Add a formalization of the nested-loop language
Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>
This commit is contained in:
@@ -145,6 +145,9 @@ _⊢_↦|_ σ is st = σ ⊢ is ↦* st ⟨ [] ⟩
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basict₁ : [] ⟨ [] ⟩ ⊢ (pushint (+ 1) ∷ pushint (+ 2) ∷ pushint (+ 3) ∷ add ∷ add ∷ []) ↦* (tint ∷ []) ⟨ [] ⟩
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basict₁ = pushint-t thenᵗ pushint-t thenᵗ pushint-t thenᵗ add-t thenᵗ add-t thenᵗ doneᵗ
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basict₄ : [] ⟨ [] ⟩ ⊢ (pushint (+ 1) ∷ loop 3 ∷ pushint (+ 2) ∷ add ∷ end ∷ []) ↦* (tint ∷ []) ⟨ [] ⟩
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basict₄ = pushint-t thenᵗ loop-t thenᵗ pushint-t thenᵗ add-t thenᵗ end-t thenᵗ doneᵗ
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-- doesn't typecheck: violates type discipline because on break, stack has different type than on end.
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--
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-- basict₂ : ([] ⟨ [] ⟩) ⊢ (loop 1 ∷ pushbool true ∷ break ∷ pushint (+ 1) ∷ end ∷ []) ↦* ([] ⟨ [] ⟩)
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@@ -270,4 +273,4 @@ stackToString (bool b ∷ s) = showBool b ++ " :: " ++ stackToString s
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open import IO
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open import Level using (0ℓ)
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main = run {0ℓ} (putStrLn (stackToString (proj₁ (static-dynamic _ (⟦⟧ˢ-empty , ⟦⟧ᶠ-empty , basict₁)))))
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main = run {0ℓ} (putStrLn (stackToString (proj₁ (static-dynamic _ (⟦⟧ˢ-empty , ⟦⟧ᶠ-empty , basict₄)))))
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189
Language/Nested.agda
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189
Language/Nested.agda
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@@ -0,0 +1,189 @@
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{-# OPTIONS --guardedness #-}
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module Language.Nested where
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open import Language.Values using
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( Value; int; bool
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; ValueType; tint; tbool
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; ⟦_⟧ˢ; ⟦⟧ˢ-empty; ⟦⟧ˢ-int; ⟦⟧ˢ-bool
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; s; s'; s''
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; st; st'; st''
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; b; b₁; b₂
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; z; z₁; z₂
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)
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open import Data.Integer using (ℤ; _+_; +_)
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open import Data.Nat using (ℕ; suc)
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open import Data.Bool using (Bool; true; false)
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open import Data.List using (List; _∷_; []; length)
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open import Data.Unit using (⊤; tt)
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open import Data.Empty using (⊥; ⊥-elim)
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open import Data.Product using (Σ; _×_; _,_)
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open import Data.Maybe using (Maybe; just; nothing)
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open import Data.Sum using (_⊎_; inj₁; inj₂)
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open import Relation.Binary.PropositionalEquality using (_≡_; refl)
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data Instruction : Set where
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pushint : ℤ → Instruction
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pushbool : Bool → Instruction
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add : Instruction
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loop : ℕ → List Instruction → Instruction
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break : Instruction
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Program : Set
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Program = List Instruction
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Env : Set
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Env = List (List Instruction)
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variable
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i : Instruction
