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 )
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 ())
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 body return_op ty)
444 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
445 (convertOpFormsLCmd body)
446 (convertOpFormsCmd return_op) ty
448 -- Anything else is unchanged. This includes HsArrForm (already done),
449 -- things with no sub-commands, and illegal commands (which will be
450 -- caught by the type checker)
451 convertOpFormsCmd c = c
453 convertOpFormsStmt :: StmtLR id id -> StmtLR id id
454 convertOpFormsStmt (BindStmt pat cmd _ _)
455 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
456 convertOpFormsStmt (ExprStmt cmd _ _ _)
457 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr placeHolderType
458 convertOpFormsStmt stmt@(RecStmt { recS_stmts = stmts })
459 = stmt { recS_stmts = map (fmap convertOpFormsStmt) stmts }
460 convertOpFormsStmt stmt = stmt
462 convertOpFormsMatch :: MatchGroup id -> MatchGroup id
463 convertOpFormsMatch (MatchGroup ms ty)
464 = MatchGroup (map (fmap convert) ms) ty
465 where convert (Match pat mty grhss)
466 = Match pat mty (convertOpFormsGRHSs grhss)
468 convertOpFormsGRHSs :: GRHSs id -> GRHSs id
469 convertOpFormsGRHSs (GRHSs grhss binds)
470 = GRHSs (map convertOpFormsGRHS grhss) binds
472 convertOpFormsGRHS :: Located (GRHS id) -> Located (GRHS id)
473 convertOpFormsGRHS = fmap convert
475 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
477 ---------------------------------------------------
478 type CmdNeeds = FreeVars -- Only inhabitants are
479 -- appAName, choiceAName, loopAName
481 -- find what methods the Cmd needs (loop, choice, apply)
482 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
483 methodNamesLCmd = methodNamesCmd . unLoc
485 methodNamesCmd :: HsCmd Name -> CmdNeeds
487 methodNamesCmd (HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
489 methodNamesCmd (HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
491 methodNamesCmd (HsArrForm {}) = emptyFVs
493 methodNamesCmd (HsPar c) = methodNamesLCmd c
495 methodNamesCmd (HsIf _ _ c1 c2)
496 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
498 methodNamesCmd (HsLet _ c) = methodNamesLCmd c
500 methodNamesCmd (HsDo _ stmts body _ _)
501 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
503 methodNamesCmd (HsApp c _) = methodNamesLCmd c
505 methodNamesCmd (HsLam match) = methodNamesMatch match
507 methodNamesCmd (HsCase _ matches)
508 = methodNamesMatch matches `addOneFV` choiceAName
510 methodNamesCmd _ = emptyFVs
511 -- Other forms can't occur in commands, but it's not convenient
512 -- to error here so we just do what's convenient.
513 -- The type checker will complain later
515 ---------------------------------------------------
516 methodNamesMatch :: MatchGroup Name -> FreeVars
517 methodNamesMatch (MatchGroup ms _)
518 = plusFVs (map do_one ms)
520 do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
522 -------------------------------------------------
524 methodNamesGRHSs :: GRHSs Name -> FreeVars
525 methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
527 -------------------------------------------------
529 methodNamesGRHS :: Located (GRHS Name) -> CmdNeeds
530 methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
532 ---------------------------------------------------
533 methodNamesStmts :: [Located (StmtLR Name Name)] -> FreeVars
534 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
536 ---------------------------------------------------
537 methodNamesLStmt :: Located (StmtLR Name Name) -> FreeVars
538 methodNamesLStmt = methodNamesStmt . unLoc
540 methodNamesStmt :: StmtLR Name Name -> FreeVars
541 methodNamesStmt (ExprStmt cmd _ _ _) = methodNamesLCmd cmd
542 methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
543 methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName
544 methodNamesStmt (LetStmt _) = emptyFVs
545 methodNamesStmt (ParStmt _ _ _ _) = emptyFVs
546 methodNamesStmt (TransformStmt {}) = emptyFVs
547 methodNamesStmt (GroupStmt {}) = emptyFVs
548 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
549 -- here so we just do what's convenient
553 %************************************************************************
557 %************************************************************************
