open import 1Lab.Reflection open import 1Lab.Path open import 1Lab.Type open import Data.Maybe.Base open import Prim.Data.Nat module 1Lab.Reflection.Marker where -- The marker. The marker is literally just the identity function, but -- written surrounding rather than prefix. Unlike literally the identity -- function, however, the marker is marked NOINLINE, so it will not -- disappear without reduction. ⌜_⌝ : ∀ {ℓ} {A : Type ℓ} → A → A ⌜ x ⌝ = x {-# NOINLINE ⌜_⌝ #-} -- Abstract over the marked term(s). All marked terms refer to the same -- variable, so e.g. -- -- abstract-marker (quoteTerm (f ⌜ x ⌝ (λ _ → ⌜ x ⌝))) -- -- is (λ e → f e (λ _ → e)). The resulting term is open in precisely one -- variable: that variable is what substitutes the marked terms. abstract-marker : Term → Maybe Term abstract-marker = go 0 where go : Nat → Term → Maybe Term go* : Nat → List (Arg Term) → Maybe (List (Arg Term)) go k (var j args) = var j' <$> go* k args where j' : Nat j' with j < k ... | false = suc j ... | true = j go k (con c args) = con c <$> go* k args go k (def f args) with f ... | quote ⌜_⌝ = pure (var k []) -- ^ This is the one interesting case. Any application of the marker -- gets replaced with the 'k'th variable. Initially k = 0, so this is -- the variable bound by the lambda. But as we encounter further -- binders, we must increment this, since the marked term gets farther -- and farther away in the context. ... | x = def f <$> go* k args go k (lam v (abs x t)) = lam v ∘ abs x <$> go (suc k) t go k (pat-lam cs args) = nothing go k (pi (arg i a) (abs x t)) = do t ← go (suc k) t a ← go k a pure (pi (arg i a) (abs x t)) go k (agda-sort s) with s ... | set t = agda-sort ∘ set <$> go k t ... | lit n = pure (agda-sort (lit n)) ... | prop t = agda-sort ∘ prop <$> go k t ... | propLit n = pure (agda-sort (propLit n)) ... | inf n = pure (agda-sort (inf n)) ... | unknown = pure (agda-sort unknown) go k (lit l) = pure (lit l) go k (meta m args) = meta m <$> go* k args go k unknown = pure unknown go* k [] = pure [] go* k (arg i x ∷ xs) = do x ← go k x xs ← go* k xs pure (arg i x ∷ xs) macro -- Generalised ap. Automatically generates the function to apply to by -- abstracting over any markers in the LEFT ENDPOINT of the path. Use -- with _≡⟨_⟩_. ap! : ∀ {ℓ} {A : Type ℓ} {x y : A} → x ≡ y → Term → TC ⊤ ap! path goal = do goalt ← inferType goal just (l , r) ← get-boundary goalt where nothing → typeError (strErr "ap!: Goal type " ∷ termErr goalt ∷ strErr " is not a path type" ∷ []) just l′ ← pure (abstract-marker l) where _ → typeError $ "Failed to abstract over marker in term " ∷ termErr l ∷ [] let dm = lam visible (abs "x" l′) path′ ← quoteTC path debugPrint "1lab.marked-ap" 10 $ strErr "original term " ∷ termErr l ∷ [] debugPrint "1lab.marked-ap" 10 $ strErr "abstracted term " ∷ termErr dm ∷ [] unify goal (def (quote ap) (dm v∷ path′ v∷ [])) -- Generalised ap. Automatically generates the function to apply to by -- abstracting over any markers in the RIGHT ENDPOINT of the path. Use -- with _≡˘⟨_⟩_. ap¡ : ∀ {ℓ} {A : Type ℓ} {x y : A} → x ≡ y → Term → TC ⊤ ap¡ path goal = do goalt ← inferType goal just (l , r) ← get-boundary goalt where nothing → typeError (strErr "ap¡: Goal type " ∷ termErr goalt ∷ strErr " is not a path type" ∷ []) just r′ ← pure (abstract-marker r) where _ → typeError $ "Failed to abstract over marker in term " ∷ termErr r ∷ [] path′ ← quoteTC path unify goal $ def (quote ap) (lam visible (abs "x" r′) v∷ path′ v∷ []) module _ {ℓ} {A : Type ℓ} {x y : A} {p : x ≡ y} {f : A → (A → A) → A} where private q : f x (λ y → x) ≡ f y (λ z → y) q = f ⌜ x ⌝ (λ _ → ⌜ x ⌝) ≡⟨ ap! p ⟩ f y (λ _ → y) ∎ r : f y (λ _ → y) ≡ f x (λ _ → x) r = f ⌜ y ⌝ (λ _ → ⌜ y ⌝) ≡˘⟨ ap¡ p ⟩ f x (λ _ → x) ∎