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is is' is'' : Program
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S S' S'' : Env
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n : ℕ
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Triple : Set
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Triple = List Value × Program × Env
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data _⇒_ : Triple → Triple → Set where
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pushint-eval : ( s , (pushint z ∷ is) , S ) ⇒ ( ((int z) ∷ s) , is , S )
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pushbool-eval : ( s , (pushbool b ∷ is) , S ) ⇒ ( ((bool b) ∷ s) , is , S )
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add-eval : ( (int z₁ ∷ int z₂ ∷ s) , (add ∷ is), S ) ⇒ ( ((int (z₁ + z₂)) ∷ s) , is , S )
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loop-eval⁰ : (s , loop 0 is' ∷ is , S) ⇒ (s , is , S)
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loop-evalⁿ : (s , loop (suc n) is' ∷ is , S) ⇒ (s , is' , (loop n is' ∷ is) ∷ S)
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break-evalᶠ : (bool false ∷ s , break ∷ is , is' ∷ S) ⇒ (s , is , is' ∷ S)
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break-evalᵗ : (bool true ∷ s , break ∷ is , (loop n is'' ∷ is') ∷ S) ⇒ (s , is' , S)
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empty-eval : (s , [] , is' ∷ S) ⇒ (s , is' , S)
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infixr 30 _thenᵉ_
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data _⇒*_ : Triple → Triple → Set where
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doneᵉ : ( s , [] , [] ) ⇒* ( s , [] , [] )
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_thenᵉ_ : ( s , is , S ) ⇒ ( s' , is' , S' ) →
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( s' , is' , S' ) ⇒* ( s'' , is'' , S'' ) →
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( s , is , S ) ⇒* ( s'' , is'' , S'' )
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StackType : Set
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StackType = List ValueType
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variable
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F F' F'' : List (List ValueType)
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σ σ' σ'' : StackType
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mst : Maybe StackType
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interleaved mutual
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data _⊢⟨_⟩_↦_ : StackType → Maybe StackType → Instruction → StackType → Set
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data _⊢⟨_⟩_↦*_ : StackType → Maybe StackType → Program → StackType → Set
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data _⊢⟨_⟩_↦_ where
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pushint-t : st ⊢⟨ mst ⟩ (pushint z) ↦ (tint ∷ st)
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pushbool-t : st ⊢⟨ mst ⟩ (pushbool b) ↦ (tbool ∷ st)
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add-t : (tint ∷ tint ∷ st) ⊢⟨ mst ⟩ add ↦ (tint ∷ st)
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loop-t : st ⊢⟨ just st ⟩ is ↦* st →
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st ⊢⟨ mst ⟩ loop n is ↦ st
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break-t : (tbool ∷ st) ⊢⟨ just st ⟩ break ↦ st
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infixr 30 _thenᵗ_
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data _⊢⟨_⟩_↦*_ where
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doneᵗ-just : st ⊢⟨ just st ⟩ [] ↦* st
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doneᵗ-nothing : st ⊢⟨ nothing ⟩ [] ↦* st
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_thenᵗ_ : st ⊢⟨ mst ⟩ i ↦ st' →
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st' ⊢⟨ mst ⟩ is ↦* st'' →
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st ⊢⟨ mst ⟩ (i ∷ is) ↦* st''
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_⊢_↦|_ : StackType → Program → StackType → Set
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_⊢_↦|_ st is st' = st ⊢⟨ nothing ⟩ is ↦* st'
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basict₄ : [] ⊢ (pushint (+ 1) ∷ loop 3 (pushint (+ 2) ∷ add ∷ []) ∷ pushint (+ 1) ∷ add ∷ []) ↦| (tint ∷ [])
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basict₄ = pushint-t thenᵗ loop-t (pushint-t thenᵗ add-t thenᵗ doneᵗ-just) thenᵗ pushint-t thenᵗ add-t thenᵗ doneᵗ-nothing
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data _⊢_↦*_ : StackType → (Program × Env) → StackType → Set where