560 rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
561 rnArithSeq (From expr)
562 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
563 return (From expr', fvExpr)
565 rnArithSeq (FromThen expr1 expr2)
566 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
567 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
568 return (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
570 rnArithSeq (FromTo expr1 expr2)
571 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
572 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
573 return (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
575 rnArithSeq (FromThenTo expr1 expr2 expr3)
576 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
577 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
578 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
579 return (FromThenTo expr1' expr2' expr3',
580 plusFVs [fvExpr1, fvExpr2, fvExpr3])
583 %************************************************************************
585 Template Haskell brackets
587 %************************************************************************
590 rnBracket :: HsBracket RdrName -> RnM (HsBracket Name, FreeVars)
591 rnBracket (VarBr n) = do { name <- lookupOccRn n
592 ; this_mod <- getModule
593 ; unless (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
594 do { _ <- loadInterfaceForName msg name -- home interface is loaded, and this is the
595 ; return () } -- only way that is going to happen
596 ; return (VarBr name, unitFV name) }
598 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
600 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
601 ; return (ExpBr e', fvs) }
603 rnBracket (PatBr p) = rnPat ThPatQuote p $ \ p' -> return (PatBr p', emptyFVs)
605 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
606 ; return (TypBr t', fvs) }
608 doc = ptext (sLit "In a Template-Haskell quoted type")
610 rnBracket (DecBrL decls)
611 = do { (group, mb_splice) <- findSplice decls
614 Just (SpliceDecl (L loc _) _, _)
616 addErr (ptext (sLit "Declaration splices are not permitted inside declaration brackets"))
617 -- Why not? See Section 7.3 of the TH paper.
619 ; gbl_env <- getGblEnv
620 ; let new_gbl_env = gbl_env { tcg_dus = emptyDUs }
621 -- The emptyDUs is so that we just collect uses for this
622 -- group alone in the call to rnSrcDecls below
623 ; (tcg_env, group') <- setGblEnv new_gbl_env $
627 -- Discard the tcg_env; it contains only extra info about fixity
628 ; traceRn (text "rnBracket dec" <+> (ppr (tcg_dus tcg_env) $$ ppr (duUses (tcg_dus tcg_env))))
629 ; return (DecBrG group', duUses (tcg_dus tcg_env)) }
631 rnBracket (DecBrG _) = panic "rnBracket: unexpected DecBrG"
634 %************************************************************************
636 \subsubsection{@Stmt@s: in @do@ expressions}
638 %************************************************************************
641 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
642 -> ([Name] -> RnM (thing, FreeVars))
643 -> RnM (([LStmt Name], thing), FreeVars)
644 -- Variables bound by the Stmts, and mentioned in thing_inside,
645 -- do not appear in the result FreeVars
647 -- Renaming a single RecStmt can give a sequence of smaller Stmts
649 rnStmts ctxt [] thing_inside
650 = do { addErr (ptext (sLit "Empty") <+> pprStmtContext ctxt)
651 ; (thing, fvs) <- thing_inside []
652 ; return (([], thing), fvs) }
654 rnStmts MDoExpr stmts thing_inside -- Deal with mdo
655 = -- Behave like do { rec { ...all but last... }; last }
656 do { ((stmts1, (stmts2, thing)), fvs)
657 <- rnStmt MDoExpr (mkRecStmt all_but_last) $ \ bndrs ->
658 do { checkStmt MDoExpr True last_stmt
659 ; rnStmt MDoExpr last_stmt thing_inside }
660 ; return (((stmts1 ++ stmts2), thing), fvs) }
662 Just (all_but_last, last_stmt) = snocView stmts
664 rnStmts ctxt (stmt@(L loc _) : stmts) thing_inside
667 do { let last_stmt = case stmt of
668 ExprStmt e _ _ _ -> LastStmt e noSyntaxExpr
669 ; checkStmt ctxt True {- last stmt -} stmt
670 ; rnStmt ctxt stmt thing_inside }
673 = do { ((stmts1, (stmts2, thing)), fvs)
675 do { checkStmt ctxt False {- Not last -} stmt
676 ; rnStmt ctxt stmt $ \ bndrs1 ->
677 rnStmts ctxt stmts $ \ bndrs2 ->
678 thing_inside (bndrs1 ++ bndrs2) }
679 ; return (((stmts1 ++ stmts2), thing), fvs) }
681 ----------------------
682 rnStmt :: HsStmtContext Name
