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, findSplice )
24 import RnBinds ( rnLocalBindsAndThen, rnLocalValBindsLHS, rnLocalValBindsRHS,
25 rnMatchGroup, makeMiniFixityEnv)
28 import TcEnv ( thRnBrack )
30 import RnTypes ( rnHsTypeFVs, rnSplice, checkTH,
31 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec)
34 import BasicTypes ( FixityDirection(..) )
40 import LoadIface ( loadInterfaceForName )
43 import Util ( isSingleton, snocView )
44 import ListSetOps ( removeDups )
54 thenM :: Monad a => a b -> (b -> a c) -> a c
57 thenM_ :: Monad a => a b -> a c -> a c
61 %************************************************************************
63 \subsubsection{Expressions}
65 %************************************************************************
68 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
69 rnExprs ls = rnExprs' ls emptyUniqSet
71 rnExprs' [] acc = return ([], acc)
72 rnExprs' (expr:exprs) acc
73 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
75 -- Now we do a "seq" on the free vars because typically it's small
76 -- or empty, especially in very long lists of constants
78 acc' = acc `plusFV` fvExpr
80 acc' `seq` rnExprs' exprs acc' `thenM` \ (exprs', fvExprs) ->
81 return (expr':exprs', fvExprs)
84 Variables. We look up the variable and return the resulting name.
87 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
88 rnLExpr = wrapLocFstM rnExpr
90 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
92 finishHsVar :: Name -> RnM (HsExpr Name, FreeVars)
93 -- Separated from rnExpr because it's also used
94 -- when renaming infix expressions
95 -- See Note [Adding the implicit parameter to 'assert']
97 = do { ignore_asserts <- doptM Opt_IgnoreAsserts
98 ; if ignore_asserts || not (name `hasKey` assertIdKey)
99 then return (HsVar name, unitFV name)
100 else do { e <- mkAssertErrorExpr
101 ; return (e, unitFV name) } }
104 = do name <- lookupOccRn v
108 = newIPNameRn v `thenM` \ name ->
109 return (HsIPVar name, emptyFVs)
111 rnExpr (HsLit lit@(HsString s))
113 opt_OverloadedStrings <- xoptM Opt_OverloadedStrings
114 ; if opt_OverloadedStrings then
115 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
116 else -- Same as below
118 return (HsLit lit, emptyFVs)
123 return (HsLit lit, emptyFVs)
125 rnExpr (HsOverLit lit)
126 = rnOverLit lit `thenM` \ (lit', fvs) ->
127 return (HsOverLit lit', fvs)
129 rnExpr (HsApp fun arg)
130 = rnLExpr fun `thenM` \ (fun',fvFun) ->
131 rnLExpr arg `thenM` \ (arg',fvArg) ->
132 return (HsApp fun' arg', fvFun `plusFV` fvArg)
134 rnExpr (OpApp e1 (L op_loc (HsVar op_rdr)) _ e2)
135 = do { (e1', fv_e1) <- rnLExpr e1
136 ; (e2', fv_e2) <- rnLExpr e2
137 ; op_name <- setSrcSpan op_loc (lookupOccRn op_rdr)
138 ; (op', fv_op) <- finishHsVar op_name
139 -- NB: op' is usually just a variable, but might be
140 -- an applicatoin (assert "Foo.hs:47")
142 -- When renaming code synthesised from "deriving" declarations
143 -- we used to avoid fixity stuff, but we can't easily tell any
144 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
145 -- should prevent bad things happening.
146 ; fixity <- lookupFixityRn op_name
147 ; final_e <- mkOpAppRn e1' (L op_loc op') fixity e2'
148 ; return (final_e, fv_e1 `plusFV` fv_op `plusFV` fv_e2) }
149 rnExpr (OpApp _ other_op _ _)
150 = failWith (vcat [ hang (ptext (sLit "Operator application with a non-variable operator:"))
152 , ptext (sLit "(Probably resulting from a Template Haskell splice)") ])
155 = rnLExpr e `thenM` \ (e', fv_e) ->
156 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
157 mkNegAppRn e' neg_name `thenM` \ final_e ->
158 return (final_e, fv_e `plusFV` fv_neg)
160 ------------------------------------------
161 -- Template Haskell extensions
162 -- Don't ifdef-GHCI them because we want to fail gracefully
163 -- (not with an rnExpr crash) in a stage-1 compiler.
