Adjust old type checker to new syntax, and refactor lambda lifter to use typed AST
This commit is contained in:
Martin Fredin
parent
514c809b1e
commit
210e55bb15
18 changed files with 554 additions and 145 deletions
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@ -5,21 +5,20 @@
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module LambdaLifter (lambdaLift, freeVars, abstract, rename, collectScs) where
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import Auxiliary (snoc)
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import Control.Applicative (Applicative (liftA2))
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import Control.Monad.State (MonadState (get, put), State, evalState)
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import Data.Foldable.Extra (notNull)
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import Data.List (mapAccumL, mapAccumR, partition)
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import Data.Map (Map)
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import qualified Data.Map as Map
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import Data.Maybe (fromMaybe, mapMaybe)
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import Data.List (mapAccumL, partition)
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import Data.Set (Set, (\\))
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import qualified Data.Set as Set
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import Data.Tuple.Extra (uncurry3)
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import Grammar.Abs
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import Prelude hiding (exp)
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import Renamer hiding (fromBinders)
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import TypeCheckerIr
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-- | Lift lambdas and let expression into supercombinators.
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lambdaLift :: Program -> Program
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lambdaLift = collectScs . rename . abstract . freeVars
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lambdaLift = collectScs . abstract . freeVars
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-- | Annotate free variables
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@ -28,25 +27,25 @@ freeVars (Program ds) = [ (n, xs, freeVarsExp (Set.fromList xs) e)
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| Bind n xs e <- ds
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]
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freeVarsExp :: Set Ident -> Exp -> AnnExp
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freeVarsExp :: Set Id -> Exp -> AnnExp
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freeVarsExp localVars = \case
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EId n | Set.member n localVars -> (Set.singleton n, AId n)
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| otherwise -> (mempty, AId n)
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EId n | Set.member n localVars -> (Set.singleton n, AId n)
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| otherwise -> (mempty, AId n)
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EInt i -> (mempty, AInt i)
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EApp e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AApp e1' e2')
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EApp t e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AApp t e1' e2')
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where
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e1' = freeVarsExp localVars e1
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e2' = freeVarsExp localVars e2
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EAdd e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AAdd e1' e2')
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EAdd t e1 e2 -> (Set.union (freeVarsOf e1') (freeVarsOf e2'), AAdd t e1' e2')
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where
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e1' = freeVarsExp localVars e1
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e2' = freeVarsExp localVars e2
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EAbs par e -> (Set.delete par $ freeVarsOf e', AAbs par e')
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EAbs t par e -> (Set.delete par $ freeVarsOf e', AAbs t par e')
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where
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e' = freeVarsExp (Set.insert par localVars) e
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@ -66,143 +65,111 @@ freeVarsExp localVars = \case
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binders' = zipWith3 ABind names parms rhss'
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e' = freeVarsExp e_localVars e
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EAnn e t -> (freeVarsOf e', AAnn e' t)
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where
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e' = freeVarsExp localVars e
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freeVarsOf :: AnnExp -> Set Ident
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freeVarsOf :: AnnExp -> Set Id
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freeVarsOf = fst
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fromBinders :: [Bind] -> ([Ident], [[Ident]], [Exp])
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fromBinders :: [Bind] -> ([Id], [[Id]], [Exp])
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fromBinders bs = unzip3 [ (name, parms, rhs) | Bind name parms rhs <- bs ]
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-- AST annotated with free variables
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type AnnProgram = [(Ident, [Ident], AnnExp)]
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type AnnProgram = [(Id, [Id], AnnExp)]
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type AnnExp = (Set Ident, AnnExp')
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type AnnExp = (Set Id, AnnExp')
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data ABind = ABind Ident [Ident] AnnExp deriving Show
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data ABind = ABind Id [Id] AnnExp deriving Show
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data AnnExp' = AId Ident
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data AnnExp' = AId Id
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| AInt Integer
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| AApp AnnExp AnnExp
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| AAdd AnnExp AnnExp
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| AAbs Ident AnnExp
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| ALet [ABind] AnnExp
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| AApp Type AnnExp AnnExp
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| AAdd Type AnnExp AnnExp
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| AAbs Type Id AnnExp
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| AAnn AnnExp Type
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deriving Show
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-- | Lift lambdas to let expression of the form @let sc = \v₁ x₁ -> e₁@.
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-- Free variables are @v₁ v₂ .. vₙ@ are bound.
