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"
19 import RnSource ( rnSrcDecls, rnSplice, checkTH )
20 import RnBinds ( rnLocalBindsAndThen, rnValBinds,
21 rnMatchGroup, trimWith )
26 import OccName ( plusOccEnv )
27 import RnNames ( getLocalDeclBinders, extendRdrEnvRn )
28 import RnTypes ( rnHsTypeFVs, rnLPat, rnOverLit, rnPatsAndThen, rnLit,
29 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec,
30 dupFieldErr, checkTupSize )
31 import DynFlags ( DynFlag(..) )
32 import BasicTypes ( FixityDirection(..) )
33 import SrcLoc ( SrcSpan )
34 import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName,
35 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
36 negateName, thenMName, bindMName, failMName )
37 #if defined(GHCI) && defined(BREAKPOINT)
38 import PrelNames ( breakpointJumpName, breakpointCondJumpName
39 , undefined_RDR, breakpointIdKey, breakpointCondIdKey )
40 import UniqFM ( eltsUFM )
41 import DynFlags ( GhcMode(..) )
42 import Name ( isTyVarName )
44 import Name ( Name, nameOccName, nameIsLocalOrFrom )
46 import RdrName ( RdrName, emptyGlobalRdrEnv, extendLocalRdrEnv, lookupLocalRdrEnv, hideSomeUnquals )
47 import LoadIface ( loadInterfaceForName )
48 import UniqFM ( isNullUFM )
49 import UniqSet ( emptyUniqSet )
51 import Util ( isSingleton )
52 import ListSetOps ( removeDups )
53 import Maybes ( expectJust )
55 import SrcLoc ( Located(..), unLoc, getLoc, cmpLocated )
58 import List ( unzip4 )
62 %************************************************************************
64 \subsubsection{Expressions}
66 %************************************************************************
69 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
70 rnExprs ls = rnExprs' ls emptyUniqSet
72 rnExprs' [] acc = returnM ([], acc)
73 rnExprs' (expr:exprs) acc
74 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
76 -- Now we do a "seq" on the free vars because typically it's small
77 -- or empty, especially in very long lists of constants
79 acc' = acc `plusFV` fvExpr
81 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
82 returnM (expr':exprs', fvExprs)
84 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
85 grubby_seqNameSet ns result | isNullUFM ns = result
89 Variables. We look up the variable and return the resulting name.
92 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
93 rnLExpr = wrapLocFstM rnExpr
95 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
98 = do name <- lookupOccRn v
99 localRdrEnv <- getLocalRdrEnv
101 ignore_asserts <- doptM Opt_IgnoreAsserts
102 ignore_breakpoints <- doptM Opt_IgnoreBreakpoints
103 ghcMode <- getGhcMode
104 let conds = [ (name `hasKey` assertIdKey
105 && not ignore_asserts,
106 do (e, fvs) <- mkAssertErrorExpr
107 return (e, fvs `addOneFV` name))
108 #if defined(GHCI) && defined(BREAKPOINT)
109 , (name `hasKey` breakpointIdKey
110 && not ignore_breakpoints
111 && ghcMode == Interactive,
112 do let isWantedName = not.isTyVarName
113 (e, fvs) <- mkBreakpointExpr (filter isWantedName (eltsUFM localRdrEnv))
114 return (e, fvs `addOneFV` name)
116 , (name `hasKey` breakpointCondIdKey
117 && not ignore_breakpoints
118 && ghcMode == Interactive,
119 do let isWantedName = not.isTyVarName
120 (e, fvs) <- mkBreakpointCondExpr (filter isWantedName (eltsUFM localRdrEnv))
121 return (e, fvs `addOneFV` name)
125 case lookup True conds of
126 Just action -> action
127 Nothing -> return (HsVar name, unitFV name)
130 = newIPNameRn v `thenM` \ name ->