164 rnExpr e@(HsBracket br_body)
165 = checkTH e "bracket" `thenM_`
166 rnBracket br_body `thenM` \ (body', fvs_e) ->
167 return (HsBracket body', fvs_e)
169 rnExpr (HsSpliceE splice)
170 = rnSplice splice `thenM` \ (splice', fvs) ->
171 return (HsSpliceE splice', fvs)
174 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
176 rnExpr (HsQuasiQuoteE qq)
177 = runQuasiQuoteExpr qq `thenM` \ (L _ expr') ->
181 ---------------------------------------------
183 -- See Note [Parsing sections] in Parser.y.pp
184 rnExpr (HsPar (L loc (section@(SectionL {}))))
185 = do { (section', fvs) <- rnSection section
186 ; return (HsPar (L loc section'), fvs) }
188 rnExpr (HsPar (L loc (section@(SectionR {}))))
189 = do { (section', fvs) <- rnSection section
190 ; return (HsPar (L loc section'), fvs) }
193 = do { (e', fvs_e) <- rnLExpr e
194 ; return (HsPar e', fvs_e) }
196 rnExpr expr@(SectionL {})
197 = do { addErr (sectionErr expr); rnSection expr }
198 rnExpr expr@(SectionR {})
199 = do { addErr (sectionErr expr); rnSection expr }
201 ---------------------------------------------
202 rnExpr (HsCoreAnn ann expr)
203 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
204 return (HsCoreAnn ann expr', fvs_expr)
206 rnExpr (HsSCC lbl expr)
207 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
208 return (HsSCC lbl expr', fvs_expr)
209 rnExpr (HsTickPragma info expr)
210 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
211 return (HsTickPragma info expr', fvs_expr)
213 rnExpr (HsLam matches)
214 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
215 return (HsLam matches', fvMatch)
217 rnExpr (HsCase expr matches)
218 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
219 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
220 return (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
222 rnExpr (HsLet binds expr)
223 = rnLocalBindsAndThen binds $ \ binds' ->
224 rnLExpr expr `thenM` \ (expr',fvExpr) ->
225 return (HsLet binds' expr', fvExpr)
227 rnExpr (HsDo do_or_lc stmts _)
228 = do { ((stmts', _), fvs) <- rnStmts do_or_lc stmts (\ _ -> return ((), emptyFVs))
229 ; return ( HsDo do_or_lc stmts' placeHolderType, fvs ) }
231 rnExpr (ExplicitList _ exps)
232 = rnExprs exps `thenM` \ (exps', fvs) ->
233 return (ExplicitList placeHolderType exps', fvs)
235 rnExpr (ExplicitPArr _ exps)
236 = rnExprs exps `thenM` \ (exps', fvs) ->
237 return (ExplicitPArr placeHolderType exps', fvs)
239 rnExpr (ExplicitTuple tup_args boxity)
240 = do { checkTupleSection tup_args
241 ; checkTupSize (length tup_args)
242 ; (tup_args', fvs) <- mapAndUnzipM rnTupArg tup_args
243 ; return (ExplicitTuple tup_args' boxity, plusFVs fvs) }
245 rnTupArg (Present e) = do { (e',fvs) <- rnLExpr e; return (Present e', fvs) }
246 rnTupArg (Missing _) = return (Missing placeHolderType, emptyFVs)
248 rnExpr (RecordCon con_id _ rbinds)
249 = do { conname <- lookupLocatedOccRn con_id
250 ; (rbinds', fvRbinds) <- rnHsRecBinds (HsRecFieldCon (unLoc conname)) rbinds
251 ; return (RecordCon conname noPostTcExpr rbinds',
252 fvRbinds `addOneFV` unLoc conname) }
254 rnExpr (RecordUpd expr rbinds _ _ _)
255 = do { (expr', fvExpr) <- rnLExpr expr
256 ; (rbinds', fvRbinds) <- rnHsRecBinds HsRecFieldUpd rbinds
257 ; return (RecordUpd expr' rbinds' [] [] [],
258 fvExpr `plusFV` fvRbinds) }
260 rnExpr (ExprWithTySig expr pty)
261 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
262 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
264 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
266 doc = text "In an expression type signature"
268 rnExpr (HsIf _ p b1 b2)
269 = do { (p', fvP) <- rnLExpr p
270 ; (b1', fvB1) <- rnLExpr b1
271 ; (b2', fvB2) <- rnLExpr b2
272 ; (mb_ite, fvITE) <- lookupIfThenElse
273 ; return (HsIf mb_ite p' b1' b2', plusFVs [fvITE, fvP, fvB1, fvB2]) }
276 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
277 return (HsType t, fvT)
279 doc = text "In a type argument"
281 rnExpr (ArithSeq _ seq)
282 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
283 return (ArithSeq noPostTcExpr new_seq, fvs)
285 rnExpr (PArrSeq _ seq)
286 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
287 return (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 rnPat ProcExpr pat $ \ pat' ->
311 rnCmdTop body `thenM` \ (body',fvBody) ->
312 return (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 return (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',fv_op) ->
328 let L _ (HsVar op_name) = op' in
329 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
330 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
334 lookupFixityRn op_name `thenM` \ fixity ->
335 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
338 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
340 rnExpr (HsArrForm op fixity cmds)
341 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
342 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
343 return (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
345 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
348 ----------------------
349 -- See Note [Parsing sections] in Parser.y.pp
350 rnSection :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
351 rnSection section@(SectionR op expr)
352 = do { (op', fvs_op) <- rnLExpr op
353 ; (expr', fvs_expr) <- rnLExpr expr
354 ; checkSectionPrec InfixR section op' expr'
355 ; return (SectionR op' expr', fvs_op `plusFV` fvs_expr) }
357 rnSection section@(SectionL expr op)
358 = do { (expr', fvs_expr) <- rnLExpr expr
359 ; (op', fvs_op) <- rnLExpr op
360 ; checkSectionPrec InfixL section op' expr'
361 ; return (SectionL expr' op', fvs_op `plusFV` fvs_expr) }
363 rnSection other = pprPanic "rnSection" (ppr other)
366 %************************************************************************
370 %************************************************************************
373 rnHsRecBinds :: HsRecFieldContext -> HsRecordBinds RdrName
374 -> RnM (HsRecordBinds Name, FreeVars)
375 rnHsRecBinds ctxt rec_binds@(HsRecFields { rec_dotdot = dd })
376 = do { (flds, fvs) <- rnHsRecFields1 ctxt HsVar rec_binds
377 ; (flds', fvss) <- mapAndUnzipM rn_field flds
378 ; return (HsRecFields { rec_flds = flds', rec_dotdot = dd },
379 fvs `plusFV` plusFVs fvss) }
381 rn_field fld = do { (arg', fvs) <- rnLExpr (hsRecFieldArg fld)
382 ; return (fld { hsRecFieldArg = arg' }, fvs) }
386 %************************************************************************
390 %************************************************************************
393 rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars)
394 rnCmdArgs [] = return ([], emptyFVs)
396 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
397 rnCmdArgs args `thenM` \ (args',fvArgs) ->
398 return (arg':args', fvArg `plusFV` fvArgs)
400 rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars)
401 rnCmdTop = wrapLocFstM rnCmdTop'
403 rnCmdTop' (HsCmdTop cmd _ _ _)
404 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
406 cmd_names = [arrAName, composeAName, firstAName] ++
407 nameSetToList (methodNamesCmd (unLoc cmd'))
409 -- Generate the rebindable syntax for the monad
410 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
412 return (HsCmdTop cmd' [] placeHolderType cmd_names',
413 fvCmd `plusFV` cmd_fvs)
