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 acc' `seq` rnExprs' exprs acc' `thenM` \ (exprs', fvExprs) ->
96 returnM (expr':exprs', fvExprs)
99 Variables. We look up the variable and return the resulting name.
102 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
103 rnLExpr = wrapLocFstM rnExpr
105 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
108 = do name <- lookupOccRn v
109 ignore_asserts <- doptM Opt_IgnoreAsserts
110 finish_var ignore_asserts name
112 finish_var ignore_asserts name
113 | ignore_asserts || not (name `hasKey` assertIdKey)
114 = return (HsVar name, unitFV name)
116 = do { (e, fvs) <- mkAssertErrorExpr
117 ; return (e, fvs `addOneFV` name) }
120 = newIPNameRn v `thenM` \ name ->
121 returnM (HsIPVar name, emptyFVs)
123 rnExpr (HsLit lit@(HsString s))
125 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
126 ; if opt_OverloadedStrings then
127 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
128 else -- Same as below
130 returnM (HsLit lit, emptyFVs)
135 returnM (HsLit lit, emptyFVs)
137 rnExpr (HsOverLit lit)
138 = rnOverLit lit `thenM` \ (lit', fvs) ->
139 returnM (HsOverLit lit', fvs)
141 rnExpr (HsApp fun arg)
142 = rnLExpr fun `thenM` \ (fun',fvFun) ->
143 rnLExpr arg `thenM` \ (arg',fvArg) ->
144 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
146 rnExpr (OpApp e1 op _ e2)
147 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
148 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
149 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
152 -- When renaming code synthesised from "deriving" declarations
153 -- we used to avoid fixity stuff, but we can't easily tell any
154 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
155 -- should prevent bad things happening.
156 lookupFixityRn op_name `thenM` \ fixity ->
157 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
160 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
163 = rnLExpr e `thenM` \ (e', fv_e) ->
164 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
165 mkNegAppRn e' neg_name `thenM` \ final_e ->
166 returnM (final_e, fv_e `plusFV` fv_neg)
169 = rnLExpr e `thenM` \ (e', fvs_e) ->
170 returnM (HsPar e', fvs_e)
172 -- Template Haskell extensions
173 -- Don't ifdef-GHCI them because we want to fail gracefully
174 -- (not with an rnExpr crash) in a stage-1 compiler.
175 rnExpr e@(HsBracket br_body)
176 = checkTH e "bracket" `thenM_`
177 rnBracket br_body `thenM` \ (body', fvs_e) ->
178 returnM (HsBracket body', fvs_e)
180 rnExpr (HsSpliceE splice)
181 = rnSplice splice `thenM` \ (splice', fvs) ->
182 returnM (HsSpliceE splice', fvs)
185 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
187 rnExpr (HsQuasiQuoteE qq)
188 = rnQuasiQuote qq `thenM` \ (qq', fvs_qq) ->
189 runQuasiQuoteExpr qq' `thenM` \ (L _ expr') ->
190 rnExpr expr' `thenM` \ (expr'', fvs_expr) ->
191 returnM (expr'', fvs_qq `plusFV` fvs_expr)
194 rnExpr section@(SectionL expr op)
195 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
196 rnLExpr op `thenM` \ (op', fvs_op) ->
197 checkSectionPrec InfixL section op' expr' `thenM_`
198 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
200 rnExpr section@(SectionR op expr)
201 = rnLExpr op `thenM` \ (op', fvs_op) ->
202 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
203 checkSectionPrec InfixR section op' expr' `thenM_`
204 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
206 rnExpr (HsCoreAnn ann expr)
207 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
208 returnM (HsCoreAnn ann expr', fvs_expr)
210 rnExpr (HsSCC lbl expr)
211 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
212 returnM (HsSCC lbl expr', fvs_expr)
213 rnExpr (HsTickPragma info expr)
214 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
215 returnM (HsTickPragma info expr', fvs_expr)
217 rnExpr (HsLam matches)
218 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
219 returnM (HsLam matches', fvMatch)
221 rnExpr (HsCase expr matches)
222 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
223 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
224 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
226 rnExpr (HsLet binds expr)
227 = rnLocalBindsAndThen binds $ \ binds' ->
228 rnLExpr expr `thenM` \ (expr',fvExpr) ->
229 returnM (HsLet binds' expr', fvExpr)
231 rnExpr (HsDo do_or_lc stmts body _)
232 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
234 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
236 rnExpr (ExplicitList _ exps)
237 = rnExprs exps `thenM` \ (exps', fvs) ->
238 returnM (ExplicitList placeHolderType exps', fvs)
240 rnExpr (ExplicitPArr _ exps)
241 = rnExprs exps `thenM` \ (exps', fvs) ->
242 returnM (ExplicitPArr placeHolderType exps', fvs)
244 rnExpr (ExplicitTuple exps boxity)
245 = checkTupSize (length exps) `thenM_`
246 rnExprs exps `thenM` \ (exps', fvs) ->
