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 RnNames ( getLocalDeclBinders, extendRdrEnvRn )
27 import RnTypes ( rnHsTypeFVs, rnLPat, rnOverLit, rnPatsAndThen, rnLit,
28 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec,
29 dupFieldErr, checkTupSize )
30 import DynFlags ( DynFlag(..) )
31 import BasicTypes ( FixityDirection(..) )
32 import SrcLoc ( SrcSpan )
33 import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName,
34 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
35 negateName, thenMName, bindMName, failMName )
36 #if defined(GHCI) && defined(BREAKPOINT)
37 import PrelNames ( breakpointJumpName, breakpointCondJumpName
38 , undefined_RDR, breakpointIdKey, breakpointCondIdKey )
39 import UniqFM ( eltsUFM )
40 import DynFlags ( GhcMode(..) )
41 import Name ( isTyVarName )
43 import Name ( Name, nameOccName, nameIsLocalOrFrom )
45 import RdrName ( RdrName, extendLocalRdrEnv, lookupLocalRdrEnv, hideSomeUnquals )
46 import LoadIface ( loadInterfaceForName )
47 import UniqFM ( isNullUFM )
48 import UniqSet ( emptyUniqSet )
50 import Util ( isSingleton )
51 import ListSetOps ( removeDups )
52 import Maybes ( expectJust )
54 import SrcLoc ( Located(..), unLoc, getLoc, cmpLocated )
57 import List ( unzip4 )
61 %************************************************************************
63 \subsubsection{Expressions}
65 %************************************************************************
68 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
69 rnExprs ls = rnExprs' ls emptyUniqSet
71 rnExprs' [] acc = returnM ([], 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 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
81 returnM (expr':exprs', fvExprs)
83 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
84 grubby_seqNameSet ns result | isNullUFM ns = result
88 Variables. We look up the variable and return the resulting name.
91 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
92 rnLExpr = wrapLocFstM rnExpr
94 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
97 = do name <- lookupOccRn v
98 localRdrEnv <- getLocalRdrEnv
100 ignore_asserts <- doptM Opt_IgnoreAsserts
101 ignore_breakpoints <- doptM Opt_IgnoreBreakpoints
102 ghcMode <- getGhcMode
103 let conds = [ (name `hasKey` assertIdKey
104 && not ignore_asserts,
105 do (e, fvs) <- mkAssertErrorExpr
106 return (e, fvs `addOneFV` name))
107 #if defined(GHCI) && defined(BREAKPOINT)
108 , (name `hasKey` breakpointIdKey
109 && not ignore_breakpoints
110 && ghcMode == Interactive,
111 do let isWantedName = not.isTyVarName
112 (e, fvs) <- mkBreakpointExpr (filter isWantedName (eltsUFM localRdrEnv))
113 return (e, fvs `addOneFV` name)
115 , (name `hasKey` breakpointCondIdKey
116 && not ignore_breakpoints
117 && ghcMode == Interactive,
118 do let isWantedName = not.isTyVarName
119 (e, fvs) <- mkBreakpointCondExpr (filter isWantedName (eltsUFM localRdrEnv))
120 return (e, fvs `addOneFV` name)
124 case lookup True conds of
125 Just action -> action
126 Nothing -> return (HsVar name, unitFV name)
129 = newIPNameRn v `thenM` \ name ->
130 returnM (HsIPVar name, emptyFVs)
134 returnM (HsLit lit, emptyFVs)
136 rnExpr (HsOverLit lit)
137 = rnOverLit lit `thenM` \ (lit', fvs) ->
138 returnM (HsOverLit lit', fvs)
140 rnExpr (HsApp fun arg)
141 = rnLExpr fun `thenM` \ (fun',fvFun) ->
142 rnLExpr arg `thenM` \ (arg',fvArg) ->
143 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
145 rnExpr (OpApp e1 op _ e2)
146 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
147 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
148 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
151 -- When renaming code synthesised from "deriving" declarations
152 -- we used to avoid fixity stuff, but we can't easily tell any
153 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
154 -- should prevent bad things happening.
