module Quox.Typechecker import public Quox.Typing import public Quox.Equal import Quox.Displace import Data.List import Data.SnocVect import Data.List1 import Quox.EffExtra %default total public export 0 TC : List (Type -> Type) TC = [ErrorEff, DefsReader, NameGen] parameters (loc : Loc) export popQs : Has ErrorEff fs => QContext s -> QOutput (s + n) -> Eff fs (QOutput n) popQs [<] qout = pure qout popQs (pis :< pi) (qout :< rh) = do expectCompatQ loc rh pi; popQs pis qout export %inline popQ : Has ErrorEff fs => Qty -> QOutput (S n) -> Eff fs (QOutput n) popQ pi = popQs [< pi] export lubs1 : List1 (QOutput n) -> QOutput n lubs1 ([<] ::: _) = [<] lubs1 ((qs :< p) ::: pqs) = let (qss, ps) = unzip $ map unsnoc pqs in lubs1 (qs ::: qss) :< foldl lub p ps export lubs : TyContext d n -> List (QOutput n) -> QOutput n lubs ctx [] = zeroFor ctx lubs ctx (x :: xs) = lubs1 $ x ::: xs mutual ||| "Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ" ||| ||| `check ctx sg subj ty` checks that in the context `ctx`, the term ||| `subj` has the type `ty`, with quantity `sg`. if so, returns the ||| quantities of all bound variables that it used. ||| ||| if the dimension context is inconsistent, then return `Nothing`, without ||| doing any further work. export covering %inline check : (ctx : TyContext d n) -> SQty -> Term d n -> Term d n -> Eff TC (CheckResult ctx.dctx n) check ctx sg subj ty = ifConsistent ctx.dctx $ checkC ctx sg subj ty ||| "Ψ | Γ ⊢₀ s ⇐ A" ||| ||| `check0 ctx subj ty` checks a term (as `check`) in a zero context. export covering %inline check0 : TyContext d n -> Term d n -> Term d n -> Eff TC () check0 ctx tm ty = ignore $ check ctx SZero tm ty -- the output will always be 𝟎 because the subject quantity is 0 ||| `check`, assuming the dimension context is consistent export covering %inline checkC : (ctx : TyContext d n) -> SQty -> Term d n -> Term d n -> Eff TC (CheckResult' n) checkC ctx sg subj ty = wrapErr (WhileChecking ctx sg subj ty) $ checkCNoWrap ctx sg subj ty export covering %inline checkCNoWrap : (ctx : TyContext d n) -> SQty -> Term d n -> Term d n -> Eff TC (CheckResult' n) checkCNoWrap ctx sg subj ty = let Element subj nc = pushSubsts subj in check' ctx sg subj ty ||| "Ψ | Γ ⊢₀ s ⇐ ★ᵢ" ||| ||| `checkType ctx subj ty` checks a type (in a zero context). sometimes the ||| universe doesn't matter, only that a term is _a_ type, so it is optional. export covering %inline checkType : TyContext d n -> Term d n -> Maybe Universe -> Eff TC () checkType ctx subj l = ignore $ ifConsistent ctx.dctx $ checkTypeC ctx subj l export covering %inline checkTypeC : TyContext d n -> Term d n -> Maybe Universe -> Eff TC () checkTypeC ctx subj l = wrapErr (WhileCheckingTy ctx subj l) $ checkTypeNoWrap ctx subj l export covering %inline checkTypeNoWrap : TyContext d n -> Term d n -> Maybe Universe -> Eff TC () checkTypeNoWrap ctx subj l = let Element subj nc = pushSubsts subj in checkType' ctx subj l ||| "Ψ | Γ ⊢ σ · e ⇒ A ⊳ Σ" ||| ||| `infer ctx sg subj` infers the type of `subj` in the context `ctx`, ||| and returns its type and the bound variables it used. ||| ||| if the dimension context is inconsistent, then return `Nothing`, without ||| doing any further work. export covering %inline infer : (ctx : TyContext d n) -> SQty -> Elim d n -> Eff TC (InferResult ctx.dctx d n) infer ctx sg subj = ifConsistent ctx.dctx $ inferC ctx sg subj ||| `infer`, assuming the dimension context is consistent export covering %inline inferC : (ctx : TyContext d n) -> SQty -> Elim d n -> Eff TC (InferResult' d n) inferC ctx sg subj = wrapErr (WhileInferring ctx sg subj) $ let Element subj nc = pushSubsts subj in infer' ctx sg subj private covering toCheckType : TyContext d n -> SQty -> (subj : Term d n) -> (0 nc : NotClo subj) => Term d n -> Eff TC (CheckResult' n) toCheckType ctx sg t ty = do u <- expectTYPE !(askAt DEFS) ctx sg ty.loc ty expectEqualQ t.loc Zero sg.qty checkTypeNoWrap ctx t (Just u) pure $ zeroFor ctx private covering check' : TyContext d n -> SQty -> (subj : Term d n) -> (0 nc : NotClo subj) => Term d n -> Eff TC (CheckResult' n) check' ctx sg t@(TYPE {}) ty = toCheckType ctx sg t ty check' ctx sg t@(IOState {}) ty = toCheckType ctx sg t ty check' ctx sg t@(Pi {}) ty = toCheckType ctx sg t ty check' ctx sg (Lam body loc) ty = do (qty, arg, res) <- expectPi !(askAt DEFS) ctx SZero ty.loc ty -- if Ψ | Γ, x : A ⊢ σ · t ⇐ B ⊳ Σ, ρ·x -- with ρ ≤ σπ let qty' = sg.qty * qty qout <- checkC (extendTy qty' body.name arg ctx) sg body.term res.term -- then Ψ | Γ ⊢ σ · (λx ⇒ t) ⇐ (π·x : A) → B ⊳ Σ popQ loc qty' qout check' ctx sg t@(Sig {}) ty = toCheckType ctx sg t ty check' ctx sg (Pair fst snd loc) ty = do (tfst, tsnd) <- expectSig !(askAt DEFS) ctx SZero ty.loc ty -- if Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ₁ qfst <- checkC ctx sg fst tfst let tsnd = sub1 tsnd (Ann fst tfst fst.loc) -- if Ψ | Γ ⊢ σ · t ⇐ B[s] ⊳ Σ₂ qsnd <- checkC ctx sg snd tsnd -- then Ψ | Γ ⊢ σ · (s, t) ⇐ (x : A) × B ⊳ Σ₁ + Σ₂ pure $ qfst + qsnd check' ctx sg t@(Enum {}) ty = toCheckType ctx sg t ty check' ctx sg (Tag t loc) ty = do tags <- expectEnum !(askAt DEFS) ctx SZero ty.loc ty -- if t ∈ ts unless (t `elem` tags) $ throw $ TagNotIn loc t tags -- then Ψ | Γ ⊢ σ · t ⇐ {ts} ⊳ 𝟎 pure $ zeroFor ctx check' ctx sg t@(Eq {}) ty = toCheckType ctx sg t ty check' ctx sg (DLam body loc) ty = do (ty, l, r) <- expectEq !