684 -> ([Name] -> RnM (thing, FreeVars))
685 -> RnM (([LStmt Name], thing), FreeVars)
686 -- Variables bound by the Stmt, and mentioned in thing_inside,
687 -- do not appear in the result FreeVars
689 rnStmt ctxt (L loc (LastStmt expr _)) thing_inside
690 = do { (expr', fv_expr) <- rnLExpr expr
691 ; (ret_op, fvs1) <- lookupSyntaxName returnMName
692 ; (thing, fvs3) <- thing_inside []
693 ; return (([L loc (LastStmt expr' ret_op)], thing),
694 fv_expr `plusFV` fvs1 `plusFV` fvs3) }
696 rnStmt ctxt (L loc (ExprStmt expr _ _ _)) thing_inside
697 = do { (expr', fv_expr) <- rnLExpr expr
698 ; (then_op, fvs1) <- lookupSyntaxName thenMName
699 ; (guard_op, fvs2) <- if isMonadCompExpr ctxt
700 then lookupSyntaxName guardMName
701 else return (noSyntaxExpr, emptyFVs)
702 ; (thing, fvs3) <- thing_inside []
703 ; return (([L loc (ExprStmt expr' then_op guard_op placeHolderType)], thing),
704 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }
706 rnStmt ctxt (L loc (BindStmt pat expr _ _)) thing_inside
707 = do { checkBindStmt ctxt is_last
708 ; (expr', fv_expr) <- rnLExpr expr
709 -- The binders do not scope over the expression
710 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
711 ; (fail_op, fvs2) <- lookupSyntaxName failMName
712 ; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do
713 { (thing, fvs3) <- thing_inside (collectPatBinders pat')
714 ; return (([L loc (BindStmt pat' expr' bind_op fail_op)], thing),
715 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
716 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
717 -- but it does not matter because the names are unique
719 rnStmt ctxt (L loc (LetStmt binds)) thing_inside
720 = do { checkLetStmt ctxt binds
721 ; rnLocalBindsAndThen binds $ \binds' -> do
722 { (thing, fvs) <- thing_inside (collectLocalBinders binds')
723 ; return (([L loc (LetStmt binds')], thing), fvs) } }
725 rnStmt ctxt (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside
727 -- Step1: Bring all the binders of the mdo into scope
728 -- (Remember that this also removes the binders from the
729 -- finally-returned free-vars.)
730 -- And rename each individual stmt, making a
731 -- singleton segment. At this stage the FwdRefs field
732 -- isn't finished: it's empty for all except a BindStmt
733 -- for which it's the fwd refs within the bind itself
734 -- (This set may not be empty, because we're in a recursive
736 ; rnRecStmtsAndThen rec_stmts $ \ segs -> do
738 { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds))
740 ; (thing, fvs_later) <- thing_inside bndrs
741 ; (return_op, fvs1) <- lookupSyntaxName returnMName
742 ; (mfix_op, fvs2) <- lookupSyntaxName mfixName
743 ; (bind_op, fvs3) <- lookupSyntaxName bindMName
745 -- Step 2: Fill in the fwd refs.
746 -- The segments are all singletons, but their fwd-ref
747 -- field mentions all the things used by the segment
748 -- that are bound after their use
749 segs_w_fwd_refs = addFwdRefs segs
751 -- Step 3: Group together the segments to make bigger segments
752 -- Invariant: in the result, no segment uses a variable
753 -- bound in a later segment
754 grouped_segs = glomSegments segs_w_fwd_refs
756 -- Step 4: Turn the segments into Stmts
757 -- Use RecStmt when and only when there are fwd refs
758 -- Also gather up the uses from the end towards the
759 -- start, so we can tell the RecStmt which things are
760 -- used 'after' the RecStmt
761 empty_rec_stmt = emptyRecStmt { recS_ret_fn = return_op
762 , recS_mfix_fn = mfix_op
763 , recS_bind_fn = bind_op }
764 (rec_stmts', fvs) = segsToStmts empty_rec_stmt grouped_segs fvs_later
766 ; return ((rec_stmts', thing), fvs `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } }
768 rnStmt ctxt (L loc (ParStmt segs _ _ _)) thing_inside
769 = do { ((mzip_op, fvs1), (bind_op, fvs2), (return_op, fvs3)) <- if isMonadCompExpr ctxt
770 then (,,) <$> lookupSyntaxName mzipName
771 <*> lookupSyntaxName bindMName
772 <*> lookupSyntaxName returnMName
773 else return ( (noSyntaxExpr, emptyFVs)
774 , (noSyntaxExpr, emptyFVs)
775 , (noSyntaxExpr, emptyFVs) )
776 ; ((segs', thing), fvs4) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
777 ; return ( ([L loc (ParStmt segs' mzip_op bind_op return_op)], thing)
778 , fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4) }
780 rnStmt ctxt (L loc (TransformStmt stmts _ using by _ _)) thing_inside
