import CmdLineOpts ( opt_FoldrBuildOn )
import CoreUtils ( coreExprType )
+import Id ( idType )
import Var ( Id, TyVar )
import Const ( Con(..) )
-import PrelInfo ( foldrId )
+import PrelInfo ( foldrId, buildId )
import Type ( mkTyVarTy, mkForAllTy, mkFunTys, mkFunTy, Type )
import TysPrim ( alphaTyVar, alphaTy )
import TysWiredIn ( nilDataCon, consDataCon, listTyCon )
dsListComp quals elt_ty
| not opt_FoldrBuildOn -- Be boring
- = deListComp quals nil_expr
+ = deListComp quals (mkNilExpr elt_ty)
| otherwise -- foldr/build lives!
= newTyVarsDs [alphaTyVar] `thenDs` \ [n_tyvar] ->
let
- alpha_to_alpha = alphaTy `mkFunTy` alphaTy
-
n_ty = mkTyVarTy n_tyvar
c_ty = mkFunTys [elt_ty, n_ty] n_ty
- g_ty = mkForAllTy alphaTyVar (
- (elt_ty `mkFunTy` alpha_to_alpha)
- `mkFunTy`
- alpha_to_alpha
- )
in
- newSysLocalsDs [c_ty,n_ty,g_ty] `thenDs` \ [c, n, g] ->
+ newSysLocalsDs [c_ty,n_ty] `thenDs` \ [c, n] ->
- dfListComp c_ty c
- n_ty n
- quals `thenDs` \ result ->
+ dfListComp c n quals `thenDs` \ result ->
- returnDs (mkBuild elt_ty n_tyvar c n g result)
- where
- nil_expr = mkNilExpr elt_ty
+ returnDs (Var buildId `App` Type elt_ty
+ `App` mkLams [n_tyvar, c, n] result)
\end{code}
%************************************************************************
is the TE translation scheme. Note that we carry around the @L@ list
already desugared. @dsListComp@ does the top TE rule mentioned above.
-deListComp :: [TypecheckedStmt]
- -> CoreExpr -> CoreExpr -- Cons and nil resp; can be copied freely
- -> DsM CoreExpr
-
-deListComp [ReturnStmt expr] cons nil
- = dsExpr expr `thenDs` \ expr' ->
- returnDs (mkApps cons [expr', nil])
-
-deListComp (GuardStmt guard locn : quals) cons nil
- = dsExpr guard `thenDs` \ guard' ->
- deListComp quals cons nil `thenDs` \ rest' ->
- returnDs (mkIfThenElse guard' rest' nil)
-
-deListComp (LetStmt binds : quals) cons nil
- = deListComp quals cons nil `thenDs` \ rest' ->
- dsLet binds rest'
-
-deListComp (BindStmt pat list locn : quals) cons nil
- = dsExpr list `thenDs` \ list' ->
- let
- pat_ty = outPatType pat
- nil_ty = coreExprType nil
- in
- newSysLocalsDs [pat_ty, nil_ty] `thenDs` \ [x,ys] ->
-
- dsListComp quals cons (Var ys) `thenDs` \ rest ->
- matchSimply (Var x) ListCompMatch pat
- rest (Var ys) `thenDs` \ core_match ->
- bindNonRecDs (mkLams [x,ys] fn_body) $ \ fn ->
- dsListExpr list (Var fn) nil
-
-
-data FExpr = FEOther CoreExpr -- Default case
- | FECons -- cons
- | FEConsComposedWith CoreExpr -- (cons . e)
- | FENil -- nil
-
-feComposeWith FECons g
- = returnDs (FEConsComposedWith g)
-
-feComposeWith (FEOther f) g
- = composeWith f f `thenDs` \ h ->
- returnDs (FEOther h)
-
-feComposeWith (FEConsComposedWith f) g
- = composeWith f f `thenDs` \ h ->
- returnDs (FEConsComposedWith h)
-
-
-composeWith f g
- = newSysLocalDs arg_ty `thenDs` \ x ->
- returnDs (Lam x (App e (App f (Var x))))
- where
- arg_ty = case splitFunTy_maybe (coreExprType g) of
