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{-# LANGUAGE GADTs #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE QuantifiedConstraints #-}
module Main where
import Data.Expr.SharingRecovery
import Data.Type.Equality
data Ty a where
TInt :: Ty Int
TFloat :: Ty Float
TBool :: Ty Bool
deriving instance Show (Ty a)
instance TestEquality Ty where
testEquality TInt TInt = Just Refl
testEquality TInt _ = Nothing
testEquality TFloat TFloat = Just Refl
testEquality TFloat _ = Nothing
testEquality TBool TBool = Just Refl
testEquality TBool _ = Nothing
type family IsOrdTy a where
IsOrdTy Int = True
IsOrdTy Float = True
IsOrdTy _ = False
data Unop a b where
UONeg :: Ty a -> Unop a a
UONot :: Unop Bool Bool
deriving instance Show (Unop a b)
data Binop a b c where
BOAdd :: Ty a -> Binop a a a
BOSub :: Ty a -> Binop a a a
BOMul :: Ty a -> Binop a a a
BOAnd :: Binop Bool Bool Bool
BOOr :: Binop Bool Bool Bool
BOLt :: IsOrdTy a ~ True => Ty a -> Binop a a Bool
BOLeq :: IsOrdTy a ~ True => Ty a -> Binop a a Bool
BOEq :: IsOrdTy a ~ True => Ty a -> Binop a a Bool
BONeq :: IsOrdTy a ~ True => Ty a -> Binop a a Bool
deriving instance Show (Binop a b c)
data Lang r a where
Un :: Unop a b -> r a -> Lang r b
Bin :: Binop a b c -> r a -> r b -> Lang r c
Cond :: r Bool -> r a -> r a -> Lang r a
Cnst :: Show a => a -> Lang r a -- there's a type in the BExpr in the end, no need for one here
deriving instance (forall b. Show (r b)) => Show (Lang r a)
instance Functor1 Lang
instance Traversable1 Lang where
traverse1 f = \case
Un op x -> Un op <$> f x
Bin op x y -> Bin op <$> f x <*> f y
Cond x y z -> Cond <$> f x <*> f y <*> f z
Cnst v -> pure (Cnst v)
class KnownTy a where knownTy :: Ty a
instance KnownTy Int where knownTy = TInt
instance KnownTy Float where knownTy = TFloat
instance KnownTy Bool where knownTy = TBool
type Expr v = PHOASExpr Ty v Lang
cond :: KnownTy a => Expr v Bool -> Expr v a -> Expr v a -> Expr v a
cond a b c = PHOASOp knownTy (Cond a b c)
(.<), (.<=), (.>), (.>=) :: (KnownTy a, IsOrdTy a ~ True) => Expr v a -> Expr v a -> Expr v Bool
a .< b = PHOASOp TBool (Bin (BOLt knownTy) a b)
a .<= b = PHOASOp TBool (Bin (BOLeq knownTy) a b)
(.>) = flip (.<)
(.>=) = flip (.<=)
infix 4 .<
infix 4 .<=
infix 4 .>
infix 4 .>=
instance (KnownTy a, IsOrdTy a ~ True, Num a, Show a) => Num (Expr v a) where
a + b = PHOASOp knownTy (Bin (BOAdd knownTy) a b)
a - b = PHOASOp knownTy (Bin (BOSub knownTy) a b)
a * b = PHOASOp knownTy (Bin (BOMul knownTy) a b)
negate a = PHOASOp knownTy (Un (UONeg knownTy) a)
abs a = cond (a .< 0) (-a) a
signum a = cond (a .< 0) (-1) (cond (a .> 0) 1 0)
fromInteger n = PHOASOp knownTy (Cnst (fromInteger n))
main :: IO ()
main = do
print $ sharingRecovery @Lang @_ $
let a = 2 ; b = 3 :: Expr v Int
in a + b .< b + a
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