luau/prototyping/Luau/VarCtxt.agda

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{-# OPTIONS --rewriting #-}
module Luau.VarCtxt where
open import Agda.Builtin.Equality using (_≡_)
open import Luau.Type using (Type; __; _∩_)
open import Luau.Var using (Var)
open import FFI.Data.Aeson using (KeyMap; Key; empty; unionWith; singleton; insert; delete; lookup; toString; fromString; lookup-insert; lookup-insert-not; lookup-empty; to-from; insert-swap; insert-over)
open import FFI.Data.Maybe using (Maybe; just; nothing)
open import Properties.Equality using (_≢_; cong; sym; trans)
VarCtxt : Set
VarCtxt = KeyMap Type
: VarCtxt
= empty
_⋒_ : VarCtxt VarCtxt VarCtxt
_⋒_ = unionWith _∩_
_⋓_ : VarCtxt VarCtxt VarCtxt
_⋓_ = unionWith __
_[_] : VarCtxt Var Maybe Type
Γ [ x ] = lookup (fromString x) Γ
_⊝_ : VarCtxt Var VarCtxt
Γ x = delete (fromString x) Γ
_↦_ : Var Type VarCtxt
x T = singleton (fromString x) T
_⊕_↦_ : VarCtxt Var Type VarCtxt
Γ x T = insert (fromString x) T Γ
⊕-over : {Γ x y T U} (x y) ((Γ x T) y U) (Γ y U)
⊕-over p = insert-over _ _ _ _ _ (cong fromString (sym p))
⊕-swap : {Γ x y T U} (x y) ((Γ x T) y U) ((Γ y U) x T)
⊕-swap p = insert-swap _ _ _ _ _ (λ q p (trans (sym (to-from _)) (trans (cong toString (sym q) ) (to-from _))) )
⊕-lookup-miss : x y T Γ (x y) (Γ [ y ] (Γ x T) [ y ])
⊕-lookup-miss x y T Γ p = lookup-insert-not (fromString x) (fromString y) T Γ λ q p (trans (sym (to-from x)) (trans (cong toString q) (to-from y)))