155 lookupFixityRn op_name `thenM` \ fixity ->
156 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
159 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
162 = rnLExpr e `thenM` \ (e', fv_e) ->
163 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
164 mkNegAppRn e' neg_name `thenM` \ final_e ->
165 returnM (final_e, fv_e `plusFV` fv_neg)
168 = rnLExpr e `thenM` \ (e', fvs_e) ->
169 returnM (HsPar e', fvs_e)
171 -- Template Haskell extensions
172 -- Don't ifdef-GHCI them because we want to fail gracefully
173 -- (not with an rnExpr crash) in a stage-1 compiler.
174 rnExpr e@(HsBracket br_body)
175 = checkTH e "bracket" `thenM_`
176 rnBracket br_body `thenM` \ (body', fvs_e) ->
177 returnM (HsBracket body', fvs_e)
179 rnExpr e@(HsSpliceE splice)
180 = rnSplice splice `thenM` \ (splice', fvs) ->
181 returnM (HsSpliceE splice', fvs)
183 rnExpr section@(SectionL expr op)
184 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
185 rnLExpr op `thenM` \ (op', fvs_op) ->
186 checkSectionPrec InfixL section op' expr' `thenM_`
187 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
189 rnExpr section@(SectionR op expr)
190 = rnLExpr op `thenM` \ (op', fvs_op) ->
191 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
192 checkSectionPrec InfixR section op' expr' `thenM_`
193 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
195 rnExpr (HsCoreAnn ann expr)
196 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
197 returnM (HsCoreAnn ann expr', fvs_expr)
199 rnExpr (HsSCC lbl expr)
200 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
201 returnM (HsSCC lbl expr', fvs_expr)
203 rnExpr (HsLam matches)
204 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
205 returnM (HsLam matches', fvMatch)
207 rnExpr (HsCase expr matches)
208 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
209 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
210 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
212 rnExpr (HsLet binds expr)
213 = rnLocalBindsAndThen binds $ \ binds' ->
214 rnLExpr expr `thenM` \ (expr',fvExpr) ->
215 returnM (HsLet binds' expr', fvExpr)
217 rnExpr e@(HsDo do_or_lc stmts body _)
218 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
220 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
222 rnExpr (ExplicitList _ exps)
223 = rnExprs exps `thenM` \ (exps', fvs) ->
224 returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name)
226 rnExpr (ExplicitPArr _ exps)
227 = rnExprs exps `thenM` \ (exps', fvs) ->
228 returnM (ExplicitPArr placeHolderType exps', fvs)
230 rnExpr e@(ExplicitTuple exps boxity)
231 = checkTupSize tup_size `thenM_`
232 rnExprs exps `thenM` \ (exps', fvs) ->
233 returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name)
235 tup_size = length exps
236 tycon_name = tupleTyCon_name boxity tup_size
238 rnExpr (RecordCon con_id _ rbinds)
239 = lookupLocatedOccRn con_id `thenM` \ conname ->
240 rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) ->
241 returnM (RecordCon conname noPostTcExpr rbinds',
242 fvRbinds `addOneFV` unLoc conname)
244 rnExpr (RecordUpd expr rbinds _ _)
245 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
246 rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) ->
247 returnM (RecordUpd expr' rbinds' placeHolderType placeHolderType,
248 fvExpr `plusFV` fvRbinds)
250 rnExpr (ExprWithTySig expr pty)
251 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
252 rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) ->
253 returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy)
255 doc = text "In an expression type signature"
257 rnExpr (HsIf p b1 b2)
258 = rnLExpr p `thenM` \ (p', fvP) ->
259 rnLExpr b1 `thenM` \ (b1', fvB1) ->
260 rnLExpr b2 `thenM` \ (b2', fvB2) ->
261 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
264 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
265 returnM (HsType t, fvT)
267 doc = text "In a type argument"
269 rnExpr (ArithSeq _ seq)
270 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
271 returnM (ArithSeq noPostTcExpr new_seq, fvs)
273 rnExpr (PArrSeq _ seq)
274 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
275 returnM (PArrSeq noPostTcExpr new_seq, fvs)
