2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnExpr]{Renaming of expressions}
6 Basically dependency analysis.
8 Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In
9 general, all of these functions return a renamed thing, and a set of
14 rnLExpr, rnExpr, rnStmts
17 #include "HsVersions.h"
20 import {-# SOURCE #-} TcSplice( runQuasiQuoteExpr )
23 import RnSource ( rnSrcDecls, rnSplice, checkTH )
24 import RnBinds ( rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS,
25 rnMatchGroup, makeMiniFixityEnv)
29 import RnTypes ( rnHsTypeFVs,
30 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec)
31 import RnPat (rnQuasiQuote, rnOverLit, rnPatsAndThen_LocalRightwards, rnBindPat,
32 localRecNameMaker, rnLit,
33 rnHsRecFields_Con, rnHsRecFields_Update, checkTupSize)
34 import DynFlags ( DynFlag(..) )
35 import BasicTypes ( FixityDirection(..) )
36 import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName,
37 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
38 negateName, thenMName, bindMName, failMName, groupWithName )
43 import LoadIface ( loadInterfaceForName )
46 import Util ( isSingleton )
47 import ListSetOps ( removeDups )
48 import Maybes ( expectJust )
53 import List ( unzip4 )
60 thenM :: Monad a => a b -> (b -> a c) -> a c
63 thenM_ :: Monad a => a b -> a c -> a c
66 returnM :: Monad m => a -> m a
69 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
72 checkM :: Monad m => Bool -> m () -> m ()
76 %************************************************************************
78 \subsubsection{Expressions}
80 %************************************************************************
83 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
84 rnExprs ls = rnExprs' ls emptyUniqSet
86 rnExprs' [] acc = returnM ([], acc)
87 rnExprs' (expr:exprs) acc
88 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
90 -- Now we do a "seq" on the free vars because typically it's small
91 -- or empty, especially in very long lists of constants
93 acc' = acc `plusFV` fvExpr
95 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
96 returnM (expr':exprs', fvExprs)
98 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
99 grubby_seqNameSet :: UniqSet Name -> a -> a
100 grubby_seqNameSet ns result | isEmptyUniqSet ns = result
104 Variables. We look up the variable and return the resulting name.
107 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
108 rnLExpr = wrapLocFstM rnExpr
110 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
113 = do name <- lookupOccRn v
114 ignore_asserts <- doptM Opt_IgnoreAsserts
115 finish_var ignore_asserts name
117 finish_var ignore_asserts name
118 | ignore_asserts || not (name `hasKey` assertIdKey)
119 = return (HsVar name, unitFV name)
121 = do { (e, fvs) <- mkAssertErrorExpr
122 ; return (e, fvs `addOneFV` name) }
125 = newIPNameRn v `thenM` \ name ->
126 returnM (HsIPVar name, emptyFVs)
128 rnExpr (HsLit lit@(HsString s))
130 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
131 ; if opt_OverloadedStrings then
132 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
133 else -- Same as below
135 returnM (HsLit lit, emptyFVs)
140 returnM (HsLit lit, emptyFVs)
142 rnExpr (HsOverLit lit)
143 = rnOverLit lit `thenM` \ (lit', fvs) ->
144 returnM (HsOverLit lit', fvs)
146 rnExpr (HsApp fun arg)
147 = rnLExpr fun `thenM` \ (fun',fvFun) ->
148 rnLExpr arg `thenM` \ (arg',fvArg) ->
149 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
151 rnExpr (OpApp e1 op _ e2)
152 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
153 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
154 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
157 -- When renaming code synthesised from "deriving" declarations
158 -- we used to avoid fixity stuff, but we can't easily tell any
159 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
160 -- should prevent bad things happening.
161 lookupFixityRn op_name `thenM` \ fixity ->
162 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
165 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
168 = rnLExpr e `thenM` \ (e', fv_e) ->
169 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
170 mkNegAppRn e' neg_name `thenM` \ final_e ->
171 returnM (final_e, fv_e `plusFV` fv_neg)
174 = rnLExpr e `thenM` \ (e', fvs_e) ->
175 returnM (HsPar e', fvs_e)
177 -- Template Haskell extensions
178 -- Don't ifdef-GHCI them because we want to fail gracefully
179 -- (not with an rnExpr crash) in a stage-1 compiler.
