Prototype, extremely bad code implementation of CCHM Cubical Type Theory
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{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE LambdaCase #-}
module Eval where
import Control.Exception
import qualified Data.Map.Strict as Map
import Data.Foldable
import Data.Typeable
import Data.IORef
import Data.Maybe
import GHC.Stack
import qualified Presyntax as P
import Presyntax (Formula)
import Syntax
import System.IO.Unsafe (unsafePerformIO)
import Systems
import Debug.Trace (traceShowId)
iand :: Value -> Value -> Value
iand = \case
VI1 -> id
VI0 -> const VI0
x -> \case
VI0 -> VI0
VI1 -> x
y -> VIAnd x y
ior :: Value -> Value -> Value
ior = \case
VI0 -> id
VI1 -> const VI1
x -> \case
VI1 -> VI1
VI0 -> x
y -> VIOr x y
inot :: Value -> Value
inot VI1 = VI0
inot VI0 = VI1
inot (VIOr x y) = iand (inot x) (inot y)
inot (VIAnd x y) = ior (inot x) (inot y)
inot (VINot x) = x
inot x = VINot x
(@@) :: Value -> Value -> Value
VNe hd xs @@ vl = VNe hd (PApp vl:xs)
VLam _ _ k @@ vl = k vl
VEqGlued a b @@ vl = VEqGlued (a @@ vl) (b @@ vl)
VOfSub (VPi _ _ k) phi u0 x @@ vl = VOfSub (k vl) phi (u0 @@ vl) (x @@ vl)
VSystem fs @@ vl = mapVSystem (VSystem fs) (@@ vl)
VIf (VLam s d k) c t b @@ vl = VIf (VLam s d (ap . force . k)) (c @@ vl) (t @@ vl) b where
ap (VPi _ _ r) = r vl
ap _ = error "type error when pushing application into if"
f @@ _ = error $ "\ncan't apply argument to " ++ show f
proj1 :: Value -> Value
proj1 (VPair x _) = x
proj1 (VEqGlued x y) = VEqGlued (proj1 x) (proj1 y)
proj1 (VNe s xs) = VNe s (PProj1:xs)
proj1 (VOfSub (VSigma _ d _) phi u0 x) = VOfSub d phi (proj1 u0) (proj1 x)
proj1 v@VSystem{} = mapVSystem v proj1
proj1 (VIf (VLam s d k) c t b) = VIf (VLam s d (proj1t . k)) (proj1 c) (proj1 t) b where
proj1t (VSigma _ d _) = d
proj1t _ = error "type error when pushing proj1 into if"
proj1 x = error $ "can't proj1 " ++ show x
proj2 :: Value -> Value
proj2 (VPair _ y) = y
proj2 (VEqGlued x y) = VEqGlued (proj2 x) (proj2 y)
proj2 (VNe s xs) = VNe s (PProj2:xs)
proj2 (VOfSub (VSigma _ d r) phi u0 x) =
VOfSub (r (proj1 x)) phi (proj2 u0) (proj2 x)
proj2 v@VSystem{} = mapVSystem v proj2
proj2 (VIf (VLam s d k) c t b) = VIf (VLam s d (proj2t . k)) (proj2 c) (proj2 t) b where
proj2t (VSigma _ d r) = r (VIf (VLam s VBool (const d)) (proj1 c) (proj1 t) b)
proj2t _ = error "type error when pushing proj1 into if"
proj2 x = error $ "can't proj2 " ++ show x
pathp :: Env -> Value -> Value -> Value -> Value -> Value -> Value
pathp env p x y f@(VLine _a _x _y e) i =
case reduceCube env i of
Just P.Bot -> VEqGlued (e i) x
Just P.Top -> VEqGlued (e i) y
_ -> e i
pathp env p x y (VEqGlued e e') i = VEqGlued (pathp env p x y e i) (pathp env p x y e' i)
pathp env p x y (VNe hd sp) i =
case reduceCube env i of
Just P.Bot -> VEqGlued (VNe hd (PPathP p x y i:sp)) x
