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 rnMatch, rnGRHSs, rnExpr, rnExprs, rnStmts,
18 #include "HsVersions.h"
20 import {-# SOURCE #-} RnSource ( rnSrcDecls, rnBindsAndThen, rnBinds )
22 -- RnSource imports RnBinds.rnTopMonoBinds, RnExpr.rnExpr
23 -- RnBinds imports RnExpr.rnMatch, etc
24 -- RnExpr imports [boot] RnSource.rnSrcDecls, RnSource.rnBinds
31 import RdrName ( plusGlobalRdrEnv )
32 import RnNames ( importsFromLocalDecls )
33 import RnTypes ( rnHsTypeFVs, rnPat, litFVs, rnOverLit, rnPatsAndThen,
34 dupFieldErr, precParseErr, sectionPrecErr, patSigErr, checkTupSize )
35 import CmdLineOpts ( DynFlag(..) )
36 import BasicTypes ( Fixity(..), FixityDirection(..), negateFixity, compareFixity )
37 import PrelNames ( hasKey, assertIdKey, assertErrorName,
38 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
39 negateName, monadNames, mfixName )
40 import Name ( Name, nameOccName )
42 import UnicodeUtil ( stringToUtf8 )
43 import UniqFM ( isNullUFM )
44 import UniqSet ( emptyUniqSet )
45 import Util ( isSingleton )
46 import List ( unzip4 )
47 import ListSetOps ( removeDups )
49 import SrcLoc ( noSrcLoc )
54 ************************************************************************
58 ************************************************************************
61 rnMatch :: HsMatchContext Name -> RdrNameMatch -> RnM (RenamedMatch, FreeVars)
63 rnMatch ctxt match@(Match pats maybe_rhs_sig grhss)
64 = addSrcLoc (getMatchLoc match) $
66 -- Deal with the rhs type signature
67 bindPatSigTyVarsFV rhs_sig_tys $
68 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
69 (case maybe_rhs_sig of
70 Nothing -> returnM (Nothing, emptyFVs)
71 Just ty | opt_GlasgowExts -> rnHsTypeFVs doc_sig ty `thenM` \ (ty', ty_fvs) ->
72 returnM (Just ty', ty_fvs)
73 | otherwise -> addErr (patSigErr ty) `thenM_`
74 returnM (Nothing, emptyFVs)
75 ) `thenM` \ (maybe_rhs_sig', ty_fvs) ->
78 rnPatsAndThen ctxt True pats $ \ pats' ->
79 rnGRHSs ctxt grhss `thenM` \ (grhss', grhss_fvs) ->
81 returnM (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
82 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
84 rhs_sig_tys = case maybe_rhs_sig of
87 doc_sig = text "In a result type-signature"
91 %************************************************************************
93 \subsubsection{Guarded right-hand sides (GRHSs)}
95 %************************************************************************
98 rnGRHSs :: HsMatchContext Name -> RdrNameGRHSs -> RnM (RenamedGRHSs, FreeVars)
100 rnGRHSs ctxt (GRHSs grhss binds _)
101 = rnBindsAndThen binds $ \ binds' ->
102 mapFvRn (rnGRHS ctxt) grhss `thenM` \ (grhss', fvGRHSs) ->
103 returnM (GRHSs grhss' binds' placeHolderType, fvGRHSs)
105 rnGRHS ctxt (GRHS guarded locn)
107 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
108 checkM (opt_GlasgowExts || is_standard_guard guarded)
109 (addWarn (nonStdGuardErr guarded)) `thenM_`
111 rnStmts (PatGuard ctxt) guarded `thenM` \ (guarded', fvs) ->
112 returnM (GRHS guarded' locn, fvs)
114 -- Standard Haskell 1.4 guards are just a single boolean
115 -- expression, rather than a list of qualifiers as in the
117 is_standard_guard [ResultStmt _ _] = True
118 is_standard_guard [ExprStmt _ _ _, ResultStmt _ _] = True
119 is_standard_guard other = False
122 %************************************************************************
124 \subsubsection{Expressions}
126 %************************************************************************
129 rnExprs :: [RdrNameHsExpr] -> RnM ([RenamedHsExpr], FreeVars)
130 rnExprs ls = rnExprs' ls emptyUniqSet
132 rnExprs' [] acc = returnM ([], acc)
133 rnExprs' (expr:exprs) acc
134 = rnExpr expr `thenM` \ (expr', fvExpr) ->
136 -- Now we do a "seq" on the free vars because typically it's small
137 -- or empty, especially in very long lists of constants
139 acc' = acc `plusFV` fvExpr
141 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
142 returnM (expr':exprs', fvExprs)
