelm@20819
   516
wenzelm@20819
   517
section {* Datatypes *}
wenzelm@20819
   518
haftmann@24699
   519
subsection {* Representing sums *}
wenzelm@12918
   520
haftmann@27104
   521
rep_datatype (sum) Inl Inr
haftmann@27104
   522
proof -
haftmann@27104
   523
  fix P
haftmann@27104
   524
  fix s :: "'a + 'b"
haftmann@27104
   525
  assume x: "\<And>x\<Colon>'a. P (Inl x)" and y: "\<And>y\<Colon>'b. P (Inr y)"
haftmann@27104
   526
  then show "P s" by (auto intro: sumE [of s])
haftmann@27104
   527
qed simp_all
haftmann@24194
   528
nipkow@22230
   529
lemma sum_case_KK[simp]: "sum_case (%x. a) (%x. a) = (%x. a)"
nipkow@22230
   530
  by (rule ext) (simp split: sum.split)
nipkow@22230
   531
wenzelm@12918
   532
lemma surjective_sum: "sum_case (%x::'a. f (Inl x)) (%y::'b. f (Inr y)) s = f(s)"
wenzelm@12918
   533
  apply (rule_tac s = s in sumE)
wenzelm@12918
   534
   apply (erule ssubst)
wenzelm@20798
   535
   apply (rule sum.cases(1))
wenzelm@12918
   536
  apply (erule ssubst)
wenzelm@20798
   537
  apply (rule sum.cases(2))
wenzelm@12918
   538
  done
wenzelm@12918
   539
wenzelm@12918
   540
lemma sum_case_weak_cong: "s = t ==> sum_case f g s = sum_case f g t"
wenzelm@12918
   541
  -- {* Prevents simplification of @{text f} and @{text g}: much faster. *}
wenzelm@20798
   542
  by simp
wenzelm@12918
   543
wenzelm@12918
   544
lemma sum_case_inject:
wenzelm@12918
   545
  "sum_case f1 f2 = sum_case g1 g2 ==> (f1 = g1 ==> f2 = g2 ==> P) ==> P"
wenzelm@12918
   546
proof -
wenzelm@12918
   547
  assume a: "sum_case f1 f2 = sum_case g1 g2"
wenzelm@12918
   548
  assume r: "f1 = g1 ==> f2 = g2 ==> P"
wenzelm@12918
   549
  show P
wenzelm@12918
   550
    apply (rule r)
wenzelm@12918
   551
     apply (rule ext)
paulson@14208
   552
     apply (cut_tac x = "Inl x" in a [THEN fun_cong], simp)
wenzelm@12918
   553
    apply (rule ext)
paulson@14208
   554
    apply (cut_tac x = "Inr x" in a [THEN fun_cong], simp)
wenzelm@12918
   555
    done
wenzelm@12918
   556
qed
wenzelm@12918
   557
berghofe@13635
   558
constdefs
berghofe@13635
   559
  Suml :: "('a => 'c) => 'a + 'b => 'c"
haftmann@28524
   560
  "Suml == (%f. sum_case f undefined)"
berghofe@13635
   561
berghofe@13635
   562
  Sumr :: "('b => 'c) => 'a + 'b => 'c"
haftmann@28524
   563
  "Sumr == sum_case undefined"
berghofe@13635
   564
berghofe@13635
   565
lemma Suml_inject: "Suml f = Suml g ==> f = g"
berghofe@13635
   566
  by (unfold Suml_def) (erule sum_case_inject)
berghofe@13635
   567
berghofe@13635
   568
lemma Sumr_inject: "Sumr f = Sumr g ==> f = g"
berghofe@13635
   569
  by (unfold Sumr_def) (erule sum_case_inject)
berghofe@13635
   570
krauss@29183
   571
primrec Projl :: "'a + 'b => 'a"
krauss@29183
   572
where Projl_Inl: "Projl (Inl x) = x"
krauss@29183
   573
krauss@29183
   574
primrec Projr :: "'a + 'b => 'b"
krauss@29183
   575
where Projr_Inr: "Projr (Inr x) = x"
krauss@29183
   576
krauss@29183
   577
hide (open) const Suml Sumr Projl Projr
berghofe@13635
   578
berghofe@5181
   579
end