Just P.Top -> VEqGlued (VNe hd (PPathP p x y i:sp)) y
_ | quote x == quote y -> VEqGlued (VNe hd (PPathP p x y i:sp)) x
_ -> VNe hd (PPathP p x y i:sp)
pathp env p x y (VOfSub _ _ _ v) i = pathp env p x y v i
pathp env p x y v@VSystem{} i = mapVSystem v (\f -> pathp env p x y f i)
pathp env p x y f i = error $ "Invalid pathP " ++ show f ++ " @@ " ++ show i
comp :: Env -> Value -> Formula -> Value -> Value -> Value
comp env a@(VLam ivar VI fam) phi u a0 = glue $ go (fam (VVar "woopsie")) phi u a0 where
stuck :: Value
stuck = VComp a (toValue phi) u a0
glue :: Value -> Value
glue = VOfSub (fam VI1) (toValue phi) (u @@ VI1)
go :: HasCallStack => Value -> Formula -> Value -> Value -> Value
go VPi{} phi u a0 =
let
dom x = let VPi _ d _ = fam x in d
rng x = let VPi _ _ r = fam x in r
ai1 = dom VI0
y' i y = fill env i (dom . inot) P.Bot (VSystem emptySystem) y
ybar i y = y' (inot i) y
in VLam "x" ai1 \arg ->
comp env
(VLam ivar VI (\i -> rng i (ybar i arg)))
phi
(VLam "i" VI \i -> mapVSystem (u @@ i) (@@ ybar i arg))
(a0 @@ ybar VI0 arg)
go VSigma{} phi u a0 =
let
dom x = let VSigma _ d _ = fam x in d
rng x = let VSigma _ d _ = fam x in d
a i = fill env i (dom . fam) phi (VLam "j" VI \v -> mapVSystem (u @@ v) proj1) (proj1 a0)
c1 = comp env (VLam ivar VI (getd . fam)) phi (VLam "i" VI \v -> mapVSystem (u @@ v) proj1) (proj1 a0)
c2 = comp env (VLam ivar VI (apr (a VI1) . fam)) phi (VLam "i" VI \v -> mapVSystem (u @@ v) proj2) (proj2 a0)
getd (VSigma _ d _) = d
apr x (VSigma _ _ r) = r x
in VPair c1 c2
go VPath{} phi p p0 =
let
~(VPath ai1 u1 v1) = fam VI1
~(VPath ai0 u0 v0) = fam VI0
getA (VPath a _ _) = a
u' x = let ~(VPath _ u _) = fam x in u
v' x = let ~(VPath _ _ v) = fam x in v
in
VLine (ai1 @@ VI1) u1 v1 \j ->
let
jc = reduceCube' env j
in comp env (VLam ivar VI (getA . fam))
(orFormula [phi, jc, notFormula jc])
(VLam "j" VI \v ->
let
VSystem (FMap sys) = p @@ v
sys' = fmap (flip (pathp env ai0 u0 v0) j) sys
in mkVSystem $ Map.fromList [ (phi, mapVSystem (p @@ v) (flip (pathp env ai0 u0 v0) j))
, (notFormula jc, u' v)
, (jc, v' v)
])
(pathp env (ai0 @@ VI0) u0 v0 p0 j)
go VGlue{} psi b b0 =
let
base i = let VGlue base _ _ _ = force $ fam i in base
phi i =
case force (fam i) of
VGlue _ phi _ _ -> fromJust (reduceCube env phi)
x -> error (show x)
types i = let VGlue _ _ types _ = force $ fam i in types
equivs i = let VGlue _ _ _ equivs = force $ fam i in equivs
a i = mapVSystem (b @@ i) (unglue (base i) (phi i) (types i) (equivs i))
a0 = unglue (base VI0) (phi VI0) (types VI0) (equivs VI0) b0
del = faceForall phi
a1' = comp env (VLam "i" VI base) psi (VLam "i" VI a) a0
t1' = comp env (VLam "i" VI types) psi (VLam "i" VI (b @@)) b0
omega = pres env types base (flip mapVSystem proj1 . equivs) psi b b0
t1alpha = opEquiv env (base VI1) (types VI1) (equivs VI1) (orFormula [del, psi]) ts ps a1'