180 rnExpr e@(HsBracket br_body)
181 = checkTH e "bracket" `thenM_`
182 rnBracket br_body `thenM` \ (body', fvs_e) ->
183 returnM (HsBracket body', fvs_e)
185 rnExpr (HsSpliceE splice)
186 = rnSplice splice `thenM` \ (splice', fvs) ->
187 returnM (HsSpliceE splice', fvs)
190 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
192 rnExpr (HsQuasiQuoteE qq)
193 = rnQuasiQuote qq `thenM` \ (qq', fvs_qq) ->
194 runQuasiQuoteExpr qq' `thenM` \ (L _ expr') ->
195 rnExpr expr' `thenM` \ (expr'', fvs_expr) ->
196 returnM (expr'', fvs_qq `plusFV` fvs_expr)
199 rnExpr section@(SectionL expr op)
200 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
201 rnLExpr op `thenM` \ (op', fvs_op) ->
202 checkSectionPrec InfixL section op' expr' `thenM_`
203 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
205 rnExpr section@(SectionR op expr)
206 = rnLExpr op `thenM` \ (op', fvs_op) ->
207 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
208 checkSectionPrec InfixR section op' expr' `thenM_`
209 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
211 rnExpr (HsCoreAnn ann expr)
212 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
213 returnM (HsCoreAnn ann expr', fvs_expr)
215 rnExpr (HsSCC lbl expr)
216 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
217 returnM (HsSCC lbl expr', fvs_expr)
218 rnExpr (HsTickPragma info expr)
219 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
220 returnM (HsTickPragma info expr', fvs_expr)
222 rnExpr (HsLam matches)
223 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
224 returnM (HsLam matches', fvMatch)
226 rnExpr (HsCase expr matches)
227 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
228 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
229 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
231 rnExpr (HsLet binds expr)
232 = rnLocalBindsAndThen binds $ \ binds' ->
233 rnLExpr expr `thenM` \ (expr',fvExpr) ->
234 returnM (HsLet binds' expr', fvExpr)
236 rnExpr (HsDo do_or_lc stmts body _)
237 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
239 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
241 rnExpr (ExplicitList _ exps)
242 = rnExprs exps `thenM` \ (exps', fvs) ->
243 returnM (ExplicitList placeHolderType exps', fvs)
245 rnExpr (ExplicitPArr _ exps)
246 = rnExprs exps `thenM` \ (exps', fvs) ->
247 returnM (ExplicitPArr placeHolderType exps', fvs)
249 rnExpr (ExplicitTuple exps boxity)
250 = checkTupSize (length exps) `thenM_`
251 rnExprs exps `thenM` \ (exps', fvs) ->
252 returnM (ExplicitTuple exps' boxity, fvs)
254 rnExpr (RecordCon con_id _ rbinds)
255 = do { conname <- lookupLocatedOccRn con_id
256 ; (rbinds', fvRbinds) <- rnHsRecFields_Con conname rnLExpr rbinds
257 ; return (RecordCon conname noPostTcExpr rbinds',
258 fvRbinds `addOneFV` unLoc conname) }
260 rnExpr (RecordUpd expr rbinds _ _ _)
261 = do { (expr', fvExpr) <- rnLExpr expr
262 ; (rbinds', fvRbinds) <- rnHsRecFields_Update rnLExpr rbinds
263 ; return (RecordUpd expr' rbinds' [] [] [],
264 fvExpr `plusFV` fvRbinds) }
266 rnExpr (ExprWithTySig expr pty)
267 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
268 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
270 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
272 doc = text "In an expression type signature"
274 rnExpr (HsIf p b1 b2)
275 = rnLExpr p `thenM` \ (p', fvP) ->
276 rnLExpr b1 `thenM` \ (b1', fvB1) ->
277 rnLExpr b2 `thenM` \ (b2', fvB2) ->
278 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
281 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
282 returnM (HsType t, fvT)
284 doc = text "In a type argument"
286 rnExpr (ArithSeq _ seq)
287 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
288 returnM (ArithSeq noPostTcExpr new_seq, fvs)
290 rnExpr (PArrSeq _ seq)
291 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
292 returnM (PArrSeq noPostTcExpr new_seq, fvs)