278 These three are pattern syntax appearing in expressions.
279 Since all the symbols are reservedops we can simply reject them.
280 We return a (bogus) EWildPat in each case.
283 rnExpr e@EWildPat = patSynErr e
284 rnExpr e@(EAsPat {}) = patSynErr e
285 rnExpr e@(ELazyPat {}) = patSynErr e
288 %************************************************************************
292 %************************************************************************
295 rnExpr (HsProc pat body)
297 rnPatsAndThen ProcExpr [pat] $ \ [pat'] ->
298 rnCmdTop body `thenM` \ (body',fvBody) ->
299 returnM (HsProc pat' body', fvBody)
301 rnExpr (HsArrApp arrow arg _ ho rtl)
302 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
303 rnLExpr arg `thenM` \ (arg',fvArg) ->
304 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
305 fvArrow `plusFV` fvArg)
307 select_arrow_scope tc = case ho of
308 HsHigherOrderApp -> tc
309 HsFirstOrderApp -> escapeArrowScope tc
312 rnExpr (HsArrForm op (Just _) [arg1, arg2])
313 = escapeArrowScope (rnLExpr op)
314 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
315 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
316 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
320 lookupFixityRn op_name `thenM` \ fixity ->
321 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
324 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
326 rnExpr (HsArrForm op fixity cmds)
327 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
328 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
329 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
331 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
336 %************************************************************************
340 %************************************************************************
343 rnCmdArgs [] = returnM ([], emptyFVs)
345 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
346 rnCmdArgs args `thenM` \ (args',fvArgs) ->
347 returnM (arg':args', fvArg `plusFV` fvArgs)
350 rnCmdTop = wrapLocFstM rnCmdTop'
352 rnCmdTop' (HsCmdTop cmd _ _ _)
353 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
355 cmd_names = [arrAName, composeAName, firstAName] ++
356 nameSetToList (methodNamesCmd (unLoc cmd'))
358 -- Generate the rebindable syntax for the monad
359 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
361 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
362 fvCmd `plusFV` cmd_fvs)
364 ---------------------------------------------------
365 -- convert OpApp's in a command context to HsArrForm's
367 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
368 convertOpFormsLCmd = fmap convertOpFormsCmd
370 convertOpFormsCmd :: HsCmd id -> HsCmd id
372 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
373 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
374 convertOpFormsCmd (OpApp c1 op fixity c2)
376 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
377 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
379 HsArrForm op (Just fixity) [arg1, arg2]
381 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
384 convertOpFormsCmd (HsCase exp matches)
385 = HsCase exp (convertOpFormsMatch matches)
387 convertOpFormsCmd (HsIf exp c1 c2)
388 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
390 convertOpFormsCmd (HsLet binds cmd)
391 = HsLet binds (convertOpFormsLCmd cmd)
393 convertOpFormsCmd (HsDo ctxt stmts body ty)
394 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
395 (convertOpFormsLCmd body) ty
397 -- Anything else is unchanged. This includes HsArrForm (already done),
398 -- things with no sub-commands, and illegal commands (which will be
399 -- caught by the type checker)
400 convertOpFormsCmd c = c
402 convertOpFormsStmt (BindStmt pat cmd _ _)
403 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
404 convertOpFormsStmt (ExprStmt cmd _ _)
405 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
406 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
407 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
408 convertOpFormsStmt stmt = stmt
410 convertOpFormsMatch (MatchGroup ms ty)
411 = MatchGroup (map (fmap convert) ms) ty
412 where convert (Match pat mty grhss)
413 = Match pat mty (convertOpFormsGRHSs grhss)
415 convertOpFormsGRHSs (GRHSs grhss binds)
416 = GRHSs (map convertOpFormsGRHS grhss) binds
418 convertOpFormsGRHS = fmap convert
420 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
422 ---------------------------------------------------
423 type CmdNeeds = FreeVars -- Only inhabitants are
424 -- appAName, choiceAName, loopAName
426 -- find what methods the Cmd needs (loop, choice, apply)
427 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
428 methodNamesLCmd = methodNamesCmd . unLoc
430 methodNamesCmd :: HsCmd Name -> CmdNeeds
432 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
434 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
436 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
438 methodNamesCmd (HsPar c) = methodNamesLCmd c
440 methodNamesCmd (HsIf p c1 c2)
441 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
443 methodNamesCmd (HsLet b c) = methodNamesLCmd c
445 methodNamesCmd (HsDo sc stmts body ty)
446 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
448 methodNamesCmd (HsApp c e) = methodNamesLCmd c
450 methodNamesCmd (HsLam match) = methodNamesMatch match
452 methodNamesCmd (HsCase scrut matches)
453 = methodNamesMatch matches `addOneFV` choiceAName
455 methodNamesCmd other = emptyFVs
456 -- Other forms can't occur in commands, but it's not convenient
457 -- to error here so we just do what's convenient.