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program-typed-flat : st ⊢⟨ nothing ⟩ is ↦* st' →
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st ⊢ (is , []) ↦* st'
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program-typed-rec : ∀ {stˡ} →
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st ⊢⟨ just st' ⟩ is ↦* st' →
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st' ⊢ (loop n is'' ∷ is' , S) ↦* stˡ →
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st ⊢ (is , (loop n is'' ∷ is') ∷ S) ↦* stˡ
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skip-loop-continuation : st ⊢ (loop n is ∷ is' , S) ↦* st' →
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st ⊢ (is' , S) ↦* st'
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skip-loop-continuation (program-typed-flat (loop-t _ thenᵗ rest)) = (program-typed-flat rest)
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skip-loop-continuation (program-typed-rec (loop-t _ thenᵗ rest) frames) = (program-typed-rec rest frames)
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preservation : ∀ {stˡ} →
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(s , is , S) ⇒ (s' , is' , S') →
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⟦ st ⟧ˢ s →
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st ⊢ (is , S) ↦* stˡ →
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Σ StackType (λ st' → ⟦ st' ⟧ˢ s' × st' ⊢ (is' , S') ↦* stˡ)
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preservation pushint-eval ⟦st⟧ (program-typed-flat (pushint-t thenᵗ rest)) = (_ , ⟦⟧ˢ-int ⟦st⟧ , (program-typed-flat rest))
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preservation pushint-eval ⟦st⟧ (program-typed-rec (pushint-t thenᵗ rest) frames) = (_ , ⟦⟧ˢ-int ⟦st⟧ , (program-typed-rec rest frames))
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preservation pushbool-eval ⟦st⟧ (program-typed-flat (pushbool-t thenᵗ rest)) = (_ , ⟦⟧ˢ-bool ⟦st⟧ , (program-typed-flat rest))
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preservation pushbool-eval ⟦st⟧ (program-typed-rec (pushbool-t thenᵗ rest) frames) = (_ , ⟦⟧ˢ-bool ⟦st⟧ , (program-typed-rec rest frames))
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preservation add-eval (⟦⟧ˢ-int (⟦⟧ˢ-int ⟦st⟧)) (program-typed-flat (add-t thenᵗ rest)) = (_ , ⟦⟧ˢ-int ⟦st⟧ , (program-typed-flat rest))
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preservation add-eval (⟦⟧ˢ-int (⟦⟧ˢ-int ⟦st⟧)) (program-typed-rec (add-t thenᵗ rest) frames) = (_ , ⟦⟧ˢ-int ⟦st⟧ , (program-typed-rec rest frames))
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preservation loop-eval⁰ ⟦st⟧ (program-typed-flat ((loop-t _) thenᵗ rest)) = (_ , ⟦st⟧ , (program-typed-flat rest))
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preservation loop-eval⁰ ⟦st⟧ (program-typed-rec ((loop-t _) thenᵗ rest) frames) = (_ , ⟦st⟧ , (program-typed-rec rest) frames)
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preservation loop-evalⁿ ⟦st⟧ (program-typed-flat ((loop-t loopt) thenᵗ rest)) = (_ , ⟦st⟧ , (program-typed-rec loopt (program-typed-flat (loop-t loopt thenᵗ rest))))
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preservation loop-evalⁿ ⟦st⟧ (program-typed-rec ((loop-t loopt) thenᵗ rest) frames) = (_ , ⟦st⟧ , (program-typed-rec loopt (program-typed-rec (loop-t loopt thenᵗ rest) frames)))
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preservation break-evalᵗ (⟦⟧ˢ-bool ⟦st⟧) (program-typed-rec (break-t thenᵗ rest) frames) = (_ , ⟦st⟧ , skip-loop-continuation frames)
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preservation break-evalᶠ (⟦⟧ˢ-bool ⟦st⟧) (program-typed-rec (break-t thenᵗ rest) frames) = (_ , ⟦st⟧ , (program-typed-rec rest frames))
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preservation empty-eval ⟦st⟧ (program-typed-rec (doneᵗ-just) frames) = (_ , ⟦st⟧ , frames)
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progress : ∀ {stˡ} →
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st ⊢ (is , S) ↦* stˡ →
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⟦ st ⟧ˢ s →
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(Σ Triple ((s , is , S) ⇒_)) ⊎ (is ≡ [] × S ≡ [] × ⟦ stˡ ⟧ˢ s)
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progress (program-typed-flat (pushint-t thenᵗ rest)) ⟦st⟧ = inj₁ (_ , pushint-eval)
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progress (program-typed-rec (pushint-t thenᵗ rest) frames) ⟦st⟧ = inj₁ (_ , pushint-eval)
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progress (program-typed-flat (pushbool-t thenᵗ rest)) ⟦st⟧ = inj₁ (_ , pushbool-eval)