- Just (arg_ty,_) -> arg_ty
- other -> panic "feComposeWith"
-
-deListExpr :: TypecheckedHsExpr
- -> FExpr -> FExpr -- Cons and nil expressions
- -> DsM CoreExpr
-
-deListExpr cons nil (HsDoOut ListComp stmts _ _ _ result_ty src_loc)
- = deListComp stmts cons nil
-
-deListExpr cons nil (HsVar map, _, [f,xs])
- | goodInst var mapIdKey = dsExpr f `thenDs` \ f' ->
- feComposeWith cons f' `thenDs` \ cons' ->
- in
- deListExpr xs cons' nil
-
-
-data HsExprForm = GoodForm What [Type] [TypecheckedHsExpr]
- | BadForm
-
-data What = HsMap | HsConcat | HsFilter | HsZip | HsFoldr
-
-analyseListProducer (HsVar v) ty_args val_args
- | good_inst mapIdKey 2 = GoodForm HsMap ty_args val_args
- | good_inst concatIdKey 1 = GoodForm HsConcat ty_args val_args
- | good_inst filterIdKey 2 = GoodForm HsFilter ty_args val_args
- | good_id zipIdKey 2 = GoodForm HsZip ty_args val_args
- | otherwise =
- where
- good_inst key arity = isInstIdOf key v && result_is_list && n_args == arity
- good_id key arity = getUnique v == key && result_is_list && n_args == arity
-
- n_args :: Int
- n_args = length val_args
-
- result_is_list = resultTyIsList (idType v) ty_args val_args
-
-resultTyIsList ty ty_args val_args
- = go ty ty_args
- where
- go1 ty (_:tys) = case splitForAllTy_maybe ty of
- Just (_,ty) -> go1 ty tys
- Nothing -> False
- go1 ty [] = go2 ty val_args
-
- go2 ty (_:args) = case splitFunTy_maybe of
- Just (_,ty) -> go2 ty args
- Nothing -> False
-
- go2 ty [] = case splitTyConApp_maybe of
- Just (tycon, [_]) | tycon == listTyCon -> True
- other -> False
-
\begin{code}
deListComp :: [TypecheckedStmt] -> CoreExpr -> DsM CoreExpr
deListComp [ReturnStmt expr] list -- Figure 7.4, SLPJ, p 135, rule C above
= dsExpr expr `thenDs` \ core_expr ->
- returnDs (mkConApp consDataCon [Type (coreExprType core_expr), core_expr, list])
+ returnDs (mkConsExpr (coreExprType core_expr) core_expr list)
deListComp (GuardStmt guard locn : quals) list -- rule B above
= dsExpr guard `thenDs` \ core_guard ->
returnDs (Let (Rec [(h, rhs)]) letrec_body)
\end{code}
+
%************************************************************************
%* *
\subsection[DsListComp-foldr-build]{Foldr/Build desugaring of list comprehensions}
%************************************************************************
@dfListComp@ are the rules used with foldr/build turned on:
+
\begin{verbatim}
-TE < [ e | ] >> c n = c e n
-TE << [ e | b , q ] >> c n = if b then TE << [ e | q ] >> c n else n
-TE << [ e | p <- l , q ] c n = foldr
- (\ TE << p >> b -> TE << [ e | q ] >> c b
- _ b -> b) n l
+TE[ e | ] c n = c e n
+TE[ e | b , q ] c n = if b then TE[ e | q ] c n else n
+TE[ e | p <- l , q ] c n = let
+ f = \ x b -> case x of
+ p -> TE[ e | q ] c b
+ _ -> b
+ in
+ foldr f n l
\end{verbatim}
+
\begin{code}
-dfListComp :: Type -> Id -- 'c'; its type and id
- -> Type -> Id -- 'n'; its type and id