(askAt DEFS) ctx SZero ty.loc ty let ctx' = extendDim body.name ctx ty = ty.term body = body.term -- if Ψ, i | Γ ⊢ σ · t ⇐ A ⊳ Σ qout <- checkC ctx' sg body ty -- if Ψ, i, i = 0 | Γ ⊢ t = l : A let ctx0 = eqDim (B VZ loc) (K Zero loc) ctx' lift $ equal loc ctx0 sg ty body $ dweakT 1 l -- if Ψ, i, i = 1 | Γ ⊢ t = r : A let ctx1 = eqDim (B VZ loc) (K One loc) ctx' lift $ equal loc ctx1 sg ty body $ dweakT 1 r -- then Ψ | Γ ⊢ σ · (δ i ⇒ t) ⇐ Eq [i ⇒ A] l r ⊳ Σ pure qout check' ctx sg t@(NAT {}) ty = toCheckType ctx sg t ty check' ctx sg (Nat {}) ty = do expectNAT !(askAt DEFS) ctx SZero ty.loc ty pure $ zeroFor ctx check' ctx sg (Succ n {}) ty = do expectNAT !(askAt DEFS) ctx SZero ty.loc ty checkC ctx sg n ty check' ctx sg t@(STRING {}) ty = toCheckType ctx sg t ty check' ctx sg t@(Str s {}) ty = do expectSTRING !(askAt DEFS) ctx SZero ty.loc ty pure $ zeroFor ctx check' ctx sg t@(BOX {}) ty = toCheckType ctx sg t ty check' ctx sg (Box val loc) ty = do (q, ty) <- expectBOX !(askAt DEFS) ctx SZero ty.loc ty -- if Ψ | Γ ⊢ σ ⨴ π · s ⇐ A ⊳ Σ valout <- checkC ctx (subjMult sg q) val ty -- then Ψ | Γ ⊢ σ · [s] ⇐ [π.A] ⊳ πΣ pure $ q * valout check' ctx sg (Let qty rhs body loc) ty = do eres <- inferC ctx (subjMult sg qty) rhs let sqty = sg.qty * qty qout <- checkC (extendTyLet sqty body.name eres.type (E rhs) ctx) sg body.term (weakT 1 ty) >>= popQ loc sqty pure $ qty * eres.qout + qout check' ctx sg (E e) ty = do -- if Ψ | Γ ⊢ σ · e ⇒ A' ⊳ Σ infres <- inferC ctx sg e -- if Ψ | Γ ⊢ A' <: A lift $ subtype e.loc ctx infres.type ty -- then Ψ | Γ ⊢ σ · e ⇐ A ⊳ Σ pure infres.qout private covering checkType' : TyContext d n -> (subj : Term d n) -> (0 nc : NotClo subj) => Maybe Universe -> Eff TC () checkType' ctx (TYPE k loc) u = do -- if 𝓀 < ℓ then Ψ | Γ ⊢₀ Type 𝓀 ⇐ Type ℓ case u of Just l => unless (k < l) $ throw $ BadUniverse loc k l Nothing => pure () checkType' ctx (IOState loc) u = pure () -- Ψ | Γ ⊢₀ IOState ⇒ Type ℓ checkType' ctx (Pi qty arg res _) u = do -- if Ψ | Γ ⊢₀ A ⇐ Type ℓ checkTypeC ctx arg u -- if Ψ | Γ, x : A ⊢₀ B ⇐ Type ℓ checkTypeScope ctx arg res u -- then Ψ | Γ ⊢₀ (π·x : A) → B ⇐ Type ℓ checkType' ctx t@(Lam {}) u = throw $ NotType t.loc ctx t checkType' ctx (Sig fst snd _) u = do -- if Ψ | Γ ⊢₀ A ⇐ Type ℓ checkTypeC ctx fst u -- if Ψ | Γ, x : A ⊢₀ B ⇐ Type ℓ checkTypeScope ctx fst snd u -- then Ψ | Γ ⊢₀ (x : A) × B ⇐ Type ℓ checkType' ctx t@(Pair {}) u = throw $ NotType t.loc ctx t checkType' ctx (Enum {}) u = pure () -- Ψ | Γ ⊢₀ {ts} ⇐ Type ℓ checkType' ctx t@(Tag {}) u = throw $ NotType t.loc ctx t checkType' ctx (Eq t l r _) u = do -- if Ψ, i | Γ ⊢₀ A ⇐ Type ℓ case t.body of Y t' => checkTypeC (extendDim t.name ctx) t' u N t' => checkTypeC ctx t' u -- if Ψ | Γ ⊢₀ l ⇐ A‹0› check0 ctx l t.zero -- if Ψ | Γ ⊢₀ r ⇐ A‹1› check0 ctx r t.one -- then Ψ | Γ ⊢₀ Eq [i ⇒ A] l r ⇐ Type ℓ checkType' ctx t@(DLam {}) u = throw $ NotType t.loc ctx t checkType' ctx (NAT {}) u = pure () checkType' ctx