131 returnM (HsIPVar name, 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 e@(HsSpliceE splice)
181 = rnSplice splice `thenM` \ (splice', fvs) ->
182 returnM (HsSpliceE splice', fvs)
184 rnExpr section@(SectionL expr op)
185 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
186 rnLExpr op `thenM` \ (op', fvs_op) ->
187 checkSectionPrec InfixL section op' expr' `thenM_`
188 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
190 rnExpr section@(SectionR op expr)
191 = rnLExpr op `thenM` \ (op', fvs_op) ->
192 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
193 checkSectionPrec InfixR section op' expr' `thenM_`
194 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
196 rnExpr (HsCoreAnn ann expr)
197 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
198 returnM (HsCoreAnn ann expr', fvs_expr)
200 rnExpr (HsSCC lbl expr)
201 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
202 returnM (HsSCC lbl expr', fvs_expr)
204 rnExpr (HsLam matches)
205 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
206 returnM (HsLam matches', fvMatch)
208 rnExpr (HsCase expr matches)
209 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
210 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
211 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
213 rnExpr (HsLet binds expr)
214 = rnLocalBindsAndThen binds $ \ binds' ->
215 rnLExpr expr `thenM` \ (expr',fvExpr) ->
216 returnM (HsLet binds' expr', fvExpr)
218 rnExpr e@(HsDo do_or_lc stmts body _)
219 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
221 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
223 rnExpr (ExplicitList _ exps)
224 = rnExprs exps `thenM` \ (exps', fvs) ->
225 returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name)
227 rnExpr (ExplicitPArr _ exps)
228 = rnExprs exps `thenM` \ (exps', fvs) ->
229 returnM (ExplicitPArr placeHolderType exps', fvs)
231 rnExpr e@(ExplicitTuple exps boxity)
232 = checkTupSize tup_size `thenM_`
233 rnExprs exps `thenM` \ (exps', fvs) ->
234 returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name)
236 tup_size = length exps
237 tycon_name = tupleTyCon_name boxity tup_size
239 rnExpr (RecordCon con_id _ rbinds)
240 = lookupLocatedOccRn con_id `thenM` \ conname ->
241 rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) ->
242 returnM (RecordCon conname noPostTcExpr rbinds',
243 fvRbinds `addOneFV` unLoc conname)
245 rnExpr (RecordUpd expr rbinds _ _)
246 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
247 rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) ->
248 returnM (RecordUpd expr' rbinds' placeHolderType placeHolderType,
249 fvExpr `plusFV` fvRbinds)
251 rnExpr (ExprWithTySig expr pty)
252 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
253 rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) ->
254 returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy)
256 doc = text "In an expression type signature"
258 rnExpr (HsIf p b1 b2)
259 = rnLExpr p `thenM` \ (p', fvP) ->
260 rnLExpr b1 `thenM` \ (b1', fvB1) ->
261 rnLExpr b2 `thenM` \ (b2', fvB2) ->
262 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
265 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
266 returnM (HsType t, fvT)
268 doc = text "In a type argument"
270 rnExpr (ArithSeq _ seq)
271 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
272 returnM (ArithSeq noPostTcExpr new_seq, fvs)
274 rnExpr (PArrSeq _ seq)
275 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
276 returnM (PArrSeq noPostTcExpr new_seq, fvs)