144 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
145 grubby_seqNameSet ns result | isNullUFM ns = result
149 Variables. We look up the variable and return the resulting name.
152 rnExpr :: RdrNameHsExpr -> RnM (RenamedHsExpr, FreeVars)
155 = lookupOccRn v `thenM` \ name ->
156 doptM Opt_IgnoreAsserts `thenM` \ ignore_asserts ->
157 if name `hasKey` assertIdKey && not ignore_asserts then
158 -- We expand it to (GHC.Err.assertError location_string)
159 mkAssertErrorExpr `thenM` \ (e, fvs) ->
160 returnM (e, fvs `addOneFV` name)
161 -- Keep 'assert' as a free var, to ensure it's not reported as unused!
163 -- The normal case. Even if the Id was 'assert', if we are
164 -- ignoring assertions we leave it as GHC.Base.assert;
165 -- this function just ignores its first arg.
166 returnM (HsVar name, unitFV name)
169 = newIPNameRn v `thenM` \ name ->
170 returnM (HsIPVar name, emptyFVs)
173 = litFVs lit `thenM` \ fvs ->
174 returnM (HsLit lit, fvs)
176 rnExpr (HsOverLit lit)
177 = rnOverLit lit `thenM` \ (lit', fvs) ->
178 returnM (HsOverLit lit', fvs)
181 = rnMatch LambdaExpr match `thenM` \ (match', fvMatch) ->
182 returnM (HsLam match', fvMatch)
184 rnExpr (HsApp fun arg)
185 = rnExpr fun `thenM` \ (fun',fvFun) ->
186 rnExpr arg `thenM` \ (arg',fvArg) ->
187 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
189 rnExpr (OpApp e1 op _ e2)
190 = rnExpr e1 `thenM` \ (e1', fv_e1) ->
191 rnExpr e2 `thenM` \ (e2', fv_e2) ->
192 rnExpr op `thenM` \ (op'@(HsVar op_name), fv_op) ->
195 -- When renaming code synthesised from "deriving" declarations
196 -- we used to avoid fixity stuff, but we can't easily tell any
197 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
198 -- should prevent bad things happening.
199 lookupFixityRn op_name `thenM` \ fixity ->
200 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
203 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
206 = rnExpr e `thenM` \ (e', fv_e) ->
207 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
208 mkNegAppRn e' neg_name `thenM` \ final_e ->
209 returnM (final_e, fv_e `plusFV` fv_neg)
212 = rnExpr e `thenM` \ (e', fvs_e) ->
213 returnM (HsPar e', fvs_e)
215 -- Template Haskell extensions
216 -- Don't ifdef-GHCI them because we want to fail gracefully
217 -- (not with an rnExpr crash) in a stage-1 compiler.