295 These three are pattern syntax appearing in expressions.
296 Since all the symbols are reservedops we can simply reject them.
297 We return a (bogus) EWildPat in each case.
300 rnExpr e@EWildPat = patSynErr e
301 rnExpr e@(EAsPat {}) = patSynErr e
302 rnExpr e@(EViewPat {}) = patSynErr e
303 rnExpr e@(ELazyPat {}) = patSynErr e
306 %************************************************************************
310 %************************************************************************
313 rnExpr (HsProc pat body)
315 rnPatsAndThen_LocalRightwards ProcExpr [pat] $ \ [pat'] ->
316 rnCmdTop body `thenM` \ (body',fvBody) ->
317 returnM (HsProc pat' body', fvBody)
319 rnExpr (HsArrApp arrow arg _ ho rtl)
320 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
321 rnLExpr arg `thenM` \ (arg',fvArg) ->
322 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
323 fvArrow `plusFV` fvArg)
325 select_arrow_scope tc = case ho of
326 HsHigherOrderApp -> tc
327 HsFirstOrderApp -> escapeArrowScope tc
330 rnExpr (HsArrForm op (Just _) [arg1, arg2])
331 = escapeArrowScope (rnLExpr op)
332 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
333 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
334 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
338 lookupFixityRn op_name `thenM` \ fixity ->
339 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
342 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
344 rnExpr (HsArrForm op fixity cmds)
345 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
346 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
347 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
349 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
354 %************************************************************************
358 %************************************************************************
361 rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars)
362 rnCmdArgs [] = returnM ([], emptyFVs)
364 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
365 rnCmdArgs args `thenM` \ (args',fvArgs) ->
366 returnM (arg':args', fvArg `plusFV` fvArgs)
368 rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars)
369 rnCmdTop = wrapLocFstM rnCmdTop'
371 rnCmdTop' (HsCmdTop cmd _ _ _)
372 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
374 cmd_names = [arrAName, composeAName, firstAName] ++
375 nameSetToList (methodNamesCmd (unLoc cmd'))
377 -- Generate the rebindable syntax for the monad
378 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
380 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
381 fvCmd `plusFV` cmd_fvs)
383 ---------------------------------------------------
384 -- convert OpApp's in a command context to HsArrForm's
386 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
387 convertOpFormsLCmd = fmap convertOpFormsCmd
389 convertOpFormsCmd :: HsCmd id -> HsCmd id
391 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
392 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
393 convertOpFormsCmd (OpApp c1 op fixity c2)
395 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
396 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
398 HsArrForm op (Just fixity) [arg1, arg2]
400 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
402 convertOpFormsCmd (HsCase exp matches)
403 = HsCase exp (convertOpFormsMatch matches)
405 convertOpFormsCmd (HsIf exp c1 c2)
406 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
408 convertOpFormsCmd (HsLet binds cmd)
409 = HsLet binds (convertOpFormsLCmd cmd)
411 convertOpFormsCmd (HsDo ctxt stmts body ty)
412 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
413 (convertOpFormsLCmd body) ty
415 -- Anything else is unchanged. This includes HsArrForm (already done),
416 -- things with no sub-commands, and illegal commands (which will be
417 -- caught by the type checker)
418 convertOpFormsCmd c = c
420 convertOpFormsStmt :: StmtLR id id -> StmtLR id id
421 convertOpFormsStmt (BindStmt pat cmd _ _)
422 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
423 convertOpFormsStmt (ExprStmt cmd _ _)
424 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
425 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
426 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
427 convertOpFormsStmt stmt = stmt
429 convertOpFormsMatch :: MatchGroup id -> MatchGroup id
430 convertOpFormsMatch (MatchGroup ms ty)
431 = MatchGroup (map (fmap convert) ms) ty
432 where convert (Match pat mty grhss)
433 = Match pat mty (convertOpFormsGRHSs grhss)
435 convertOpFormsGRHSs :: GRHSs id -> GRHSs id
436 convertOpFormsGRHSs (GRHSs grhss binds)
437 = GRHSs (map convertOpFormsGRHS grhss) binds
439 convertOpFormsGRHS :: Located (GRHS id) -> Located (GRHS id)
440 convertOpFormsGRHS = fmap convert
442 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
444 ---------------------------------------------------
445 type CmdNeeds = FreeVars -- Only inhabitants are
446 -- appAName, choiceAName, loopAName
448 -- find what methods the Cmd needs (loop, choice, apply)
449 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
450 methodNamesLCmd = methodNamesCmd . unLoc
452 methodNamesCmd :: HsCmd Name -> CmdNeeds
454 methodNamesCmd (HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
456 methodNamesCmd (HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
458 methodNamesCmd (HsArrForm {}) = emptyFVs
460 methodNamesCmd (HsPar c) = methodNamesLCmd c
462 methodNamesCmd (HsIf _ c1 c2)
463 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
465 methodNamesCmd (HsLet _ c) = methodNamesLCmd c
467 methodNamesCmd (HsDo _ stmts body _)
468 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
470 methodNamesCmd (HsApp c _) = methodNamesLCmd c
472 methodNamesCmd (HsLam match) = methodNamesMatch match
474 methodNamesCmd (HsCase _ matches)
475 = methodNamesMatch matches `addOneFV` choiceAName
477 methodNamesCmd _ = emptyFVs
478 -- Other forms can't occur in commands, but it's not convenient
479 -- to error here so we just do what's convenient.