279 These three are pattern syntax appearing in expressions.
280 Since all the symbols are reservedops we can simply reject them.
281 We return a (bogus) EWildPat in each case.
284 rnExpr e@EWildPat = patSynErr e
285 rnExpr e@(EAsPat {}) = patSynErr e
286 rnExpr e@(ELazyPat {}) = patSynErr e
289 %************************************************************************
293 %************************************************************************
296 rnExpr (HsProc pat body)
298 rnPatsAndThen ProcExpr [pat] $ \ [pat'] ->
299 rnCmdTop body `thenM` \ (body',fvBody) ->
300 returnM (HsProc pat' body', fvBody)
302 rnExpr (HsArrApp arrow arg _ ho rtl)
303 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
304 rnLExpr arg `thenM` \ (arg',fvArg) ->
305 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
306 fvArrow `plusFV` fvArg)
308 select_arrow_scope tc = case ho of
309 HsHigherOrderApp -> tc
310 HsFirstOrderApp -> escapeArrowScope tc
313 rnExpr (HsArrForm op (Just _) [arg1, arg2])
314 = escapeArrowScope (rnLExpr op)
315 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
316 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
317 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
321 lookupFixityRn op_name `thenM` \ fixity ->
322 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
325 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
327 rnExpr (HsArrForm op fixity cmds)
328 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
329 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
330 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
332 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
337 %************************************************************************
341 %************************************************************************
344 rnCmdArgs [] = returnM ([], emptyFVs)
346 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
347 rnCmdArgs args `thenM` \ (args',fvArgs) ->
348 returnM (arg':args', fvArg `plusFV` fvArgs)
351 rnCmdTop = wrapLocFstM rnCmdTop'
353 rnCmdTop' (HsCmdTop cmd _ _ _)
354 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
356 cmd_names = [arrAName, composeAName, firstAName] ++
357 nameSetToList (methodNamesCmd (unLoc cmd'))
359 -- Generate the rebindable syntax for the monad
360 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
362 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
363 fvCmd `plusFV` cmd_fvs)
365 ---------------------------------------------------
366 -- convert OpApp's in a command context to HsArrForm's
368 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
369 convertOpFormsLCmd = fmap convertOpFormsCmd
371 convertOpFormsCmd :: HsCmd id -> HsCmd id
373 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
374 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
375 convertOpFormsCmd (OpApp c1 op fixity c2)
377 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
378 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
380 HsArrForm op (Just fixity) [arg1, arg2]
382 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
385 convertOpFormsCmd (HsCase exp matches)
386 = HsCase exp (convertOpFormsMatch matches)
388 convertOpFormsCmd (HsIf exp c1 c2)
389 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
391 convertOpFormsCmd (HsLet binds cmd)
392 = HsLet binds (convertOpFormsLCmd cmd)
394 convertOpFormsCmd (HsDo ctxt stmts body ty)
395 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
396 (convertOpFormsLCmd body) ty
398 -- Anything else is unchanged. This includes HsArrForm (already done),
399 -- things with no sub-commands, and illegal commands (which will be
400 -- caught by the type checker)
401 convertOpFormsCmd c = c
403 convertOpFormsStmt (BindStmt pat cmd _ _)
404 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
405 convertOpFormsStmt (ExprStmt cmd _ _)
406 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
407 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
408 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
409 convertOpFormsStmt stmt = stmt
411 convertOpFormsMatch (MatchGroup ms ty)
412 = MatchGroup (map (fmap convert) ms) ty
413 where convert (Match pat mty grhss)
414 = Match pat mty (convertOpFormsGRHSs grhss)
416 convertOpFormsGRHSs (GRHSs grhss binds)
417 = GRHSs (map convertOpFormsGRHS grhss) binds
419 convertOpFormsGRHS = fmap convert
421 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
423 ---------------------------------------------------
424 type CmdNeeds = FreeVars -- Only inhabitants are
425 -- appAName, choiceAName, loopAName
427 -- find what methods the Cmd needs (loop, choice, apply)
428 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
429 methodNamesLCmd = methodNamesCmd . unLoc
431 methodNamesCmd :: HsCmd Name -> CmdNeeds
433 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
435 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
437 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
439 methodNamesCmd (HsPar c) = methodNamesLCmd c
441 methodNamesCmd (HsIf p c1 c2)
442 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
444 methodNamesCmd (HsLet b c) = methodNamesLCmd c
446 methodNamesCmd (HsDo sc stmts body ty)
447 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
449 methodNamesCmd (HsApp c e) = methodNamesLCmd c
451 methodNamesCmd (HsLam match) = methodNamesMatch match
453 methodNamesCmd (HsCase scrut matches)
454 = methodNamesMatch matches `addOneFV` choiceAName
456 methodNamesCmd other = emptyFVs
457 -- Other forms can't occur in commands, but it's not convenient
458 -- to error here so we just do what's convenient.
