+++ /dev/null
-{-# OPTIONS -Wall -fno-warn-name-shadowing #-}
-{-
-Preprocess a module to normalize it in the following ways:
- (1) Saturate all constructor and primop applications.
- (2) Arrange that any non-trivial expression of unlifted kind ('#')
- is turned into the scrutinee of a Case.
-After these preprocessing steps, Core can be interpreted (or given an operational semantics)
- ignoring type information almost completely.
--}
-
-
-module Prep where
-
-import Data.Either
-
-import Prims
-import Core
-import Env
-import Check
-
-import Data.List
-
-prepModule :: Menv -> Module -> Module
-prepModule globalEnv (Module mn tdefs vdefgs) =
- Module mn tdefs vdefgs'
- where
-
- (_,vdefgs') = foldl prepTopVdefg (eempty,[]) vdefgs
-
- prepTopVdefg (venv,vdefgs) vdefg = (venv',vdefgs ++ [vdefg'])
- where (venv',vdefg') = prepVdefg (venv,eempty) vdefg
-
- prepVdefg (env@(venv,_)) (Nonrec(Vdef((Nothing,x),t,e))) =
- (eextend venv (x,t), Nonrec(Vdef((Nothing,x),t,prepExp env e)))
- prepVdefg (env@(venv,_)) (Nonrec(Vdef(qx,t,e))) =
- (venv, Nonrec(Vdef(qx,t,prepExp env e)))
- prepVdefg (venv,tvenv) (Rec vdefs) =
- (venv',Rec [ Vdef(qx,t,prepExp (venv',tvenv) e) | Vdef(qx,t,e) <- vdefs])
- where venv' = foldl eextend venv [(x,t) | Vdef((Nothing,x),t,_) <- vdefs]
-
- prepExp _ (Var qv) = Var qv
- prepExp _ (Dcon qdc) = Dcon qdc
- prepExp _ (Lit l) = Lit l
- prepExp env e@(App _ _) = unwindApp env e []
- prepExp env e@(Appt _ _) = unwindApp env e []
- prepExp (venv,tvenv) (Lam (Vb vb) e) = Lam (Vb vb) (prepExp (eextend venv vb,tvenv) e)
- prepExp (venv,tvenv) (Lam (Tb tb) e) = Lam (Tb tb) (prepExp (venv,eextend tvenv tb) e)
- prepExp env@(venv,tvenv) (Let (Nonrec(Vdef((Nothing,x),t,b))) e)
- | (kindOfTy tvenv t `eqKind` Kunlifted && suspends b) =
- -- There are two places where we call the typechecker, one of them
- -- here.
- -- We need to know the type of the let body in order to construct
- -- a case expression.
- -- need to extend the env with the let-bound var too!
- let eTy = typeOfExp (eextend venv (x, t), tvenv) e in
- Case (prepExp env b) (x,t)
- eTy
- [Adefault (prepExp (eextend venv (x,t),tvenv) e)]
- prepExp (venv,tvenv) (Let vdefg e) = Let vdefg' (prepExp (venv',tvenv) e)
- where (venv',vdefg') = prepVdefg (venv,tvenv) vdefg
- prepExp env@(venv,tvenv) (Case e vb t alts) = Case (prepExp env e) vb t (map (prepAlt (eextend venv vb,tvenv)) alts)
- prepExp env (Cast e t) = Cast (prepExp env e) t
- prepExp env (Note s e) = Note s (prepExp env e)
- prepExp _ (External s t) = External s t
-
- prepAlt (venv,tvenv) (Acon qdc tbs vbs e) = Acon qdc tbs vbs (prepExp (foldl eextend venv vbs,foldl eextend tvenv tbs) e)
- prepAlt env (Alit l e) = Alit l (prepExp env e)
- prepAlt env (Adefault e) = Adefault (prepExp env e)
-
-
- unwindApp env (App e1 e2) as = unwindApp env e1 (Left e2:as)
- unwindApp env (Appt e t) as = unwindApp env e (Right t:as)
- unwindApp env (op@(Dcon qdc)) as =
- -- possibly dubious to assume no type args
- etaExpand [] (drop n atys) (rewindApp env op as)
- where (tbs,atys0,_) = splitTy (qlookup cenv_ eempty qdc)
- atys = map (substl (map fst tbs) ts) atys0
- ts = [t | Right t <- as]
- n = length [e | Left e <- as]
- unwindApp env (op@(Var(qv@(_,p)))) as | isPrimVar qv =
- etaExpand (snd (unzip extraTbs)) (drop n atys) (rewindApp env op as)
- where -- TODO: avoid copying code. these two cases are the same
-
- -- etaExpand needs to add the type arguments too! Bah!