480 -- The type checker will complain later
482 ---------------------------------------------------
483 methodNamesMatch :: MatchGroup Name -> FreeVars
484 methodNamesMatch (MatchGroup ms _)
485 = plusFVs (map do_one ms)
487 do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
489 -------------------------------------------------
491 methodNamesGRHSs :: GRHSs Name -> FreeVars
492 methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
494 -------------------------------------------------
496 methodNamesGRHS :: Located (GRHS Name) -> CmdNeeds
497 methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
499 ---------------------------------------------------
500 methodNamesStmts :: [Located (StmtLR Name Name)] -> FreeVars
501 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
503 ---------------------------------------------------
504 methodNamesLStmt :: Located (StmtLR Name Name) -> FreeVars
505 methodNamesLStmt = methodNamesStmt . unLoc
507 methodNamesStmt :: StmtLR Name Name -> FreeVars
508 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
509 methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
510 methodNamesStmt (RecStmt stmts _ _ _ _)
511 = methodNamesStmts stmts `addOneFV` loopAName
512 methodNamesStmt (LetStmt _) = emptyFVs
513 methodNamesStmt (ParStmt _) = emptyFVs
514 methodNamesStmt (TransformStmt _ _ _) = emptyFVs
515 methodNamesStmt (GroupStmt _ _) = emptyFVs
516 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
517 -- here so we just do what's convenient
521 %************************************************************************
525 %************************************************************************
528 rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
529 rnArithSeq (From expr)
530 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
531 returnM (From expr', fvExpr)
533 rnArithSeq (FromThen expr1 expr2)
534 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
535 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
536 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
538 rnArithSeq (FromTo expr1 expr2)
539 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
540 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
541 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
543 rnArithSeq (FromThenTo expr1 expr2 expr3)
544 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
545 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
546 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
547 returnM (FromThenTo expr1' expr2' expr3',
548 plusFVs [fvExpr1, fvExpr2, fvExpr3])
551 %************************************************************************
553 Template Haskell brackets
555 %************************************************************************
558 rnBracket :: HsBracket RdrName -> RnM (HsBracket Name, FreeVars)
559 rnBracket (VarBr n) = do { name <- lookupOccRn n
560 ; this_mod <- getModule
561 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
562 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
563 ; return () } -- only way that is going to happen
564 ; returnM (VarBr name, unitFV name) }
566 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
568 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
569 ; return (ExpBr e', fvs) }
571 rnBracket (PatBr _) = do { addErr (ptext (sLit "Tempate Haskell pattern brackets are not supported yet"));
574 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
575 ; return (TypBr t', fvs) }
577 doc = ptext (sLit "In a Template-Haskell quoted type")
578 rnBracket (DecBr group)
579 = do { gbl_env <- getGblEnv
581 ; let new_gbl_env = gbl_env { -- Set the module to thFAKE. The top-level names from the bracketed
582 -- declarations will go into the name cache, and we don't want them to
583 -- confuse the Names for the current module.
584 -- By using a pretend module, thFAKE, we keep them safely out of the way.
587 -- The emptyDUs is so that we just collect uses for this group alone
588 -- in the call to rnSrcDecls below
590 ; setGblEnv new_gbl_env $ do {
592 -- In this situation we want to *shadow* top-level bindings.
594 -- bar = [d| foo = 1 |]
595 -- If we don't shadow, we'll get an ambiguity complaint when we do
596 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
598 -- Furthermore, arguably if the splice does define foo, that should hide
599 -- any foo's further out
601 -- The shadowing is acheived by calling rnSrcDecls with True as the shadowing flag
602 ; (tcg_env, group') <- rnSrcDecls True group
604 -- Discard the tcg_env; it contains only extra info about fixity
605 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
608 %************************************************************************
610 \subsubsection{@Stmt@s: in @do@ expressions}
612 %************************************************************************
615 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
616 -> RnM (thing, FreeVars)
617 -> RnM (([LStmt Name], thing), FreeVars)
619 rnStmts (MDoExpr _) = rnMDoStmts
620 rnStmts ctxt = rnNormalStmts ctxt
622 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
623 -> RnM (thing, FreeVars)
624 -> RnM (([LStmt Name], thing), FreeVars)
625 -- Used for cases *other* than recursive mdo
626 -- Implements nested scopes
628 rnNormalStmts _ [] thing_inside
629 = do { (thing, fvs) <- thing_inside
630 ; return (([],thing), fvs) }
632 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
633 = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $
634 rnNormalStmts ctxt stmts thing_inside
635 ; return (((L loc stmt' : stmts'), thing), fvs) }
638 rnStmt :: HsStmtContext Name -> Stmt RdrName
639 -> RnM (thing, FreeVars)
640 -> RnM ((Stmt Name, thing), FreeVars)
642 rnStmt _ (ExprStmt expr _ _) thing_inside
643 = do { (expr', fv_expr) <- rnLExpr expr
644 ; (then_op, fvs1) <- lookupSyntaxName thenMName
645 ; (thing, fvs2) <- thing_inside
646 ; return ((ExprStmt expr' then_op placeHolderType, thing),
647 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
649 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