459 -- The type checker will complain later
461 ---------------------------------------------------
462 methodNamesMatch (MatchGroup ms _)
463 = plusFVs (map do_one ms)
465 do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss
467 -------------------------------------------------
469 methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss)
471 -------------------------------------------------
472 methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs
474 ---------------------------------------------------
475 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
477 ---------------------------------------------------
478 methodNamesLStmt = methodNamesStmt . unLoc
480 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
481 methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd
482 methodNamesStmt (RecStmt stmts _ _ _ _)
483 = methodNamesStmts stmts `addOneFV` loopAName
484 methodNamesStmt (LetStmt b) = emptyFVs
485 methodNamesStmt (ParStmt ss) = emptyFVs
486 -- ParStmt can't occur in commands, but it's not convenient to error
487 -- here so we just do what's convenient
491 %************************************************************************
495 %************************************************************************
498 rnArithSeq (From expr)
499 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
500 returnM (From expr', fvExpr)
502 rnArithSeq (FromThen expr1 expr2)
503 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
504 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
505 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
507 rnArithSeq (FromTo expr1 expr2)
508 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
509 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
510 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
512 rnArithSeq (FromThenTo expr1 expr2 expr3)
513 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
514 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
515 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
516 returnM (FromThenTo expr1' expr2' expr3',
517 plusFVs [fvExpr1, fvExpr2, fvExpr3])
521 %************************************************************************
523 \subsubsection{@Rbinds@s and @Rpats@s: in record expressions}
525 %************************************************************************
529 = mappM_ field_dup_err dup_fields `thenM_`
530 mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) ->
531 returnM (rbinds', fvRbind)
533 (_, dup_fields) = removeDups cmpLocated [ f | (f,_) <- rbinds ]
535 field_dup_err dups = mappM_ (\f -> addLocErr f (dupFieldErr str)) dups
537 rn_rbind (field, expr)
538 = lookupLocatedGlobalOccRn field `thenM` \ fieldname ->
539 rnLExpr expr `thenM` \ (expr', fvExpr) ->
540 returnM ((fieldname, expr'), fvExpr `addOneFV` unLoc fieldname)
543 %************************************************************************
545 Template Haskell brackets
547 %************************************************************************
550 rnBracket (VarBr n) = do { name <- lookupOccRn n
551 ; this_mod <- getModule
552 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
553 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
554 ; return () } -- only way that is going to happen
555 ; returnM (VarBr name, unitFV name) }
557 msg = ptext SLIT("Need interface for Template Haskell quoted Name")
559 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
560 ; return (ExpBr e', fvs) }
561 rnBracket (PatBr p) = do { (p', fvs) <- rnLPat p
562 ; return (PatBr p', fvs) }
563 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
564 ; return (TypBr t', fvs) }
566 doc = ptext SLIT("In a Template-Haskell quoted type")
567 rnBracket (DecBr group)
568 = do { gbl_env <- getGblEnv
570 ; let gbl_env1 = gbl_env { tcg_mod = thFAKE }
571 -- Note the thFAKE. The top-level names from the bracketed
572 -- declarations will go into the name cache, and we don't want them to
573 -- confuse the Names for the current module.
574 -- By using a pretend module, thFAKE, we keep them safely out of the way.
576 ; names <- getLocalDeclBinders gbl_env1 group
578 ; let new_occs = map nameOccName names
579 trimmed_rdr_env = hideSomeUnquals (tcg_rdr_env gbl_env) new_occs
581 ; rdr_env' <- extendRdrEnvRn trimmed_rdr_env names
582 -- In this situation we want to *shadow* top-level bindings.
584 -- bar = [d| foo = 1|]
585 -- If we don't shadow, we'll get an ambiguity complaint when we do
586 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
588 -- Furthermore, arguably if the splice does define foo, that should hide
589 -- any foo's further out
591 -- The shadowing is acheived by the call to hideSomeUnquals, which removes
592 -- the unqualified bindings of things defined by the bracket
594 ; setGblEnv (gbl_env { tcg_rdr_env = rdr_env',
595 tcg_dus = emptyDUs }) $ do
596 -- The emptyDUs is so that we just collect uses for this group alone
598 { (tcg_env, group') <- rnSrcDecls 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 ctxt [] 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)
629 <- rnStmt ctxt stmt $
630 rnNormalStmts ctxt stmts thing_inside
631 ; 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 ctxt (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 (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 { checkErr (ok ctxt binds)
658 (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds)
659 ; rnLocalBindsAndThen binds $ \ binds' -> do
660 { (thing, fvs) <- thing_inside
661 ; return ((LetStmt binds', thing), fvs) }}
663 -- We do not allow implicit-parameter bindings in a parallel
664 -- list comprehension. I'm not sure what it might mean.