415 ---------------------------------------------------
416 -- convert OpApp's in a command context to HsArrForm's
418 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
419 convertOpFormsLCmd = fmap convertOpFormsCmd
421 convertOpFormsCmd :: HsCmd id -> HsCmd id
423 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
424 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
425 convertOpFormsCmd (OpApp c1 op fixity c2)
427 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
428 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
430 HsArrForm op (Just fixity) [arg1, arg2]
432 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
434 convertOpFormsCmd (HsCase exp matches)
435 = HsCase exp (convertOpFormsMatch matches)
437 convertOpFormsCmd (HsIf f exp c1 c2)
438 = HsIf f exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
440 convertOpFormsCmd (HsLet binds cmd)
441 = HsLet binds (convertOpFormsLCmd cmd)
443 convertOpFormsCmd (HsDo ctxt stmts ty)
444 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts) ty
446 -- Anything else is unchanged. This includes HsArrForm (already done),
447 -- things with no sub-commands, and illegal commands (which will be
448 -- caught by the type checker)
449 convertOpFormsCmd c = c
451 convertOpFormsStmt :: StmtLR id id -> StmtLR id id
452 convertOpFormsStmt (BindStmt pat cmd _ _)
453 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
454 convertOpFormsStmt (ExprStmt cmd _ _ _)
455 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr placeHolderType
456 convertOpFormsStmt stmt@(RecStmt { recS_stmts = stmts })
457 = stmt { recS_stmts = map (fmap convertOpFormsStmt) stmts }
458 convertOpFormsStmt stmt = stmt
460 convertOpFormsMatch :: MatchGroup id -> MatchGroup id
461 convertOpFormsMatch (MatchGroup ms ty)
462 = MatchGroup (map (fmap convert) ms) ty
463 where convert (Match pat mty grhss)
464 = Match pat mty (convertOpFormsGRHSs grhss)
466 convertOpFormsGRHSs :: GRHSs id -> GRHSs id
467 convertOpFormsGRHSs (GRHSs grhss binds)
468 = GRHSs (map convertOpFormsGRHS grhss) binds
470 convertOpFormsGRHS :: Located (GRHS id) -> Located (GRHS id)
471 convertOpFormsGRHS = fmap convert
473 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
475 ---------------------------------------------------
476 type CmdNeeds = FreeVars -- Only inhabitants are
477 -- appAName, choiceAName, loopAName
479 -- find what methods the Cmd needs (loop, choice, apply)
480 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
481 methodNamesLCmd = methodNamesCmd . unLoc
483 methodNamesCmd :: HsCmd Name -> CmdNeeds
485 methodNamesCmd (HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
487 methodNamesCmd (HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
489 methodNamesCmd (HsArrForm {}) = emptyFVs
491 methodNamesCmd (HsPar c) = methodNamesLCmd c
493 methodNamesCmd (HsIf _ _ c1 c2)
494 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
496 methodNamesCmd (HsLet _ c) = methodNamesLCmd c
497 methodNamesCmd (HsDo _ stmts _) = methodNamesStmts stmts
498 methodNamesCmd (HsApp c _) = methodNamesLCmd c
499 methodNamesCmd (HsLam match) = methodNamesMatch match
501 methodNamesCmd (HsCase _ matches)
502 = methodNamesMatch matches `addOneFV` choiceAName
504 methodNamesCmd _ = emptyFVs
505 -- Other forms can't occur in commands, but it's not convenient
506 -- to error here so we just do what's convenient.
507 -- The type checker will complain later
509 ---------------------------------------------------
510 methodNamesMatch :: MatchGroup Name -> FreeVars
511 methodNamesMatch (MatchGroup ms _)
512 = plusFVs (map do_one ms)
514 do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
516 -------------------------------------------------
518 methodNamesGRHSs :: GRHSs Name -> FreeVars
519 methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
521 -------------------------------------------------
523 methodNamesGRHS :: Located (GRHS Name) -> CmdNeeds
524 methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
526 ---------------------------------------------------
527 methodNamesStmts :: [Located (StmtLR Name Name)] -> FreeVars
528 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
530 ---------------------------------------------------
531 methodNamesLStmt :: Located (StmtLR Name Name) -> FreeVars
532 methodNamesLStmt = methodNamesStmt . unLoc
534 methodNamesStmt :: StmtLR Name Name -> FreeVars
535 methodNamesStmt (LastStmt cmd _) = methodNamesLCmd cmd
536 methodNamesStmt (ExprStmt cmd _ _ _) = methodNamesLCmd cmd
537 methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
538 methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName
539 methodNamesStmt (LetStmt _) = emptyFVs
540 methodNamesStmt (ParStmt _ _ _ _) = emptyFVs
541 methodNamesStmt (TransStmt {}) = emptyFVs
542 -- ParStmt and TransStmt can't occur in commands, but it's not convenient to error
543 -- here so we just do what's convenient
547 %************************************************************************
551 %************************************************************************
554 rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
555 rnArithSeq (From expr)
556 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
557 return (From expr', fvExpr)
559 rnArithSeq (FromThen expr1 expr2)
560 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
561 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
562 return (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
564 rnArithSeq (FromTo expr1 expr2)
565 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
566 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
567 return (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
569 rnArithSeq (FromThenTo expr1 expr2 expr3)
570 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
571 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
572 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
573 return (FromThenTo expr1' expr2' expr3',
574 plusFVs [fvExpr1, fvExpr2, fvExpr3])
577 %************************************************************************
579 Template Haskell brackets
581 %************************************************************************
584 rnBracket :: HsBracket RdrName -> RnM (HsBracket Name, FreeVars)
585 rnBracket (VarBr n) = do { name <- lookupOccRn n
586 ; this_mod <- getModule
587 ; unless (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
588 do { _ <- loadInterfaceForName msg name -- home interface is loaded, and this is the
589 ; return () } -- only way that is going to happen
590 ; return (VarBr name, unitFV name) }
592 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
594 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
595 ; return (ExpBr e', fvs) }
597 rnBracket (PatBr p) = rnPat ThPatQuote p $ \ p' -> return (PatBr p', emptyFVs)
599 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
600 ; return (TypBr t', fvs) }
602 doc = ptext (sLit "In a Template-Haskell quoted type")
604 rnBracket (DecBrL decls)
605 = do { (group, mb_splice) <- findSplice decls
608 Just (SpliceDecl (L loc _) _, _)
610 addErr (ptext (sLit "Declaration splices are not permitted inside declaration brackets"))
611 -- Why not? See Section 7.3 of the TH paper.