650 = do { (expr', fv_expr) <- rnLExpr expr
651 -- The binders do not scope over the expression
652 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
653 ; (fail_op, fvs2) <- lookupSyntaxName failMName
654 ; rnPatsAndThen_LocalRightwards (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
655 { (thing, fvs3) <- thing_inside
656 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
657 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
658 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
659 -- but it does not matter because the names are unique
661 rnStmt ctxt (LetStmt binds) thing_inside
662 = do { checkLetStmt ctxt binds
663 ; rnLocalBindsAndThen binds $ \binds' -> do
664 { (thing, fvs) <- thing_inside
665 ; return ((LetStmt binds', thing), fvs) } }
667 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
668 = do { checkRecStmt ctxt
669 ; rn_rec_stmts_and_then rec_stmts $ \ segs -> do
670 { (thing, fvs) <- thing_inside
672 segs_w_fwd_refs = addFwdRefs segs
673 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
674 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
675 fwd_vars = nameSetToList (plusFVs fs)
677 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
678 ; return ((rec_stmt, thing), uses `plusFV` fvs) } }
680 rnStmt ctxt (ParStmt segs) thing_inside
681 = do { checkParStmt ctxt
682 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
683 ; return ((ParStmt segs', thing), fvs) }
685 rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do
686 checkTransformStmt ctxt
688 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
689 ((stmts', binders, (maybeByExpr', thing)), fvs) <-
690 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \_unshadowed_bndrs -> do
691 (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr
692 (thing, fv_thing) <- thing_inside
694 return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing)
696 return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs)
698 rnMaybeLExpr Nothing = return (Nothing, emptyFVs)
699 rnMaybeLExpr (Just expr) = do
700 (expr', fv_expr) <- rnLExpr expr
701 return (Just expr', fv_expr)
703 rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do
704 checkTransformStmt ctxt
706 -- We must rename the using expression in the context before the transform is begun
707 groupByClauseAction <-
708 case groupByClause of
709 GroupByNothing usingExpr -> do
710 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
711 (return . return) (GroupByNothing usingExpr', fv_usingExpr)
712 GroupBySomething eitherUsingExpr byExpr -> do
713 (eitherUsingExpr', fv_eitherUsingExpr) <-
714 case eitherUsingExpr of
715 Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName)
717 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
718 return (Left usingExpr', fv_usingExpr)
721 (byExpr', fv_byExpr) <- rnLExpr byExpr
722 return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr)
724 -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so
725 -- perhaps we could refactor this to use rnNormalStmts directly?
726 ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <-
727 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
728 (groupByClause', fv_groupByClause) <- groupByClauseAction
730 unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs
731 let binderMap = zip unshadowed_bndrs unshadowed_bndrs'
733 -- Bind the "thing" inside a context where we have REBOUND everything
734 -- bound by the statements before the group. This is necessary since after
735 -- the grouping the same identifiers actually have different meanings
736 -- i.e. they refer to lists not singletons!
737 (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside
739 -- We remove entries from the binder map that are not used in the thing_inside.
740 -- We can then use that usage information to ensure that the free variables do
741 -- not contain the things we just bound, but do contain the things we need to
742 -- make those bindings (i.e. the corresponding non-listy variables)
744 -- Note that we also retain those entries which have an old binder in our
745 -- own free variables (the using or by expression). This is because this map
746 -- is reused in the desugarer to create the type to bind from the statements
747 -- that occur before this one. If the binders we need are not in the map, they
748 -- will never get bound into our desugared expression and hence the simplifier
749 -- crashes as we refer to variables that don't exist!
750 let usedBinderMap = filter
751 (\(old_binder, new_binder) ->
752 (new_binder `elemNameSet` fv_thing) ||
753 (old_binder `elemNameSet` fv_groupByClause)) binderMap
754 (usedOldBinders, usedNewBinders) = unzip usedBinderMap
755 real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders)
757 return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing)
759 traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap)
760 return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs)
762 rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name
764 -> ([Name] -> RnM (thing, FreeVars))
765 -> RnM (([LStmt Name], [Name], thing), FreeVars)
766 rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do
767 ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do
768 -- Find the Names that are bound by stmts that
769 -- by assumption we have just renamed
770 local_env <- getLocalRdrEnv
772 stmts_binders = collectLStmtsBinders stmts
773 bndrs = map (expectJust "rnStmt"
774 . lookupLocalRdrEnv local_env
775 . unLoc) stmts_binders
777 -- If shadow, we'll look up (Unqual x) twice, getting
778 -- the second binding both times, which is the
780 unshadowed_bndrs = nub bndrs
782 -- Typecheck the thing inside, passing on all
783 -- the Names bound before it for its information
784 (thing, fvs) <- thing_inside unshadowed_bndrs
786 -- Figure out which of the bound names are used
787 -- after the statements we renamed
788 let used_bndrs = filter (`elemNameSet` fvs) bndrs
789 return ((used_bndrs, thing), fvs)
791 -- Flatten the tuple returned by the above call a bit!