247 returnM (ExplicitTuple exps' boxity, fvs)
249 rnExpr (RecordCon con_id _ rbinds)
250 = do { conname <- lookupLocatedOccRn con_id
251 ; (rbinds', fvRbinds) <- rnHsRecFields_Con conname rnLExpr rbinds
252 ; return (RecordCon conname noPostTcExpr rbinds',
253 fvRbinds `addOneFV` unLoc conname) }
255 rnExpr (RecordUpd expr rbinds _ _ _)
256 = do { (expr', fvExpr) <- rnLExpr expr
257 ; (rbinds', fvRbinds) <- rnHsRecFields_Update rnLExpr rbinds
258 ; return (RecordUpd expr' rbinds' [] [] [],
259 fvExpr `plusFV` fvRbinds) }
261 rnExpr (ExprWithTySig expr pty)
262 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
263 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
265 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
267 doc = text "In an expression type signature"
269 rnExpr (HsIf p b1 b2)
270 = rnLExpr p `thenM` \ (p', fvP) ->
271 rnLExpr b1 `thenM` \ (b1', fvB1) ->
272 rnLExpr b2 `thenM` \ (b2', fvB2) ->
273 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
276 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
277 returnM (HsType t, fvT)
279 doc = text "In a type argument"
281 rnExpr (ArithSeq _ seq)
282 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
283 returnM (ArithSeq noPostTcExpr new_seq, fvs)
285 rnExpr (PArrSeq _ seq)
286 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
287 returnM (PArrSeq noPostTcExpr new_seq, fvs)
290 These three are pattern syntax appearing in expressions.
291 Since all the symbols are reservedops we can simply reject them.
292 We return a (bogus) EWildPat in each case.
295 rnExpr e@EWildPat = patSynErr e
296 rnExpr e@(EAsPat {}) = patSynErr e
297 rnExpr e@(EViewPat {}) = patSynErr e
298 rnExpr e@(ELazyPat {}) = patSynErr e
301 %************************************************************************
305 %************************************************************************
308 rnExpr (HsProc pat body)
310 rnPatsAndThen_LocalRightwards ProcExpr [pat] $ \ [pat'] ->
311 rnCmdTop body `thenM` \ (body',fvBody) ->
312 returnM (HsProc pat' body', fvBody)
314 rnExpr (HsArrApp arrow arg _ ho rtl)
315 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
316 rnLExpr arg `thenM` \ (arg',fvArg) ->
317 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
318 fvArrow `plusFV` fvArg)
320 select_arrow_scope tc = case ho of
321 HsHigherOrderApp -> tc
322 HsFirstOrderApp -> escapeArrowScope tc
325 rnExpr (HsArrForm op (Just _) [arg1, arg2])
326 = escapeArrowScope (rnLExpr op)
327 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
328 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
329 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
333 lookupFixityRn op_name `thenM` \ fixity ->
334 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
337 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
339 rnExpr (HsArrForm op fixity cmds)
340 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
341 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
342 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
344 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
349 %************************************************************************
353 %************************************************************************
356 rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars)
357 rnCmdArgs [] = returnM ([], emptyFVs)
359 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
360 rnCmdArgs args `thenM` \ (args',fvArgs) ->
361 returnM (arg':args', fvArg `plusFV` fvArgs)
363 rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars)
364 rnCmdTop = wrapLocFstM rnCmdTop'
366 rnCmdTop' (HsCmdTop cmd _ _ _)
367 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
369 cmd_names = [arrAName, composeAName, firstAName] ++
370 nameSetToList (methodNamesCmd (unLoc cmd'))
372 -- Generate the rebindable syntax for the monad
373 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
375 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
376 fvCmd `plusFV` cmd_fvs)
378 ---------------------------------------------------
379 -- convert OpApp's in a command context to HsArrForm's
381 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
382 convertOpFormsLCmd = fmap convertOpFormsCmd
384 convertOpFormsCmd :: HsCmd id -> HsCmd id
386 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
387 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
388 convertOpFormsCmd (OpApp c1 op fixity c2)
390 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
391 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
393 HsArrForm op (Just fixity) [arg1, arg2]
395 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
397 convertOpFormsCmd (HsCase exp matches)
398 = HsCase exp (convertOpFormsMatch matches)
400 convertOpFormsCmd (HsIf exp c1 c2)
401 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
403 convertOpFormsCmd (HsLet binds cmd)
404 = HsLet binds (convertOpFormsLCmd cmd)