(t1, alpha) = (proj1 t1alpha, proj2 t1alpha)
ts = VSystem (FMap (Map.fromList [(del, t1'), (psi, b @@ VI1)]))
ps = VSystem (FMap (Map.fromList [(del, omega), (psi, VLine (VLam "j" VI \_ -> base VI1) a1' a1' (\j -> a1'))]))
a1 = comp env (VLam "j" VI (const (base VI1))) (orFormula [phi VI1, psi]) (VLam "j" VI \j -> a1_sys j) a1'
a1_sys j = VSystem (FMap (Map.fromList [(phi VI1, pathp env (base VI1) a1' (mapVSystem (equivs VI1) proj1) alpha j), (psi, a VI1)]))
b1 = introGlue (base VI1) (phi VI1) (types VI1) (equivs VI1) t1 a1
in b1
go VBool{} _ _ a0 = a0
go a P.Top u a0 = u @@ VI1
go a phi u a0 = stuck
comp env va phi u a0 =
if phi == P.Top
then VEqGlued (VComp va phi' u a0) (u @@ VI1)
else VComp va phi' u a0
where
phi' = toValue phi
opEquiv :: Env -> Value -> Value -> Value -> Formula -> Value -> Value -> Value -> Value
opEquiv env aT tT f phi t p a = VOfSub ty (toValue phi) (VPair t p) v where
fun = proj1 f
ty = VSigma "x" tT \x -> VPath (VLam "i" VI (const aT)) a (fun @@ x)
sys = Map.singleton phi (VPair t p)
v = contr env ty (proj2 f @@ a) phi (VSystem (FMap sys))
force :: Value -> Value
force (VEqGlued x _) = force x
force (VOfSub _ _ _ x) = force x
force x = x
faceForall :: (Value -> Formula) -> Formula
faceForall k = go (k (VVar "$elim")) where
go (P.Is0 "$elim") = P.Bot
go (P.Is1 "$elim") = P.Bot
go (P.Or a b) = orFormula [go a, go b]
go (P.And a b) = andFormula [go a, go b]
go x = x
pres :: Env -> (Value -> Value) -> (Value -> Value) -> (Value -> Value) -> Formula -> Value -> Value -> Value
pres env tT tA f phi t t0 = VOfSub (VPath (tA VI1) c1 c2) (toValue phi) base (VLine (tA VI1) c1 c2 cont) where
c1 = comp env (VLam "i" VI tA) phi (VLam "i" VI \j -> mapVSystem t (f j @@)) (f VI0 @@ t0)
c2 = f VI1 @@ comp env (VLam "i" VI tA) phi t t0
base = VLine (tA VI1) (f VI1 @@ (t @@ VI1)) (f VI1 @@ (t @@ VI1)) (\i -> f VI1 @@ (t @@ VI1))
cont j =
let v i = fill env i tT phi t t0
form = orFormula [phi, fromJust (reduceCube env j)]
a0 = f VI0 @@ t0
in comp env (VLam "I" VI tA) form
(VLam "I" VI (\j -> VSystem (FMap (Map.fromList [(form, f j @@ v j)]))))
a0
contr :: Env -> Value -> Value -> Formula -> Value -> Value
contr env a aC phi u =
comp env (VLam "i" VI (const a)) phi
(VLam "i" VI (pathp env a u (proj1 aC) (proj2 aC @@ u)))
(proj1 aC)
-- t : Partial phi T
-- T : Type
-- a : A
-- f : Equiv T A
mkVSystem :: Map.Map Formula Value -> Value
mkVSystem mp
| Just e <- Map.lookup P.Top mp = e
| otherwise = VSystem $ FMap $ Map.filterWithKey f mp
where
f P.Bot _ = False
f _ _ = True
reduceCube' :: Env -> Value -> Formula
reduceCube' env = fromJust . reduceCube env
mapVSystem :: Value -> (Value -> Value) -> Value
mapVSystem (VSystem ss) f = VSystem (mapSystem ss f)
mapVSystem x f = f x
evalSystem :: Env -> Map.Map Formula Term -> Value