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abstract :: AnnProgram -> Program
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abstract prog = Program $ map go prog
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abstract prog = Program $ evalState (mapM go prog) 0
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where
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go :: (Ident, [Ident], AnnExp) -> Bind
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go (name, pars, rhs@(_, e)) =
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go :: (Id, [Id], AnnExp) -> State Int Bind
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go (name, parms, rhs@(_, e)) =
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case e of
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AAbs par e1 -> Bind name (snoc par pars ++ pars2) $ abstractExp e2
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AAbs _ parm e1 -> do
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e2' <- abstractExp e2
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pure $ Bind name (snoc parm parms ++ parms2) e2'
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where
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(e2, pars2) = flattenLambdasAnn e1
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_ -> Bind name pars $ abstractExp rhs
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(e2, parms2) = flattenLambdasAnn e1
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_ -> Bind name parms <$> abstractExp rhs
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-- | Flatten nested lambdas and collect the parameters
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-- @\x.\y.\z. ae → (ae, [x,y,z])@
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flattenLambdasAnn :: AnnExp -> (AnnExp, [Ident])
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flattenLambdasAnn :: AnnExp -> (AnnExp, [Id])
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flattenLambdasAnn ae = go (ae, [])
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where
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go :: (AnnExp, [Ident]) -> (AnnExp, [Ident])
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go :: (AnnExp, [Id]) -> (AnnExp, [Id])
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go ((free, e), acc) =
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case e of
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AAbs par (free1, e1) -> go ((Set.delete par free1, e1), snoc par acc)
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_ -> ((free, e), acc)
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AAbs _ par (free1, e1) ->
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go ((Set.delete par free1, e1), snoc par acc)
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_ -> ((free, e), acc)
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abstractExp :: AnnExp -> Exp
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abstractExp :: AnnExp -> State Int Exp
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abstractExp (free, exp) = case exp of
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AId n -> EId n
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AInt i -> EInt i
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AApp e1 e2 -> EApp (abstractExp e1) (abstractExp e2)
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AAdd e1 e2 -> EAdd (abstractExp e1) (abstractExp e2)
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ALet bs e -> ELet (map go bs) $ abstractExp e
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AId n -> pure $ EId n
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AInt i -> pure $ EInt i
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AApp t e1 e2 -> liftA2 (EApp t) (abstractExp e1) (abstractExp e2)
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AAdd t e1 e2 -> liftA2 (EAdd t) (abstractExp e1) (abstractExp e2)
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ALet bs e -> liftA2 ELet (mapM go bs) (abstractExp e)
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where
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go (ABind name parms rhs) =
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let
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(rhs', parms1) = flattenLambdas $ skipLambdas abstractExp rhs
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in
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Bind name (parms ++ parms1) rhs'
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go (ABind name parms rhs) = do
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(rhs', parms1) <- flattenLambdas <$> skipLambdas abstractExp rhs
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pure $ Bind name (parms ++ parms1) rhs'
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skipLambdas :: (AnnExp -> Exp) -> AnnExp -> Exp
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skipLambdas :: (AnnExp -> State Int Exp) -> AnnExp -> State Int Exp
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skipLambdas f (free, ae) = case ae of
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AAbs name ae1 -> EAbs name $ skipLambdas f ae1
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_ -> f (free, ae)
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AAbs t par ae1 -> EAbs t par <$> skipLambdas f ae1
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_ -> f (free, ae)
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-- Lift lambda into let and bind free variables
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AAbs par e -> foldl EApp sc $ map EId freeList
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AAbs t parm e -> do
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i <- nextNumber
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rhs <- abstractExp e
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let sc_name = Ident ("sc_" ++ show i)
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sc = ELet [Bind (sc_name, t_bind) parms rhs] $ EId (sc_name, t)
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pure $ foldl (EApp TInt) sc $ map EId freeList
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where
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freeList = Set.toList free
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sc = ELet [Bind "sc" (snoc par freeList) $ abstractExp e] $ EId "sc"
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t_bind = typeApplyPars (length parm) t
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parms = snoc parm freeList
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-- | Rename all supercombinators and variables
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rename :: Program -> Program
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rename (Program ds) = Program $ map (uncurry3 Bind) tuples
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where
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tuples = snd (mapAccumL renameSc 0 ds)
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renameSc i (Bind n xs e) = (i2, (n, xs', e'))
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where
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(i1, xs', env) = newNames i xs
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(i2, e') = renameExp env i1 e
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AAnn e t -> abstractExp e >>= \e' -> pure $ EAnn e' t
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renameExp :: Map Ident Ident -> Int -> Exp -> (Int, Exp)
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renameExp env i = \case
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EId n -> (i, EId . fromMaybe n $ Map.lookup n env)
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EInt i1 -> (i, EInt i1)
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EApp e1 e2 -> (i2, EApp e1' e2')
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where
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(i1, e1') = renameExp env i e1
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(i2, e2') = renameExp env i1 e2
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EAdd e1 e2 -> (i2, EAdd e1' e2')
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where
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(i1, e1') = renameExp env i e1
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(i2, e2') = renameExp env i1 e2
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ELet bs e -> (i3, ELet (zipWith3 Bind ns' pars' es') e')
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where
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(i1, e') = renameExp e_env i e
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(names, pars, rhss) = fromBinders bs
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(i2, ns', env') = newNames i1 (names ++ concat pars)
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pars' = (map . map) renamePar pars
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e_env = Map.union env' env
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(i3, es') = mapAccumL (renameExp e_env) i2 rhss
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renamePar p = case Map.lookup p env' of
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Just p' -> p'
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Nothing -> error ("Can't find name for " ++ show p)
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nextNumber :: State Int Int
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nextNumber = do
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i <- get
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put $ succ i
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pure i
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EAbs par e -> (i2, EAbs par' e')
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where
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(i1, par', env') = newName par
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(i2, e') = renameExp (Map.union env' env ) i1 e
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newName :: Ident -> (Int, Ident, Map Ident Ident)
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newName old_name = (i, head names, env)
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where (i, names, env) = newNames 1 [old_name]
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newNames :: Int -> [Ident] -> (Int, [Ident], Map Ident Ident)
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newNames i old_names = (i', new_names, env)
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where
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(i', new_names) = getNames i old_names
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env = Map.fromList $ zip old_names new_names
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getNames :: Int -> [Ident] -> (Int, [Ident])
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getNames i ns = (i + length ss, zipWith makeName ss [i..])