406 convertOpFormsCmd (HsDo ctxt stmts body ty)
407 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
408 (convertOpFormsLCmd body) ty
410 -- Anything else is unchanged. This includes HsArrForm (already done),
411 -- things with no sub-commands, and illegal commands (which will be
412 -- caught by the type checker)
413 convertOpFormsCmd c = c
415 convertOpFormsStmt :: StmtLR id id -> StmtLR id id
416 convertOpFormsStmt (BindStmt pat cmd _ _)
417 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
418 convertOpFormsStmt (ExprStmt cmd _ _)
419 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
420 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
421 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
422 convertOpFormsStmt stmt = stmt
424 convertOpFormsMatch :: MatchGroup id -> MatchGroup id
425 convertOpFormsMatch (MatchGroup ms ty)
426 = MatchGroup (map (fmap convert) ms) ty
427 where convert (Match pat mty grhss)
428 = Match pat mty (convertOpFormsGRHSs grhss)
430 convertOpFormsGRHSs :: GRHSs id -> GRHSs id
431 convertOpFormsGRHSs (GRHSs grhss binds)
432 = GRHSs (map convertOpFormsGRHS grhss) binds
434 convertOpFormsGRHS :: Located (GRHS id) -> Located (GRHS id)
435 convertOpFormsGRHS = fmap convert
437 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
439 ---------------------------------------------------
440 type CmdNeeds = FreeVars -- Only inhabitants are
441 -- appAName, choiceAName, loopAName
443 -- find what methods the Cmd needs (loop, choice, apply)
444 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
445 methodNamesLCmd = methodNamesCmd . unLoc
447 methodNamesCmd :: HsCmd Name -> CmdNeeds
449 methodNamesCmd (HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
451 methodNamesCmd (HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
453 methodNamesCmd (HsArrForm {}) = emptyFVs
455 methodNamesCmd (HsPar c) = methodNamesLCmd c
457 methodNamesCmd (HsIf _ c1 c2)
458 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
460 methodNamesCmd (HsLet _ c) = methodNamesLCmd c
462 methodNamesCmd (HsDo _ stmts body _)
463 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
465 methodNamesCmd (HsApp c _) = methodNamesLCmd c
467 methodNamesCmd (HsLam match) = methodNamesMatch match
469 methodNamesCmd (HsCase _ matches)
470 = methodNamesMatch matches `addOneFV` choiceAName
472 methodNamesCmd _ = emptyFVs
473 -- Other forms can't occur in commands, but it's not convenient
474 -- to error here so we just do what's convenient.
475 -- The type checker will complain later
477 ---------------------------------------------------
478 methodNamesMatch :: MatchGroup Name -> FreeVars
479 methodNamesMatch (MatchGroup ms _)
480 = plusFVs (map do_one ms)
482 do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
484 -------------------------------------------------
486 methodNamesGRHSs :: GRHSs Name -> FreeVars
487 methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
489 -------------------------------------------------
491 methodNamesGRHS :: Located (GRHS Name) -> CmdNeeds
492 methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
494 ---------------------------------------------------
495 methodNamesStmts :: [Located (StmtLR Name Name)] -> FreeVars
496 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
498 ---------------------------------------------------
499 methodNamesLStmt :: Located (StmtLR Name Name) -> FreeVars
500 methodNamesLStmt = methodNamesStmt . unLoc
502 methodNamesStmt :: StmtLR Name Name -> FreeVars
503 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
504 methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
505 methodNamesStmt (RecStmt stmts _ _ _ _)
506 = methodNamesStmts stmts `addOneFV` loopAName
507 methodNamesStmt (LetStmt _) = emptyFVs
508 methodNamesStmt (ParStmt _) = emptyFVs
509 methodNamesStmt (TransformStmt _ _ _) = emptyFVs
510 methodNamesStmt (GroupStmt _ _) = emptyFVs
511 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
512 -- here so we just do what's convenient
516 %************************************************************************
520 %************************************************************************
523 rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
524 rnArithSeq (From expr)
525 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
526 returnM (From expr', fvExpr)
528 rnArithSeq (FromThen expr1 expr2)
529 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
530 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
531 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
533 rnArithSeq (FromTo expr1 expr2)
534 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
535 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
536 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
538 rnArithSeq (FromThenTo expr1 expr2 expr3)
539 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