792 return ((stmts', used_bndrs, inner_thing), fvs)
794 rnParallelStmts :: HsStmtContext Name -> [([LStmt RdrName], [RdrName])]
795 -> RnM (thing, FreeVars)
796 -> RnM (([([LStmt Name], [Name])], thing), FreeVars)
797 rnParallelStmts ctxt segs thing_inside = do
798 orig_lcl_env <- getLocalRdrEnv
799 go orig_lcl_env [] segs
801 go orig_lcl_env bndrs [] = do
802 let (bndrs', dups) = removeDups cmpByOcc bndrs
803 inner_env = extendLocalRdrEnv orig_lcl_env bndrs'
806 (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
807 return (([], thing), fvs)
809 go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do
810 ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do
811 -- Typecheck the thing inside, passing on all
812 -- the Names bound, but separately; revert the envt
813 setLocalRdrEnv orig_lcl_env $ do
814 go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs
816 let seg' = (stmts', bndrs)
817 return (((seg':segs'), thing), delListFromNameSet fvs bndrs)
819 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
820 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
821 <+> quotes (ppr (head vs)))
825 %************************************************************************
827 \subsubsection{mdo expressions}
829 %************************************************************************
832 type FwdRefs = NameSet
833 type Segment stmts = (Defs,
834 Uses, -- May include defs
835 FwdRefs, -- A subset of uses that are
836 -- (a) used before they are bound in this segment, or
837 -- (b) used here, and bound in subsequent segments
838 stmts) -- Either Stmt or [Stmt]
841 ----------------------------------------------------
843 rnMDoStmts :: [LStmt RdrName]
844 -> RnM (thing, FreeVars)
845 -> RnM (([LStmt Name], thing), FreeVars)
846 rnMDoStmts stmts thing_inside
847 = -- Step1: Bring all the binders of the mdo into scope
848 -- (Remember that this also removes the binders from the
849 -- finally-returned free-vars.)
850 -- And rename each individual stmt, making a
851 -- singleton segment. At this stage the FwdRefs field
852 -- isn't finished: it's empty for all except a BindStmt
853 -- for which it's the fwd refs within the bind itself
854 -- (This set may not be empty, because we're in a recursive
856 rn_rec_stmts_and_then stmts $ \ segs -> do {
858 ; (thing, fvs_later) <- thing_inside
861 -- Step 2: Fill in the fwd refs.
862 -- The segments are all singletons, but their fwd-ref
863 -- field mentions all the things used by the segment
864 -- that are bound after their use
865 segs_w_fwd_refs = addFwdRefs segs
867 -- Step 3: Group together the segments to make bigger segments
868 -- Invariant: in the result, no segment uses a variable
869 -- bound in a later segment
870 grouped_segs = glomSegments segs_w_fwd_refs
872 -- Step 4: Turn the segments into Stmts
873 -- Use RecStmt when and only when there are fwd refs
874 -- Also gather up the uses from the end towards the
875 -- start, so we can tell the RecStmt which things are
876 -- used 'after' the RecStmt
877 (stmts', fvs) = segsToStmts grouped_segs fvs_later
879 ; return ((stmts', thing), fvs) }
881 ---------------------------------------------
883 -- wrapper that does both the left- and right-hand sides
884 rn_rec_stmts_and_then :: [LStmt RdrName]
885 -- assumes that the FreeVars returned includes
886 -- the FreeVars of the Segments
887 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
889 rn_rec_stmts_and_then s cont
890 = do { -- (A) Make the mini fixity env for all of the stmts
891 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
894 ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
896 -- ...bring them and their fixities into scope
897 ; let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
898 ; bindLocalNamesFV_WithFixities bound_names fix_env $ do
900 -- (C) do the right-hand-sides and thing-inside
901 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
902 ; (res, fvs) <- cont segs
903 ; warnUnusedLocalBinds bound_names fvs
904 ; return (res, fvs) }}
906 -- get all the fixity decls in any Let stmt
907 collectRecStmtsFixities :: [LStmtLR RdrName RdrName] -> [LFixitySig RdrName]
908 collectRecStmtsFixities l =
909 foldr (\ s -> \acc -> case s of
910 (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
911 foldr (\ sig -> \ acc -> case sig of
912 (L loc (FixSig s)) -> (L loc s) : acc
918 rn_rec_stmt_lhs :: MiniFixityEnv
920 -- rename LHS, and return its FVs
921 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
922 -- so we don't bother to compute it accurately in the other cases
923 -> RnM [(LStmtLR Name RdrName, FreeVars)]
925 rn_rec_stmt_lhs _ (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
926 -- this is actually correct
929 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
931 -- should the ctxt be MDo instead?