458 -- The type checker will complain later
460 ---------------------------------------------------
461 methodNamesMatch (MatchGroup ms _)
462 = plusFVs (map do_one ms)
464 do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss
466 -------------------------------------------------
468 methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss)
470 -------------------------------------------------
471 methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs
473 ---------------------------------------------------
474 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
476 ---------------------------------------------------
477 methodNamesLStmt = methodNamesStmt . unLoc
479 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
480 methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd
481 methodNamesStmt (RecStmt stmts _ _ _ _)
482 = methodNamesStmts stmts `addOneFV` loopAName
483 methodNamesStmt (LetStmt b) = emptyFVs
484 methodNamesStmt (ParStmt ss) = emptyFVs
485 -- ParStmt can't occur in commands, but it's not convenient to error
486 -- here so we just do what's convenient
490 %************************************************************************
494 %************************************************************************
497 rnArithSeq (From expr)
498 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
499 returnM (From expr', fvExpr)
501 rnArithSeq (FromThen expr1 expr2)
502 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
503 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
504 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
506 rnArithSeq (FromTo expr1 expr2)
507 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
508 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
509 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
511 rnArithSeq (FromThenTo expr1 expr2 expr3)
512 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
513 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
514 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
515 returnM (FromThenTo expr1' expr2' expr3',
516 plusFVs [fvExpr1, fvExpr2, fvExpr3])
520 %************************************************************************
522 \subsubsection{@Rbinds@s and @Rpats@s: in record expressions}
524 %************************************************************************
528 = mappM_ field_dup_err dup_fields `thenM_`
529 mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) ->
530 returnM (rbinds', fvRbind)
532 (_, dup_fields) = removeDups cmpLocated [ f | (f,_) <- rbinds ]
534 field_dup_err dups = mappM_ (\f -> addLocErr f (dupFieldErr str)) dups
536 rn_rbind (field, expr)
537 = lookupLocatedGlobalOccRn field `thenM` \ fieldname ->
538 rnLExpr expr `thenM` \ (expr', fvExpr) ->
539 returnM ((fieldname, expr'), fvExpr `addOneFV` unLoc fieldname)
542 %************************************************************************
544 Template Haskell brackets
546 %************************************************************************
549 rnBracket (VarBr n) = do { name <- lookupOccRn n
550 ; this_mod <- getModule
551 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
552 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
553 ; return () } -- only way that is going to happen
554 ; returnM (VarBr name, unitFV name) }
556 msg = ptext SLIT("Need interface for Template Haskell quoted Name")
558 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
559 ; return (ExpBr e', fvs) }
560 rnBracket (PatBr p) = do { (p', fvs) <- rnLPat p
561 ; return (PatBr p', fvs) }
562 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
563 ; return (TypBr t', fvs) }
565 doc = ptext SLIT("In a Template-Haskell quoted type")
566 rnBracket (DecBr group)
567 = do { gbl_env <- getGblEnv
569 ; let gbl_env1 = gbl_env { tcg_mod = thFAKE }
570 -- Note the thFAKE. The top-level names from the bracketed
571 -- declarations will go into the name cache, and we don't want them to
572 -- confuse the Names for the current module.
