426 lines
15 KiB
Idris
426 lines
15 KiB
Idris
module Quox.Typechecker
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import public Quox.Typing
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import public Quox.Equal
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import Data.List
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import Data.SnocVect
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import Data.List1
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import Quox.EffExtra
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%default total
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public export
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0 TCEff : List (Type -> Type)
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TCEff = [ErrorEff, DefsReader]
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public export
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0 TC : Type -> Type
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TC = Eff TCEff
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export
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runTC : Definitions -> TC a -> Either Error a
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runTC defs = extract . runExcept . runReader defs
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export
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popQs : Has ErrorEff fs => QOutput s -> QOutput (s + n) -> Eff fs (QOutput n)
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popQs [<] qout = pure qout
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popQs (pis :< pi) (qout :< rh) = do expectCompatQ rh pi; popQs pis qout
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export %inline
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popQ : Has ErrorEff fs => Qty -> QOutput (S n) -> Eff fs (QOutput n)
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popQ pi = popQs [< pi]
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export
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lubs1 : List1 (QOutput n) -> Maybe (QOutput n)
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lubs1 ([<] ::: _) = Just [<]
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lubs1 ((qs :< p) ::: pqs) =
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let (qss, ps) = unzip $ map unsnoc pqs in
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[|lubs1 (qs ::: qss) :< foldlM lub p ps|]
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export
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lubs : TyContext d n -> List (QOutput n) -> Maybe (QOutput n)
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lubs ctx [] = Just $ zeroFor ctx
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lubs ctx (x :: xs) = lubs1 $ x ::: xs
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mutual
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||| "Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ"
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|||
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||| `check ctx sg subj ty` checks that in the context `ctx`, the term
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||| `subj` has the type `ty`, with quantity `sg`. if so, returns the
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||| quantities of all bound variables that it used.
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|||
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||| if the dimension context is inconsistent, then return `Nothing`, without
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||| doing any further work.
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export covering %inline
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check : (ctx : TyContext d n) -> SQty -> Term d n -> Term d n ->
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TC (CheckResult ctx.dctx n)
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check ctx sg subj ty = ifConsistent ctx.dctx $ checkC ctx sg subj ty
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||| "Ψ | Γ ⊢₀ s ⇐ A"
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|||
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||| `check0 ctx subj ty` checks a term (as `check`) in a zero context.
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export covering %inline
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check0 : TyContext d n -> Term d n -> Term d n -> TC ()
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check0 ctx tm ty = ignore $ check ctx szero tm ty
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-- the output will always be 𝟎 because the subject quantity is 0
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||| `check`, assuming the dimension context is consistent
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export covering %inline
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checkC : (ctx : TyContext d n) -> SQty -> Term d n -> Term d n ->
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TC (CheckResult' n)
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checkC ctx sg subj ty =
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wrapErr (WhileChecking ctx sg.fst subj ty) $
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let Element subj nc = pushSubsts subj in
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check' ctx sg subj ty
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||| "Ψ | Γ ⊢₀ s ⇐ ★ᵢ"
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|||
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||| `checkType ctx subj ty` checks a type (in a zero context). sometimes the
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||| universe doesn't matter, only that a term is _a_ type, so it is optional.
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export covering %inline
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checkType : TyContext d n -> Term d n -> Maybe Universe -> TC ()
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checkType ctx subj l = ignore $ ifConsistent ctx.dctx $ checkTypeC ctx subj l
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export covering %inline
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checkTypeC : TyContext d n -> Term d n -> Maybe Universe -> TC ()
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checkTypeC ctx subj l =
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wrapErr (WhileCheckingTy ctx subj l) $ checkTypeNoWrap ctx subj l
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export covering %inline
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checkTypeNoWrap : TyContext d n -> Term d n -> Maybe Universe -> TC ()
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checkTypeNoWrap ctx subj l =
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let Element subj nc = pushSubsts subj in
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checkType' ctx subj l
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||| "Ψ | Γ ⊢ σ · e ⇒ A ⊳ Σ"
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|||
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||| `infer ctx sg subj` infers the type of `subj` in the context `ctx`,
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||| and returns its type and the bound variables it used.
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|||
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||| if the dimension context is inconsistent, then return `Nothing`, without
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||| doing any further work.
