#endif
import HsSyn
-import TcHsSyn
-- NB: The desugarer, which straddles the source and Core worlds, sometimes
-- needs to see source types
dsExpr (HsIPVar ip) = return (Var (ipNameName ip))
dsExpr (HsLit lit) = dsLit lit
dsExpr (HsOverLit lit) = dsOverLit lit
-dsExpr (HsWrap co_fn e) = do { co_fn' <- dsHsWrapper co_fn
- ; e' <- dsExpr e
- ; return (co_fn' e') }
+
+dsExpr (HsWrap co_fn e)
+ = do { co_fn' <- dsHsWrapper co_fn
+ ; e' <- dsExpr e
+ ; warn_id <- doptDs Opt_WarnIdentities
+ ; when warn_id $ warnAboutIdentities e' co_fn'
+ ; return (co_fn' e') }
dsExpr (NegApp expr neg_expr)
= App <$> dsExpr neg_expr <*> dsLExpr expr
-- We need the `ListComp' form to use `deListComp' (rather than the "do" form)
-- because the interpretation of `stmts' depends on what sort of thing it is.
--
-dsExpr (HsDo ListComp stmts body result_ty)
+dsExpr (HsDo ListComp stmts body _ result_ty)
= -- Special case for list comprehensions
dsListComp stmts body elt_ty
where
[elt_ty] = tcTyConAppArgs result_ty
-dsExpr (HsDo DoExpr stmts body result_ty)
+dsExpr (HsDo DoExpr stmts body _ result_ty)
+ = dsDo stmts body result_ty
+
+dsExpr (HsDo GhciStmt stmts body _ result_ty)
= dsDo stmts body result_ty
-dsExpr (HsDo GhciStmt stmts body result_ty)
+dsExpr (HsDo MDoExpr stmts body _ result_ty)
= dsDo stmts body result_ty
-dsExpr (HsDo ctxt@(MDoExpr tbl) stmts body result_ty)
- = do { (meth_binds, tbl') <- dsSyntaxTable tbl
- ; core_expr <- dsMDo ctxt tbl' stmts body result_ty
- ; return (mkLets meth_binds core_expr) }
+dsExpr (HsDo MonadComp stmts body return_op result_ty)
+ = dsMonadComp stmts return_op body result_ty
-dsExpr (HsDo PArrComp stmts body result_ty)
+dsExpr (HsDo PArrComp stmts body _ result_ty)
= -- Special case for array comprehensions
dsPArrComp (map unLoc stmts) body elt_ty
where
-- singletonP x1 +:+ ... +:+ singletonP xn
--
dsExpr (ExplicitPArr ty []) = do
- emptyP <- dsLookupGlobalId emptyPName
+ emptyP <- dsLookupDPHId emptyPName
return (Var emptyP `App` Type ty)
dsExpr (ExplicitPArr ty xs) = do
- singletonP <- dsLookupGlobalId singletonPName
- appP <- dsLookupGlobalId appPName
+ singletonP <- dsLookupDPHId singletonPName
+ appP <- dsLookupDPHId appPName
xs' <- mapM dsLExpr xs
return . foldr1 (binary appP) $ map (unary singletonP) xs'
where
goL [] = dsLExpr body
goL ((L loc stmt):lstmts) = putSrcSpanDs loc (go loc stmt lstmts)
- go _ (ExprStmt rhs then_expr _) stmts
+ go _ (ExprStmt rhs then_expr _ _) stmts
= do { rhs2 <- dsLExpr rhs
; case tcSplitAppTy_maybe (exprType rhs2) of
Just (container_ty, returning_ty) -> warnDiscardedDoBindings rhs container_ty returning_ty
go loc (RecStmt { recS_stmts = rec_stmts, recS_later_ids = later_ids
, recS_rec_ids = rec_ids, recS_ret_fn = return_op
, recS_mfix_fn = mfix_op, recS_bind_fn = bind_op
- , recS_rec_rets = rec_rets, recS_dicts = _ev_binds }) stmts
+ , recS_rec_rets = rec_rets }) stmts
= ASSERT( length rec_ids > 0 )
- ASSERT( isEmptyTcEvBinds _ev_binds ) -- No method binds
goL (new_bind_stmt : stmts)
where
-- returnE <- dsExpr return_id
-- mfixE <- dsExpr mfix_id