665 ok (ParStmtCtxt _) (HsIPBinds _) = False
668 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
669 = bindLocatedLocalsRn doc (collectLStmtsBinders rec_stmts) $ \ bndrs ->
670 rn_rec_stmts bndrs rec_stmts `thenM` \ segs ->
671 thing_inside `thenM` \ (thing, fvs) ->
673 segs_w_fwd_refs = addFwdRefs segs
674 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
675 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
676 fwd_vars = nameSetToList (plusFVs fs)
678 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
680 returnM ((rec_stmt, thing), uses `plusFV` fvs)
682 doc = text "In a recursive do statement"
684 rnStmt ctxt (ParStmt segs) thing_inside
685 = do { opt_GlasgowExts <- doptM Opt_GlasgowExts
686 ; checkM opt_GlasgowExts parStmtErr
687 ; orig_lcl_env <- getLocalRdrEnv
688 ; ((segs',thing), fvs) <- go orig_lcl_env [] segs
689 ; return ((ParStmt segs', thing), fvs) }
691 -- type ParSeg id = [([LStmt id], [id])]
692 -- go :: NameSet -> [ParSeg RdrName]
693 -- -> RnM (([ParSeg Name], thing), FreeVars)
695 go orig_lcl_env bndrs []
696 = do { let { (bndrs', dups) = removeDups cmpByOcc bndrs
697 ; inner_env = extendLocalRdrEnv orig_lcl_env bndrs' }
699 ; (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
700 ; return (([], thing), fvs) }
702 go orig_lcl_env bndrs_so_far ((stmts, _) : segs)
703 = do { ((stmts', (bndrs, segs', thing)), fvs)
704 <- rnNormalStmts par_ctxt stmts $ do
705 { -- Find the Names that are bound by stmts
706 lcl_env <- getLocalRdrEnv
707 ; let { rdr_bndrs = collectLStmtsBinders stmts
708 ; bndrs = map ( expectJust "rnStmt"
709 . lookupLocalRdrEnv lcl_env
711 ; new_bndrs = nub bndrs ++ bndrs_so_far
712 -- The nub is because there might be shadowing
714 -- So we'll look up (Unqual x) twice, getting
715 -- the second binding both times, which is the
718 -- Typecheck the thing inside, passing on all
719 -- the Names bound, but separately; revert the envt
720 ; ((segs', thing), fvs) <- setLocalRdrEnv orig_lcl_env $
721 go orig_lcl_env new_bndrs segs
723 -- Figure out which of the bound names are used
724 ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
725 ; return ((used_bndrs, segs', thing), fvs) }
727 ; let seg' = (stmts', bndrs)
728 ; return (((seg':segs'), thing),
729 delListFromNameSet fvs bndrs) }
731 par_ctxt = ParStmtCtxt ctxt
733 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
734 dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
735 <+> quotes (ppr (head vs)))
739 %************************************************************************
741 \subsubsection{mdo expressions}
743 %************************************************************************
746 type FwdRefs = NameSet
747 type Segment stmts = (Defs,
748 Uses, -- May include defs
749 FwdRefs, -- A subset of uses that are
750 -- (a) used before they are bound in this segment, or
751 -- (b) used here, and bound in subsequent segments
752 stmts) -- Either Stmt or [Stmt]
755 ----------------------------------------------------
756 rnMDoStmts :: [LStmt RdrName]
757 -> RnM (thing, FreeVars)
758 -> RnM (([LStmt Name], thing), FreeVars)
759 rnMDoStmts stmts thing_inside
760 = -- Step1: bring all the binders of the mdo into scope
761 -- Remember that this also removes the binders from the
762 -- finally-returned free-vars
763 bindLocatedLocalsRn doc (collectLStmtsBinders stmts) $ \ bndrs ->
765 -- Step 2: Rename each individual stmt, making a
766 -- singleton segment. At this stage the FwdRefs field
767 -- isn't finished: it's empty for all except a BindStmt
768 -- for which it's the fwd refs within the bind itself
769 -- (This set may not be empty, because we're in a recursive
771 segs <- rn_rec_stmts bndrs stmts
773 ; (thing, fvs_later) <- thing_inside
776 -- Step 3: Fill in the fwd refs.