evalSystem env face = mk . Map.fromList . mapMaybe (uncurry go) . Map.toList $ face where
go :: Formula -> Term -> Maybe (Formula, Value)
go face tm
| VI0 <- toValue' env face = Nothing
| otherwise = Just (evalF env face, eval env tm)
evalF env tm =
case toFormula (toValue' env tm) of
Just f -> f
Nothing -> error $ "eval turned formula into non formula"
mk x = case Map.toList x of
[(_, x)] -> x
_ -> mkVSystem x
glue :: Value -> Formula -> Value -> Value -> Value
-- glue baseT P.Top types _equivs = types
glue baseT phi types equivs = VGlue baseT (toValue phi) types equivs
introGlue :: Value -> Formula -> Value -> Value -> Value -> Value -> Value
introGlue baseT P.Top types equivs t a = t
introGlue baseT phi types equivs t a = VGlueIntro baseT (toValue phi) types equivs t a
unglue :: Value -> Formula -> Value -> Value -> Value -> Value
unglue baseT P.Top types equivs b = mapVSystem equivs ((@@ b) . proj1)
unglue baseT phi types equivs val =
VOfSub baseT (toValue phi) (mapVSystem equivs ((@@ val) . proj1)) (VGlueElim baseT (toValue phi) types equivs val)
eval :: Env -> Term -> Value
eval env = \case
Var v ->
case Map.lookup v (names env) of
Just (_, vl) -> vl
Nothing -> error $ "variable not in scope: " ++ show v
App f x -> eval env f @@ eval env x
Lam s d b ->
let d' = eval env d
in VLam s d' \a -> eval env{ names = Map.insert s (d', a) (names env) } b
Let s t b d ->
let b' = eval env b
t' = eval env t
in eval env{ names = Map.insert s (t', b') (names env) } d
Pi s d r ->
let d' = eval env d
in VPi s d' \a -> eval env{ names = Map.insert s (d', a) (names env) } r
Sigma s d r ->
let d' = eval env d
in VSigma s d' \a -> eval env{ names = Map.insert s (d', a) (names env) } r
Pair a b -> VPair (eval env a) (eval env b)
Proj1 x -> proj1 (eval env x)
Proj2 y -> proj2 (eval env y)
Type -> VType
Typeω -> VTypeω
I -> VI
I0 -> VI0
I1 -> VI1
Path p x y -> VPath (eval env p) (eval env x) (eval env y)
Partial r a -> VPartial (eval env r) (eval env a)
PartialP r a -> VPartialP (eval env r) (eval env a)
PathI p x y s e -> VLine (eval env p) (eval env x) (eval env y) (\ a -> eval env{ names = Map.insert s (VI, a) (names env) } e)
PathP p x y f i -> pathp env (eval env p) (eval env x) (eval env y) (eval env f) (eval env i)
Sub p x y -> VSub (eval env p) (eval env x) (eval env y)
InclSub a phi u a0 -> VOfSub (eval env a) (eval env phi) (eval env u) (eval env a0)
IAnd x y -> iand (eval env x) (eval env y)
IOr x y -> ior (eval env x) (eval env y)
INot x -> inot (eval env x)
Comp a phi u a0 ->
case reduceCube env (eval env phi) of
Just formula -> comp env (eval env a) formula (eval env u) (eval env a0)
Nothing -> VComp (eval env a) (eval env phi) (eval env u) (eval env a0)
System fs -> evalSystem env (getSystem fs)
GlueTy a phi types equivs ->
let phi' = eval env phi in
case reduceCube env phi' of
Just formula -> glue (eval env a) formula (eval env types) (eval env equivs)
