luau/prototyping/Properties/Step.agda
ajeffrey@roblox.com 9c7311c19d WIP
2022-02-24 11:08:12 -06:00

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{-# OPTIONS --rewriting #-}
module Properties.Step where
open import Agda.Builtin.Equality using (_≡_; refl)
open import Agda.Builtin.Float using (primFloatPlus; primFloatMinus; primFloatTimes; primFloatDiv)
open import FFI.Data.Maybe using (just; nothing)
open import Luau.Heap using (Heap; _[_]; alloc; ok; function_is_end)
open import Luau.Syntax using (Block; Expr; nil; var; addr; function_is_end; block_is_end; _$_; local_←_; return; done; _∙_; name; fun; arg; number; binexp; +)
open import Luau.OpSem using (_⊢_⟶ᴱ_⊣_; _⊢_⟶ᴮ_⊣_; app₁ ; app₂ ; beta; function; block; return; done; local; subst; binOpEval; evalBinOp; binOp₁; binOp₂)
open import Luau.RuntimeError using (RuntimeErrorᴱ; RuntimeErrorᴮ; FunctionMismatch; BinopMismatch₁; BinopMismatch₂; UnboundVariable; SEGV; app₁; app₂; block; local; return; bin₁; bin₂)
open import Luau.RuntimeType using (function; number)
open import Luau.Substitution using (_[_/_]ᴮ)
open import Luau.Value using (nil; addr; val; number)
open import Properties.Remember using (remember; _,_)
data StepResultᴮ {a} (H : Heap a) (B : Block a) : Set
data StepResultᴱ {a} (H : Heap a) (M : Expr a) : Set
data StepResultᴮ H B where
step : H B (H B ⟶ᴮ B H) StepResultᴮ H B
return : V {B} (B (return (val V) B)) StepResultᴮ H B
done : (B done) StepResultᴮ H B
error : (RuntimeErrorᴮ H B) StepResultᴮ H B
data StepResultᴱ H M where
step : H M (H M ⟶ᴱ M H) StepResultᴱ H M
value : V (M val V) StepResultᴱ H M
error : (RuntimeErrorᴱ H M) StepResultᴱ H M
stepᴱ : {a} H M StepResultᴱ {a} H M
stepᴮ : {a} H B StepResultᴮ {a} H B
stepᴱ H nil = value nil refl
stepᴱ H (var x) = error (UnboundVariable x)
stepᴱ H (addr a) = value (addr a) refl
stepᴱ H (number x) = value (number x) refl
stepᴱ H (M $ N) with stepᴱ H M
stepᴱ H (M $ N) | step H M D = step H (M $ N) (app₁ D)
stepᴱ H (_ $ N) | value v refl with stepᴱ H N
stepᴱ H (_ $ N) | value v refl | step H N s = step H (val v $ N) (app₂ v s)
stepᴱ H (_ $ _) | value (addr a) refl | value w refl with remember (H [ a ])
stepᴱ H (_ $ _) | value (addr a) refl | value w refl | (nothing , p) = error (app₁ (SEGV a p))
stepᴱ H (_ $ _) | value (addr a) refl | value w refl | (just(function F is B end) , p) = step H (block (fun F) is B [ w / name (arg F) ]ᴮ end) (beta function F is B end w refl p)
stepᴱ H (_ $ _) | value nil refl | value w refl = error (FunctionMismatch nil w refl refl (λ ()))
stepᴱ H (_ $ _) | value (number x) refl | value w refl = error (FunctionMismatch (number x) w refl refl (λ ()))
stepᴱ H (M $ N) | value V p | error E = error (app₂ E)
stepᴱ H (M $ N) | error E = error (app₁ E)
stepᴱ H (block b is B end) with stepᴮ H B
stepᴱ H (block b is B end) | step H B D = step H (block b is B end) (block D)
stepᴱ H (block b is (return _ B) end) | return v refl = step H (val v) (return v)
stepᴱ H (block b is done end) | done refl = step H nil done
stepᴱ H (block b is B end) | error E = error (block b E)
stepᴱ H (function F is C end) with alloc H (function F is C end)
stepᴱ H function F is C end | ok a H p = step H (addr a) (function a p)
stepᴱ H (binexp M op N) with stepᴱ H M
stepᴱ H (binexp M op N) | value v refl with stepᴱ H N
stepᴱ H (binexp M op N) | value v refl | step H N s = step H (binexp (val v) op N) (binOp₂ s)
stepᴱ H (binexp M op N) | value v refl | error E = error (bin₂ E)
stepᴱ H (binexp M op N) | value (number m) refl | value (number n) refl = step H (number (evalBinOp m op n)) binOpEval
stepᴱ H (binexp M op N) | value nil refl | value w refl = error (BinopMismatch₁ op nil w refl refl λ ())
stepᴱ H (binexp M op N) | value (addr a) refl | value w refl = error (BinopMismatch₁ op (addr a) w refl refl λ ())
stepᴱ H (binexp M op N) | value v refl | value nil refl = error (BinopMismatch₂ op v nil refl refl (λ ()))
stepᴱ H (binexp M op N) | value v refl | value (addr a) refl = error (BinopMismatch₂ op v (addr a) refl refl (λ ()))
stepᴱ H (binexp M op N) | step H M s = step H (binexp M op N) (binOp₁ s)
stepᴱ H (binexp M op N) | error E = error (bin₁ E)
stepᴮ H (function F is C end B) with alloc H (function F is C end)
stepᴮ H (function F is C end B) | ok a H p = step H (B [ addr a / name (fun F) ]ᴮ) (function a p)
stepᴮ H (local x M B) with stepᴱ H M
stepᴮ H (local x M B) | step H M D = step H (local x M B) (local D)
stepᴮ H (local x _ B) | value v refl = step H (B [ v / name x ]ᴮ) (subst v)
stepᴮ H (local x M B) | error E = error (local x E)
stepᴮ H (return M B) with stepᴱ H M
stepᴮ H (return M B) | step H M D = step H (return M B) (return D)
stepᴮ H (return _ B) | value V refl = return V refl
stepᴮ H (return M B) | error E = error (return E)
stepᴮ H done = done refl