t@(Nat {}) u = throw $ NotType t.loc ctx t checkType' ctx t@(Succ {}) u = throw $ NotType t.loc ctx t checkType' ctx (STRING loc) u = pure () -- Ψ | Γ ⊢₀ STRING ⇒ Type ℓ checkType' ctx t@(Str {}) u = throw $ NotType t.loc ctx t checkType' ctx (BOX q ty _) u = checkType ctx ty u checkType' ctx t@(Box {}) u = throw $ NotType t.loc ctx t checkType' ctx (Let qty rhs body loc) u = do expectEqualQ loc qty Zero ety <- inferC ctx SZero rhs checkType (extendTy Zero body.name ety.type ctx) body.term u checkType' ctx (E e) u = do -- if Ψ | Γ ⊢₀ E ⇒ Type ℓ infres <- inferC ctx SZero e -- if Ψ | Γ ⊢ Type ℓ <: Type 𝓀 case u of Just u => lift $ subtype e.loc ctx infres.type (TYPE u e.loc) Nothing => ignore $ expectTYPE !(askAt DEFS) ctx SZero e.loc infres.type -- then Ψ | Γ ⊢₀ E ⇐ Type 𝓀 private covering checkTypeScope : TyContext d n -> Term d n -> ScopeTerm d n -> Maybe Universe -> Eff TC () checkTypeScope ctx s (S _ (N body)) u = checkType ctx body u checkTypeScope ctx s (S [< x] (Y body)) u = checkType (extendTy Zero x s ctx) body u private covering infer' : TyContext d n -> SQty -> (subj : Elim d n) -> (0 nc : NotClo subj) => Eff TC (InferResult' d n) infer' ctx sg (F x u loc) = do -- if π·x : A {≔ s} in global context g <- lookupFree x loc !(askAt DEFS) -- if σ ≤ π expectCompatQ loc sg.qty g.qty.qty -- then Ψ | Γ ⊢ σ · x ⇒ A ⊳ 𝟎 pure $ InfRes { type = g.typeWithAt ctx.dimLen ctx.termLen u, qout = zeroFor ctx } infer' ctx sg (B i _) = -- if x : A ∈ Γ -- then Ψ | Γ ⊢ σ · x ⇒ A ⊳ (𝟎, σ·x, 𝟎) pure $ lookupBound sg.qty i ctx.tctx where lookupBound : forall n. Qty -> Var n -> TContext d n -> InferResult' d n lookupBound pi VZ (ctx :< var) = InfRes {type = weakT 1 var.type, qout = zeroFor ctx :< pi} lookupBound pi (VS i) (ctx :< _) = let InfRes {type, qout} = lookupBound pi i ctx in InfRes {type = weakT 1 type, qout = qout :< Zero} infer' ctx sg (App fun arg loc) = do -- if Ψ | Γ ⊢ σ · f ⇒ (π·x : A) → B ⊳ Σ₁ funres <- inferC ctx sg fun (qty, argty, res) <- expectPi !(askAt DEFS) ctx SZero fun.loc funres.type -- if Ψ | Γ ⊢ σ ⨴ π · s ⇐ A ⊳ Σ₂ argout <- checkC ctx (subjMult sg qty) arg argty -- then Ψ | Γ ⊢ σ · f s ⇒ B[s] ⊳ Σ₁ + πΣ₂ pure $ InfRes { type = sub1 res $ Ann arg argty arg.loc, qout = funres.qout + qty * argout } infer' ctx sg (CasePair pi pair ret body loc) = do -- no check for 1 ≤ π, since pairs have a single constructor. -- e.g. at 0 the components are also 0 in the body -- -- if Ψ | Γ ⊢ σ · pair ⇒ (x : A) × B ⊳ Σ₁ pairres <- inferC ctx sg pair -- if Ψ | Γ, p : (x : A) × B ⊢₀ ret ⇐ Type checkTypeC (extendTy Zero ret.name pairres.type ctx) ret.term Nothing (tfst, tsnd) <- expectSig !