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progress (program-typed-rec (pushbool-t thenᵗ rest) frames) ⟦st⟧ = inj₁ (_ , pushbool-eval)
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progress (program-typed-flat (add-t thenᵗ rest)) (⟦⟧ˢ-int (⟦⟧ˢ-int ⟦st⟧)) = inj₁ (_ , add-eval)
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progress (program-typed-rec (add-t thenᵗ rest) frames) (⟦⟧ˢ-int (⟦⟧ˢ-int ⟦st⟧)) = inj₁ (_ , add-eval)
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progress {is = loop 0 is' ∷ is} (program-typed-flat (loop-t _ thenᵗ rest)) ⟦st⟧ = inj₁ (_ , loop-eval⁰)
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progress {is = loop 0 is' ∷ is} (program-typed-rec (loop-t _ thenᵗ rest) frames) ⟦st⟧ = inj₁ (_ , loop-eval⁰)
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progress {is = loop (suc n) is' ∷ is} (program-typed-flat (loop-t _ thenᵗ rest)) ⟦st⟧ = inj₁ (_ , loop-evalⁿ)
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progress {is = loop (suc n) is' ∷ is} (program-typed-rec (loop-t _ thenᵗ rest) frames) ⟦st⟧ = inj₁ (_ , loop-evalⁿ)
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progress {s = bool true ∷ s} (program-typed-rec (break-t thenᵗ rest) frames) (⟦⟧ˢ-bool ⟦st⟧) = inj₁ (_ , break-evalᵗ)
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progress {s = bool false ∷ s} (program-typed-rec (break-t thenᵗ rest) frames) (⟦⟧ˢ-bool ⟦st⟧) = inj₁ (_ , break-evalᶠ)
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progress {is = []} (program-typed-rec (doneᵗ-just) frames) ⟦st⟧ = inj₁ (_ , empty-eval)
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progress {is = []} (program-typed-flat (doneᵗ-nothing)) ⟦st⟧ = inj₂ (refl , refl , ⟦st⟧)
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{-# TERMINATING #-} -- evaluation always terminates, but proving it is tedious
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static-dynamic-help : ∀ {stˡ} →
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st ⊢ (is , S) ↦* stˡ →
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⟦ st ⟧ˢ s →
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Σ (List Value) (λ sˡ → ⟦ stˡ ⟧ˢ sˡ × (s , is , S) ⇒* (sˡ , [] , []))
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static-dynamic-help {s = s} frames ⟦st⟧
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with progress frames ⟦st⟧
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... | inj₁ ((s' , is' , S') , is⇒is') =
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let (st' , (⟦st'⟧ , frames')) = preservation is⇒is' ⟦st⟧ frames in
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let (sˡ , (⟦stˡ⟧ , is'⇒*[])) = static-dynamic-help frames' ⟦st'⟧ in
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(sˡ , (⟦stˡ⟧ , is⇒is' thenᵉ is'⇒*[]))
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... | inj₂ (refl , refl , ⟦stˡ⟧) = (s , (⟦stˡ⟧ , doneᵉ))
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static-dynamic : ∀ {stˡ} →
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st ⊢ is ↦| stˡ →
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⟦ st ⟧ˢ s →
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Σ (List Value) (λ sˡ → ⟦ stˡ ⟧ˢ sˡ × (s , is , []) ⇒* (sˡ , [] , []))
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static-dynamic st⊢is↦|stˡ = static-dynamic-help (program-typed-flat st⊢is↦|stˡ)
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-- Copied from Flat.agda
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open import Data.Nat.Show using () renaming (show to showℕ)
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open import Data.Integer.Show using () renaming (show to showℤ)
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open import Data.Bool.Show using () renaming (show to showBool)
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open import Data.String using (String; _++_)
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open import Data.Product using (proj₁)
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stackToString : List Value → String
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stackToString [] = "[]"
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stackToString (int i ∷ s) = showℤ i ++ " :: " ++ stackToString s
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stackToString (bool b ∷ s) = showBool b ++ " :: " ++ stackToString s
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open import IO
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open import Level using (0ℓ)
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main = run {0ℓ} (putStrLn (stackToString (proj₁ (static-dynamic basict₄ ⟦⟧ˢ-empty))))
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