613 ; gbl_env <- getGblEnv
614 ; let new_gbl_env = gbl_env { tcg_dus = emptyDUs }
615 -- The emptyDUs is so that we just collect uses for this
616 -- group alone in the call to rnSrcDecls below
617 ; (tcg_env, group') <- setGblEnv new_gbl_env $
621 -- Discard the tcg_env; it contains only extra info about fixity
622 ; traceRn (text "rnBracket dec" <+> (ppr (tcg_dus tcg_env) $$ ppr (duUses (tcg_dus tcg_env))))
623 ; return (DecBrG group', duUses (tcg_dus tcg_env)) }
625 rnBracket (DecBrG _) = panic "rnBracket: unexpected DecBrG"
628 %************************************************************************
630 \subsubsection{@Stmt@s: in @do@ expressions}
632 %************************************************************************
635 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
636 -> ([Name] -> RnM (thing, FreeVars))
637 -> RnM (([LStmt Name], thing), FreeVars)
638 -- Variables bound by the Stmts, and mentioned in thing_inside,
639 -- do not appear in the result FreeVars
641 rnStmts ctxt [] thing_inside
642 = do { checkEmptyStmts ctxt
643 ; (thing, fvs) <- thing_inside []
644 ; return (([], thing), fvs) }
646 rnStmts MDoExpr stmts thing_inside -- Deal with mdo
647 = -- Behave like do { rec { ...all but last... }; last }
648 do { ((stmts1, (stmts2, thing)), fvs)
649 <- rnStmt MDoExpr (noLoc $ mkRecStmt all_but_last) $ \ _ ->
650 do { last_stmt' <- checkLastStmt MDoExpr last_stmt
651 ; rnStmt MDoExpr last_stmt' thing_inside }
652 ; return (((stmts1 ++ stmts2), thing), fvs) }
654 Just (all_but_last, last_stmt) = snocView stmts
656 rnStmts ctxt (lstmt@(L loc _) : lstmts) thing_inside
659 do { lstmt' <- checkLastStmt ctxt lstmt
660 ; rnStmt ctxt lstmt' thing_inside }
663 = do { ((stmts1, (stmts2, thing)), fvs)
665 do { checkStmt ctxt lstmt
666 ; rnStmt ctxt lstmt $ \ bndrs1 ->
667 rnStmts ctxt lstmts $ \ bndrs2 ->
668 thing_inside (bndrs1 ++ bndrs2) }
669 ; return (((stmts1 ++ stmts2), thing), fvs) }
671 ----------------------
672 rnStmt :: HsStmtContext Name
674 -> ([Name] -> RnM (thing, FreeVars))
675 -> RnM (([LStmt Name], thing), FreeVars)
676 -- Variables bound by the Stmt, and mentioned in thing_inside,
677 -- do not appear in the result FreeVars
679 rnStmt _ (L loc (LastStmt expr _)) thing_inside
680 = do { (expr', fv_expr) <- rnLExpr expr
681 ; (ret_op, fvs1) <- lookupSyntaxName returnMName
682 ; (thing, fvs3) <- thing_inside []
683 ; return (([L loc (LastStmt expr' ret_op)], thing),
684 fv_expr `plusFV` fvs1 `plusFV` fvs3) }
686 rnStmt ctxt (L loc (ExprStmt expr _ _ _)) thing_inside
687 = do { (expr', fv_expr) <- rnLExpr expr
688 ; (then_op, fvs1) <- lookupSyntaxName thenMName
689 ; (guard_op, fvs2) <- if isMonadCompExpr ctxt
690 then lookupSyntaxName guardMName
691 else return (noSyntaxExpr, emptyFVs)
692 ; (thing, fvs3) <- thing_inside []
693 ; return (([L loc (ExprStmt expr' then_op guard_op placeHolderType)], thing),
694 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }
696 rnStmt ctxt (L loc (BindStmt pat expr _ _)) thing_inside
697 = do { (expr', fv_expr) <- rnLExpr expr
698 -- The binders do not scope over the expression
699 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
700 ; (fail_op, fvs2) <- lookupSyntaxName failMName
701 ; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do
702 { (thing, fvs3) <- thing_inside (collectPatBinders pat')
703 ; return (([L loc (BindStmt pat' expr' bind_op fail_op)], thing),
704 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
705 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
706 -- but it does not matter because the names are unique
708 rnStmt _ (L loc (LetStmt binds)) thing_inside
709 = do { rnLocalBindsAndThen binds $ \binds' -> do
710 { (thing, fvs) <- thing_inside (collectLocalBinders binds')
711 ; return (([L loc (LetStmt binds')], thing), fvs) } }
713 rnStmt _ (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside
715 -- Step1: Bring all the binders of the mdo into scope
716 -- (Remember that this also removes the binders from the
717 -- finally-returned free-vars.)
