147 lines
5.8 KiB
Idris
147 lines
5.8 KiB
Idris
module Core.Check
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import Control.Monad.RWS
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import Control.Monad.Either
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import Control.Monad.Identity
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import Data.Vect
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import Data.Fin
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import Core.Term
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import Core.Value
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import Core.Normalize
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import Core.Misc
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import Core.Convert
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%default total
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-- extend environment, used to ensure environment is always in normal form
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extV : Ctx n -> Value -> PI (Ctx (S n))
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extV ctx val = whnf val >>= pure . (`Data.Vect.(::)` ctx)
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-- to extend, closure env, term
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extT : Ctx m -> Ctx n -> Term n -> PI (Ctx (S m))
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extT ctx env = extV ctx . VClos env
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mutual
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public export
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-- terms types expected term
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check : Ctx n -> Ctx n -> Value -> Term n -> PI Bool
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check trs tys xpt' tr = do
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xpt <- whnf xpt'
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case tr of
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TLam sc => case xpt of
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VClos env (TPi a b) => do
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v <- VGen <$> fresh
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check (v :: trs) !(extT tys env a) (VClos (v :: env) b) sc
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_ => oops "expected pi"
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TPair x y => case xpt of
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(VClos env (TSigma a b)) => do
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guardS "Pair a" =<< check trs tys (VClos env a) x
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check trs tys (VClos env b `VApp` VClos trs x) y
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_ => oops "expected sigma"
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TLet ty tr tri => do
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guardS "let" =<< check trs tys (VClos trs ty) tr
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check !(extT trs trs tr) !(extT tys trs ty) xpt tri
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_ => convert xpt =<< infer trs tys tr
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-- terms types term
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infer : Ctx n -> Ctx n -> Term n -> PI Value
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infer trs tys TType = pure VType
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infer trs tys TTop = pure VType
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infer trs tys TBot = pure VType
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infer trs tys TNat = pure VType
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infer trs tys TStar = pure VTop
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infer trs tys TZero = pure VNat
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infer trs tys (TVar i) = pure (index i tys)
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infer trs tys (TApp f x) = infer trs tys f >>= whnf >>=
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\case
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VClos env (TPi a b) => do
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guardS ("app x:\n" ++ show !(whnf (VClos env a))) =<< check trs tys (VClos env a) x
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tr <- whnf (VClos trs x)
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pure (VClos (tr :: env) b)
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_ => oops "expected infer pi"
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infer trs tys (TPi a b) = do
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v <- VGen <$> fresh
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guardS "Pi a" =<< check trs tys VType a
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guardS "Pi b" =<< check (v :: trs) !(extT tys trs a) VType b
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pure VType
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infer trs tys (TSigma a b) = do
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guardS "Σ a" =<< check trs tys VType a
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guardS "Σ b" =<< check trs tys (VClos trs (TPi a TType)) b
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pure VType
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infer trs tys (TId ty a b) = do
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guardS "Id ty" =<< check trs tys VType ty
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guardS "Id a" =<< check trs tys (VClos trs ty) a
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guardS "Id b" =<< check trs tys (VClos trs ty) b
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pure VType
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infer trs tys (TSuc n) = do
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guardS "suc n" =<< check trs tys VNat n
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pure VNat
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infer trs tys (TRefl ty tr) = do
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guardS "Refl ty" =<< check trs tys VType ty
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guardS "Refl tr" =<< check trs tys (VClos trs ty) tr
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pure (VClos trs (TId ty tr tr))
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infer trs tys (TNatInd c z s) = do
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guardS "ℕ C" =<< check trs tys (VClos trs (TPi TNat TType)) c
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guardS "ℕ z" =<< check trs tys (VApp (VClos trs c) (VClos [] TZero)) z
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guardS "ℕ s" =<< check trs tys (VClos trs (TPi TNat
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(TPi (TApp (weakTr c) (TVar 0))
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(TApp (weakTr2 c) (TSuc (TVar (FS FZ))))))) s
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pure (VClos trs (TPi TNat (TApp (weakTr c) (TVar 0))))
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infer trs tys (TJ ty a b c d) = do
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guardS "J ty" =<< check trs tys VType ty
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guardS "J a" =<< check trs tys (VClos trs ty) a
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guardS "J b" =<< check trs tys (VClos trs ty) b
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guardS "J c" =<< check trs tys
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(VClos trs (TPi ty {- a : A -}
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(TPi (weakTr ty) {- b : A -}
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(TPi (TId (weakTr2 ty)
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(TVar (FS FZ))
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(TVar FZ)) {- Id A a b -}
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TType)))) c
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guardS "J d" =<< check trs tys (VClos trs (c `TApp` a `TApp` a `TApp` TRefl ty a)) d
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pure (VClos trs (TPi (TId ty a b) (weakTr c `TApp` weakTr a `TApp` weakTr b `TApp` TVar 0)))
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infer trs tys (TSigInd a b c f) = do
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guardS "Σ A" =<< check trs tys VType a
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guardS "Σ B" =<< check trs tys (VClos trs (TPi a TType)) b
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guardS "Σ C" =<< check trs tys (VClos trs (TPi (TSigma a b) TType)) c
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guardS "Σ f" =<< check trs tys (VClos trs (TPi a {-a:A-}
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(TPi (weakTr b `TApp` TVar 0) {-b:Ba-}
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(weakTr2 c `TApp` TPair (TVar (FS FZ)) (TVar 0))))) f
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pure (VClos trs (TPi (TSigma a b) (weakTr c `TApp` TVar 0)))
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infer trs tys (TLet ty tr tri) = do
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guardS "let infer" =<< check trs tys (VClos trs ty) tr
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infer !(extT trs trs tr) !(extT tys trs ty) tri
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infer trs tys (TTopInd c st) = do
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guardS "⊤ C" =<< check trs tys (VClos trs (TPi TTop TType)) c
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guardS "⊤ ★" =<< check trs tys (VClos trs (TApp c TStar)) st
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pure (VClos trs (TPi TTop (TApp (weakTr c) (TVar 0))))
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infer trs tys (TBotInd c) = do
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guardS "⊥ C" =<< check trs tys (VClos trs (TPi TBot TType)) c
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pure (VClos trs (TPi TBot (TApp (weakTr c) (TVar 0))))
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infer trs tys x = oops ("cannot infer type " ++ show x)
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public export
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typecheck : Term 0 -> Term 0 -> Either String (Bool, List String)
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typecheck tr ty = resolve $ (&&) <$> check [] [] VType ty
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<*> delay <$> check [] [] (VClos [] ty) tr
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