241 lines
6.6 KiB
Haskell
241 lines
6.6 KiB
Haskell
{-# LANGUAGE LambdaCase #-}
|
|
{-# LANGUAGE OverloadedStrings #-}
|
|
|
|
|
|
module LambdaLifter (lambdaLift, freeVars, abstract, rename, collectScs) where
|
|
|
|
import Data.List (mapAccumL)
|
|
import Data.Map (Map)
|
|
import qualified Data.Map as Map
|
|
import Data.Maybe (fromMaybe)
|
|
import Data.Set (Set, (\\))
|
|
import qualified Data.Set as Set
|
|
import Data.Tuple.Extra (uncurry3)
|
|
import Grammar.Abs
|
|
import Prelude hiding (exp)
|
|
|
|
lambdaLift :: Program -> Program
|
|
lambdaLift = collectScs . rename . abstract . freeVars
|
|
|
|
-- Annotate free variables
|
|
|
|
freeVars :: Program -> AnnProgram
|
|
freeVars (Program ds) = [ (n, xs, freeVarsExp (Set.fromList xs) e)
|
|
| Bind n xs e <- ds
|
|
]
|
|
|
|
|
|
freeVarsExp :: Set Ident -> Exp -> AnnExp
|
|
freeVarsExp lv = \case
|
|
|
|
EId n | Set.member n lv -> (Set.singleton n, AId n)
|
|
| otherwise -> (mempty, AId n)
|
|
|
|
EInt i -> (mempty, AInt i)
|
|
|
|
EApp e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AApp e1' e2')
|
|
where e1' = freeVarsExp lv e1
|
|
e2' = freeVarsExp lv e2
|
|
|
|
EAdd e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AAdd e1' e2')
|
|
where e1' = freeVarsExp lv e1
|
|
e2' = freeVarsExp lv e2
|
|
|
|
EAbs n e -> (Set.delete n $ freeVarsOf e', AAbs n e')
|
|
where e' = freeVarsExp (Set.insert n lv) e
|
|
|
|
ELet bs e -> (Set.union bsFree eFree, ALet bs' e')
|
|
where
|
|
bsFree = freeInValues \\ nsSet
|
|
eFree = freeVarsOf e' \\ nsSet
|
|
bs' = zipWith3 ABind ns xs es'
|
|
e' = freeVarsExp e_lv e
|
|
(ns, xs, es) = fromBinders bs
|
|
nsSet = Set.fromList ns
|
|
e_lv = Set.union lv nsSet
|
|
es' = map (freeVarsExp e_lv) es
|
|
freeInValues = foldr1 Set.union (map freeVarsOf es')
|
|
|
|
|
|
freeVarsOf :: AnnExp -> Set Ident
|
|
freeVarsOf = fst
|
|
|
|
fromBinders :: [Bind] -> ([Ident], [[Ident]], [Exp])
|
|
fromBinders bs = unzip3 [ (n, xs, e) | Bind n xs e <- bs ]
|
|
|
|
-- Lift lambda expression into let with binder "sc"
|
|
|
|
abstract :: AnnProgram -> Program
|
|
abstract prog = Program $ map f prog
|
|
where
|
|
f :: (Ident, [Ident], AnnExp) -> Bind
|
|
f (name, pars, rhs@(_, e)) =
|
|
case e of
|
|
AAbs par body -> Bind name (snoc par pars) $ abstractExp body
|
|
_ -> Bind name pars $ abstractExp rhs
|
|
|
|
|
|
|
|
-- [ case rhs of
|
|
-- EAbs par body -> Bind name (snoc par pars) body
|
|
-- _ -> Bind name pars rhs
|
|
--
|
|
-- | (name, pars, rhs) <- prog
|
|
|
|
|
|
abstractExp :: AnnExp -> Exp
|
|
abstractExp (free, exp) = case exp of
|
|
AId n -> EId n
|
|
AInt i -> EInt i
|
|
AApp e1 e2 -> EApp (abstractExp e1) (abstractExp e2)
|
|
AAdd e1 e2 -> EAdd (abstractExp e1) (abstractExp e2)
|
|
ALet bs e -> ELet [Bind n xs (abstractExp e1) | ABind n xs e1 <- bs ] $ abstractExp e
|
|
AAbs n e -> foldl EApp sc (map EId fvList)
|
|
where
|
|
fvList = Set.toList free
|
|
bind = Bind "sc" [] e'
|
|
e' = foldr EAbs (abstractExp e) (fvList ++ [n])
|
|
sc = ELet [bind] (EId (Ident "sc"))
|
|
|
|
|
|
snoc :: a -> [a] -> [a]
|
|
snoc x xs = xs ++ [x]
|
|
|
|
-- Rename
|
|
|
|
rename :: Program -> Program
|
|
rename (Program ds) = Program $ map (uncurry3 Bind) tuples
|
|
where
|
|
tuples = snd (mapAccumL renameSc 0 ds)
|
|
renameSc i (Bind n xs e) = (i2, (n, xs', e'))
|
|
where
|
|
(i1, xs', env) = newNames i xs
|
|
(i2, e') = renameExp env i1 e