540 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
541 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
542 returnM (FromThenTo expr1' expr2' expr3',
543 plusFVs [fvExpr1, fvExpr2, fvExpr3])
546 %************************************************************************
548 Template Haskell brackets
550 %************************************************************************
553 rnBracket :: HsBracket RdrName -> RnM (HsBracket Name, FreeVars)
554 rnBracket (VarBr n) = do { name <- lookupOccRn n
555 ; this_mod <- getModule
556 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
557 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
558 ; return () } -- only way that is going to happen
559 ; returnM (VarBr name, unitFV name) }
561 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
563 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
564 ; return (ExpBr e', fvs) }
566 rnBracket (PatBr _) = do { addErr (ptext (sLit "Tempate Haskell pattern brackets are not supported yet"));
569 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
570 ; return (TypBr t', fvs) }
572 doc = ptext (sLit "In a Template-Haskell quoted type")
573 rnBracket (DecBr group)
574 = do { gbl_env <- getGblEnv
576 ; let new_gbl_env = gbl_env { -- Set the module to thFAKE. The top-level names from the bracketed
577 -- declarations will go into the name cache, and we don't want them to
578 -- confuse the Names for the current module.
579 -- By using a pretend module, thFAKE, we keep them safely out of the way.
582 -- The emptyDUs is so that we just collect uses for this group alone
583 -- in the call to rnSrcDecls below
585 ; setGblEnv new_gbl_env $ do {
587 -- In this situation we want to *shadow* top-level bindings.
589 -- bar = [d| foo = 1 |]
590 -- If we don't shadow, we'll get an ambiguity complaint when we do
591 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
593 -- Furthermore, arguably if the splice does define foo, that should hide
594 -- any foo's further out
596 -- The shadowing is acheived by calling rnSrcDecls with True as the shadowing flag
597 ; (tcg_env, group') <- rnSrcDecls True group
599 -- Discard the tcg_env; it contains only extra info about fixity
600 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
603 %************************************************************************
605 \subsubsection{@Stmt@s: in @do@ expressions}
607 %************************************************************************
610 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
611 -> RnM (thing, FreeVars)
612 -> RnM (([LStmt Name], thing), FreeVars)
614 rnStmts (MDoExpr _) = rnMDoStmts
615 rnStmts ctxt = rnNormalStmts ctxt
617 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
618 -> RnM (thing, FreeVars)
619 -> RnM (([LStmt Name], thing), FreeVars)
620 -- Used for cases *other* than recursive mdo
621 -- Implements nested scopes
623 rnNormalStmts _ [] thing_inside
624 = do { (thing, fvs) <- thing_inside
625 ; return (([],thing), fvs) }
627 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
628 = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $
629 rnNormalStmts ctxt stmts thing_inside
630 ; return (((L loc stmt' : stmts'), thing), fvs) }
633 rnStmt :: HsStmtContext Name -> Stmt RdrName
634 -> RnM (thing, FreeVars)
635 -> RnM ((Stmt Name, thing), FreeVars)
637 rnStmt _ (ExprStmt expr _ _) thing_inside
638 = do { (expr', fv_expr) <- rnLExpr expr
639 ; (then_op, fvs1) <- lookupSyntaxName thenMName
640 ; (thing, fvs2) <- thing_inside
641 ; return ((ExprStmt expr' then_op placeHolderType, thing),
642 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
644 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
645 = do { (expr', fv_expr) <- rnLExpr expr
646 -- The binders do not scope over the expression
647 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
648 ; (fail_op, fvs2) <- lookupSyntaxName failMName
649 ; rnPatsAndThen_LocalRightwards (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
650 { (thing, fvs3) <- thing_inside
651 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
652 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
653 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
654 -- but it does not matter because the names are unique
656 rnStmt ctxt (LetStmt binds) thing_inside
657 = do { checkLetStmt ctxt binds
658 ; rnLocalBindsAndThen binds $ \binds' -> do
659 { (thing, fvs) <- thing_inside
660 ; return ((LetStmt binds', thing), fvs) } }
662 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
663 = do { checkRecStmt ctxt
664 ; rn_rec_stmts_and_then rec_stmts $ \ segs -> do
665 { (thing, fvs) <- thing_inside
667 segs_w_fwd_refs = addFwdRefs segs
668 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
669 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
670 fwd_vars = nameSetToList (plusFVs fs)