718 -- And rename each individual stmt, making a
719 -- singleton segment. At this stage the FwdRefs field
720 -- isn't finished: it's empty for all except a BindStmt
721 -- for which it's the fwd refs within the bind itself
722 -- (This set may not be empty, because we're in a recursive
724 ; rnRecStmtsAndThen rec_stmts $ \ segs -> do
726 { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds))
728 ; (thing, fvs_later) <- thing_inside bndrs
729 ; (return_op, fvs1) <- lookupSyntaxName returnMName
730 ; (mfix_op, fvs2) <- lookupSyntaxName mfixName
731 ; (bind_op, fvs3) <- lookupSyntaxName bindMName
733 -- Step 2: Fill in the fwd refs.
734 -- The segments are all singletons, but their fwd-ref
735 -- field mentions all the things used by the segment
736 -- that are bound after their use
737 segs_w_fwd_refs = addFwdRefs segs
739 -- Step 3: Group together the segments to make bigger segments
740 -- Invariant: in the result, no segment uses a variable
741 -- bound in a later segment
742 grouped_segs = glomSegments segs_w_fwd_refs
744 -- Step 4: Turn the segments into Stmts
745 -- Use RecStmt when and only when there are fwd refs
746 -- Also gather up the uses from the end towards the
747 -- start, so we can tell the RecStmt which things are
748 -- used 'after' the RecStmt
749 empty_rec_stmt = emptyRecStmt { recS_ret_fn = return_op
750 , recS_mfix_fn = mfix_op
751 , recS_bind_fn = bind_op }
752 (rec_stmts', fvs) = segsToStmts empty_rec_stmt grouped_segs fvs_later
754 ; return ((rec_stmts', thing), fvs `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } }
756 rnStmt ctxt (L loc (ParStmt segs _ _ _)) thing_inside
757 = do { ((mzip_op, fvs1), (bind_op, fvs2), (return_op, fvs3)) <- if isMonadCompExpr ctxt
758 then (,,) <$> lookupSyntaxName mzipName
759 <*> lookupSyntaxName bindMName
760 <*> lookupSyntaxName returnMName
761 else return ( (noSyntaxExpr, emptyFVs)
762 , (noSyntaxExpr, emptyFVs)
763 , (noSyntaxExpr, emptyFVs) )
764 ; ((segs', thing), fvs4) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
765 ; return ( ([L loc (ParStmt segs' mzip_op bind_op return_op)], thing)
766 , fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4) }
768 rnStmt ctxt (L loc (TransStmt { trS_stmts = stmts, trS_by = by, trS_form = form
769 , trS_using = using })) thing_inside
770 = do { -- Rename the 'using' expression in the context before the transform is begun
771 let implicit_name | isMonadCompExpr ctxt = groupMName
772 | otherwise = groupWithName
773 ; (using', fvs1) <- case form of
774 GroupFormB -> do { (e,fvs) <- lookupSyntaxName implicit_name
775 ; return (noLoc e, fvs) }
778 -- Rename the stmts and the 'by' expression
779 -- Keep track of the variables mentioned in the 'by' expression
780 ; ((stmts', (by', used_bndrs, thing)), fvs2)
781 <- rnStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
782 do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by
783 ; (thing, fvs_thing) <- thing_inside bndrs
784 ; let fvs = fvs_by `plusFV` fvs_thing
785 used_bndrs = filter (`elemNameSet` fvs) bndrs
786 -- The paper (Fig 5) has a bug here; we must treat any free varaible of
787 -- the "thing inside", **or of the by-expression**, as used
788 ; return ((by', used_bndrs, thing), fvs) }
790 -- Lookup `return`, `(>>=)` and `liftM` for monad comprehensions
791 ; (return_op, fvs3) <- lookupSyntaxName returnMName
792 ; (bind_op, fvs4) <- lookupSyntaxName bindMName
793 ; (fmap_op, fvs5) <- case form of
794 ThenForm -> return (noSyntaxExpr, emptyFVs)
795 _ -> lookupSyntaxName fmapName
797 ; let all_fvs = fvs1 `plusFV` fvs2 `plusFV` fvs3
798 `plusFV` fvs4 `plusFV` fvs5
799 bndr_map = used_bndrs `zip` used_bndrs
800 -- See Note [TransStmt binder map] in HsExpr
802 ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map)
803 ; return (([L loc (TransStmt { trS_stmts = stmts', trS_bndrs = bndr_map
804 , trS_by = by', trS_using = using', trS_form = form
805 , trS_ret = return_op, trS_bind = bind_op
806 , trS_fmap = fmap_op })], thing), all_fvs) }
808 type ParSeg id = ([LStmt id], [id]) -- The Names are bound by the Stmts
810 rnParallelStmts :: forall thing. HsStmtContext Name
812 -> ([Name] -> RnM (thing, FreeVars))
813 -> RnM (([ParSeg Name], thing), FreeVars)
814 -- Note [Renaming parallel Stmts]
815 rnParallelStmts ctxt segs thing_inside
816 = do { orig_lcl_env <- getLocalRdrEnv
817 ; rn_segs orig_lcl_env [] segs }
819 rn_segs :: LocalRdrEnv
820 -> [Name] -> [ParSeg RdrName]
821 -> RnM (([ParSeg Name], thing), FreeVars)
822 rn_segs _ bndrs_so_far []
823 = do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far
825 ; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs')
826 ; return (([], thing), fvs) }
828 rn_segs env bndrs_so_far ((stmts,_) : segs)
829 = do { ((stmts', (used_bndrs, segs', thing)), fvs)
830 <- rnStmts ctxt stmts $ \ bndrs ->
831 setLocalRdrEnv env $ do
832 { ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs
833 ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
834 ; return ((used_bndrs, segs', thing), fvs) }
836 ; let seg' = (stmts', used_bndrs)
837 ; return ((seg':segs', thing), fvs) }
839 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
840 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
841 <+> quotes (ppr (head vs)))
844 Note [Renaming parallel Stmts]
845 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
846 Renaming parallel statements is painful. Given, say
847 [ a+c | a <- as, bs <- bss
850 (a) In order to report "Defined by not used" about 'bs', we must rename
851 each group of Stmts with a thing_inside whose FreeVars include at least {a,c}