Nothing -> VGlue (eval env a) phi' (eval env types) (eval env equivs)
Glue a phi types equivs t a0 ->
let phi' = eval env phi
t' = eval env t
a0' = eval env a0
types' = eval env types
equivs' = eval env equivs
a' = eval env a
in
case reduceCube env phi' of
Just formula -> introGlue a' formula types' equivs' t' a0'
Nothing -> VGlueIntro a' phi' types' equivs' t' a0'
Unglue a phi types equivs val ->
let phi' = eval env phi
val' = eval env val
types' = eval env types
equivs' = eval env equivs
a' = eval env a
in
case reduceCube env phi' of
Just formula -> unglue a' formula types' equivs' val'
Nothing -> VGlueElim a' phi' types' equivs' val'
If p x y t -> elimBool (eval env p) (eval env x) (eval env y) (eval env t)
Tt -> VTrue
Ff -> VFalse
Bool -> VBool
elimBool :: Value -> Value -> Value -> Value -> Value
elimBool _ x _ (VEqGlued _ VTrue) = x
elimBool _ x _ (VOfSub _ _ _ VTrue) = x
elimBool _ x _ VTrue = x
elimBool _ _ y (VEqGlued _ VFalse) = y
elimBool _ _ y (VOfSub _ _ _ VFalse) = y
elimBool _ _ y VFalse = y
elimBool p x y t = VIf p x y t
data UnifyError
= Mismatch Value Value
| NotPiType Value
| NotPartialType Formula Value
| NotSigmaType Value
| NotSort Value
deriving (Show, Typeable, Exception)
unify :: HasCallStack => Env -> Value -> Value -> IO ()
unify env (VEqGlued a b) c =
unify env a c `catch` \e -> const (unify env b c) (e :: UnifyError)
unify env c (VEqGlued a b) =
unify env c a `catch` \e -> const (unify env c b) (e :: UnifyError)
unify env (VLine a x y f) e =
let env' = env { names = Map.insert "i" (VI, VVar "i") (names env) }
in unify env' (f (VVar "i")) (pathp env' a x y e (VVar "i"))
unify env e (VLine a x y f) =
let env' = env { names = Map.insert "i" (VI, VVar "i") (names env) }
in unify env' (f (VVar "i")) (pathp env' a x y e (VVar "i"))
unify env (VPartial r b) (VPartial r' b') = do
unify env b b'
case sameCube env r r' of
Just True -> pure ()
_ -> unify env r r'
unify env (VPartial r b) x = do
case sameCube env r VI1 of
Just True -> pure ()
_ -> unify env r VI1
unify env b x
unify env x (VPartial r b) = do
case sameCube env r VI1 of
Just True -> pure ()
_ -> unify env r VI1
unify env x b
unify env (VSub a phi _u0) vl = unify env a vl
unify env u1 (VOfSub _a phi u0 a) = do
case sameCube env phi VI1 of
Just True -> unify env u1 u0
_ -> unify env u1 a
unify env (VOfSub _a phi u0 a) u1 = do
case sameCube env phi VI1 of
Just True -> unify env u1 u0
_ -> unify env u1 a
unify env vl1@(VNe x sp) vl2@(VNe y sp')
| x == y = traverse_ (uncurry unifySp) (zip sp sp')
| otherwise = throwIO $ Mismatch vl1 vl2
where
unifySp (PApp x) (PApp y) = unify env x y
unifySp (PPathP _a _x _y i) (PPathP _a' _x' _y' i') = unify env i i'
unifySp PProj1 PProj1 = pure ()
unifySp PProj2 PProj2 = pure ()
unifySp _ _ = throwIO $ Mismatch vl1 vl2