672 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
673 ; return ((rec_stmt, thing), uses `plusFV` fvs) } }
675 rnStmt ctxt (ParStmt segs) thing_inside
676 = do { checkParStmt ctxt
677 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
678 ; return ((ParStmt segs', thing), fvs) }
680 rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do
681 checkTransformStmt ctxt
683 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
684 ((stmts', binders, (maybeByExpr', thing)), fvs) <-
685 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \_unshadowed_bndrs -> do
686 (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr
687 (thing, fv_thing) <- thing_inside
689 return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing)
691 return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs)
693 rnMaybeLExpr Nothing = return (Nothing, emptyFVs)
694 rnMaybeLExpr (Just expr) = do
695 (expr', fv_expr) <- rnLExpr expr
696 return (Just expr', fv_expr)
698 rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do
699 checkTransformStmt ctxt
701 -- We must rename the using expression in the context before the transform is begun
702 groupByClauseAction <-
703 case groupByClause of
704 GroupByNothing usingExpr -> do
705 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
706 (return . return) (GroupByNothing usingExpr', fv_usingExpr)
707 GroupBySomething eitherUsingExpr byExpr -> do
708 (eitherUsingExpr', fv_eitherUsingExpr) <-
709 case eitherUsingExpr of
710 Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName)
712 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
713 return (Left usingExpr', fv_usingExpr)
716 (byExpr', fv_byExpr) <- rnLExpr byExpr
717 return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr)
719 -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so
720 -- perhaps we could refactor this to use rnNormalStmts directly?
721 ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <-
722 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
723 (groupByClause', fv_groupByClause) <- groupByClauseAction
725 unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs
726 let binderMap = zip unshadowed_bndrs unshadowed_bndrs'
728 -- Bind the "thing" inside a context where we have REBOUND everything
729 -- bound by the statements before the group. This is necessary since after
730 -- the grouping the same identifiers actually have different meanings
731 -- i.e. they refer to lists not singletons!
732 (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside
734 -- We remove entries from the binder map that are not used in the thing_inside.
735 -- We can then use that usage information to ensure that the free variables do
736 -- not contain the things we just bound, but do contain the things we need to
737 -- make those bindings (i.e. the corresponding non-listy variables)
739 -- Note that we also retain those entries which have an old binder in our
740 -- own free variables (the using or by expression). This is because this map
741 -- is reused in the desugarer to create the type to bind from the statements
742 -- that occur before this one. If the binders we need are not in the map, they
743 -- will never get bound into our desugared expression and hence the simplifier
744 -- crashes as we refer to variables that don't exist!
745 let usedBinderMap = filter
746 (\(old_binder, new_binder) ->
747 (new_binder `elemNameSet` fv_thing) ||
748 (old_binder `elemNameSet` fv_groupByClause)) binderMap
749 (usedOldBinders, usedNewBinders) = unzip usedBinderMap
750 real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders)
752 return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing)
754 traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap)
755 return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs)
757 rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name
759 -> ([Name] -> RnM (thing, FreeVars))
760 -> RnM (([LStmt Name], [Name], thing), FreeVars)
761 rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do
762 ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do
763 -- Find the Names that are bound by stmts that
764 -- by assumption we have just renamed
765 local_env <- getLocalRdrEnv
767 stmts_binders = collectLStmtsBinders stmts
768 bndrs = map (expectJust "rnStmt"
769 . lookupLocalRdrEnv local_env
770 . unLoc) stmts_binders
772 -- If shadow, we'll look up (Unqual x) twice, getting
773 -- the second binding both times, which is the
775 unshadowed_bndrs = nub bndrs
777 -- Typecheck the thing inside, passing on all
778 -- the Names bound before it for its information
779 (thing, fvs) <- thing_inside unshadowed_bndrs
781 -- Figure out which of the bound names are used
782 -- after the statements we renamed
783 let used_bndrs = filter (`elemNameSet` fvs) bndrs
784 return ((used_bndrs, thing), fvs)
786 -- Flatten the tuple returned by the above call a bit!