853 (b) We want to report that 'a' is illegally bound in both branches
855 (c) The 'bs' in the second group must obviously not be captured by
856 the binding in the first group
858 To satisfy (a) we nest the segements.
859 To satisfy (b) we check for duplicates just before thing_inside.
860 To satisfy (c) we reset the LocalRdrEnv each time.
862 %************************************************************************
864 \subsubsection{mdo expressions}
866 %************************************************************************
869 type FwdRefs = NameSet
870 type Segment stmts = (Defs,
871 Uses, -- May include defs
872 FwdRefs, -- A subset of uses that are
873 -- (a) used before they are bound in this segment, or
874 -- (b) used here, and bound in subsequent segments
875 stmts) -- Either Stmt or [Stmt]
878 -- wrapper that does both the left- and right-hand sides
879 rnRecStmtsAndThen :: [LStmt RdrName]
880 -- assumes that the FreeVars returned includes
881 -- the FreeVars of the Segments
882 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
884 rnRecStmtsAndThen 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 = collectLStmtsBinders (map fst new_lhs_and_fv)
893 -- Fake uses of variables introduced implicitly (warning suppression, see #4404)
894 implicit_uses = lStmtsImplicits (map fst new_lhs_and_fv)
895 ; bindLocalNamesFV bound_names $
896 addLocalFixities fix_env bound_names $ do
898 -- (C) do the right-hand-sides and thing-inside
899 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
900 ; (res, fvs) <- cont segs
901 ; warnUnusedLocalBinds bound_names (fvs `unionNameSets` implicit_uses)
902 ; return (res, fvs) }}
904 -- get all the fixity decls in any Let stmt
905 collectRecStmtsFixities :: [LStmtLR RdrName RdrName] -> [LFixitySig RdrName]
906 collectRecStmtsFixities l =
907 foldr (\ s -> \acc -> case s of
908 (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
909 foldr (\ sig -> \ acc -> case sig of
910 (L loc (FixSig s)) -> (L loc s) : acc
916 rn_rec_stmt_lhs :: MiniFixityEnv
918 -- rename LHS, and return its FVs
919 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
920 -- so we don't bother to compute it accurately in the other cases
921 -> RnM [(LStmtLR Name RdrName, FreeVars)]
923 rn_rec_stmt_lhs _ (L loc (ExprStmt expr a b c))
924 = return [(L loc (ExprStmt expr a b c), emptyFVs)]
926 rn_rec_stmt_lhs _ (L loc (LastStmt expr a))
927 = return [(L loc (LastStmt expr a), emptyFVs)]
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 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
939 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
940 = do (_bound_names, binds') <- rnLocalValBindsLHS fix_env binds
941 return [(L loc (LetStmt (HsValBinds binds')),
942 -- Warning: this is bogus; see function invariant
946 -- XXX Do we need to do something with the return and mfix names?
947 rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = 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 _ (TransStmt {})) -- Syntactically illegal in mdo
954 = pprPanic "rn_rec_stmt" (ppr stmt)
956 rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
957 = panic "rn_rec_stmt LetStmt EmptyLocalBinds"
959 rn_rec_stmts_lhs :: MiniFixityEnv
961 -> RnM [(LStmtLR Name RdrName, FreeVars)]
962 rn_rec_stmts_lhs fix_env stmts
963 = do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts
964 ; let boundNames = collectLStmtsBinders (map fst ls)
965 -- First do error checking: we need to check for dups here because we
966 -- don't bind all of the variables from the Stmt at once
967 -- with bindLocatedLocals.