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export covering %inline
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infer : (ctx : TyContext d n) -> SQty -> Elim d n ->
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TC (InferResult ctx.dctx d n)
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infer ctx sg subj = ifConsistent ctx.dctx $ inferC ctx sg subj
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||| `infer`, assuming the dimension context is consistent
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export covering %inline
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inferC : (ctx : TyContext d n) -> SQty -> Elim d n ->
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TC (InferResult' d n)
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inferC ctx sg subj =
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wrapErr (WhileInferring ctx sg.fst subj) $
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let Element subj nc = pushSubsts subj in
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infer' ctx sg subj
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private covering
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toCheckType : TyContext d n -> SQty ->
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(subj : Term d n) -> (0 nc : NotClo subj) => Term d n ->
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TC (CheckResult' n)
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toCheckType ctx sg t ty = do
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u <- expectTYPE !ask ctx ty
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expectEqualQ Zero sg.fst
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checkTypeNoWrap ctx t (Just u)
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pure $ zeroFor ctx
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private covering
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check' : TyContext d n -> SQty ->
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(subj : Term d n) -> (0 nc : NotClo subj) => Term d n ->
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TC (CheckResult' n)
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check' ctx sg t@(TYPE _) ty = toCheckType ctx sg t ty
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check' ctx sg t@(Pi {}) ty = toCheckType ctx sg t ty
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check' ctx sg (Lam body) ty = do
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(qty, arg, res) <- expectPi !ask ctx ty
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-- if Ψ | Γ, x : A ⊢ σ · t ⇐ B ⊳ Σ, ρ·x
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-- with ρ ≤ σπ
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let qty' = sg.fst * qty
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qout <- checkC (extendTy qty' body.name arg ctx) sg body.term res.term
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-- then Ψ | Γ ⊢ σ · (λx ⇒ t) ⇐ (π·x : A) → B ⊳ Σ
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popQ qty' qout
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check' ctx sg t@(Sig {}) ty = toCheckType ctx sg t ty
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check' ctx sg (Pair fst snd) ty = do
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(tfst, tsnd) <- expectSig !ask ctx ty
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-- if Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ₁
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qfst <- checkC ctx sg fst tfst
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let tsnd = sub1 tsnd (fst :# tfst)
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-- if Ψ | Γ ⊢ σ · t ⇐ B[s] ⊳ Σ₂
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qsnd <- checkC ctx sg snd tsnd
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-- then Ψ | Γ ⊢ σ · (s, t) ⇐ (x : A) × B ⊳ Σ₁ + Σ₂
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pure $ qfst + qsnd
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check' ctx sg t@(Enum _) ty = toCheckType ctx sg t ty
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check' ctx sg (Tag t) ty = do
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tags <- expectEnum !ask ctx ty
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-- if t ∈ ts
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unless (t `elem` tags) $ throw $ TagNotIn t tags
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-- then Ψ | Γ ⊢ σ · t ⇐ {ts} ⊳ 𝟎
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pure $ zeroFor ctx
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check' ctx sg t@(Eq {}) ty = toCheckType ctx sg t ty
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check' ctx sg (DLam body) ty = do
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(ty, l, r) <- expectEq !ask ctx ty
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-- if Ψ, i | Γ ⊢ σ · t ⇐ A ⊳ Σ
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qout <- checkC (extendDim body.name ctx) sg body.term ty.term
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-- if Ψ | Γ ⊢ t‹0› = l : A‹0›
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equal ctx ty.zero body.zero l
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-- if Ψ | Γ ⊢ t‹1› = r : A‹1›
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equal ctx ty.one body.one r
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-- then Ψ | Γ ⊢ σ · (δ i ⇒ t) ⇐ Eq [i ⇒ A] l r ⊳ Σ
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pure qout
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check' ctx sg Nat ty = toCheckType ctx sg Nat ty
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check' ctx sg Zero ty = do
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expectNat !ask ctx ty
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pure $ zeroFor ctx