787 return ((stmts', used_bndrs, inner_thing), fvs)
789 rnParallelStmts :: HsStmtContext Name -> [([LStmt RdrName], [RdrName])]
790 -> RnM (thing, FreeVars)
791 -> RnM (([([LStmt Name], [Name])], thing), FreeVars)
792 rnParallelStmts ctxt segs thing_inside = do
793 orig_lcl_env <- getLocalRdrEnv
794 go orig_lcl_env [] segs
796 go orig_lcl_env bndrs [] = do
797 let (bndrs', dups) = removeDups cmpByOcc bndrs
798 inner_env = extendLocalRdrEnv orig_lcl_env bndrs'
801 (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
802 return (([], thing), fvs)
804 go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do
805 ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do
806 -- Typecheck the thing inside, passing on all
807 -- the Names bound, but separately; revert the envt
808 setLocalRdrEnv orig_lcl_env $ do
809 go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs
811 let seg' = (stmts', bndrs)
812 return (((seg':segs'), thing), delListFromNameSet fvs bndrs)
814 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
815 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
816 <+> quotes (ppr (head vs)))
820 %************************************************************************
822 \subsubsection{mdo expressions}
824 %************************************************************************
827 type FwdRefs = NameSet
828 type Segment stmts = (Defs,
829 Uses, -- May include defs
830 FwdRefs, -- A subset of uses that are
831 -- (a) used before they are bound in this segment, or
832 -- (b) used here, and bound in subsequent segments
833 stmts) -- Either Stmt or [Stmt]
836 ----------------------------------------------------
838 rnMDoStmts :: [LStmt RdrName]
839 -> RnM (thing, FreeVars)
840 -> RnM (([LStmt Name], thing), FreeVars)
841 rnMDoStmts stmts thing_inside
842 = -- Step1: Bring all the binders of the mdo into scope
843 -- (Remember that this also removes the binders from the
844 -- finally-returned free-vars.)
845 -- And rename each individual stmt, making a
846 -- singleton segment. At this stage the FwdRefs field
847 -- isn't finished: it's empty for all except a BindStmt
848 -- for which it's the fwd refs within the bind itself
849 -- (This set may not be empty, because we're in a recursive
851 rn_rec_stmts_and_then stmts $ \ segs -> do {
853 ; (thing, fvs_later) <- thing_inside
856 -- Step 2: Fill in the fwd refs.
857 -- The segments are all singletons, but their fwd-ref
858 -- field mentions all the things used by the segment
859 -- that are bound after their use
860 segs_w_fwd_refs = addFwdRefs segs
862 -- Step 3: Group together the segments to make bigger segments
863 -- Invariant: in the result, no segment uses a variable
864 -- bound in a later segment
865 grouped_segs = glomSegments segs_w_fwd_refs
867 -- Step 4: Turn the segments into Stmts
868 -- Use RecStmt when and only when there are fwd refs
869 -- Also gather up the uses from the end towards the
870 -- start, so we can tell the RecStmt which things are
871 -- used 'after' the RecStmt
872 (stmts', fvs) = segsToStmts grouped_segs fvs_later
874 ; return ((stmts', thing), fvs) }
876 ---------------------------------------------
878 -- wrapper that does both the left- and right-hand sides
879 rn_rec_stmts_and_then :: [LStmt RdrName]
880 -- assumes that the FreeVars returned includes
881 -- the FreeVars of the Segments
882 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
884 rn_rec_stmts_and_then s cont
885 = do { -- (A) Make the mini fixity env for all of the stmts
886 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
889 ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
891 -- ...bring them and their fixities into scope
892 ; let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
893 ; bindLocalNamesFV_WithFixities bound_names fix_env $ do
895 -- (C) do the right-hand-sides and thing-inside
896 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
897 ; (res, fvs) <- cont segs
898 ; warnUnusedLocalBinds bound_names fvs
899 ; return (res, fvs) }}
901 -- get all the fixity decls in any Let stmt
902 collectRecStmtsFixities :: [LStmtLR RdrName RdrName] -> [LFixitySig RdrName]
903 collectRecStmtsFixities l =
904 foldr (\ s -> \acc -> case s of
905 (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
906 foldr (\ sig -> \ acc -> case sig of
907 (L loc (FixSig s)) -> (L loc s) : acc
913 rn_rec_stmt_lhs :: MiniFixityEnv
915 -- rename LHS, and return its FVs
916 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
917 -- so we don't bother to compute it accurately in the other cases
918 -> RnM [(LStmtLR Name RdrName, FreeVars)]
920 rn_rec_stmt_lhs _ (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
921 -- this is actually correct
924 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
926 -- should the ctxt be MDo instead?