968 ; checkDupNames boundNames
974 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
975 -- Rename a Stmt that is inside a RecStmt (or mdo)
976 -- Assumes all binders are already in scope
977 -- Turns each stmt into a singleton Stmt
978 rn_rec_stmt _ (L loc (LastStmt expr _)) _
979 = do { (expr', fv_expr) <- rnLExpr expr
980 ; (ret_op, fvs1) <- lookupSyntaxName returnMName
981 ; return [(emptyNameSet, fv_expr `plusFV` fvs1, emptyNameSet,
982 L loc (LastStmt expr' ret_op))] }
984 rn_rec_stmt _ (L loc (ExprStmt expr _ _ _)) _
985 = rnLExpr expr `thenM` \ (expr', fvs) ->
986 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
987 return [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
988 L loc (ExprStmt expr' then_op noSyntaxExpr placeHolderType))]
990 rn_rec_stmt _ (L loc (BindStmt pat' expr _ _)) fv_pat
991 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
992 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
993 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
995 bndrs = mkNameSet (collectPatBinders pat')
996 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
998 return [(bndrs, fvs, bndrs `intersectNameSet` fvs,
999 L loc (BindStmt pat' expr' bind_op fail_op))]
1001 rn_rec_stmt _ (L _ (LetStmt binds@(HsIPBinds _))) _
1002 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
1004 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
1005 (binds', du_binds) <-
1006 -- fixities and unused are handled above in rnRecStmtsAndThen
1007 rnLocalValBindsRHS (mkNameSet all_bndrs) binds'
1008 return [(duDefs du_binds, allUses du_binds,
1009 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1011 -- no RecStmt case becuase they get flattened above when doing the LHSes
1012 rn_rec_stmt _ stmt@(L _ (RecStmt {})) _
1013 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1015 rn_rec_stmt _ stmt@(L _ (ParStmt {})) _ -- Syntactically illegal in mdo
1016 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1018 rn_rec_stmt _ stmt@(L _ (TransStmt {})) _ -- Syntactically illegal in mdo
1019 = pprPanic "rn_rec_stmt: TransStmt" (ppr stmt)
1021 rn_rec_stmt _ (L _ (LetStmt EmptyLocalBinds)) _
1022 = panic "rn_rec_stmt: LetStmt EmptyLocalBinds"
1024 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1025 rn_rec_stmts bndrs stmts = mapM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1026 return (concat segs_s)
1028 ---------------------------------------------
1029 addFwdRefs :: [Segment a] -> [Segment a]
1030 -- So far the segments only have forward refs *within* the Stmt
1031 -- (which happens for bind: x <- ...x...)
1032 -- This function adds the cross-seg fwd ref info
1035 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1037 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1038 = (new_seg : segs, all_defs)
1040 new_seg = (defs, uses, new_fwds, stmts)
1041 all_defs = later_defs `unionNameSets` defs
1042 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1043 -- Add the downstream fwd refs here
1045 ----------------------------------------------------
1046 -- Glomming the singleton segments of an mdo into
1047 -- minimal recursive groups.
1049 -- At first I thought this was just strongly connected components, but
1050 -- there's an important constraint: the order of the stmts must not change.
1053 -- mdo { x <- ...y...
1060 -- Here, the first stmt mention 'y', which is bound in the third.
1061 -- But that means that the innocent second stmt (p <- z) gets caught
1062 -- up in the recursion. And that in turn means that the binding for
1063 -- 'z' has to be included... and so on.
1065 -- Start at the tail { r <- x }
1066 -- Now add the next one { z <- y ; r <- x }
1067 -- Now add one more { q <- x ; z <- y ; r <- x }
1068 -- Now one more... but this time we have to group a bunch into rec
1069 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1070 -- Now one more, which we can add on without a rec
1072 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1074 -- Finally we add the last one; since it mentions y we have to
1075 -- glom it togeher with the first two groups
1076 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1077 -- q <- x ; z <- y } ;
1080 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1082 glomSegments [] = []
1083 glomSegments ((defs,uses,fwds,stmt) : segs)
1084 -- Actually stmts will always be a singleton
1085 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1087 segs' = glomSegments segs
1088 (extras, others) = grab uses segs'
1089 (ds, us, fs, ss) = unzip4 extras
1091 seg_defs = plusFVs ds `plusFV` defs
1092 seg_uses = plusFVs us `plusFV` uses
1093 seg_fwds = plusFVs fs `plusFV` fwds
1094 seg_stmts = stmt : concat ss
1096 grab :: NameSet -- The client
1098 -> ([Segment a], -- Needed by the 'client'
1099 [Segment a]) -- Not needed by the client
1100 -- The result is simply a split of the input
1102 = (reverse yeses, reverse noes)
1104 (noes, yeses) = span not_needed (reverse dus)
1105 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1108 ----------------------------------------------------
1109 segsToStmts :: Stmt Name -- A RecStmt with the SyntaxOps filled in
1110 -> [Segment [LStmt Name]]
1111 -> FreeVars -- Free vars used 'later'
1112 -> ([LStmt Name], FreeVars)
1114 segsToStmts _ [] fvs_later = ([], fvs_later)
1115 segsToStmts empty_rec_stmt ((defs, uses, fwds, ss) : segs) fvs_later
1116 = ASSERT( not (null ss) )
1117 (new_stmt : later_stmts, later_uses `plusFV` uses)
1119 (later_stmts, later_uses) = segsToStmts empty_rec_stmt segs fvs_later
1120 new_stmt | non_rec = head ss
1121 | otherwise = L (getLoc (head ss)) rec_stmt
1122 rec_stmt = empty_rec_stmt { recS_stmts = ss
1123 , recS_later_ids = nameSetToList used_later
1124 , recS_rec_ids = nameSetToList fwds }
1125 non_rec = isSingleton ss && isEmptyNameSet fwds
1126 used_later = defs `intersectNameSet` later_uses
1127 -- The ones needed after the RecStmt
1130 %************************************************************************
1132 \subsubsection{Assertion utils}
1134 %************************************************************************
1137 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1138 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDocOneLine (ppr span))))
1140 mkAssertErrorExpr :: RnM (HsExpr Name)
1141 -- Return an expression for (assertError "Foo.hs:27")
1143 = getSrcSpanM `thenM` \ sloc ->
1144 return (HsApp (L sloc (HsVar assertErrorName))
1145 (L sloc (srcSpanPrimLit sloc)))
1148 Note [Adding the implicit parameter to 'assert']
1149 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1150 The renamer transforms (assert e1 e2) to (assert "Foo.hs:27" e1 e2).