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check' ctx sg (Succ n) ty = do
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expectNat !ask ctx ty
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checkC ctx sg n Nat
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check' ctx sg t@(BOX {}) ty = toCheckType ctx sg t ty
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check' ctx sg (Box val) ty = do
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(q, ty) <- expectBOX !ask ctx ty
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-- if Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ
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valout <- checkC ctx sg val ty
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-- then Ψ | Γ ⊢ σ · [s] ⇐ [π.A] ⊳ πΣ
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pure $ q * valout
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check' ctx sg (E e) ty = do
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-- if Ψ | Γ ⊢ σ · e ⇒ A' ⊳ Σ
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infres <- inferC ctx sg e
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-- if Ψ | Γ ⊢ A' <: A
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subtype ctx infres.type ty
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-- then Ψ | Γ ⊢ σ · e ⇐ A ⊳ Σ
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pure infres.qout
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private covering
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checkType' : TyContext d n ->
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(subj : Term d n) -> (0 nc : NotClo subj) =>
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Maybe Universe -> TC ()
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checkType' ctx (TYPE k) u = do
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-- if 𝓀 < ℓ then Ψ | Γ ⊢₀ Type 𝓀 ⇐ Type ℓ
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case u of
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Just l => unless (k < l) $ throw $ BadUniverse k l
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Nothing => pure ()
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checkType' ctx (Pi qty arg res) u = do
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-- if Ψ | Γ ⊢₀ A ⇐ Type ℓ
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checkTypeC ctx arg u
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-- if Ψ | Γ, x : A ⊢₀ B ⇐ Type ℓ
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case res.body of
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Y res' => checkTypeC (extendTy Zero res.name arg ctx) res' u
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N res' => checkTypeC ctx res' u
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-- then Ψ | Γ ⊢₀ (π·x : A) → B ⇐ Type ℓ
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checkType' ctx t@(Lam {}) u =
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throw $ NotType ctx t
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checkType' ctx (Sig fst snd) u = do
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-- if Ψ | Γ ⊢₀ A ⇐ Type ℓ
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checkTypeC ctx fst u
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-- if Ψ | Γ, x : A ⊢₀ B ⇐ Type ℓ
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case snd.body of
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Y snd' => checkTypeC (extendTy Zero snd.name fst ctx) snd' u
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N snd' => checkTypeC ctx snd' u
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-- then Ψ | Γ ⊢₀ (x : A) × B ⇐ Type ℓ
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checkType' ctx t@(Pair {}) u =
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throw $ NotType ctx t
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checkType' ctx (Enum _) u = pure ()
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-- Ψ | Γ ⊢₀ {ts} ⇐ Type ℓ
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checkType' ctx t@(Tag {}) u =
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throw $ NotType ctx t
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checkType' ctx (Eq t l r) u = do
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-- if Ψ, i | Γ ⊢₀ A ⇐ Type ℓ
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case t.body of
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Y t' => checkTypeC (extendDim t.name ctx) t' u
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N t' => checkTypeC ctx t' u
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-- if Ψ | Γ ⊢₀ l ⇐ A‹0›
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check0 ctx l t.zero
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-- if Ψ | Γ ⊢₀ r ⇐ A‹1›
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check0 ctx r t.one
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-- then Ψ | Γ ⊢₀ Eq [i ⇒ A] l r ⇐ Type ℓ
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checkType' ctx t@(DLam {}) u =
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throw $ NotType ctx t
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checkType' ctx Nat u = pure ()
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checkType' ctx Zero u = throw $ NotType ctx Zero
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checkType' ctx t@(Succ _) u = throw $ NotType ctx t
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checkType' ctx (BOX q ty) u = checkType ctx ty u
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checkType' ctx t@(Box _) u = throw $ NotType ctx t
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checkType' ctx (E e) u = do
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-- if Ψ | Γ ⊢₀ E ⇒ Type ℓ
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infres <- inferC ctx szero e
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-- if Ψ | Γ ⊢ Type ℓ <: Type 𝓀