218 rnExpr e@(HsBracket br_body loc)
220 checkTH e "bracket" `thenM_`
221 rnBracket br_body `thenM` \ (body', fvs_e) ->
222 returnM (HsBracket body' loc, fvs_e)
224 rnExpr e@(HsSplice n splice loc)
226 checkTH e "splice" `thenM_`
227 newLocalsRn [(n,loc)] `thenM` \ [n'] ->
228 rnExpr splice `thenM` \ (splice', fvs_e) ->
229 returnM (HsSplice n' splice' loc, fvs_e)
231 rnExpr e@(HsReify (Reify flavour name))
232 = checkTH e "reify" `thenM_`
233 lookupGlobalOccRn name `thenM` \ name' ->
234 -- For now, we can only reify top-level things
235 returnM (HsReify (Reify flavour name'), unitFV name')
237 rnExpr section@(SectionL expr op)
238 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
239 rnExpr op `thenM` \ (op', fvs_op) ->
240 checkSectionPrec InfixL section op' expr' `thenM_`
241 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
243 rnExpr section@(SectionR op expr)
244 = rnExpr op `thenM` \ (op', fvs_op) ->
245 rnExpr expr `thenM` \ (expr', fvs_expr) ->
246 checkSectionPrec InfixR section op' expr' `thenM_`
247 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
249 rnExpr (HsCoreAnn ann expr)
250 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
251 returnM (HsCoreAnn ann expr', fvs_expr)
253 rnExpr (HsSCC lbl expr)
254 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
255 returnM (HsSCC lbl expr', fvs_expr)
257 rnExpr (HsCase expr ms src_loc)
258 = addSrcLoc src_loc $
259 rnExpr expr `thenM` \ (new_expr, e_fvs) ->
260 mapFvRn (rnMatch CaseAlt) ms `thenM` \ (new_ms, ms_fvs) ->
261 returnM (HsCase new_expr new_ms src_loc, e_fvs `plusFV` ms_fvs)
263 rnExpr (HsLet binds expr)
264 = rnBindsAndThen binds $ \ binds' ->
265 rnExpr expr `thenM` \ (expr',fvExpr) ->
266 returnM (HsLet binds' expr', fvExpr)
268 rnExpr e@(HsDo do_or_lc stmts _ _ src_loc)
269 = addSrcLoc src_loc $
270 rnStmts do_or_lc stmts `thenM` \ (stmts', fvs) ->
272 -- Check the statement list ends in an expression
273 case last stmts' of {
274 ResultStmt _ _ -> returnM () ;
275 _ -> addErr (doStmtListErr do_or_lc e)
278 -- Generate the rebindable syntax for the monad
279 lookupSyntaxNames syntax_names `thenM` \ (syntax_names', monad_fvs) ->
281 returnM (HsDo do_or_lc stmts' syntax_names' placeHolderType src_loc,
282 fvs `plusFV` monad_fvs)
284 syntax_names = case do_or_lc of
286 MDoExpr -> monadNames ++ [mfixName]
289 rnExpr (ExplicitList _ exps)
290 = rnExprs exps `thenM` \ (exps', fvs) ->
291 returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name)
293 rnExpr (ExplicitPArr _ exps)
294 = rnExprs exps `thenM` \ (exps', fvs) ->
295 returnM (ExplicitPArr placeHolderType exps', fvs)
297 rnExpr e@(ExplicitTuple exps boxity)
298 = checkTupSize tup_size `thenM_`
299 rnExprs exps `thenM` \ (exps', fvs) ->
300 returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name)
302 tup_size = length exps
303 tycon_name = tupleTyCon_name boxity tup_size
305 rnExpr (RecordCon con_id rbinds)
306 = lookupOccRn con_id `thenM` \ conname ->
307 rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) ->
308 returnM (RecordCon conname rbinds', fvRbinds `addOneFV` conname)
310 rnExpr (RecordUpd expr rbinds)
311 = rnExpr expr `thenM` \ (expr', fvExpr) ->
312 rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) ->
313 returnM (RecordUpd expr' rbinds', fvExpr `plusFV` fvRbinds)
315 rnExpr (ExprWithTySig expr pty)
316 = rnExpr expr `thenM` \ (expr', fvExpr) ->
317 rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) ->
318 returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy)
320 doc = text "In an expression type signature"
322 rnExpr (HsIf p b1 b2 src_loc)
323 = addSrcLoc src_loc $
324 rnExpr p `thenM` \ (p', fvP) ->
325 rnExpr b1 `thenM` \ (b1', fvB1) ->
326 rnExpr b2 `thenM` \ (b2', fvB2) ->
327 returnM (HsIf p' b1' b2' src_loc, plusFVs [fvP, fvB1, fvB2])
330 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
331 returnM (HsType t, fvT)
333 doc = text "In a type argument"
335 rnExpr (ArithSeqIn seq)
336 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
337 returnM (ArithSeqIn new_seq, fvs)
339 rnExpr (PArrSeqIn seq)
340 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
341 returnM (PArrSeqIn new_seq, fvs)