927 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
928 return [(L loc (BindStmt pat' expr a b),
931 rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _)))
932 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
935 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
936 = do binds' <- rnValBindsLHS fix_env binds
937 return [(L loc (LetStmt (HsValBinds binds')),
938 -- Warning: this is bogus; see function invariant
942 rn_rec_stmt_lhs fix_env (L _ (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
943 = rn_rec_stmts_lhs fix_env stmts
945 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
946 = pprPanic "rn_rec_stmt" (ppr stmt)
948 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo
949 = pprPanic "rn_rec_stmt" (ppr stmt)
951 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo
952 = pprPanic "rn_rec_stmt" (ppr stmt)
954 rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
955 = panic "rn_rec_stmt LetStmt EmptyLocalBinds"
957 rn_rec_stmts_lhs :: MiniFixityEnv
959 -> RnM [(LStmtLR Name RdrName, FreeVars)]
960 rn_rec_stmts_lhs fix_env stmts =
961 let boundNames = collectLStmtsBinders stmts
962 doc = text "In a recursive mdo-expression"
964 -- First do error checking: we need to check for dups here because we
965 -- don't bind all of the variables from the Stmt at once
966 -- with bindLocatedLocals.
967 checkDupRdrNames doc boundNames
968 mappM (rn_rec_stmt_lhs fix_env) stmts `thenM` \ ls -> returnM (concat ls)
973 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
974 -- Rename a Stmt that is inside a RecStmt (or mdo)
975 -- Assumes all binders are already in scope
976 -- Turns each stmt into a singleton Stmt
977 rn_rec_stmt _ (L loc (ExprStmt expr _ _)) _
978 = rnLExpr expr `thenM` \ (expr', fvs) ->
979 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
980 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
981 L loc (ExprStmt expr' then_op placeHolderType))]
983 rn_rec_stmt _ (L loc (BindStmt pat' expr _ _)) fv_pat
984 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
985 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
986 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
988 bndrs = mkNameSet (collectPatBinders pat')
989 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
991 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
992 L loc (BindStmt pat' expr' bind_op fail_op))]
994 rn_rec_stmt _ (L _ (LetStmt binds@(HsIPBinds _))) _
995 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
998 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
999 (binds', du_binds) <-
1000 -- fixities and unused are handled above in rn_rec_stmts_and_then
1001 rnValBindsRHS all_bndrs binds'
1002 returnM [(duDefs du_binds, duUses du_binds,
1003 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1005 -- no RecStmt case becuase they get flattened above when doing the LHSes
1006 rn_rec_stmt _ stmt@(L _ (RecStmt _ _ _ _ _)) _
1007 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1009 rn_rec_stmt _ stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo
1010 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1012 rn_rec_stmt _ stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo
1013 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1015 rn_rec_stmt _ stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo
1016 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1018 rn_rec_stmt _ (L _ (LetStmt EmptyLocalBinds)) _
1019 = panic "rn_rec_stmt: LetStmt EmptyLocalBinds"
1021 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1022 rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1023 returnM (concat segs_s)
1025 ---------------------------------------------
1026 addFwdRefs :: [Segment a] -> [Segment a]
1027 -- So far the segments only have forward refs *within* the Stmt
1028 -- (which happens for bind: x <- ...x...)
1029 -- This function adds the cross-seg fwd ref info
1032 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1034 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1035 = (new_seg : segs, all_defs)
1037 new_seg = (defs, uses, new_fwds, stmts)
1038 all_defs = later_defs `unionNameSets` defs
1039 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1040 -- Add the downstream fwd refs here
1042 ----------------------------------------------------
1043 -- Glomming the singleton segments of an mdo into
1044 -- minimal recursive groups.
1046 -- At first I thought this was just strongly connected components, but
1047 -- there's an important constraint: the order of the stmts must not change.
1050 -- mdo { x <- ...y...
1057 -- Here, the first stmt mention 'y', which is bound in the third.
1058 -- But that means that the innocent second stmt (p <- z) gets caught
1059 -- up in the recursion. And that in turn means that the binding for
1060 -- 'z' has to be included... and so on.