(askAt DEFS) ctx SZero pair.loc pairres.type -- if Ψ | Γ, x : A, y : B ⊢ σ · body ⇐ -- ret[(x, y) ∷ (x : A) × B/p] ⊳ Σ₂, ρ₁·x, ρ₂·y -- with ρ₁, ρ₂ ≤ πσ let [< x, y] = body.names pisg = pi * sg.qty bodyctx = extendTyN [< (pisg, x, tfst), (pisg, y, tsnd.term)] ctx bodyty = substCasePairRet body.names pairres.type ret bodyout <- checkC bodyctx sg body.term bodyty >>= popQs loc [< pisg, pisg] -- then Ψ | Γ ⊢ σ · caseπ ⋯ ⇒ ret[pair/p] ⊳ πΣ₁ + Σ₂ pure $ InfRes { type = sub1 ret pair, qout = pi * pairres.qout + bodyout } infer' ctx sg (Fst pair loc) = do -- if Ψ | Γ ⊢ σ · e ⇒ (x : A) × B ⊳ Σ pairres <- inferC ctx sg pair (tfst, _) <- expectSig !(askAt DEFS) ctx SZero pair.loc pairres.type -- then Ψ | Γ ⊢ σ · fst e ⇒ A ⊳ ωΣ pure $ InfRes { type = tfst, qout = Any * pairres.qout } infer' ctx sg (Snd pair loc) = do -- if Ψ | Γ ⊢ σ · e ⇒ (x : A) × B ⊳ Σ pairres <- inferC ctx sg pair (_, tsnd) <- expectSig !(askAt DEFS) ctx SZero pair.loc pairres.type -- then Ψ | Γ ⊢ σ · snd e ⇒ B[fst e/x] ⊳ ωΣ pure $ InfRes { type = sub1 tsnd (Fst pair loc), qout = Any * pairres.qout } infer' ctx sg (CaseEnum pi t ret arms loc) {d, n} = do -- if Ψ | Γ ⊢ σ · t ⇒ {ts} ⊳ Σ₁ tres <- inferC ctx sg t ttags <- expectEnum !(askAt DEFS) ctx SZero t.loc tres.type -- if 1 ≤ π, OR there is only zero or one option unless (length (SortedSet.toList ttags) <= 1) $ expectCompatQ loc One pi -- if Ψ | Γ, x : {ts} ⊢₀ A ⇐ Type checkTypeC (extendTy Zero ret.name tres.type ctx) ret.term Nothing -- if for each "a ⇒ s" in arms, -- Ψ | Γ ⊢ σ · s ⇐ A[a ∷ {ts}/x] ⊳ Σᵢ -- with Σ₂ = lubs Σᵢ let arms = SortedMap.toList arms let armTags = SortedSet.fromList $ map fst arms unless (ttags == armTags) $ throw $ BadCaseEnum loc ttags armTags armres <- for arms $ \(a, s) => checkC ctx sg s $ sub1 ret $ Ann (Tag a s.loc) tres.type s.loc pure $ InfRes { type = sub1 ret t, qout = pi * tres.qout + lubs ctx armres } infer' ctx sg (CaseNat pi pi' n ret zer suc loc) = do -- if 1 ≤ π expectCompatQ loc One pi -- if Ψ | Γ ⊢ σ · n ⇒ ℕ ⊳ Σn nres <- inferC ctx sg n let nat = nres.type expectNAT !(askAt DEFS) ctx SZero n.loc nat -- if Ψ | Γ, n : ℕ ⊢₀ A ⇐ Type checkTypeC (extendTy Zero ret.name nat ctx) ret.term Nothing -- if Ψ | Γ ⊢ σ · zer ⇐ A[0 ∷ ℕ/n] ⊳ Σz zerout <- checkC ctx sg zer $ sub1 ret $ Ann (Zero zer.loc) nat zer.loc -- if Ψ | Γ, n : ℕ, ih : A ⊢ σ · suc ⇐ A[succ p ∷ ℕ/n] ⊳ Σs, ρ.p, ς.ih -- with ς ≤ π'σ, (ρ + ς) ≤ πσ let [< p, ih] = suc.names pisg = pi * sg.qty sucCtx = extendTyN [< (pisg, p, NAT p.loc), (pi', ih, ret.term)] ctx sucType = substCaseSuccRet suc.names ret sucout :< qp :< qih <- checkC sucCtx sg suc.term sucType expectCompatQ loc qih (pi' * sg.qty) -- [fixme] better error here expectCompatQ loc (qp + qih) pisg -- if ς = 0, then Σb = lubs(Σz, Σs), otherwise Σb = Σz + ωςΣs let bodyout = case qih of Zero => lubs ctx [zerout, sucout] _ => zerout + Any * sucout -- then Ψ | Γ ⊢ caseπ ⋯ ⇒ A[n] ⊳ πΣn + Σb pure $ InfRes { type = sub1 ret n, qout = pi * nres.qout + bodyout } infer' ctx sg (CaseBox pi box ret body loc) = do -- if Ψ | Γ ⊢ σ · b ⇒ [ρ.A] ⊳ Σ₁ boxres <- inferC ctx sg box (rh, ty) <- expectBOX !