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case u of
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Just u => subtype ctx infres.type (TYPE u)
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Nothing => ignore $ expectTYPE !ask ctx infres.type
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-- then Ψ | Γ ⊢₀ E ⇐ Type 𝓀
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private covering
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infer' : TyContext d n -> SQty ->
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(subj : Elim d n) -> (0 nc : NotClo subj) =>
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TC (InferResult' d n)
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infer' ctx sg (F x) = do
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-- if π·x : A {≔ s} in global context
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g <- lookupFree x
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-- if σ ≤ π
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expectCompatQ sg.fst g.qty.fst
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-- then Ψ | Γ ⊢ σ · x ⇒ A ⊳ 𝟎
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pure $ InfRes {type = injectT ctx g.type, qout = zeroFor ctx}
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where
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lookupFree : Name -> TC Definition
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lookupFree x = lookupFree' !ask x
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infer' ctx sg (B i) =
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-- if x : A ∈ Γ
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-- then Ψ | Γ ⊢ σ · x ⇒ A ⊳ (𝟎, σ·x, 𝟎)
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pure $ lookupBound sg.fst i ctx.tctx
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where
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lookupBound : forall n. Qty -> Var n -> TContext d n -> InferResult' d n
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lookupBound pi VZ (ctx :< ty) =
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InfRes {type = weakT ty, qout = zeroFor ctx :< pi}
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lookupBound pi (VS i) (ctx :< _) =
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let InfRes {type, qout} = lookupBound pi i ctx in
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InfRes {type = weakT type, qout = qout :< Zero}
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infer' ctx sg (fun :@ arg) = do
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-- if Ψ | Γ ⊢ σ · f ⇒ (π·x : A) → B ⊳ Σ₁
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funres <- inferC ctx sg fun
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(qty, argty, res) <- expectPi !ask ctx funres.type
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-- if Ψ | Γ ⊢ σ ⨴ π · s ⇐ A ⊳ Σ₂
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argout <- checkC ctx (subjMult sg qty) arg argty
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-- then Ψ | Γ ⊢ σ · f s ⇒ B[s] ⊳ Σ₁ + Σ₂
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pure $ InfRes {
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type = sub1 res $ arg :# argty,
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qout = funres.qout + argout
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}
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infer' ctx sg (CasePair pi pair ret body) = do
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-- no check for 1 ≤ π, since pairs have a single constructor.
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-- e.g. at 0 the components are also 0 in the body
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--
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-- if Ψ | Γ ⊢ σ · pair ⇒ (x : A) × B ⊳ Σ₁
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pairres <- inferC ctx sg pair
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-- if Ψ | Γ, p : (x : A) × B ⊢₀ ret ⇐ Type
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checkTypeC (extendTy Zero ret.name pairres.type ctx) ret.term Nothing
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(tfst, tsnd) <- expectSig !ask ctx pairres.type
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-- if Ψ | Γ, x : A, y : B ⊢ σ · body ⇐
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-- ret[(x, y) ∷ (x : A) × B/p] ⊳ Σ₂, ρ₁·x, ρ₂·y
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-- with ρ₁, ρ₂ ≤ πσ
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let [< x, y] = body.names
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pisg = pi * sg.fst
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bodyctx = extendTyN [< (pisg, x, tfst), (pisg, y, tsnd.term)] ctx
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bodyty = substCasePairRet pairres.type ret
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bodyout <- checkC bodyctx sg body.term bodyty >>= popQs [< pisg, pisg]
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-- then Ψ | Γ ⊢ σ · case ⋯ ⇒ ret[pair/p] ⊳ πΣ₁ + Σ₂
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pure $ InfRes {
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type = sub1 ret pair,
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qout = pi * pairres.qout + bodyout
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}
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infer' ctx sg (CaseEnum pi t ret arms) {d, n} = do
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-- if Ψ | Γ ⊢ σ · t ⇒ {ts} ⊳ Σ₁
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tres <- inferC ctx sg t
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ttags <- expectEnum !ask ctx tres.type
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-- if 1 ≤ π, OR there is only zero or one option