573 -- By using a pretend module, thFAKE, we keep them safely out of the way.
575 ; names <- getLocalDeclBinders gbl_env1 group
577 ; let new_occs = map nameOccName names
578 trimmed_rdr_env = hideSomeUnquals (tcg_rdr_env gbl_env) new_occs
580 ; rdr_env' <- extendRdrEnvRn trimmed_rdr_env names
581 -- In this situation we want to *shadow* top-level bindings.
583 -- bar = [d| foo = 1|]
584 -- If we don't shadow, we'll get an ambiguity complaint when we do
585 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
587 -- Furthermore, arguably if the splice does define foo, that should hide
588 -- any foo's further out
590 -- The shadowing is acheived by the call to hideSomeUnquals, which removes
591 -- the unqualified bindings of things defined by the bracket
593 ; setGblEnv (gbl_env { tcg_rdr_env = rdr_env',
594 tcg_dus = emptyDUs }) $ do
595 -- The emptyDUs is so that we just collect uses for this group alone
597 { (tcg_env, group') <- rnSrcDecls group
598 -- Discard the tcg_env; it contains only extra info about fixity
599 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
602 %************************************************************************
604 \subsubsection{@Stmt@s: in @do@ expressions}
606 %************************************************************************
609 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
610 -> RnM (thing, FreeVars)
611 -> RnM (([LStmt Name], thing), FreeVars)
613 rnStmts (MDoExpr _) = rnMDoStmts
614 rnStmts ctxt = rnNormalStmts ctxt
616 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
617 -> RnM (thing, FreeVars)
618 -> RnM (([LStmt Name], thing), FreeVars)
619 -- Used for cases *other* than recursive mdo
620 -- Implements nested scopes
622 rnNormalStmts ctxt [] thing_inside
623 = do { (thing, fvs) <- thing_inside
624 ; return (([],thing), fvs) }
626 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
627 = do { ((stmt', (stmts', thing)), fvs)
628 <- rnStmt ctxt stmt $
629 rnNormalStmts ctxt stmts thing_inside
630 ; return (((L loc stmt' : stmts'), thing), fvs) }
632 rnStmt :: HsStmtContext Name -> Stmt RdrName
633 -> RnM (thing, FreeVars)
634 -> RnM ((Stmt Name, thing), FreeVars)
636 rnStmt ctxt (ExprStmt expr _ _) thing_inside
637 = do { (expr', fv_expr) <- rnLExpr expr
638 ; (then_op, fvs1) <- lookupSyntaxName thenMName
639 ; (thing, fvs2) <- thing_inside
640 ; return ((ExprStmt expr' then_op placeHolderType, thing),
641 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
643 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
644 = do { (expr', fv_expr) <- rnLExpr expr
645 -- The binders do not scope over the expression
646 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
647 ; (fail_op, fvs2) <- lookupSyntaxName failMName
648 ; rnPatsAndThen (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
649 { (thing, fvs3) <- thing_inside
650 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
651 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
652 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
653 -- but it does not matter because the names are unique
655 rnStmt ctxt (LetStmt binds) thing_inside
656 = do { checkErr (ok ctxt binds)
657 (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds)
658 ; rnLocalBindsAndThen binds $ \ binds' -> do
659 { (thing, fvs) <- thing_inside
660 ; return ((LetStmt binds', thing), fvs) }}
662 -- We do not allow implicit-parameter bindings in a parallel
663 -- list comprehension. I'm not sure what it might mean.