new_bind_stmt = L loc $ BindStmt (mkLHsPatTup later_pats) mfix_app
bind_op
- noSyntaxExpr -- Tuple cannot fail
+ noSyntaxExpr -- Tuple cannot fail
tup_ids = rec_ids ++ filterOut (`elem` rec_ids) later_ids
rec_tup_pats = map nlVarPat tup_ids
mfix_arg = noLoc $ HsLam (MatchGroup [mkSimpleMatch [mfix_pat] body]
(mkFunTy tup_ty body_ty))
mfix_pat = noLoc $ LazyPat $ mkLHsPatTup rec_tup_pats
- body = noLoc $ HsDo DoExpr rec_stmts return_app body_ty
+ body = noLoc $ HsDo DoExpr rec_stmts return_app noSyntaxExpr body_ty
return_app = nlHsApp (noLoc return_op) (mkLHsTupleExpr rets)
body_ty = mkAppTy m_ty tup_ty
tup_ty = mkBoxedTupleTy (map idType tup_ids) -- Deals with singleton case
+handle_failure :: LPat Id -> MatchResult -> SyntaxExpr Id -> DsM CoreExpr
-- In a do expression, pattern-match failure just calls
-- the monadic 'fail' rather than throwing an exception
- handle_failure pat match fail_op
- | matchCanFail match
- = do { fail_op' <- dsExpr fail_op
- ; fail_msg <- mkStringExpr (mk_fail_msg pat)
- ; extractMatchResult match (App fail_op' fail_msg) }
- | otherwise
- = extractMatchResult match (error "It can't fail")
+handle_failure pat match fail_op
+ | matchCanFail match
+ = do { fail_op' <- dsExpr fail_op
+ ; fail_msg <- mkStringExpr (mk_fail_msg pat)
+ ; extractMatchResult match (App fail_op' fail_msg) }
+ | otherwise
+ = extractMatchResult match (error "It can't fail")
mk_fail_msg :: Located e -> String
mk_fail_msg pat = "Pattern match failure in do expression at " ++
return (v1,..vn))
\begin{code}
-dsMDo :: HsStmtContext Name
+{-
+dsMDo :: HsStmtContext Name
-> [(Name,Id)]
-> [LStmt Id]
-> LHsExpr Id
goL ((L loc stmt):lstmts) = putSrcSpanDs loc (go loc stmt lstmts)
(m_ty, b_ty) = tcSplitAppTy result_ty -- result_ty must be of the form (m b)
- mfix_id = lookupEvidence tbl mfixName
return_id = lookupEvidence tbl returnMName
bind_id = lookupEvidence tbl bindMName
then_id = lookupEvidence tbl thenMName
= do { rest <- goL stmts
; dsLocalBinds binds rest }
- go _ (ExprStmt rhs _ rhs_ty) stmts
+ go _ (ExprStmt rhs then_expr rhs_ty) stmts
= do { rhs2 <- dsLExpr rhs
; warnDiscardedDoBindings rhs m_ty rhs_ty
+ ; then_expr2 <- dsExpr then_expr
; rest <- goL stmts
- ; return (mkApps (Var then_id) [Type rhs_ty, Type b_ty, rhs2, rest]) }
+ ; return (mkApps then_expr2 [rhs2, rest]) }
- go _ (BindStmt pat rhs _ _) stmts
- = do { body <- goL stmts
- ; var <- selectSimpleMatchVarL pat
+ go _ (BindStmt pat rhs bind_op _) stmts
+ = do { body <- goL stmts
+ ; rhs' <- dsLExpr rhs
+ ; bind_op' <- dsExpr bind_op
+ ; var <- selectSimpleMatchVarL pat
; match <- matchSinglePat (Var var) (StmtCtxt ctxt) pat
- result_ty (cantFailMatchResult body)
- ; fail_msg <- mkStringExpr (mk_fail_msg pat)
- ; let fail_expr = mkApps (Var fail_id) [Type b_ty, fail_msg]
- ; match_code <- extractMatchResult match fail_expr
-
- ; rhs' <- dsLExpr rhs
- ; return (mkApps (Var bind_id) [Type (hsLPatType pat), Type b_ty,
- rhs', Lam var match_code]) }
+ result_ty (cantFailMatchResult body)
+ ; match_code <- handle_failure pat match fail_op