- (tbs, atys0, _) = (maybe (error "unwindApp") splitTy (elookup (venv_ primEnv) p))
- n_args = length ts
- (appliedTbs, extraTbs) = (take n_args tbs, drop n_args tbs)
- atys = map (substl (map fst appliedTbs) ts) atys0
- ts = [t | Right t <- as]
- n = length [e | Left e <- as]
- unwindApp env op as = rewindApp env op as
-
-
- etaExpand :: [Kind] -> [Ty] -> Exp -> Exp
- etaExpand ks ts e =
- -- what a pain
- let tyArgs = [("$t_"++(show i),k) | (i, k) <- zip [(1::Integer)..] ks]
- termArgs = [ ('$':(show i),t) | (i,t) <- zip [(1::Integer)..] ts] in
- foldr (\ (t1,k1) e -> Lam (Tb (t1,k1)) e)
- (foldr (\ (v,t) e -> Lam (Vb (v,t)) e)
- (foldl (\ e (v,_) -> App e (Var (unqual v)))
- (foldl (\ e (tv,_) -> Appt e (Tvar tv))
- e tyArgs)
- termArgs) termArgs)
- tyArgs
-
- rewindApp _ e [] = e
- rewindApp env@(venv,tvenv) e1 (Left e2:as) | kindOfTy tvenv t `eqKind` Kunlifted && suspends e2 =
- -- This is the other place where we call the typechecker.
- Case newScrut (v,t) (typeOfExp env' rhs) [Adefault rhs]
- where newScrut = prepExp env e2
- rhs = (rewindApp env' (App e1 (Var (unqual v))) as)
- -- note:
- -- e1 gets moved inside rhs. so if we pick a case
- -- var name (outside e1) equal to a name bound *inside*
- -- e1, the binding *inside* e1 will shadow "v"
- -- Which would be name capture!
- -- So, we pass the bound vars of e1 to freshVar along with
- -- the domain of the current env.
- v = freshVar (edomain venv `union` (boundVars e1))
- t = typeOfExp env e2
- env' = (eextend venv (v,t),tvenv)
- rewindApp env e1 (Left e2:as) = rewindApp env (App e1 (prepExp env e2)) as
- rewindApp env e (Right t:as) = rewindApp env (Appt e t) as
-
- freshVar vs = maximum ("":vs) ++ "x" -- one simple way!
-
- typeOfExp :: (Venv, Tvenv) -> Exp -> Ty
- typeOfExp = uncurry (checkExpr mn globalEnv tdefs)
-
- kindOfTy :: Tvenv -> Ty -> Kind
- kindOfTy tvenv = checkType mn globalEnv tdefs tvenv
-
- {- Return false for those expressions for which Interp.suspendExp builds a thunk. -}
- suspends (Var _) = False
- suspends (Lit _) = False
- suspends (Lam (Vb _) _) = False
- suspends (Lam _ e) = suspends e
- suspends (Appt e _) = suspends e
- suspends (Cast e _) = suspends e
- suspends (Note _ e) = suspends e
- suspends (External _ _) = False
- suspends _ = True
-
- mlookup :: (Envs -> Env a b) -> Env a b -> Mname -> Env a b
- mlookup _ local_env Nothing = local_env
- mlookup selector _ (Just m) =
- case elookup globalEnv m of
- Just env -> selector env
- Nothing -> error ("Prep: undefined module name: " ++ show m)
-
- qlookup :: (Ord a, Show a) => (Envs -> Env a b) -> Env a b -> (Mname,a) -> b
- qlookup selector local_env (m,k) =
- case elookup (mlookup selector local_env m) k of
- Just v -> v
- Nothing -> error ("undefined identifier: " ++ show k)
-
-boundVars :: Exp -> [Id]
-boundVars (Lam (Vb (v,_)) e) = [v] `union` boundVars e
-boundVars (Lam _ e) = boundVars e
-boundVars (Let vds e) = (boundVarsVdefs vds) `union` boundVars e
-boundVars (Case scrut (v,_) _ alts) =
- [v] `union` (boundVars scrut) `union` boundVarsAlts alts
-boundVars (Cast e _) = boundVars e
-boundVars (Note _ e) = boundVars e
-boundVars (App e1 e2) = boundVars e1 `union` boundVars e2
-boundVars (Appt e _) = boundVars e
-boundVars _ = []
-
-boundVarsVdefs :: Vdefg -> [Id]
-boundVarsVdefs (Rec vds) = nub (concatMap boundVarsVdef vds)
-boundVarsVdefs (Nonrec vd) = boundVarsVdef vd
-
-boundVarsVdef :: Vdef -> [Id]
-boundVarsVdef (Vdef ((_,v),_,e)) = [v] `union` boundVars e
-
-boundVarsAlts :: [Alt] -> [Var]
-boundVarsAlts as = nub (concatMap boundVarsAlt as)
-
-boundVarsAlt :: Alt -> [Var]
-boundVarsAlt (Acon _ _ vbs e) = (map fst vbs) `union` (boundVars e)
-boundVarsAlt (Alit _ e) = boundVars e
-boundVarsAlt (Adefault e) = boundVars e
\ No newline at end of file
projects / ghc-hetmet.git / blobdiff