664 ok (ParStmtCtxt _) (HsIPBinds _) = False
667 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
668 = bindLocatedLocalsRn doc (collectLStmtsBinders rec_stmts) $ \ bndrs ->
669 rn_rec_stmts bndrs rec_stmts `thenM` \ segs ->
670 thing_inside `thenM` \ (thing, fvs) ->
672 segs_w_fwd_refs = addFwdRefs segs
673 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
674 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
675 fwd_vars = nameSetToList (plusFVs fs)
677 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
679 returnM ((rec_stmt, thing), uses `plusFV` fvs)
681 doc = text "In a recursive do statement"
683 rnStmt ctxt (ParStmt segs) thing_inside
684 = do { opt_GlasgowExts <- doptM Opt_GlasgowExts
685 ; checkM opt_GlasgowExts parStmtErr
686 ; orig_lcl_env <- getLocalRdrEnv
687 ; ((segs',thing), fvs) <- go orig_lcl_env [] segs
688 ; return ((ParStmt segs', thing), fvs) }
690 -- type ParSeg id = [([LStmt id], [id])]
691 -- go :: NameSet -> [ParSeg RdrName]
692 -- -> RnM (([ParSeg Name], thing), FreeVars)
694 go orig_lcl_env bndrs []
695 = do { let { (bndrs', dups) = removeDups cmpByOcc bndrs
696 ; inner_env = extendLocalRdrEnv orig_lcl_env bndrs' }
698 ; (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
699 ; return (([], thing), fvs) }
701 go orig_lcl_env bndrs_so_far ((stmts, _) : segs)
702 = do { ((stmts', (bndrs, segs', thing)), fvs)
703 <- rnNormalStmts par_ctxt stmts $ do
704 { -- Find the Names that are bound by stmts
705 lcl_env <- getLocalRdrEnv
706 ; let { rdr_bndrs = collectLStmtsBinders stmts
707 ; bndrs = map ( expectJust "rnStmt"
708 . lookupLocalRdrEnv lcl_env
710 ; new_bndrs = nub bndrs ++ bndrs_so_far
711 -- The nub is because there might be shadowing
713 -- So we'll look up (Unqual x) twice, getting
714 -- the second binding both times, which is the
717 -- Typecheck the thing inside, passing on all
718 -- the Names bound, but separately; revert the envt
719 ; ((segs', thing), fvs) <- setLocalRdrEnv orig_lcl_env $
720 go orig_lcl_env new_bndrs segs
722 -- Figure out which of the bound names are used
723 ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
724 ; return ((used_bndrs, segs', thing), fvs) }
726 ; let seg' = (stmts', bndrs)
727 ; return (((seg':segs'), thing),
728 delListFromNameSet fvs bndrs) }
730 par_ctxt = ParStmtCtxt ctxt
732 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
733 dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
734 <+> quotes (ppr (head vs)))
738 %************************************************************************
740 \subsubsection{mdo expressions}
742 %************************************************************************
745 type FwdRefs = NameSet
746 type Segment stmts = (Defs,
747 Uses, -- May include defs
748 FwdRefs, -- A subset of uses that are
749 -- (a) used before they are bound in this segment, or
750 -- (b) used here, and bound in subsequent segments
751 stmts) -- Either Stmt or [Stmt]
754 ----------------------------------------------------
755 rnMDoStmts :: [LStmt RdrName]
756 -> RnM (thing, FreeVars)
757 -> RnM (([LStmt Name], thing), FreeVars)
758 rnMDoStmts stmts thing_inside
759 = -- Step1: bring all the binders of the mdo into scope
760 -- Remember that this also removes the binders from the
761 -- finally-returned free-vars
762 bindLocatedLocalsRn doc (collectLStmtsBinders stmts) $ \ bndrs ->
764 -- Step 2: Rename each individual stmt, making a
765 -- singleton segment. At this stage the FwdRefs field
766 -- isn't finished: it's empty for all except a BindStmt
767 -- for which it's the fwd refs within the bind itself
768 -- (This set may not be empty, because we're in a recursive
770 segs <- rn_rec_stmts bndrs stmts
772 ; (thing, fvs_later) <- thing_inside
775 -- Step 3: Fill in the fwd refs.