unify env (VLam x _ k) e = unify env (k (VVar x)) (e @@ VVar x)
unify env e (VLam x _ k) = unify env (e @@ VVar x) (k (VVar x))
unify env (VPi x d r) (VPi _ d' r') = do
unify env d d'
unify env (r (VVar x)) (r' (VVar x))
unify env (VSigma x d r) (VSigma _ d' r') = do
unify env d d'
unify env (r (VVar x)) (r' (VVar x))
unify env VType VType = pure ()
unify env VI VI = pure ()
unify env VBool VBool = pure ()
unify env (VPair a b) e = unify env a (proj1 e) *> unify env b (proj2 e)
unify env e (VPair a b) = unify env a (proj1 e) *> unify env b (proj2 e)
unify env (VPath a x y) (VPath a' x' y') = unify env a a' *> unify env x x' *> unify env y y'
unify env (VComp a phi u a0) (VComp a' phi' u' a0') =
traverse_ (uncurry (unify env))
[ (a, a')
, (phi, phi')
, (u, u')
, (a0, a0')
]
unify env (VComp a (reduceCube env -> Just P.Top) u a0) vl =
unify env (u @@ VI1) vl
unify env vl (VComp a (reduceCube env -> Just P.Top) u a0) =
unify env (u @@ VI1) vl
unify env (VSystem fs) vl
| ((_, vl'):_) <-
Map.toList (Map.filterWithKey (\f _ -> isTrue (toValue' env f)) (getSystem fs))
= unify env vl' vl
| Map.null (getSystem fs) = pure ()
unify env vl (VSystem fs)
| ((_, vl'):_) <-
Map.toList (Map.filterWithKey (\f _ -> isTrue (toValue' env f)) (getSystem fs))
= unify env vl' vl
| Map.null (getSystem fs) = pure ()
unify env VType VTypeω = pure ()
unify env VTypeω VTypeω = pure ()
unify env (VGlue _ VI1 b _) x = unify env b x
unify env VTrue VTrue = pure ()
unify env VFalse VFalse = pure ()
unify env (VIf p a b c) (VIf p' a' b' c') = traverse_ (uncurry (unify env)) [(p, p'), (a, a'), (b, b'), (c, c')]
unify env x y =
case sameCube env x y of
Just True -> pure ()
_ -> throwIO $ Mismatch x y
reduceCube :: Env -> Value -> Maybe Formula
reduceCube env x = fmap (toDNF . simplify) (toFormula x) where
simplify :: Formula -> Formula
simplify (P.Is0 x) =
case Map.lookup x (names env) of
Just (VI, VI0) -> P.Top
Just (VI, VI1) -> P.Bot
_ -> P.Is0 x
simplify (P.Is1 x) =
case Map.lookup x (names env) of
Just (VI, VI1) -> P.Top
Just (VI, VI0) -> P.Bot
_ -> P.Is1 x
simplify (P.And x y) = P.And (simplify x) (simplify y)
simplify (P.Or x y) = P.Or (simplify x) (simplify y)
simplify x = x
sameCube :: Env -> Value -> Value -> Maybe Bool
sameCube env x y =
case (reduceCube env x, reduceCube env y) of
(Just x, Just y) -> Just (x == y)
_ -> Nothing
toFormula :: Value -> Maybe Formula
toFormula VI0 = Just P.Bot
toFormula VI1 = Just P.Top
toFormula (VNe x []) = Just (P.Is1 x)
toFormula (VINot f) = notFormula <$> toFormula f
toFormula (VIAnd x y) = do
s <- toFormula y
t <- toFormula x
pure $ andFormula [s, t]
toFormula (VIOr x y) = do
s <- toFormula y
t <- toFormula x
pure $ orFormula [s, t]
toFormula _ = Nothing
faceInEnv :: Env -> Face -> Bool
faceInEnv e f = Map.isSubmapOf (getFace f) (faceOfEnv (names e)) where