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unless (length (SortedSet.toList ttags) <= 1) $ expectCompatQ One pi
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-- if Ψ | Γ, x : {ts} ⊢₀ A ⇐ Type
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checkTypeC (extendTy Zero ret.name tres.type ctx) ret.term Nothing
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-- if for each "a ⇒ s" in arms,
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-- Ψ | Γ ⊢ σ · s ⇐ A[a ∷ {ts}/x] ⊳ Σᵢ
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-- with Σ₂ = lubs Σᵢ
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let arms = SortedMap.toList arms
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let armTags = SortedSet.fromList $ map fst arms
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unless (ttags == armTags) $ throw $ BadCaseEnum ttags armTags
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armres <- for arms $ \(a, s) =>
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checkC ctx sg s (sub1 ret (Tag a :# tres.type))
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let Just armout = lubs ctx armres
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| _ => throw $ BadCaseQtys ctx $
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zipWith (\qs, (t, rhs) => (qs, Tag t)) armres arms
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pure $ InfRes {
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type = sub1 ret t,
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qout = pi * tres.qout + armout
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}
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infer' ctx sg (CaseNat pi pi' n ret zer suc) = do
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-- if 1 ≤ π
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expectCompatQ One pi
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-- if Ψ | Γ ⊢ σ · n ⇒ ℕ ⊳ Σn
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nres <- inferC ctx sg n
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expectNat !ask ctx nres.type
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-- if Ψ | Γ, n : ℕ ⊢₀ A ⇐ Type
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checkTypeC (extendTy Zero ret.name Nat ctx) ret.term Nothing
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-- if Ψ | Γ ⊢ σ · zer ⇐ A[0 ∷ ℕ/n] ⊳ Σz
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zerout <- checkC ctx sg zer (sub1 ret (Zero :# Nat))
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-- if Ψ | Γ, n : ℕ, ih : A ⊢ σ · suc ⇐ A[succ p ∷ ℕ/n] ⊳ Σs, ρ₁.p, ρ₂.ih
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-- with ρ₂ ≤ π'σ, (ρ₁ + ρ₂) ≤ πσ
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let [< p, ih] = suc.names
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pisg = pi * sg.fst
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sucCtx = extendTyN [< (pisg, p, Nat), (pi', ih, ret.term)] ctx
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sucType = substCaseSuccRet ret
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sucout :< qp :< qih <- checkC sucCtx sg suc.term sucType
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expectCompatQ qih (pi' * sg.fst)
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-- [fixme] better error here
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expectCompatQ (qp + qih) pisg
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-- then Ψ | Γ ⊢ case ⋯ ⇒ A[n] ⊳ πΣn + Σz + ωΣs
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pure $ InfRes {
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type = sub1 ret n,
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qout = pi * nres.qout + zerout + Any * sucout
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}
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infer' ctx sg (CaseBox pi box ret body) = do
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-- if Ψ | Γ ⊢ σ · b ⇒ [ρ.A] ⊳ Σ₁
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boxres <- inferC ctx sg box
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(q, ty) <- expectBOX !ask ctx boxres.type
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-- if Ψ | Γ, x : [ρ.A] ⊢₀ R ⇐ Type
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checkTypeC (extendTy Zero ret.name boxres.type ctx) ret.term Nothing
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-- if Ψ | Γ, x : A ⊢ t ⇐ R[[x] ∷ [ρ.A/x]] ⊳ Σ₂, ς·x
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-- with ς ≤ ρπσ
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let qpisg = q * pi * sg.fst
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bodyCtx = extendTy qpisg body.name ty ctx
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bodyType = substCaseBoxRet ty ret
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bodyout <- checkC bodyCtx sg body.term bodyType >>= popQ qpisg
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-- then Ψ | Γ ⊢ case ⋯ ⇒ R[b/x] ⊳ Σ₁ + Σ₂
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pure $ InfRes {
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type = sub1 ret box,
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qout = boxres.qout + bodyout
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}
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infer' ctx sg (fun :% dim) = do
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-- if Ψ | Γ ⊢ σ · f ⇒ Eq [𝑖 ⇒ A] l r ⊳ Σ
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InfRes {type, qout} <- inferC ctx sg fun
|
||
ty <- fst <$> expectEq !ask ctx type
|
||
-- then Ψ | Γ ⊢ σ · f p ⇒ A‹p/𝑖› ⊳ Σ
|
||
pure $ InfRes {type = dsub1 ty dim, qout}
|
||
|
||
infer' ctx sg (term :# type) = do
|
||
-- if Ψ | Γ ⊢₀ A ⇐ Type ℓ
|
||
checkTypeC ctx type Nothing
|
||
-- if Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ
|
||
qout <- checkC ctx sg term type
|
||
-- then Ψ | Γ ⊢ σ · (s ∷ A) ⇒ A ⊳ Σ
|
||
pure $ InfRes {type, qout}
|