776 -- The segments are all singletons, but their fwd-ref
777 -- field mentions all the things used by the segment
778 -- that are bound after their use
779 segs_w_fwd_refs = addFwdRefs segs
781 -- Step 4: Group together the segments to make bigger segments
782 -- Invariant: in the result, no segment uses a variable
783 -- bound in a later segment
784 grouped_segs = glomSegments segs_w_fwd_refs
786 -- Step 5: Turn the segments into Stmts
787 -- Use RecStmt when and only when there are fwd refs
788 -- Also gather up the uses from the end towards the
789 -- start, so we can tell the RecStmt which things are
790 -- used 'after' the RecStmt
791 (stmts', fvs) = segsToStmts grouped_segs fvs_later
793 ; return ((stmts', thing), fvs) }
795 doc = text "In a recursive mdo-expression"
797 ---------------------------------------------
798 rn_rec_stmts :: [Name] -> [LStmt RdrName] -> RnM [Segment (LStmt Name)]
799 rn_rec_stmts bndrs stmts = mappM (rn_rec_stmt bndrs) stmts `thenM` \ segs_s ->
800 returnM (concat segs_s)
802 ----------------------------------------------------
803 rn_rec_stmt :: [Name] -> LStmt RdrName -> RnM [Segment (LStmt Name)]
804 -- Rename a Stmt that is inside a RecStmt (or mdo)
805 -- Assumes all binders are already in scope
806 -- Turns each stmt into a singleton Stmt
808 rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _))
809 = rnLExpr expr `thenM` \ (expr', fvs) ->
810 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
811 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
812 L loc (ExprStmt expr' then_op placeHolderType))]
814 rn_rec_stmt all_bndrs (L loc (BindStmt pat expr _ _))
815 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
816 rnLPat pat `thenM` \ (pat', fv_pat) ->
817 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
818 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
820 bndrs = mkNameSet (collectPatBinders pat')
821 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
823 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
824 L loc (BindStmt pat' expr' bind_op fail_op))]
826 rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _)))
827 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
830 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds)))
831 = rnValBinds (trimWith all_bndrs) binds `thenM` \ (binds', du_binds) ->
832 returnM [(duDefs du_binds, duUses du_binds,
833 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
835 rn_rec_stmt all_bndrs (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
836 = rn_rec_stmts all_bndrs stmts
838 rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
839 = pprPanic "rn_rec_stmt" (ppr stmt)
841 ---------------------------------------------
842 addFwdRefs :: [Segment a] -> [Segment a]
843 -- So far the segments only have forward refs *within* the Stmt
844 -- (which happens for bind: x <- ...x...)
845 -- This function adds the cross-seg fwd ref info
848 = fst (foldr mk_seg ([], emptyNameSet) pairs)
850 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
851 = (new_seg : segs, all_defs)
853 new_seg = (defs, uses, new_fwds, stmts)
854 all_defs = later_defs `unionNameSets` defs
855 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
856 -- Add the downstream fwd refs here
858 ----------------------------------------------------
859 -- Glomming the singleton segments of an mdo into
860 -- minimal recursive groups.
862 -- At first I thought this was just strongly connected components, but
863 -- there's an important constraint: the order of the stmts must not change.
866 -- mdo { x <- ...y...
873 -- Here, the first stmt mention 'y', which is bound in the third.
874 -- But that means that the innocent second stmt (p <- z) gets caught
875 -- up in the recursion. And that in turn means that the binding for
876 -- 'z' has to be included... and so on.