(askAt DEFS) ctx SZero box.loc boxres.type -- if Ψ | Γ, x : [ρ.A] ⊢₀ R ⇐ Type checkTypeC (extendTy Zero ret.name boxres.type ctx) ret.term Nothing -- if Ψ | Γ, x : A ⊢ σ · t ⇐ R[[x] ∷ [ρ.A/x]] ⊳ Σ₂, ς·x -- with ς ≤ ρπσ let rhpisg = rh * pi * sg.qty bodyCtx = extendTy rhpisg body.name ty ctx bodyType = substCaseBoxRet body.name ty ret bodyout <- checkC bodyCtx sg body.term bodyType >>= popQ loc rhpisg -- then Ψ | Γ ⊢ caseπ ⋯ ⇒ R[b/x] ⊳ Σ₁ + Σ₂ pure $ InfRes { type = sub1 ret box, qout = boxres.qout + bodyout } infer' ctx sg (DApp fun dim loc) = do -- if Ψ | Γ ⊢ σ · f ⇒ Eq [𝑖 ⇒ A] l r ⊳ Σ InfRes {type, qout} <- inferC ctx sg fun ty <- fst <$> expectEq !(askAt DEFS) ctx SZero fun.loc type -- then Ψ | Γ ⊢ σ · f p ⇒ A‹p/𝑖› ⊳ Σ pure $ InfRes {type = dsub1 ty dim, qout} infer' ctx sg (Coe ty p q val loc) = do -- if Ψ, 𝑖 | Γ ⊢₀ A ⇐ Type _ checkType (extendDim ty.name ctx) ty.term Nothing -- if Ψ | Γ ⊢ σ · s ⇐ A‹p/𝑖› ⊳ Σ qout <- checkC ctx sg val $ dsub1 ty p -- then Ψ | Γ ⊢ σ · coe (𝑖 ⇒ A) @p @q s ⇒ A‹q/𝑖› ⊳ Σ pure $ InfRes {type = dsub1 ty q, qout} infer' ctx sg (Comp ty p q val r (S [< j0] val0) (S [< j1] val1) loc) = do -- if Ψ | Γ ⊢₀ A ⇐ Type _ checkType ctx ty Nothing -- if Ψ | Γ ⊢ σ · s ⇐ A ⊳ Σ qout <- checkC ctx sg val ty -- if Ψ, 𝑗, 𝑖=0 | Γ ⊢ σ · t₀ ⇐ A ⊳ Σ₀ -- Ψ, 𝑗, 𝑖=0, 𝑗=p | Γ ⊢ t₀ = s ⇐ A let ty' = dweakT 1 ty; val' = dweakT 1 val; p' = weakD 1 p ctx0 = extendDim j0 $ eqDim r (K Zero j0.loc) ctx val0 = getTerm val0 qout0 <- check ctx0 sg val0 ty' lift $ equal loc (eqDim (B VZ p.loc) p' ctx0) sg ty' val0 val' -- if Ψ, 𝑗, 𝑖=1 | Γ ⊢ σ · t₁ ⇐ A ⊳ Σ₁ -- Ψ, 𝑗, 𝑖=1, 𝑗=p | Γ ⊢ t₁ = s ⇐ A let ctx1 = extendDim j1 $ eqDim r (K One j1.loc) ctx val1 = getTerm val1 qout1 <- check ctx1 sg val1 ty' -- if Σ = Σ₀ = Σ₁ lift $ equal loc (eqDim (B VZ p.loc) p' ctx1) sg ty' val1 val' let qouts = qout :: catMaybes [toMaybe qout0, toMaybe qout1] -- then Ψ | Γ ⊢ comp A @p @q s @r {0 𝑗 ⇒ t₀; 1 𝑗 ⇒ t₁} ⇒ A ⊳ Σ pure $ InfRes {type = ty, qout = lubs ctx qouts} infer' ctx sg (TypeCase ty ret arms def loc) = do -- if σ = 0 expectEqualQ loc Zero sg.qty -- if Ψ, Γ ⊢₀ e ⇒ Type u u <- inferC ctx SZero ty >>= expectTYPE !(askAt DEFS) ctx SZero ty.loc . type -- if Ψ, Γ ⊢₀ C ⇐ Type (non-dependent return type) checkTypeC ctx ret Nothing -- if Ψ, Γ' ⊢₀ A ⇐ C for each rhs A for_ allKinds $ \k => for_ (lookupPrecise k arms) $ \(S names t) => check0 (extendTyN (typecaseTel k names u) ctx) (getTerm t) (weakT (arity k) ret) -- then Ψ, Γ ⊢₀ type-case ⋯ ⇒ C pure $ InfRes {type = ret, qout = zeroFor ctx} infer' ctx sg (Ann term type loc) = 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}