344 These three are pattern syntax appearing in expressions.
345 Since all the symbols are reservedops we can simply reject them.
346 We return a (bogus) EWildPat in each case.
349 rnExpr e@EWildPat = addErr (patSynErr e) `thenM_`
350 returnM (EWildPat, emptyFVs)
352 rnExpr e@(EAsPat _ _) = addErr (patSynErr e) `thenM_`
353 returnM (EWildPat, emptyFVs)
355 rnExpr e@(ELazyPat _) = addErr (patSynErr e) `thenM_`
356 returnM (EWildPat, emptyFVs)
359 %************************************************************************
363 %************************************************************************
366 rnExpr (HsProc pat body src_loc)
367 = addSrcLoc src_loc $
368 rnPatsAndThen ProcExpr True [pat] $ \ [pat'] ->
369 rnCmdTop body `thenM` \ (body',fvBody) ->
370 returnM (HsProc pat' body' src_loc, fvBody)
372 rnExpr (HsArrApp arrow arg _ ho rtl srcloc)
373 = rnExpr arrow `thenM` \ (arrow',fvArrow) ->
374 rnExpr arg `thenM` \ (arg',fvArg) ->
375 returnM (HsArrApp arrow' arg' placeHolderType ho rtl srcloc,
376 fvArrow `plusFV` fvArg)
379 rnExpr (HsArrForm op (Just _) [arg1, arg2] srcloc)
380 = rnExpr op `thenM` \ (op'@(HsVar op_name),fv_op) ->
381 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
382 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
386 lookupFixityRn op_name `thenM` \ fixity ->
387 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
390 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
392 rnExpr (HsArrForm op fixity cmds srcloc)
393 = rnExpr op `thenM` \ (op',fvOp) ->
394 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
395 returnM (HsArrForm op' fixity cmds' srcloc,
396 fvOp `plusFV` fvCmds)
398 ---------------------------
399 -- Deal with fixity (cf mkOpAppRn for the method)
401 mkOpFormRn :: RenamedHsCmdTop -- Left operand; already rearranged
402 -> RenamedHsExpr -> Fixity -- Operator and fixity
403 -> RenamedHsCmdTop -- Right operand (not an infix)
406 ---------------------------
407 -- (e11 `op1` e12) `op2` e2
408 mkOpFormRn a1@(HsCmdTop (HsArrForm op1 (Just fix1) [a11,a12] loc1) _ _ _) op2 fix2 a2
410 = addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) `thenM_`
411 returnM (HsArrForm op2 (Just fix2) [a1, a2] loc1)
414 = mkOpFormRn a12 op2 fix2 a2 `thenM` \ new_c ->
415 returnM (HsArrForm op1 (Just fix1)
416 [a11, HsCmdTop new_c [] placeHolderType []] loc1)
418 (nofix_error, associate_right) = compareFixity fix1 fix2
420 ---------------------------
422 mkOpFormRn arg1 op fix arg2 -- Default case, no rearrangment
423 = returnM (HsArrForm op (Just fix) [arg1, arg2] noSrcLoc)
428 %************************************************************************
432 %************************************************************************
435 rnCmdArgs [] = returnM ([], emptyFVs)
437 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
438 rnCmdArgs args `thenM` \ (args',fvArgs) ->
439 returnM (arg':args', fvArg `plusFV` fvArgs)
441 rnCmdTop (HsCmdTop cmd _ _ _)
442 = rnExpr (convertOpFormsCmd cmd) `thenM` \ (cmd', fvCmd) ->
444 cmd_names = [arrAName, composeAName, firstAName] ++
445 nameSetToList (methodNamesCmd cmd')
447 -- Generate the rebindable syntax for the monad
448 lookupSyntaxNames cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