781 = do { (using', fvs1) <- rnLExpr using
783 ; ((stmts', (by', used_bndrs, thing)), fvs2)
784 <- rnStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
785 do { (by', fvs_by) <- case by of
786 Nothing -> return (Nothing, emptyFVs)
787 Just e -> do { (e', fvs) <- rnLExpr e; return (Just e', fvs) }
788 ; (thing, fvs_thing) <- thing_inside bndrs
789 ; let fvs = fvs_by `plusFV` fvs_thing
790 used_bndrs = filter (`elemNameSet` fvs) bndrs
791 -- The paper (Fig 5) has a bug here; we must treat any free varaible of
792 -- the "thing inside", **or of the by-expression**, as used
793 ; return ((by', used_bndrs, thing), fvs) }
795 -- Lookup `(>>=)` and `fail` for monad comprehensions
796 ; ((return_op, fvs3), (bind_op, fvs4)) <-
797 if isMonadCompExpr ctxt
798 then (,) <$> lookupSyntaxName returnMName
799 <*> lookupSyntaxName bindMName
800 else return ( (noSyntaxExpr, emptyFVs)
801 , (noSyntaxExpr, emptyFVs) )
803 ; return (([L loc (TransformStmt stmts' used_bndrs using' by' return_op bind_op)], thing),
804 fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4) }
806 rnStmt ctxt (L loc (GroupStmt stmts _ by using _ _ _)) thing_inside
807 = do { -- Rename the 'using' expression in the context before the transform is begun
808 ; (using', fvs1) <- case using of
809 Left e -> do { (e', fvs) <- rnLExpr e; return (Left e', fvs) }
811 | isMonadCompExpr ctxt ->
812 do { (e', fvs) <- lookupSyntaxName groupMName
813 ; return (Right e', fvs) }
815 do { (e', fvs) <- lookupSyntaxName groupWithName
816 ; return (Right e', fvs) }
818 -- Rename the stmts and the 'by' expression
819 -- Keep track of the variables mentioned in the 'by' expression
820 ; ((stmts', (by', used_bndrs, thing)), fvs2)
821 <- rnStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
822 do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by
823 ; (thing, fvs_thing) <- thing_inside bndrs
824 ; let fvs = fvs_by `plusFV` fvs_thing
825 used_bndrs = filter (`elemNameSet` fvs) bndrs
826 ; return ((by', used_bndrs, thing), fvs) }
828 -- Lookup `return`, `(>>=)` and `liftM` for monad comprehensions
829 ; ((return_op, fvs3), (bind_op, fvs4), (fmap_op, fvs5)) <-
830 if isMonadCompExpr ctxt
831 then (,,) <$> lookupSyntaxName returnMName
832 <*> lookupSyntaxName bindMName
833 <*> lookupSyntaxName fmapName
834 else return ( (noSyntaxExpr, emptyFVs)
835 , (noSyntaxExpr, emptyFVs)
836 , (noSyntaxExpr, emptyFVs) )
838 ; let all_fvs = fvs1 `plusFV` fvs2 `plusFV` fvs3 `plusFV` fvs4
840 bndr_map = used_bndrs `zip` used_bndrs
841 -- See Note [GroupStmt binder map] in HsExpr
843 ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map)
844 ; return (([L loc (GroupStmt stmts' bndr_map by' using' return_op bind_op fmap_op)], thing), all_fvs) }
846 type ParSeg id = ([LStmt id], [id]) -- The Names are bound by the Stmts
848 rnParallelStmts :: forall thing. HsStmtContext Name
850 -> ([Name] -> RnM (thing, FreeVars))
851 -> RnM (([ParSeg Name], thing), FreeVars)
852 -- Note [Renaming parallel Stmts]
853 rnParallelStmts ctxt segs thing_inside
854 = do { orig_lcl_env <- getLocalRdrEnv
855 ; rn_segs orig_lcl_env [] segs }
857 rn_segs :: LocalRdrEnv
858 -> [Name] -> [ParSeg RdrName]
859 -> RnM (([ParSeg Name], thing), FreeVars)
860 rn_segs _ bndrs_so_far []
861 = do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far
863 ; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs')
864 ; return (([], thing), fvs) }
866 rn_segs env bndrs_so_far ((stmts,_) : segs)
867 = do { ((stmts', (used_bndrs, segs', thing)), fvs)
868 <- rnStmts ctxt stmts $ \ bndrs ->
869 setLocalRdrEnv env $ do
870 { ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs
871 ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
872 ; return ((used_bndrs, segs', thing), fvs) }
874 ; let seg' = (stmts', used_bndrs)
875 ; return ((seg':segs', thing), fvs) }
877 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
878 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
879 <+> quotes (ppr (head vs)))
882 Note [Renaming parallel Stmts]
883 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
884 Renaming parallel statements is painful. Given, say
885 [ a+c | a <- as, bs <- bss
888 (a) In order to report "Defined by not used" about 'bs', we must rename
889 each group of Stmts with a thing_inside whose FreeVars include at least {a,c}