1151 By doing this in the renamer we allow the typechecker to just see the
1152 expanded application and do the right thing. But it's not really
1153 the Right Thing because there's no way to "undo" if you want to see
1154 the original source code. We'll have fix this in due course, when
1155 we care more about being able to reconstruct the exact original
1158 %************************************************************************
1160 \subsubsection{Errors}
1162 %************************************************************************
1165 checkEmptyStmts :: HsStmtContext Name -> RnM ()
1166 -- We've seen an empty sequence of Stmts... is that ok?
1167 checkEmptyStmts ctxt
1168 = unless (okEmpty ctxt) (addErr (emptyErr ctxt))
1170 okEmpty :: HsStmtContext a -> Bool
1171 okEmpty (PatGuard {}) = True
1174 emptyErr :: HsStmtContext Name -> SDoc
1175 emptyErr (ParStmtCtxt {}) = ptext (sLit "Empty statement group in parallel comprehension")
1176 emptyErr (TransformStmtCtxt {}) = ptext (sLit "Empty statement group preceding 'group' or 'then'")
1177 emptyErr ctxt = ptext (sLit "Empty") <+> pprStmtContext ctxt
1179 ----------------------
1180 checkLastStmt :: HsStmtContext Name
1182 -> RnM (LStmt RdrName)
1183 checkLastStmt ctxt lstmt@(L loc stmt)
1185 ListComp -> check_comp
1186 MonadComp -> check_comp
1187 PArrComp -> check_comp
1192 check_do -- Expect ExprStmt, and change it to LastStmt
1194 ExprStmt e _ _ _ -> return (L loc (mkLastStmt e))
1195 LastStmt {} -> return lstmt -- "Deriving" clauses may generate a
1196 -- LastStmt directly (unlike the parser)
1197 _ -> do { addErr (hang last_error 2 (ppr stmt)); return lstmt }
1198 last_error = (ptext (sLit "The last statement in") <+> pprAStmtContext ctxt
1199 <+> ptext (sLit "must be an expression"))
1201 check_comp -- Expect LastStmt; this should be enforced by the parser!
1203 LastStmt {} -> return lstmt
1204 _ -> pprPanic "checkLastStmt" (ppr lstmt)
1206 check_other -- Behave just as if this wasn't the last stmt
1207 = do { checkStmt ctxt lstmt; return lstmt }
1209 -- Checking when a particular Stmt is ok
1210 checkStmt :: HsStmtContext Name
1213 checkStmt ctxt (L _ stmt)
1214 = do { dflags <- getDOpts
1215 ; case okStmt dflags ctxt stmt of
1216 Nothing -> return ()
1217 Just extra -> addErr (msg $$ extra) }
1219 msg = sep [ ptext (sLit "Unexpected") <+> pprStmtCat stmt <+> ptext (sLit "statement")
1220 , ptext (sLit "in") <+> pprAStmtContext ctxt ]
1222 pprStmtCat :: Stmt a -> SDoc
1223 pprStmtCat (TransStmt {}) = ptext (sLit "transform")
1224 pprStmtCat (LastStmt {}) = ptext (sLit "return expression")
1225 pprStmtCat (ExprStmt {}) = ptext (sLit "exprssion")
1226 pprStmtCat (BindStmt {}) = ptext (sLit "binding")
1227 pprStmtCat (LetStmt {}) = ptext (sLit "let")
1228 pprStmtCat (RecStmt {}) = ptext (sLit "rec")
1229 pprStmtCat (ParStmt {}) = ptext (sLit "parallel")
1232 isOK, notOK :: Maybe SDoc
1236 okStmt, okDoStmt, okCompStmt :: DynFlags -> HsStmtContext Name
1237 -> Stmt RdrName -> Maybe SDoc
1238 -- Return Nothing if OK, (Just extra) if not ok
1239 -- The "extra" is an SDoc that is appended to an generic error message
1240 okStmt _ (PatGuard {}) stmt
1247 okStmt dflags (ParStmtCtxt ctxt) stmt
1249 LetStmt (HsIPBinds {}) -> notOK
1250 _ -> okStmt dflags ctxt stmt
1252 okStmt dflags (TransformStmtCtxt ctxt) stmt
1253 = okStmt dflags ctxt stmt
1255 okStmt dflags ctxt stmt
1256 | isDoExpr ctxt = okDoStmt dflags ctxt stmt
1257 | isListCompExpr ctxt = okCompStmt dflags ctxt stmt
1258 | otherwise = pprPanic "okStmt" (pprStmtContext ctxt)
1261 okDoStmt dflags _ stmt
1264 | Opt_DoRec `xopt` dflags -> isOK
1265 | otherwise -> Just (ptext (sLit "Use -XDoRec"))
1273 okCompStmt dflags _ stmt
1279 | Opt_ParallelListComp `xopt` dflags -> isOK
1280 | otherwise -> Just (ptext (sLit "Use -XParallelListComp"))
1282 | Opt_TransformListComp `xopt` dflags -> isOK
1283 | otherwise -> Just (ptext (sLit "Use -XTransformListComp"))
1284 LastStmt {} -> notOK
1288 checkTupleSection :: [HsTupArg RdrName] -> RnM ()
1289 checkTupleSection args
1290 = do { tuple_section <- xoptM Opt_TupleSections
1291 ; checkErr (all tupArgPresent args || tuple_section) msg }
1293 msg = ptext (sLit "Illegal tuple section: use -XTupleSections")
1296 sectionErr :: HsExpr RdrName -> SDoc
1298 = hang (ptext (sLit "A section must be enclosed in parentheses"))
1299 2 (ptext (sLit "thus:") <+> (parens (ppr expr)))
1301 patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
1302 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1304 ; return (EWildPat, emptyFVs) }
1306 badIpBinds :: Outputable a => SDoc -> a -> SDoc
1307 badIpBinds what binds
1308 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)