777 -- The segments are all singletons, but their fwd-ref
778 -- field mentions all the things used by the segment
779 -- that are bound after their use
780 segs_w_fwd_refs = addFwdRefs segs
782 -- Step 4: Group together the segments to make bigger segments
783 -- Invariant: in the result, no segment uses a variable
784 -- bound in a later segment
785 grouped_segs = glomSegments segs_w_fwd_refs
787 -- Step 5: Turn the segments into Stmts
788 -- Use RecStmt when and only when there are fwd refs
789 -- Also gather up the uses from the end towards the
790 -- start, so we can tell the RecStmt which things are
791 -- used 'after' the RecStmt
792 (stmts', fvs) = segsToStmts grouped_segs fvs_later
794 ; return ((stmts', thing), fvs) }
796 doc = text "In a recursive mdo-expression"
798 ---------------------------------------------
799 rn_rec_stmts :: [Name] -> [LStmt RdrName] -> RnM [Segment (LStmt Name)]
800 rn_rec_stmts bndrs stmts = mappM (rn_rec_stmt bndrs) stmts `thenM` \ segs_s ->
801 returnM (concat segs_s)
803 ----------------------------------------------------
804 rn_rec_stmt :: [Name] -> LStmt RdrName -> RnM [Segment (LStmt Name)]
805 -- Rename a Stmt that is inside a RecStmt (or mdo)
806 -- Assumes all binders are already in scope
807 -- Turns each stmt into a singleton Stmt
809 rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _))
810 = rnLExpr expr `thenM` \ (expr', fvs) ->
811 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
812 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
813 L loc (ExprStmt expr' then_op placeHolderType))]
815 rn_rec_stmt all_bndrs (L loc (BindStmt pat expr _ _))
816 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
817 rnLPat pat `thenM` \ (pat', fv_pat) ->
818 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
819 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
821 bndrs = mkNameSet (collectPatBinders pat')
822 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
824 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
825 L loc (BindStmt pat' expr' bind_op fail_op))]
827 rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _)))
828 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
831 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds)))
832 = rnValBinds (trimWith all_bndrs) binds `thenM` \ (binds', du_binds) ->
833 returnM [(duDefs du_binds, duUses du_binds,
834 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
836 rn_rec_stmt all_bndrs (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
837 = rn_rec_stmts all_bndrs stmts
839 rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
840 = pprPanic "rn_rec_stmt" (ppr stmt)
842 ---------------------------------------------
843 addFwdRefs :: [Segment a] -> [Segment a]
844 -- So far the segments only have forward refs *within* the Stmt
845 -- (which happens for bind: x <- ...x...)
846 -- This function adds the cross-seg fwd ref info
849 = fst (foldr mk_seg ([], emptyNameSet) pairs)
851 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
852 = (new_seg : segs, all_defs)
854 new_seg = (defs, uses, new_fwds, stmts)
855 all_defs = later_defs `unionNameSets` defs
856 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
857 -- Add the downstream fwd refs here
859 ----------------------------------------------------
860 -- Glomming the singleton segments of an mdo into
861 -- minimal recursive groups.
863 -- At first I thought this was just strongly connected components, but
864 -- there's an important constraint: the order of the stmts must not change.
867 -- mdo { x <- ...y...
874 -- Here, the first stmt mention 'y', which is bound in the third.
875 -- But that means that the innocent second stmt (p <- z) gets caught
876 -- up in the recursion. And that in turn means that the binding for
877 -- 'z' has to be included... and so on.