450 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
451 fvCmd `plusFV` cmd_fvs)
453 ---------------------------------------------------
454 -- convert OpApp's in a command context to HsArrForm's
456 convertOpFormsCmd :: HsCmd id -> HsCmd id
458 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsCmd c) e
460 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
462 convertOpFormsCmd (OpApp c1 op fixity c2)
464 arg1 = HsCmdTop (convertOpFormsCmd c1) [] placeHolderType []
465 arg2 = HsCmdTop (convertOpFormsCmd c2) [] placeHolderType []
467 HsArrForm op (Just fixity) [arg1, arg2] noSrcLoc
469 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsCmd c)
471 convertOpFormsCmd (HsCase exp matches locn)
472 = HsCase exp (map convertOpFormsMatch matches) locn
474 convertOpFormsCmd (HsIf exp c1 c2 locn)
475 = HsIf exp (convertOpFormsCmd c1) (convertOpFormsCmd c2) locn
477 convertOpFormsCmd (HsLet binds cmd)
478 = HsLet binds (convertOpFormsCmd cmd)
480 convertOpFormsCmd (HsDo ctxt stmts ids ty locn)
481 = HsDo ctxt (map convertOpFormsStmt stmts) ids ty locn
483 -- Anything else is unchanged. This includes HsArrForm (already done),
484 -- things with no sub-commands, and illegal commands (which will be
485 -- caught by the type checker)
486 convertOpFormsCmd c = c
488 convertOpFormsStmt (BindStmt pat cmd locn)
489 = BindStmt pat (convertOpFormsCmd cmd) locn
490 convertOpFormsStmt (ResultStmt cmd locn)
491 = ResultStmt (convertOpFormsCmd cmd) locn
492 convertOpFormsStmt (ExprStmt cmd ty locn)
493 = ExprStmt (convertOpFormsCmd cmd) ty locn
494 convertOpFormsStmt (RecStmt stmts lvs rvs es)
495 = RecStmt (map convertOpFormsStmt stmts) lvs rvs es
496 convertOpFormsStmt stmt = stmt
498 convertOpFormsMatch (Match pat mty grhss)
499 = Match pat mty (convertOpFormsGRHSs grhss)
501 convertOpFormsGRHSs (GRHSs grhss binds ty)
502 = GRHSs (map convertOpFormsGRHS grhss) binds ty
504 convertOpFormsGRHS (GRHS stmts locn)
506 (ResultStmt cmd locn') = last stmts
508 GRHS (init stmts ++ [ResultStmt (convertOpFormsCmd cmd) locn']) locn
510 ---------------------------------------------------
511 type CmdNeeds = FreeVars -- Only inhabitants are
512 -- appAName, choiceAName, loopAName
514 -- find what methods the Cmd needs (loop, choice, apply)
515 methodNamesCmd :: HsCmd Name -> CmdNeeds
517 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl _srcloc)
519 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl _srcloc)
521 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
523 methodNamesCmd (HsPar c) = methodNamesCmd c
525 methodNamesCmd (HsIf p c1 c2 loc)
526 = methodNamesCmd c1 `plusFV` methodNamesCmd c2 `addOneFV` choiceAName
528 methodNamesCmd (HsLet b c) = methodNamesCmd c
530 methodNamesCmd (HsDo sc stmts rbs ty loc) = methodNamesStmts stmts
532 methodNamesCmd (HsApp c e) = methodNamesCmd c
534 methodNamesCmd (HsLam match) = methodNamesMatch match
536 methodNamesCmd (HsCase scrut matches loc)
537 = plusFVs (map methodNamesMatch matches) `addOneFV` choiceAName
539 methodNamesCmd other = emptyFVs
540 -- Other forms can't occur in commands, but it's not convenient
541 -- to error here so we just do what's convenient.