891 (b) We want to report that 'a' is illegally bound in both branches
893 (c) The 'bs' in the second group must obviously not be captured by
894 the binding in the first group
896 To satisfy (a) we nest the segements.
897 To satisfy (b) we check for duplicates just before thing_inside.
898 To satisfy (c) we reset the LocalRdrEnv each time.
900 %************************************************************************
902 \subsubsection{mdo expressions}
904 %************************************************************************
907 type FwdRefs = NameSet
908 type Segment stmts = (Defs,
909 Uses, -- May include defs
910 FwdRefs, -- A subset of uses that are
911 -- (a) used before they are bound in this segment, or
912 -- (b) used here, and bound in subsequent segments
913 stmts) -- Either Stmt or [Stmt]
916 -- wrapper that does both the left- and right-hand sides
917 rnRecStmtsAndThen :: [LStmt RdrName]
918 -- assumes that the FreeVars returned includes
919 -- the FreeVars of the Segments
920 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
922 rnRecStmtsAndThen s cont
923 = do { -- (A) Make the mini fixity env for all of the stmts
924 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
927 ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
929 -- ...bring them and their fixities into scope
930 ; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv)
931 -- Fake uses of variables introduced implicitly (warning suppression, see #4404)
932 implicit_uses = lStmtsImplicits (map fst new_lhs_and_fv)
933 ; bindLocalNamesFV bound_names $
934 addLocalFixities fix_env bound_names $ do
936 -- (C) do the right-hand-sides and thing-inside
937 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
938 ; (res, fvs) <- cont segs
939 ; warnUnusedLocalBinds bound_names (fvs `unionNameSets` implicit_uses)
940 ; return (res, fvs) }}
942 -- get all the fixity decls in any Let stmt
943 collectRecStmtsFixities :: [LStmtLR RdrName RdrName] -> [LFixitySig RdrName]
944 collectRecStmtsFixities l =
945 foldr (\ s -> \acc -> case s of
946 (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
947 foldr (\ sig -> \ acc -> case sig of
948 (L loc (FixSig s)) -> (L loc s) : acc
954 rn_rec_stmt_lhs :: MiniFixityEnv
956 -- rename LHS, and return its FVs
957 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
958 -- so we don't bother to compute it accurately in the other cases
959 -> RnM [(LStmtLR Name RdrName, FreeVars)]
961 rn_rec_stmt_lhs _ (L loc (ExprStmt expr a b c)) = return [(L loc (ExprStmt expr a b c),
962 -- this is actually correct
965 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
967 -- should the ctxt be MDo instead?
968 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
969 return [(L loc (BindStmt pat' expr a b),
972 rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _)))
973 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
975 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
976 = do (_bound_names, binds') <- rnLocalValBindsLHS fix_env binds
977 return [(L loc (LetStmt (HsValBinds binds')),
978 -- Warning: this is bogus; see function invariant
982 -- XXX Do we need to do something with the return and mfix names?
983 rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = stmts })) -- Flatten Rec inside Rec
984 = rn_rec_stmts_lhs fix_env stmts
986 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _ _ _ _)) -- Syntactically illegal in mdo
987 = pprPanic "rn_rec_stmt" (ppr stmt)
989 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt {})) -- Syntactically illegal in mdo
990 = pprPanic "rn_rec_stmt" (ppr stmt)
992 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt {})) -- Syntactically illegal in mdo
993 = pprPanic "rn_rec_stmt" (ppr stmt)
995 rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
996 = panic "rn_rec_stmt LetStmt EmptyLocalBinds"
998 rn_rec_stmts_lhs :: MiniFixityEnv
1000 -> RnM [(LStmtLR Name RdrName, FreeVars)]
1001 rn_rec_stmts_lhs fix_env stmts
1002 = do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts
1003 ; let boundNames = collectLStmtsBinders (map fst ls)
1004 -- First do error checking: we need to check for dups here because we
1005 -- don't bind all of the variables from the Stmt at once
1006 -- with bindLocatedLocals.