879 -- Start at the tail { r <- x }
880 -- Now add the next one { z <- y ; r <- x }
881 -- Now add one more { q <- x ; z <- y ; r <- x }
882 -- Now one more... but this time we have to group a bunch into rec
883 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
884 -- Now one more, which we can add on without a rec
886 -- rec { y <- ...x... ; q <- x ; z <- y } ;
888 -- Finally we add the last one; since it mentions y we have to
889 -- glom it togeher with the first two groups
890 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
891 -- q <- x ; z <- y } ;
894 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
897 glomSegments ((defs,uses,fwds,stmt) : segs)
898 -- Actually stmts will always be a singleton
899 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
901 segs' = glomSegments segs
902 (extras, others) = grab uses segs'
903 (ds, us, fs, ss) = unzip4 extras
905 seg_defs = plusFVs ds `plusFV` defs
906 seg_uses = plusFVs us `plusFV` uses
907 seg_fwds = plusFVs fs `plusFV` fwds
908 seg_stmts = stmt : concat ss
910 grab :: NameSet -- The client
912 -> ([Segment a], -- Needed by the 'client'
913 [Segment a]) -- Not needed by the client
914 -- The result is simply a split of the input
916 = (reverse yeses, reverse noes)
918 (noes, yeses) = span not_needed (reverse dus)
919 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
922 ----------------------------------------------------
923 segsToStmts :: [Segment [LStmt Name]]
924 -> FreeVars -- Free vars used 'later'
925 -> ([LStmt Name], FreeVars)
927 segsToStmts [] fvs_later = ([], fvs_later)
928 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
929 = ASSERT( not (null ss) )
930 (new_stmt : later_stmts, later_uses `plusFV` uses)
932 (later_stmts, later_uses) = segsToStmts segs fvs_later
933 new_stmt | non_rec = head ss
934 | otherwise = L (getLoc (head ss)) $
935 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
938 non_rec = isSingleton ss && isEmptyNameSet fwds
939 used_later = defs `intersectNameSet` later_uses
940 -- The ones needed after the RecStmt
943 %************************************************************************
945 \subsubsection{breakpoint utils}
947 %************************************************************************
950 #if defined(GHCI) && defined(BREAKPOINT)
951 mkBreakpointExpr :: [Name] -> RnM (HsExpr Name, FreeVars)
952 mkBreakpointExpr = mkBreakpointExpr' breakpointJumpName
954 mkBreakpointCondExpr :: [Name] -> RnM (HsExpr Name, FreeVars)
955 mkBreakpointCondExpr = mkBreakpointExpr' breakpointCondJumpName
957 mkBreakpointExpr' :: Name -> [Name] -> RnM (HsExpr Name, FreeVars)
958 mkBreakpointExpr' breakpointFunc scope
959 = do sloc <- getSrcSpanM
960 undef <- lookupOccRn undefined_RDR
962 lHsApp x y = inLoc (HsApp x y)
963 mkExpr fnName args = mkExpr' fnName (reverse args)
964 mkExpr' fnName [] = inLoc (HsVar fnName)
965 mkExpr' fnName (arg:args)
966 = lHsApp (mkExpr' fnName args) (inLoc arg)
967 expr = unLoc $ mkExpr breakpointFunc [mkScopeArg scope, HsVar undef, msg]
968 mkScopeArg args = unLoc $ mkExpr undef (map HsVar args)
969 msg = srcSpanLit sloc
970 return (expr, emptyFVs)
973 srcSpanLit :: SrcSpan -> HsExpr Name
974 srcSpanLit span = HsLit (HsString (mkFastString (showSDoc (ppr span))))
976 srcSpanPrimLit :: SrcSpan -> HsExpr Name
977 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
980 %************************************************************************
982 \subsubsection{Assertion utils}
984 %************************************************************************
987 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
988 -- Return an expression for (assertError "Foo.hs:27")
990 = getSrcSpanM `thenM` \ sloc ->
992 expr = HsApp (L sloc (HsVar assertErrorName))
993 (L sloc (srcSpanPrimLit sloc))
995 returnM (expr, emptyFVs)
998 %************************************************************************
1000 \subsubsection{Errors}
1002 %************************************************************************
1005 patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context:"),
1007 ; return (EWildPat, emptyFVs) }
1009 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -fglasgow-exts"))
1011 badIpBinds what binds
1012 = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what)