542 -- The type checker will complain later
544 ---------------------------------------------------
545 methodNamesMatch (Match pats sig_ty grhss) = methodNamesGRHSs grhss
547 -------------------------------------------------
548 methodNamesGRHSs (GRHSs grhss binds ty) = plusFVs (map methodNamesGRHS grhss)
550 -------------------------------------------------
551 methodNamesGRHS (GRHS stmts loc) = methodNamesStmt (last stmts)
553 ---------------------------------------------------
554 methodNamesStmts stmts = plusFVs (map methodNamesStmt stmts)
556 ---------------------------------------------------
557 methodNamesStmt (ResultStmt cmd loc) = methodNamesCmd cmd
558 methodNamesStmt (ExprStmt cmd ty loc) = methodNamesCmd cmd
559 methodNamesStmt (BindStmt pat cmd loc) = methodNamesCmd cmd
560 methodNamesStmt (RecStmt stmts lvs rvs es)
561 = methodNamesStmts stmts `addOneFV` loopAName
562 methodNamesStmt (LetStmt b) = emptyFVs
563 methodNamesStmt (ParStmt ss) = emptyFVs
564 -- ParStmt can't occur in commands, but it's not convenient to error
565 -- here so we just do what's convenient
569 %************************************************************************
573 %************************************************************************
576 rnArithSeq (From expr)
577 = rnExpr expr `thenM` \ (expr', fvExpr) ->
578 returnM (From expr', fvExpr)
580 rnArithSeq (FromThen expr1 expr2)
581 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
582 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
583 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
585 rnArithSeq (FromTo expr1 expr2)
586 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
587 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
588 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
590 rnArithSeq (FromThenTo expr1 expr2 expr3)
591 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
592 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
593 rnExpr expr3 `thenM` \ (expr3', fvExpr3) ->
594 returnM (FromThenTo expr1' expr2' expr3',
595 plusFVs [fvExpr1, fvExpr2, fvExpr3])
599 %************************************************************************
601 \subsubsection{@Rbinds@s and @Rpats@s: in record expressions}
603 %************************************************************************
607 = mappM_ field_dup_err dup_fields `thenM_`
608 mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) ->
609 returnM (rbinds', fvRbind)
611 (_, dup_fields) = removeDups compare [ f | (f,_) <- rbinds ]
613 field_dup_err dups = addErr (dupFieldErr str dups)
615 rn_rbind (field, expr)
616 = lookupGlobalOccRn field `thenM` \ fieldname ->
617 rnExpr expr `thenM` \ (expr', fvExpr) ->
618 returnM ((fieldname, expr'), fvExpr `addOneFV` fieldname)
621 %************************************************************************
623 Template Haskell brackets
625 %************************************************************************
628 rnBracket (ExpBr e) = rnExpr e `thenM` \ (e', fvs) ->
629 returnM (ExpBr e', fvs)
630 rnBracket (PatBr p) = rnPat p `thenM` \ (p', fvs) ->
631 returnM (PatBr p', fvs)
632 rnBracket (TypBr t) = rnHsTypeFVs doc t `thenM` \ (t', fvs) ->
633 returnM (TypBr t', fvs)
635 doc = ptext SLIT("In a Template-Haskell quoted type")
636 rnBracket (DecBr group)
637 = importsFromLocalDecls group `thenM` \ (rdr_env, avails) ->
638 -- Discard avails (not useful here)
640 updGblEnv (\gbl -> gbl { tcg_rdr_env = rdr_env `plusGlobalRdrEnv` tcg_rdr_env gbl }) $
642 rnSrcDecls group `thenM` \ (tcg_env, group', dus) ->
643 -- Discard the tcg_env; it contains only extra info about fixity
645 returnM (DecBr group', duUses dus `minusNameSet` duDefs dus)
648 %************************************************************************
650 \subsubsection{@Stmt@s: in @do@ expressions}
652 %************************************************************************
655 rnStmts :: HsStmtContext Name -> [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
657 rnStmts MDoExpr stmts = rnMDoStmts stmts
658 rnStmts ctxt stmts = rnNormalStmts ctxt stmts
660 rnNormalStmts :: HsStmtContext Name -> [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
661 -- Used for cases *other* than recursive mdo
662 -- Implements nested scopes
664 rnNormalStmts ctxt [] = returnM ([], emptyFVs)
665 -- Happens at the end of the sub-lists of a ParStmts
667 rnNormalStmts ctxt (ExprStmt expr _ src_loc : stmts)
668 = addSrcLoc src_loc $
669 rnExpr expr `thenM` \ (expr', fv_expr) ->
670 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
671 returnM (ExprStmt expr' placeHolderType src_loc : stmts',
672 fv_expr `plusFV` fvs)
674 rnNormalStmts ctxt [ResultStmt expr src_loc]
675 = addSrcLoc src_loc $
676 rnExpr expr `thenM` \ (expr', fv_expr) ->
677 returnM ([ResultStmt expr' src_loc], fv_expr)
679 rnNormalStmts ctxt (BindStmt pat expr src_loc : stmts)
680 = addSrcLoc src_loc $
681 rnExpr expr `thenM` \ (expr', fv_expr) ->
682 -- The binders do not scope over the expression
687 ParStmtCtxt{} -> False
690 rnPatsAndThen (StmtCtxt ctxt) reportUnused [pat] $ \ [pat'] ->
691 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
692 returnM (BindStmt pat' expr' src_loc : stmts',
693 fv_expr `plusFV` fvs) -- fv_expr shouldn't really be filtered by
694 -- the rnPatsAndThen, but it does not matter
696 rnNormalStmts ctxt (LetStmt binds : stmts)
697 = checkErr (ok ctxt binds) (badIpBinds binds) `thenM_`
698 rnBindsAndThen binds ( \ binds' ->
699 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
700 returnM (LetStmt binds' : stmts', fvs))
702 -- We do not allow implicit-parameter bindings in a parallel
703 -- list comprehension. I'm not sure what it might mean.