|
|
|
|
renameExp :: Map Ident Ident -> Int -> Exp -> (Int, Exp)
|
|
renameExp env i = \case
|
|
|
|
EId n -> (i, EId . fromMaybe n $ Map.lookup n env)
|
|
|
|
EInt i1 -> (i, EInt i1)
|
|
|
|
EApp e1 e2 -> (i2, EApp e1' e2')
|
|
where
|
|
(i1, e1') = renameExp env i e1
|
|
(i2, e2') = renameExp env i1 e2
|
|
|
|
EAdd e1 e2 -> (i2, EAdd e1' e2')
|
|
where
|
|
(i1, e1') = renameExp env i e1
|
|
(i2, e2') = renameExp env i1 e2
|
|
|
|
ELet bs e -> (i3, ELet (zipWith3 Bind ns' xs es') e')
|
|
where
|
|
(i1, e') = renameExp e_env i e
|
|
(ns, xs, es) = fromBinders bs
|
|
(i2, ns', env') = newNames i1 ns
|
|
e_env = Map.union env' env
|
|
(i3, es') = mapAccumL (renameExp e_env) i2 es
|
|
|
|
|
|
EAbs n e -> (i2, EAbs (head ns) e')
|
|
where
|
|
(i1, ns, env') = newNames i [n]
|
|
(i2, e') = renameExp (Map.union env' env ) i1 e
|
|
|
|
|
|
newNames :: Int -> [Ident] -> (Int, [Ident], Map Ident Ident)
|
|
newNames i old_names = (i', new_names, env)
|
|
where
|
|
(i', new_names) = getNames i old_names
|
|
env = Map.fromList $ zip old_names new_names
|
|
|
|
|
|
getName :: Int -> Ident -> (Int, Ident)
|
|
getName i (Ident s) = (i + 1, makeName s i)
|
|
|
|
getNames :: Int -> [Ident] -> (Int, [Ident])
|
|
getNames i ns = (i + length ss, zipWith makeName ss [i..])
|
|
where
|
|
ss = map (\(Ident s) -> s) ns
|
|
|
|
makeName :: String -> Int -> Ident
|
|
makeName prefix i = Ident (prefix ++ "_" ++ show i)
|
|
|
|
|
|
-- Collect supercombinators
|
|
|
|
collectScs :: Program -> Program
|
|
collectScs (Program ds) = Program $ concatMap collectOneSc ds
|
|
where
|
|
collectOneSc (Bind name args rhs) = Bind name args rhs' : scs
|
|
where (scs, rhs') = collectScsExp rhs
|
|
{-
|
|
|
|
|
|
|
|
Bind (Ident "f") []
|
|
|
|
(ELet [Bind (Ident "sc") [] (EAbs (Ident "x") (EAdd (EId (Ident "x")) (EInt 1)))] (EId (Ident "sc")))
|
|
|
|
|
|
-}
|
|
|
|
|
|
collectScsExp :: Exp -> ([Bind], Exp)
|
|
collectScsExp = \case
|
|
|
|
EId n -> ([], EId n)
|
|
|
|
EInt i -> ([], EInt i)
|
|
|
|
EApp e1 e2 -> (scs1 ++ scs2, EApp e1' e2')
|
|
where
|
|
(scs1, e1') = collectScsExp e1
|
|
(scs2, e2') = collectScsExp e2
|
|
|
|
EAdd e1 e2 -> (scs1 ++ scs2, EAdd e1' e2')
|
|
where
|
|
(scs1, e1') = collectScsExp e1
|
|
(scs2, e2') = collectScsExp e2
|
|
|
|
EAbs x e -> (scs, EAbs x e')
|
|
where
|
|
(scs, e') = collectScsExp e
|
|
|
|
ELet bs e -> (rhss_scs ++ e_scs ++ local_scs, mkEAbs non_scs' e')
|
|
where
|
|
(rhss_scs, bs') = mapAccumL collectScs_d [] bs
|
|
scs' = [ Bind n xs rhs | Bind n xs rhs <- bs', isEAbs rhs]
|
|
non_scs' = [ Bind n xs rhs | Bind n xs rhs <- bs', not $ isEAbs rhs]
|
|
local_scs = [ Bind n (xs ++ [x]) e1 | Bind n xs (EAbs x e1) <- scs']
|
|
(e_scs, e') = collectScsExp e
|
|
|
|
collectScs_d scs (Bind n xs rhs) = (scs ++ rhs_scs1, Bind n xs rhs')
|
|
where
|
|
(rhs_scs1, rhs') = collectScsExp rhs
|
|
|
|
isEAbs :: Exp -> Bool
|
|
isEAbs = \case
|
|
EAbs {} -> True
|
|
_ -> False
|
|
|
|
mkEAbs :: [Bind] -> Exp -> Exp
|
|
mkEAbs [] e = e
|
|
mkEAbs bs e = ELet bs e
|
|
|
|
|
|
-- Annotated AST
|
|
|
|
type AnnProgram = [(Ident, [Ident], AnnExp)]
|
|
type AnnExp = (Set Ident, AnnExp')
|
|
|
|
data ABind = ABind Ident [Ident] AnnExp deriving Show
|
|
|
|
data AnnExp' = AId Ident
|
|
| AInt Integer
|
|
| AApp AnnExp AnnExp
|
|
| AAdd AnnExp AnnExp
|
|
| AAbs Ident AnnExp
|
|
| ALet [ABind] AnnExp
|
|
deriving Show
|