1007 ; checkDupNames boundNames
1013 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
1014 -- Rename a Stmt that is inside a RecStmt (or mdo)
1015 -- Assumes all binders are already in scope
1016 -- Turns each stmt into a singleton Stmt
1017 rn_rec_stmt _ (L loc (ExprStmt expr _ _ _)) _
1018 = rnLExpr expr `thenM` \ (expr', fvs) ->
1019 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
1020 return [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
1021 L loc (ExprStmt expr' then_op noSyntaxExpr placeHolderType))]
1023 rn_rec_stmt _ (L loc (BindStmt pat' expr _ _)) fv_pat
1024 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
1025 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
1026 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
1028 bndrs = mkNameSet (collectPatBinders pat')
1029 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
1031 return [(bndrs, fvs, bndrs `intersectNameSet` fvs,
1032 L loc (BindStmt pat' expr' bind_op fail_op))]
1034 rn_rec_stmt _ (L _ (LetStmt binds@(HsIPBinds _))) _
1035 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
1037 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
1038 (binds', du_binds) <-
1039 -- fixities and unused are handled above in rnRecStmtsAndThen
1040 rnLocalValBindsRHS (mkNameSet all_bndrs) binds'
1041 return [(duDefs du_binds, allUses du_binds,
1042 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1044 -- no RecStmt case becuase they get flattened above when doing the LHSes
1045 rn_rec_stmt _ stmt@(L _ (RecStmt {})) _
1046 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1048 rn_rec_stmt _ stmt@(L _ (ParStmt {})) _ -- Syntactically illegal in mdo
1049 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1051 rn_rec_stmt _ stmt@(L _ (TransformStmt {})) _ -- Syntactically illegal in mdo
1052 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1054 rn_rec_stmt _ stmt@(L _ (GroupStmt {})) _ -- Syntactically illegal in mdo
1055 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1057 rn_rec_stmt _ (L _ (LetStmt EmptyLocalBinds)) _
1058 = panic "rn_rec_stmt: LetStmt EmptyLocalBinds"
1060 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1061 rn_rec_stmts bndrs stmts = mapM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1062 return (concat segs_s)
1064 ---------------------------------------------
1065 addFwdRefs :: [Segment a] -> [Segment a]
1066 -- So far the segments only have forward refs *within* the Stmt
1067 -- (which happens for bind: x <- ...x...)
1068 -- This function adds the cross-seg fwd ref info
1071 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1073 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1074 = (new_seg : segs, all_defs)
1076 new_seg = (defs, uses, new_fwds, stmts)
1077 all_defs = later_defs `unionNameSets` defs
1078 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1079 -- Add the downstream fwd refs here
1081 ----------------------------------------------------
1082 -- Glomming the singleton segments of an mdo into
1083 -- minimal recursive groups.
1085 -- At first I thought this was just strongly connected components, but
1086 -- there's an important constraint: the order of the stmts must not change.
1089 -- mdo { x <- ...y...
1096 -- Here, the first stmt mention 'y', which is bound in the third.
1097 -- But that means that the innocent second stmt (p <- z) gets caught
1098 -- up in the recursion. And that in turn means that the binding for
1099 -- 'z' has to be included... and so on.