+ ; return (mkApps bind_op [rhs', Lam var match_code]) }
go loc (RecStmt { recS_stmts = rec_stmts, recS_later_ids = later_ids
- , recS_rec_ids = rec_ids, recS_rec_rets = rec_rets
- , recS_dicts = _ev_binds }) stmts
+ , recS_rec_ids = rec_ids, recS_rec_rets = rec_rets
+ , recS_mfix_fn = mfix_op, recS_bind_fn = bind_op }) stmts
= ASSERT( length rec_ids > 0 )
ASSERT( length rec_ids == length rec_rets )
ASSERT( isEmptyTcEvBinds _ev_binds )
pprTrace "dsMDo" (ppr later_ids) $
goL (new_bind_stmt : stmts)
where
- new_bind_stmt = L loc $ mkBindStmt (mk_tup_pat later_pats) mfix_app
+ new_bind_stmt = L loc $ BindStmt (mk_tup_pat later_pats) mfix_app
+ bind_op noSyntaxExpr
-- Remove the later_ids that appear (without fancy coercions)
-- in rec_rets, because there's no need to knot-tie them separately
later_ids' = filter (`notElem` mono_rec_ids) later_ids
mono_rec_ids = [ id | HsVar id <- rec_rets ]
- mfix_app = nlHsApp (nlHsTyApp mfix_id [tup_ty]) mfix_arg
+ mfix_app = nlHsApp (noLoc mfix_op) mfix_arg
mfix_arg = noLoc $ HsLam (MatchGroup [mkSimpleMatch [mfix_pat] body]
(mkFunTy tup_ty body_ty))
rets = map nlHsVar later_ids' ++ map noLoc rec_rets
mfix_pat = noLoc $ LazyPat $ mk_tup_pat rec_tup_pats
- body = noLoc $ HsDo ctxt rec_stmts return_app body_ty
+ body = noLoc $ HsDo ctxt rec_stmts return_app noSyntaxExpr body_ty
body_ty = mkAppTy m_ty tup_ty
tup_ty = mkBoxedTupleTy (map idType (later_ids' ++ rec_ids)) -- Deals with singleton case
- return_app = nlHsApp (nlHsTyApp return_id [tup_ty])
- (mkLHsTupleExpr rets)
+ return_app = nlHsApp (noLoc return_op) (mkLHsTupleExpr rets)
mk_wild_pat :: Id -> LPat Id
mk_wild_pat v = noLoc $ WildPat $ idType v
mk_tup_pat :: [LPat Id] -> LPat Id
mk_tup_pat [p] = p
mk_tup_pat ps = noLoc $ mkVanillaTuplePat ps Boxed
+-}
\end{code}
+%************************************************************************
+%* *
+ Warning about identities
+%* *
+%************************************************************************
+
+Warn about functions that convert between one type and another
+when the to- and from- types are the same. Then it's probably
+(albeit not definitely) the identity
+\begin{code}
+warnAboutIdentities :: CoreExpr -> (CoreExpr -> CoreExpr) -> DsM ()
+warnAboutIdentities (Var v) co_fn
+ | idName v `elem` conversionNames
+ , let fun_ty = exprType (co_fn (Var v))
+ , Just (arg_ty, res_ty) <- splitFunTy_maybe fun_ty
+ , arg_ty `tcEqType` res_ty -- So we are converting ty -> ty
+ = warnDs (vcat [ ptext (sLit "Call of") <+> ppr v <+> dcolon <+> ppr fun_ty
+ , nest 2 $ ptext (sLit "can probably be omitted")
+ , parens (ptext (sLit "Use -fno-warn-identities to suppress this messsage)"))
+ ])
+warnAboutIdentities _ _ = return ()
+
+conversionNames :: [Name]
+conversionNames
+ = [ toIntegerName, toRationalName
+ , fromIntegralName, realToFracName ]
+ -- We can't easily add fromIntegerName, fromRationalName,
+ -- becuase they are generated by literals
+\end{code}
%************************************************************************
%* *
projects / ghc-hetmet.git / blobdiff