932 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
933 return [(L loc (BindStmt pat' expr a b),
936 rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _)))
937 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
940 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
941 = do binds' <- rnValBindsLHS fix_env binds
942 return [(L loc (LetStmt (HsValBinds binds')),
943 -- Warning: this is bogus; see function invariant
947 rn_rec_stmt_lhs fix_env (L _ (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
948 = rn_rec_stmts_lhs fix_env stmts
950 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
951 = pprPanic "rn_rec_stmt" (ppr stmt)
953 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo
954 = pprPanic "rn_rec_stmt" (ppr stmt)
956 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo
957 = pprPanic "rn_rec_stmt" (ppr stmt)
959 rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
960 = panic "rn_rec_stmt LetStmt EmptyLocalBinds"
962 rn_rec_stmts_lhs :: MiniFixityEnv
964 -> RnM [(LStmtLR Name RdrName, FreeVars)]
965 rn_rec_stmts_lhs fix_env stmts =
966 let boundNames = collectLStmtsBinders stmts
967 doc = text "In a recursive mdo-expression"
969 -- First do error checking: we need to check for dups here because we
970 -- don't bind all of the variables from the Stmt at once
971 -- with bindLocatedLocals.
972 checkDupRdrNames doc boundNames
973 mappM (rn_rec_stmt_lhs fix_env) stmts `thenM` \ ls -> returnM (concat ls)
978 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
979 -- Rename a Stmt that is inside a RecStmt (or mdo)
980 -- Assumes all binders are already in scope
981 -- Turns each stmt into a singleton Stmt
982 rn_rec_stmt _ (L loc (ExprStmt expr _ _)) _
983 = rnLExpr expr `thenM` \ (expr', fvs) ->
984 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
985 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
986 L loc (ExprStmt expr' then_op placeHolderType))]
988 rn_rec_stmt _ (L loc (BindStmt pat' expr _ _)) fv_pat
989 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
990 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
991 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
993 bndrs = mkNameSet (collectPatBinders pat')
994 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
996 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
997 L loc (BindStmt pat' expr' bind_op fail_op))]
999 rn_rec_stmt _ (L _ (LetStmt binds@(HsIPBinds _))) _
1000 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
1003 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
1004 (binds', du_binds) <-
1005 -- fixities and unused are handled above in rn_rec_stmts_and_then
1006 rnValBindsRHS all_bndrs binds'
1007 returnM [(duDefs du_binds, duUses du_binds,
1008 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1010 -- no RecStmt case becuase they get flattened above when doing the LHSes
1011 rn_rec_stmt _ stmt@(L _ (RecStmt _ _ _ _ _)) _
1012 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1014 rn_rec_stmt _ stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo
1015 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1017 rn_rec_stmt _ stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo
1018 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1020 rn_rec_stmt _ stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo
1021 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1023 rn_rec_stmt _ (L _ (LetStmt EmptyLocalBinds)) _
1024 = panic "rn_rec_stmt: LetStmt EmptyLocalBinds"
1026 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1027 rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1028 returnM (concat segs_s)
1030 ---------------------------------------------
1031 addFwdRefs :: [Segment a] -> [Segment a]
1032 -- So far the segments only have forward refs *within* the Stmt
1033 -- (which happens for bind: x <- ...x...)
1034 -- This function adds the cross-seg fwd ref info
1037 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1039 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1040 = (new_seg : segs, all_defs)
1042 new_seg = (defs, uses, new_fwds, stmts)
1043 all_defs = later_defs `unionNameSets` defs
1044 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1045 -- Add the downstream fwd refs here
1047 ----------------------------------------------------
1048 -- Glomming the singleton segments of an mdo into
1049 -- minimal recursive groups.
1051 -- At first I thought this was just strongly connected components, but
1052 -- there's an important constraint: the order of the stmts must not change.
1055 -- mdo { x <- ...y...
1062 -- Here, the first stmt mention 'y', which is bound in the third.
1063 -- But that means that the innocent second stmt (p <- z) gets caught
1064 -- up in the recursion. And that in turn means that the binding for
1065 -- 'z' has to be included... and so on.