704 ok (ParStmtCtxt _) (IPBinds _) = False
707 rnNormalStmts ctxt (ParStmt stmtss : stmts)
708 = doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
709 checkM opt_GlasgowExts parStmtErr `thenM_`
710 mapFvRn rn_branch stmtss `thenM` \ (stmtss', fv_stmtss) ->
712 bndrss :: [[Name]] -- NB: Name, not RdrName
713 bndrss = map collectStmtsBinders stmtss'
714 (bndrs, dups) = removeDups cmpByOcc (concat bndrss)
716 mappM dupErr dups `thenM` \ _ ->
717 bindLocalNamesFV bndrs $
718 -- Note: binders are returned in scope order, so one may
719 -- shadow the next; e.g. x <- xs; x <- ys
720 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
722 -- Cut down the exported binders to just the ones needed in the body
724 used_bndrs_s = map (filter (`elemNameSet` fvs)) bndrss
725 unused_bndrs = filter (not . (`elemNameSet` fvs)) bndrs
727 -- With processing of the branches and the tail of comprehension done,
728 -- we can finally compute&report any unused ParStmt binders.
729 warnUnusedMatches unused_bndrs `thenM_`
730 returnM (ParStmt (stmtss' `zip` used_bndrs_s) : stmts',
731 fv_stmtss `plusFV` fvs)
733 rn_branch (stmts, _) = rnNormalStmts (ParStmtCtxt ctxt) stmts
735 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
736 dupErr (v:_) = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
739 rnNormalStmts ctxt (RecStmt rec_stmts _ _ _ : stmts)
740 = bindLocalsRn doc (collectStmtsBinders rec_stmts) $ \ _ ->
741 rn_rec_stmts rec_stmts `thenM` \ segs ->
742 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
744 segs_w_fwd_refs = addFwdRefs segs
745 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
746 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
747 fwd_vars = nameSetToList (plusFVs fs)
750 returnM (RecStmt rec_stmts' later_vars fwd_vars [] : stmts', uses `plusFV` fvs)
752 doc = text "In a recursive do statement"
756 %************************************************************************
758 \subsubsection{mdo expressions}
760 %************************************************************************
763 type FwdRefs = NameSet
764 type Segment stmts = (Defs,
765 Uses, -- May include defs
766 FwdRefs, -- A subset of uses that are
767 -- (a) used before they are bound in this segment, or
768 -- (b) used here, and bound in subsequent segments
769 stmts) -- Either Stmt or [Stmt]
772 ----------------------------------------------------
773 rnMDoStmts :: [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
775 = -- Step1: bring all the binders of the mdo into scope
776 -- Remember that this also removes the binders from the
777 -- finally-returned free-vars
778 bindLocalsRn doc (collectStmtsBinders stmts) $ \ _ ->
780 -- Step 2: Rename each individual stmt, making a
781 -- singleton segment. At this stage the FwdRefs field
782 -- isn't finished: it's empty for all except a BindStmt
783 -- for which it's the fwd refs within the bind itself
784 -- (This set may not be empty, because we're in a recursive
786 rn_rec_stmts stmts `thenM` \ segs ->
788 -- Step 3: Fill in the fwd refs.