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where
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ss = map (\(Ident s) -> s) ns
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makeName :: String -> Int -> Ident
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makeName prefix i = Ident (prefix ++ "_" ++ show i)
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typeApplyPars :: Int -> Type -> Type
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typeApplyPars 0 t = t
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typeApplyPars i t =
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case t of
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TFun _ t1 -> typeApplyPars (i-1) t1
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_ -> error "Number of applied pars and type not matching"
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-- | Collects supercombinators by lifting appropriate let expressions
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@ -216,20 +183,20 @@ collectScs (Program scs) = Program $ concatMap collectFromRhs scs
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collectScsExp :: Exp -> ([Bind], Exp)
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collectScsExp = \case
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EId n -> ([], EId n)
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EInt i -> ([], EInt i)
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EId n -> ([], EId n)
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EInt i -> ([], EInt i)
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EApp e1 e2 -> (scs1 ++ scs2, EApp e1' e2')
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EApp t e1 e2 -> (scs1 ++ scs2, EApp t e1' e2')
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where
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(scs1, e1') = collectScsExp e1
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(scs2, e2') = collectScsExp e2
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EAdd e1 e2 -> (scs1 ++ scs2, EAdd e1' e2')
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EAdd t e1 e2 -> (scs1 ++ scs2, EAdd t e1' e2')
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where
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(scs1, e1') = collectScsExp e1
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(scs2, e2') = collectScsExp e2
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EAbs x e -> (scs, EAbs x e')
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EAbs t par e -> (scs, EAbs t par e')
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where
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(scs, e') = collectScsExp e
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@ -241,28 +208,32 @@ collectScsExp = \case
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-- > ...
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-- > in e
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--
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ELet binds e -> (binds_scs ++ rhss_scs ++ e_scs, mkEAbs non_scs' e')
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ELet binds e -> (binds_scs ++ rhss_scs ++ e_scs, mkEAbs non_scs' e')
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where
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binds_scs = [ let (rhs', parms1) = flattenLambdas rhs in
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Bind n (parms ++ parms1) rhs'
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| Bind n parms rhs <- scs'
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]
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(rhss_scs, binds') = mapAccumL collectScsRhs [] binds
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(e_scs, e') = collectScsExp e
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binds_scs = [ let (rhs', parms1) = flattenLambdas rhs in
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Bind n (parms ++ parms1) rhs'
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| Bind n parms rhs <- scs'
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]
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(rhss_scs, binds') = mapAccumL collectScsRhs [] binds
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(e_scs, e') = collectScsExp e
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(scs', non_scs') = partition (\(Bind _ pars _) -> notNull pars) binds'
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(scs', non_scs') = partition (\(Bind _ pars _) -> notNull pars) binds'
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collectScsRhs acc (Bind n xs rhs) = (acc ++ rhs_scs, Bind n xs rhs')
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where
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(rhs_scs, rhs') = collectScsExp rhs
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EAnn e t -> (scs, EAnn e' t)
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where
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(scs, e') = collectScsExp e
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-- @\x.\y.\z. e → (e, [x,y,z])@
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flattenLambdas :: Exp -> (Exp, [Ident])
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flattenLambdas e = go (e, [])
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flattenLambdas :: Exp -> (Exp, [Id])
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flattenLambdas = go . (, [])
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where
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go (e, acc) = case e of
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EAbs par e1 -> go (e1, snoc par acc)
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_ -> (e, acc)
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EAbs _ par e1 -> go (e1, snoc par acc)
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_ -> (e, acc)
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mkEAbs :: [Bind] -> Exp -> Exp
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mkEAbs [] e = e
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