faceOfEnv = Map.map (\(_, v) -> case v of { VI1 -> True; VEqGlued _ VI1 -> True; _ -> False }) . Map.filter (\(_, v) -> isI v)
isI VI1 = True
isI VI0 = True
isI (VEqGlued _ x) = isI x
isI _ = False
isPiType :: Value -> IO (String, Value, Value -> Value)
isPiType (VPi x d r) = pure (x, d, r)
isPiType x = throwIO $ NotPiType x
isSigmaType :: Value -> IO (String, Value, Value -> Value)
isSigmaType (VSigma x d r) = pure (x, d, r)
isSigmaType x = throwIO $ NotSigmaType x
isPiOrPathType :: Value -> IO (Either (String, Value, Value -> Value) (Value, Value, Value))
isPiOrPathType (VPi x d r) = pure (Left (x, d, r))
isPiOrPathType (VPath x d r) = pure (Right (x, d, r))
isPiOrPathType x = throwIO $ NotPiType x
isPartialType :: Formula -> Value -> IO (Formula, Value)
isPartialType f p@(VPartial x y) =
case toFormula x of
Just x -> pure (x, y)
Nothing -> throwIO $ NotPartialType f p
isPartialType f p@(VPartialP x y) =
case toFormula x of
Just x -> pure (x, y)
Nothing -> throwIO $ NotPartialType f p
isPartialType f x = throwIO $ NotPartialType f x
getVar :: IO Value
getVar =
do
n <- atomicModifyIORef ref \x -> (x + 1, x)
pure (VVar (show n))
where
ref :: IORef Int
ref = unsafePerformIO (newIORef 0)
{-# NOINLINE ref #-}
fill :: Env
-> Value
-> (Value -> Value) -- (Γ i : I, A : Type)
-> Formula -- (phi : I)
-> Value -- (u : (i : I) -> Partial phi (A i))
-> Value -- (Sub (A i0) phi (u i0))
-> Value -- -> A i
fill env i a phi u a0 =
comp env
(VLam "j" VI \j -> a (i `iand` j))
(phi `P.Or` notFormula ifc)
(VLam "j" VI \j ->
mkVSystem (Map.fromList [ (phi, uiand j)
, (notFormula ifc, a0) ]))
a0
where
uiand j = u @@ (i `iand` j)
ifc = fromMaybe P.Bot $ (reduceCube env i)
toValue :: Formula -> Value
toValue P.Top = VI1
toValue P.Bot = VI0
toValue (P.And x y) = toValue x `iand` toValue y
toValue (P.Or x y) = toValue x `ior` toValue y
toValue (P.Is0 x) = inot (VVar x)
toValue (P.Is1 x) = VVar x
toValue' :: HasCallStack => Env -> Formula -> Value
toValue' env P.Top = VI1
toValue' env P.Bot = VI0
toValue' env (P.And x y) = toValue x `iand` toValue y
toValue' env (P.Or x y) = toValue x `ior` toValue y
toValue' env (P.Is0 x) =
case Map.lookup x (names env) of
Just (VI, VI0) -> VI1
Just (VI, VI1) -> VI0
Just (VI, x) -> inot x
vl -> error $ "type error in toValue' " ++ x ++ ": " ++ show vl
toValue' env (P.Is1 x) =
case Map.lookup x (names env) of
Just (VI, x) -> x
vl -> error $ "type error in toValue': Is1 " ++ show x ++ ": " ++ show vl
isTrue :: Value -> Bool
isTrue VI1 = True
isTrue _ = False
equiv :: Value -> Value -> Value
equiv t a = VSigma "f" (VPi "_" t (const a)) \f -> isEquiv t a f
isEquiv :: Value -> Value -> Value -> Value
isEquiv t a f = VPi "y" a \y -> isContr (VSigma "x" t \x -> VPath (VLam "_" VI (const a)) y (f @@ x))
isContr :: Value -> Value
isContr t = VSigma "x" t \x -> VPi "y" t \y -> VPath (VLam "_" VI (const t)) x y