1067 -- Start at the tail { r <- x }
1068 -- Now add the next one { z <- y ; r <- x }
1069 -- Now add one more { q <- x ; z <- y ; r <- x }
1070 -- Now one more... but this time we have to group a bunch into rec
1071 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1072 -- Now one more, which we can add on without a rec
1074 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1076 -- Finally we add the last one; since it mentions y we have to
1077 -- glom it togeher with the first two groups
1078 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1079 -- q <- x ; z <- y } ;
1082 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1084 glomSegments [] = []
1085 glomSegments ((defs,uses,fwds,stmt) : segs)
1086 -- Actually stmts will always be a singleton
1087 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1089 segs' = glomSegments segs
1090 (extras, others) = grab uses segs'
1091 (ds, us, fs, ss) = unzip4 extras
1093 seg_defs = plusFVs ds `plusFV` defs
1094 seg_uses = plusFVs us `plusFV` uses
1095 seg_fwds = plusFVs fs `plusFV` fwds
1096 seg_stmts = stmt : concat ss
1098 grab :: NameSet -- The client
1100 -> ([Segment a], -- Needed by the 'client'
1101 [Segment a]) -- Not needed by the client
1102 -- The result is simply a split of the input
1104 = (reverse yeses, reverse noes)
1106 (noes, yeses) = span not_needed (reverse dus)
1107 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1110 ----------------------------------------------------
1111 segsToStmts :: [Segment [LStmt Name]]
1112 -> FreeVars -- Free vars used 'later'
1113 -> ([LStmt Name], FreeVars)
1115 segsToStmts [] fvs_later = ([], fvs_later)
1116 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
1117 = ASSERT( not (null ss) )
1118 (new_stmt : later_stmts, later_uses `plusFV` uses)
1120 (later_stmts, later_uses) = segsToStmts segs fvs_later
1121 new_stmt | non_rec = head ss
1122 | otherwise = L (getLoc (head ss)) $
1123 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
1126 non_rec = isSingleton ss && isEmptyNameSet fwds
1127 used_later = defs `intersectNameSet` later_uses
1128 -- The ones needed after the RecStmt
1131 %************************************************************************
1133 \subsubsection{Assertion utils}
1135 %************************************************************************
1138 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1139 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
1141 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
1142 -- Return an expression for (assertError "Foo.hs:27")
1144 = getSrcSpanM `thenM` \ sloc ->
1146 expr = HsApp (L sloc (HsVar assertErrorName))
1147 (L sloc (srcSpanPrimLit sloc))
1149 returnM (expr, emptyFVs)
1152 %************************************************************************
1154 \subsubsection{Errors}
1156 %************************************************************************
1160 ----------------------
1161 -- Checking when a particular Stmt is ok
1162 checkLetStmt :: HsStmtContext Name -> HsLocalBinds RdrName -> RnM ()
1163 checkLetStmt (ParStmtCtxt _) (HsIPBinds binds) = addErr (badIpBinds (ptext (sLit "a parallel list comprehension:")) binds)
1164 checkLetStmt _ctxt _binds = return ()
1165 -- We do not allow implicit-parameter bindings in a parallel
1166 -- list comprehension. I'm not sure what it might mean.
1169 checkRecStmt :: HsStmtContext Name -> RnM ()
1170 checkRecStmt (MDoExpr {}) = return () -- Recursive stmt ok in 'mdo'
1171 checkRecStmt (DoExpr {}) = return () -- ..and in 'do' but only because of arrows:
1172 -- proc x -> do { ...rec... }
1173 -- We don't have enough context to distinguish this situation here
1174 -- so we leave it to the type checker
1175 checkRecStmt ctxt = addErr msg
1177 msg = ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt
1180 checkParStmt :: HsStmtContext Name -> RnM ()
1182 = do { parallel_list_comp <- doptM Opt_ParallelListComp
1183 ; checkErr parallel_list_comp msg }
1185 msg = ptext (sLit "Illegal parallel list comprehension: use -XParallelListComp")
1188 checkTransformStmt :: HsStmtContext Name -> RnM ()
1189 checkTransformStmt ListComp -- Ensure we are really within a list comprehension because otherwise the
1190 -- desugarer will break when we come to operate on a parallel array
1191 = do { transform_list_comp <- doptM Opt_TransformListComp
1192 ; checkErr transform_list_comp msg }
1194 msg = ptext (sLit "Illegal transform or grouping list comprehension: use -XTransformListComp")
1195 checkTransformStmt (ParStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1196 checkTransformStmt (TransformStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1197 checkTransformStmt ctxt = addErr msg
1199 msg = ptext (sLit "Illegal transform or grouping in") <+> pprStmtContext ctxt
1202 patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
1203 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1205 ; return (EWildPat, emptyFVs) }
1207 badIpBinds :: Outputable a => SDoc -> a -> SDoc
1208 badIpBinds what binds
1209 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)