+dfListComp :: Id -> Id -- 'c' and 'n'
-> [TypecheckedStmt] -- the rest of the qual's
-> DsM CoreExpr
-dfListComp c_ty c_id n_ty n_id [ReturnStmt expr]
+dfListComp c_id n_id [ReturnStmt expr]
= dsExpr expr `thenDs` \ core_expr ->
returnDs (mkApps (Var c_id) [core_expr, Var n_id])
-dfListComp c_ty c_id n_ty n_id (GuardStmt guard locn : quals)
+dfListComp c_id n_id (GuardStmt guard locn : quals)
= dsExpr guard `thenDs` \ core_guard ->
- dfListComp c_ty c_id n_ty n_id quals `thenDs` \ core_rest ->
+ dfListComp c_id n_id quals `thenDs` \ core_rest ->
returnDs (mkIfThenElse core_guard core_rest (Var n_id))
-dfListComp c_ty c_id n_ty n_id (LetStmt binds : quals)
+dfListComp c_id n_id (LetStmt binds : quals)
-- new in 1.3, local bindings
- = dfListComp c_ty c_id n_ty n_id quals `thenDs` \ core_rest ->
+ = dfListComp c_id n_id quals `thenDs` \ core_rest ->
dsLet binds core_rest
-dfListComp c_ty c_id n_ty n_id (BindStmt pat list1 locn : quals)
+dfListComp c_id n_id (BindStmt pat list1 locn : quals)
-- evaluate the two lists
= dsExpr list1 `thenDs` \ core_list1 ->
-- find the required type
-
- let p_ty = outPatType pat
- b_ty = n_ty -- alias b_ty to n_ty
- fn_ty = mkFunTys [p_ty, b_ty] b_ty
- lst_ty = coreExprType core_list1
+ let x_ty = outPatType pat
+ b_ty = idType n_id
in
-- create some new local id's
-
- newSysLocalsDs [b_ty,p_ty,fn_ty,lst_ty] `thenDs` \ [b,p,fn,lst] ->
+ newSysLocalsDs [b_ty,x_ty] `thenDs` \ [b,x] ->
-- build rest of the comprehesion
+ dfListComp c_id b quals `thenDs` \ core_rest ->
- dfListComp c_ty c_id b_ty b quals `thenDs` \ core_rest ->
-- build the pattern match
-
- matchSimply (Var p) ListCompMatch pat core_rest (Var b) `thenDs` \ core_expr ->
+ matchSimply (Var x) ListCompMatch pat core_rest (Var b) `thenDs` \ core_expr ->
-- now build the outermost foldr, and return
-
returnDs (
- mkLets
- [NonRec fn (mkLams [p, b] core_expr),
- NonRec lst core_list1]
- (mkFoldr p_ty n_ty fn n_id lst)
+ Var foldrId `App` Type x_ty
+ `App` Type b_ty
+ `App` mkLams [x, b] core_expr
+ `App` Var n_id
+ `App` core_list1
)
\end{code}
-@mkBuild@ is sugar for building a build!
-
-@mkbuild ty tv c n e@ $Rightarrow$ @build ty (/\ tv -> \ c n -> e)@
-@ty@ is the type of the list.
-@tv@ is always a new type variable.
-@c,n@ are Id's for the abstract cons and nil, @g@ for let binding the argument argument.
- c :: a -> b -> b
- n :: b
- v :: (\/ b . (a -> b -> b) -> b -> b) -> [a]
--- \/ a . (\/ b . (a -> b -> b) -> b -> b) -> [a]
-@e@ is the object right inside the @build@
-
-\begin{code}
-mkBuild :: Type
- -> TyVar
- -> Id
- -> Id
- -> Id
- -> CoreExpr -- template
- -> CoreExpr -- template
-
-mkBuild ty tv c n g expr
- = Let (NonRec g (mkLams [tv, c,n] expr))
- (mkApps (Var buildId) [Type ty, Var g])
-
-buildId = error "DsListComp: buildId"
-
-mkFoldr a b f z xs
- = mkApps (mkTyApps (Var foldrId) [a,b]) [Var f, Var z, Var xs]
-\end{code}
-
projects / ghc-hetmet.git / blobdiff