1062 -- Start at the tail { r <- x }
1063 -- Now add the next one { z <- y ; r <- x }
1064 -- Now add one more { q <- x ; z <- y ; r <- x }
1065 -- Now one more... but this time we have to group a bunch into rec
1066 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1067 -- Now one more, which we can add on without a rec
1069 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1071 -- Finally we add the last one; since it mentions y we have to
1072 -- glom it togeher with the first two groups
1073 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1074 -- q <- x ; z <- y } ;
1077 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1079 glomSegments [] = []
1080 glomSegments ((defs,uses,fwds,stmt) : segs)
1081 -- Actually stmts will always be a singleton
1082 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1084 segs' = glomSegments segs
1085 (extras, others) = grab uses segs'
1086 (ds, us, fs, ss) = unzip4 extras
1088 seg_defs = plusFVs ds `plusFV` defs
1089 seg_uses = plusFVs us `plusFV` uses
1090 seg_fwds = plusFVs fs `plusFV` fwds
1091 seg_stmts = stmt : concat ss
1093 grab :: NameSet -- The client
1095 -> ([Segment a], -- Needed by the 'client'
1096 [Segment a]) -- Not needed by the client
1097 -- The result is simply a split of the input
1099 = (reverse yeses, reverse noes)
1101 (noes, yeses) = span not_needed (reverse dus)
1102 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1105 ----------------------------------------------------
1106 segsToStmts :: [Segment [LStmt Name]]
1107 -> FreeVars -- Free vars used 'later'
1108 -> ([LStmt Name], FreeVars)
1110 segsToStmts [] fvs_later = ([], fvs_later)
1111 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
1112 = ASSERT( not (null ss) )
1113 (new_stmt : later_stmts, later_uses `plusFV` uses)
1115 (later_stmts, later_uses) = segsToStmts segs fvs_later
1116 new_stmt | non_rec = head ss
1117 | otherwise = L (getLoc (head ss)) $
1118 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
1121 non_rec = isSingleton ss && isEmptyNameSet fwds
1122 used_later = defs `intersectNameSet` later_uses
1123 -- The ones needed after the RecStmt
1126 %************************************************************************
1128 \subsubsection{Assertion utils}
1130 %************************************************************************
1133 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1134 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
1136 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
1137 -- Return an expression for (assertError "Foo.hs:27")
1139 = getSrcSpanM `thenM` \ sloc ->
1141 expr = HsApp (L sloc (HsVar assertErrorName))
1142 (L sloc (srcSpanPrimLit sloc))
1144 returnM (expr, emptyFVs)
1147 %************************************************************************
1149 \subsubsection{Errors}
1151 %************************************************************************
1155 ----------------------
1156 -- Checking when a particular Stmt is ok
1157 checkLetStmt :: HsStmtContext Name -> HsLocalBinds RdrName -> RnM ()
1158 checkLetStmt (ParStmtCtxt _) (HsIPBinds binds) = addErr (badIpBinds (ptext (sLit "a parallel list comprehension:")) binds)
1159 checkLetStmt _ctxt _binds = return ()
1160 -- We do not allow implicit-parameter bindings in a parallel
1161 -- list comprehension. I'm not sure what it might mean.
1164 checkRecStmt :: HsStmtContext Name -> RnM ()
1165 checkRecStmt (MDoExpr {}) = return () -- Recursive stmt ok in 'mdo'
1166 checkRecStmt (DoExpr {}) = return () -- ..and in 'do' but only because of arrows:
1167 -- proc x -> do { ...rec... }
1168 -- We don't have enough context to distinguish this situation here
1169 -- so we leave it to the type checker
1170 checkRecStmt ctxt = addErr msg
1172 msg = ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt
1175 checkParStmt :: HsStmtContext Name -> RnM ()
1177 = do { parallel_list_comp <- doptM Opt_ParallelListComp
1178 ; checkErr parallel_list_comp msg }
1180 msg = ptext (sLit "Illegal parallel list comprehension: use -XParallelListComp")
1183 checkTransformStmt :: HsStmtContext Name -> RnM ()
1184 checkTransformStmt ListComp -- Ensure we are really within a list comprehension because otherwise the
1185 -- desugarer will break when we come to operate on a parallel array
1186 = do { transform_list_comp <- doptM Opt_TransformListComp
1187 ; checkErr transform_list_comp msg }
1189 msg = ptext (sLit "Illegal transform or grouping list comprehension: use -XTransformListComp")
1190 checkTransformStmt (ParStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1191 checkTransformStmt (TransformStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1192 checkTransformStmt ctxt = addErr msg
1194 msg = ptext (sLit "Illegal transform or grouping in") <+> pprStmtContext ctxt
1197 patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
1198 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1200 ; return (EWildPat, emptyFVs) }
1202 badIpBinds :: Outputable a => SDoc -> a -> SDoc
1203 badIpBinds what binds
1204 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)