878 -- Start at the tail { r <- x }
879 -- Now add the next one { z <- y ; r <- x }
880 -- Now add one more { q <- x ; z <- y ; r <- x }
881 -- Now one more... but this time we have to group a bunch into rec
882 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
883 -- Now one more, which we can add on without a rec
885 -- rec { y <- ...x... ; q <- x ; z <- y } ;
887 -- Finally we add the last one; since it mentions y we have to
888 -- glom it togeher with the first two groups
889 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
890 -- q <- x ; z <- y } ;
893 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
896 glomSegments ((defs,uses,fwds,stmt) : segs)
897 -- Actually stmts will always be a singleton
898 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
900 segs' = glomSegments segs
901 (extras, others) = grab uses segs'
902 (ds, us, fs, ss) = unzip4 extras
904 seg_defs = plusFVs ds `plusFV` defs
905 seg_uses = plusFVs us `plusFV` uses
906 seg_fwds = plusFVs fs `plusFV` fwds
907 seg_stmts = stmt : concat ss
909 grab :: NameSet -- The client
911 -> ([Segment a], -- Needed by the 'client'
912 [Segment a]) -- Not needed by the client
913 -- The result is simply a split of the input
915 = (reverse yeses, reverse noes)
917 (noes, yeses) = span not_needed (reverse dus)
918 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
921 ----------------------------------------------------
922 segsToStmts :: [Segment [LStmt Name]]
923 -> FreeVars -- Free vars used 'later'
924 -> ([LStmt Name], FreeVars)
926 segsToStmts [] fvs_later = ([], fvs_later)
927 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
928 = ASSERT( not (null ss) )
929 (new_stmt : later_stmts, later_uses `plusFV` uses)
931 (later_stmts, later_uses) = segsToStmts segs fvs_later
932 new_stmt | non_rec = head ss
933 | otherwise = L (getLoc (head ss)) $
934 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
937 non_rec = isSingleton ss && isEmptyNameSet fwds
938 used_later = defs `intersectNameSet` later_uses
939 -- The ones needed after the RecStmt
942 %************************************************************************
944 \subsubsection{breakpoint utils}
946 %************************************************************************
949 #if defined(GHCI) && defined(BREAKPOINT)
950 mkBreakpointExpr :: [Name] -> RnM (HsExpr Name, FreeVars)
951 mkBreakpointExpr = mkBreakpointExpr' breakpointJumpName
953 mkBreakpointCondExpr :: [Name] -> RnM (HsExpr Name, FreeVars)
954 mkBreakpointCondExpr = mkBreakpointExpr' breakpointCondJumpName
956 mkBreakpointExpr' :: Name -> [Name] -> RnM (HsExpr Name, FreeVars)
957 mkBreakpointExpr' breakpointFunc scope
958 = do sloc <- getSrcSpanM
959 undef <- lookupOccRn undefined_RDR
961 lHsApp x y = inLoc (HsApp x y)
962 mkExpr fnName args = mkExpr' fnName (reverse args)
963 mkExpr' fnName [] = inLoc (HsVar fnName)
964 mkExpr' fnName (arg:args)
965 = lHsApp (mkExpr' fnName args) (inLoc arg)
966 expr = unLoc $ mkExpr breakpointFunc [mkScopeArg scope, HsVar undef, msg]
967 mkScopeArg args = unLoc $ mkExpr undef (map HsVar args)
968 msg = srcSpanLit sloc
969 return (expr, emptyFVs)
971 srcSpanLit :: SrcSpan -> HsExpr Name
972 srcSpanLit span = HsLit (HsString (mkFastString (showSDoc (ppr span))))
975 srcSpanPrimLit :: SrcSpan -> HsExpr Name
976 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
979 %************************************************************************
981 \subsubsection{Assertion utils}
983 %************************************************************************
986 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
987 -- Return an expression for (assertError "Foo.hs:27")
989 = getSrcSpanM `thenM` \ sloc ->
991 expr = HsApp (L sloc (HsVar assertErrorName))
992 (L sloc (srcSpanPrimLit sloc))
994 returnM (expr, emptyFVs)
997 %************************************************************************
999 \subsubsection{Errors}
1001 %************************************************************************
1004 patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context:"),
1006 ; return (EWildPat, emptyFVs) }
1008 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -fglasgow-exts"))
1010 badIpBinds what binds
1011 = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what)