1101 -- Start at the tail { r <- x }
1102 -- Now add the next one { z <- y ; r <- x }
1103 -- Now add one more { q <- x ; z <- y ; r <- x }
1104 -- Now one more... but this time we have to group a bunch into rec
1105 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1106 -- Now one more, which we can add on without a rec
1108 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1110 -- Finally we add the last one; since it mentions y we have to
1111 -- glom it togeher with the first two groups
1112 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1113 -- q <- x ; z <- y } ;
1116 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1118 glomSegments [] = []
1119 glomSegments ((defs,uses,fwds,stmt) : segs)
1120 -- Actually stmts will always be a singleton
1121 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1123 segs' = glomSegments segs
1124 (extras, others) = grab uses segs'
1125 (ds, us, fs, ss) = unzip4 extras
1127 seg_defs = plusFVs ds `plusFV` defs
1128 seg_uses = plusFVs us `plusFV` uses
1129 seg_fwds = plusFVs fs `plusFV` fwds
1130 seg_stmts = stmt : concat ss
1132 grab :: NameSet -- The client
1134 -> ([Segment a], -- Needed by the 'client'
1135 [Segment a]) -- Not needed by the client
1136 -- The result is simply a split of the input
1138 = (reverse yeses, reverse noes)
1140 (noes, yeses) = span not_needed (reverse dus)
1141 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1144 ----------------------------------------------------
1145 segsToStmts :: Stmt Name -- A RecStmt with the SyntaxOps filled in
1146 -> [Segment [LStmt Name]]
1147 -> FreeVars -- Free vars used 'later'
1148 -> ([LStmt Name], FreeVars)
1150 segsToStmts _ [] fvs_later = ([], fvs_later)
1151 segsToStmts empty_rec_stmt ((defs, uses, fwds, ss) : segs) fvs_later
1152 = ASSERT( not (null ss) )
1153 (new_stmt : later_stmts, later_uses `plusFV` uses)
1155 (later_stmts, later_uses) = segsToStmts empty_rec_stmt segs fvs_later
1156 new_stmt | non_rec = head ss
1157 | otherwise = L (getLoc (head ss)) rec_stmt
1158 rec_stmt = empty_rec_stmt { recS_stmts = ss
1159 , recS_later_ids = nameSetToList used_later
1160 , recS_rec_ids = nameSetToList fwds }
1161 non_rec = isSingleton ss && isEmptyNameSet fwds
1162 used_later = defs `intersectNameSet` later_uses
1163 -- The ones needed after the RecStmt
1166 %************************************************************************
1168 \subsubsection{Assertion utils}
1170 %************************************************************************
1173 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1174 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDocOneLine (ppr span))))
1176 mkAssertErrorExpr :: RnM (HsExpr Name)
1177 -- Return an expression for (assertError "Foo.hs:27")
1179 = getSrcSpanM `thenM` \ sloc ->
1180 return (HsApp (L sloc (HsVar assertErrorName))
1181 (L sloc (srcSpanPrimLit sloc)))
1184 Note [Adding the implicit parameter to 'assert']
1185 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1186 The renamer transforms (assert e1 e2) to (assert "Foo.hs:27" e1 e2).
1187 By doing this in the renamer we allow the typechecker to just see the
1188 expanded application and do the right thing. But it's not really
1189 the Right Thing because there's no way to "undo" if you want to see
1190 the original source code. We'll have fix this in due course, when
1191 we care more about being able to reconstruct the exact original
1194 %************************************************************************
1196 \subsubsection{Errors}
1198 %************************************************************************
1201 ----------------------
1202 -- Checking when a particular Stmt is ok
1203 checkStmt :: HsStmtContext Name
1204 -> Bool -- True <=> this is the last Stmt in the sequence
1207 checkStmt ctxt is_last (L _ stmt)
1208 = do { dflags <- getDOpts
1209 ; case okStmt dflags ctxt is_last stmt of
1210 Nothing -> return ()
1211 Just extr -> addErr (msg $$ extra) }
1213 msg = ptext (sLit "Unexpected") <+> pprStmtCat stmt
1214 <+> ptext (sLit "statement in") <+> pprStmtContext ctxt
1216 pprStmtCat :: Stmt a -> SDoc
1217 pprStmtCat (TransformStmt {}) = ptext (sLit "transform")
1218 pprStmtCat (GroupStmt {}) = ptext (sLit "group")
1219 pprStmtCat (LastStmt {}) = ptext (sLit "return expression")
1220 pprStmtCat (ExprStmt {}) = ptext (sLit "exprssion")
1221 pprStmtCat (BindStmt {}) = ptext (sLit "binding")
1222 pprStmtCat (LetStmt {}) = ptext (sLit "let")
1223 pprStmtCat (RecStmt {}) = ptext (sLit "rec")
1224 pprStmtCat (ParStmt {}) = ptext (sLit "parallel")
1227 isOK, notOK :: Maybe SDoc
1231 okStmt, okDoStmt, okCompStmt :: DynFlags -> HsStmtContext Name -> Bool
1232 -> Stmt RdrName -> Maybe SDoc
1233 -- Return Nothing if OK, (Just extra) if not ok
1234 -- The "extra" is an SDoc that is appended to an generic error message
1235 okStmt dflags GhciStmt is_last stmt
1242 okStmt dflags (PatGuard {}) is_last stmt
1249 okStmt dflags (ParStmtCtxt ctxt) is_last stmt
1251 LetStmt (HsIPBinds {}) -> notOK
1252 _ -> okStmt dflags ctxt is_last stmt
1254 okStmt dflags (TransformStmtCtxt ctxt) is_last stmt
1255 = okStmt dflags ctxt is_last stmt
1257 okStmt ctxt is_last stmt
1258 | isDoExpr ctxt = okDoStmt ctxt is_last stmt
1259 | isCompExpr ctxt = okCompStmt ctxt is_last stmt
1260 | otherwise = pprPanic "okStmt" (pprStmtContext ctxt)
1263 okDoStmt dflags ctxt is_last stmt
1267 _ -> Just (ptext (sLit "The last statement in") <+> what <+>
1268 ptext (sLIt "construct must be an expression"))
1271 DoExpr -> ptext (sLit "a 'do'")
1272 MDoExpr -> ptext (sLit "an 'mdo'")
1273 _ -> panic "checkStmt"
1277 RecStmt {} -> isOK -- Shouldn't we test a flag?
1285 okCompStmt dflags ctxt is_last stmt
1288 LastStmt {} -> Nothing
1289 -> pprPanic "Unexpected stmt" (ppr stmt) -- Not a user error
1298 | dopt dflags Opt_ParallelListComp -> isOK
1299 | otherwise -> Just (ptext (sLit "Use -XParallelListComp"))
1301 | dopt dflags Opt_transformListComp -> isOK
1302 | otherwise -> Just (ptext (sLit "Use -XTransformListComp"))
1304 | dopt dflags Opt_transformListComp -> isOK
1305 | otherwise -> Just (ptext (sLit "Use -XTransformListComp"))
1308 checkStmt :: HsStmtContext Name -> Stmt RdrName -> Maybe SDoc
1311 checkStmt (ParStmtCtxt _) (HsIPBinds binds)
1312 = Just (badIpBinds (ptext (sLit "a parallel list comprehension:")) binds)
1313 -- We do not allow implicit-parameter bindings in a parallel
1314 -- list comprehension. I'm not sure what it might mean.
1316 checkStmt ctxt (RecStmt {})
1317 | not (isDoExpr ctxt)
1318 = addErr (ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt)
1321 checkParStmt :: HsStmtContext Name -> RnM ()
1323 = do { monad_comp <- xoptM Opt_MonadComprehensions
1324 ; unless monad_comp $ do
1325 { parallel_list_comp <- xoptM Opt_ParallelListComp
1326 ; checkErr parallel_list_comp msg }
1329 msg = ptext (sLit "Illegal parallel list comprehension: use -XParallelListComp or -XMonadComprehensions")
1332 checkTransformStmt :: HsStmtContext Name -> RnM ()
1333 checkTransformStmt ListComp -- Ensure we are really within a list comprehension because otherwise the
1334 -- desugarer will break when we come to operate on a parallel array
1335 = do { transform_list_comp <- xoptM Opt_TransformListComp
1336 ; checkErr transform_list_comp msg }
1338 msg = ptext (sLit "Illegal transform or grouping list comprehension: use -XTransformListComp or -XMonadComprehensions")
1339 checkTransformStmt MonadComp -- Monad comprehensions are always fine, since the
1340 -- MonadComprehensions flag will already be turned on
1342 checkTransformStmt (ParStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1343 checkTransformStmt (TransformStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1344 checkTransformStmt ctxt = addErr msg
1346 msg = ptext (sLit "Illegal transform or grouping in") <+> pprStmtContext ctxt
1349 checkTupleSection :: [HsTupArg RdrName] -> RnM ()
1350 checkTupleSection args
1351 = do { tuple_section <- xoptM Opt_TupleSections
1352 ; checkErr (all tupArgPresent args || tuple_section) msg }
1354 msg = ptext (sLit "Illegal tuple section: use -XTupleSections")
1357 sectionErr :: HsExpr RdrName -> SDoc
1359 = hang (ptext (sLit "A section must be enclosed in parentheses"))
1360 2 (ptext (sLit "thus:") <+> (parens (ppr expr)))
1362 patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
1363 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1365 ; return (EWildPat, emptyFVs) }
1367 badIpBinds :: Outputable a => SDoc -> a -> SDoc
1368 badIpBinds what binds
1369 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)