789 -- The segments are all singletons, but their fwd-ref
790 -- field mentions all the things used by the segment
791 -- that are bound after their use
792 segs_w_fwd_refs = addFwdRefs segs
794 -- Step 4: Group together the segments to make bigger segments
795 -- Invariant: in the result, no segment uses a variable
796 -- bound in a later segment
797 grouped_segs = glomSegments segs_w_fwd_refs
799 -- Step 5: Turn the segments into Stmts
800 -- Use RecStmt when and only when there are fwd refs
801 -- Also gather up the uses from the end towards the
802 -- start, so we can tell the RecStmt which things are
803 -- used 'after' the RecStmt
804 stmts_w_fvs = segsToStmts grouped_segs
808 doc = text "In a mdo-expression"
811 ----------------------------------------------------
812 rn_rec_stmt :: RdrNameStmt -> RnM [Segment RenamedStmt]
813 -- Rename a Stmt that is inside a RecStmt (or mdo)
814 -- Assumes all binders are already in scope
815 -- Turns each stmt into a singleton Stmt
817 rn_rec_stmt (ExprStmt expr _ src_loc)
818 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
819 returnM [(emptyNameSet, fvs, emptyNameSet,
820 ExprStmt expr' placeHolderType src_loc)]
822 rn_rec_stmt (ResultStmt expr src_loc)
823 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
824 returnM [(emptyNameSet, fvs, emptyNameSet,
825 ResultStmt expr' src_loc)]
827 rn_rec_stmt (BindStmt pat expr src_loc)
828 = addSrcLoc src_loc $
829 rnExpr expr `thenM` \ (expr', fv_expr) ->
830 rnPat pat `thenM` \ (pat', fv_pat) ->
832 bndrs = mkNameSet (collectPatBinders pat')
833 fvs = fv_expr `plusFV` fv_pat
835 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
836 BindStmt pat' expr' src_loc)]
838 rn_rec_stmt (LetStmt binds)
839 = rnBinds binds `thenM` \ (binds', du_binds) ->
840 returnM [(duDefs du_binds, duUses du_binds,
841 emptyNameSet, LetStmt binds')]
843 rn_rec_stmt (RecStmt stmts _ _ _) -- Flatten Rec inside Rec
846 rn_rec_stmt stmt@(ParStmt _) -- Syntactically illegal in mdo
847 = pprPanic "rn_rec_stmt" (ppr stmt)
849 ---------------------------------------------
850 rn_rec_stmts :: [RdrNameStmt] -> RnM [Segment RenamedStmt]
851 rn_rec_stmts stmts = mappM rn_rec_stmt stmts `thenM` \ segs_s ->
852 returnM (concat segs_s)
855 ---------------------------------------------
856 addFwdRefs :: [Segment a] -> [Segment a]
857 -- So far the segments only have forward refs *within* the Stmt
858 -- (which happens for bind: x <- ...x...)
859 -- This function adds the cross-seg fwd ref info
862 = fst (foldr mk_seg ([], emptyNameSet) pairs)
864 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
865 = (new_seg : segs, all_defs)
867 new_seg = (defs, uses, new_fwds, stmts)
868 all_defs = later_defs `unionNameSets` defs
869 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
870 -- Add the downstream fwd refs here
872 ----------------------------------------------------
873 -- Glomming the singleton segments of an mdo into
874 -- minimal recursive groups.
876 -- At first I thought this was just strongly connected components, but
877 -- there's an important constraint: the order of the stmts must not change.
880 -- mdo { x <- ...y...
887 -- Here, the first stmt mention 'y', which is bound in the third.
888 -- But that means that the innocent second stmt (p <- z) gets caught
889 -- up in the recursion. And that in turn means that the binding for
890 -- 'z' has to be included... and so on.
892 -- Start at the tail { r <- x }
893 -- Now add the next one { z <- y ; r <- x }
894 -- Now add one more { q <- x ; z <- y ; r <- x }
895 -- Now one more... but this time we have to group a bunch into rec
896 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
897 -- Now one more, which we can add on without a rec
899 -- rec { y <- ...x... ; q <- x ; z <- y } ;
901 -- Finally we add the last one; since it mentions y we have to
902 -- glom it togeher with the first two groups
903 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
904 -- q <- x ; z <- y } ;
907 glomSegments :: [Segment RenamedStmt] -> [Segment [RenamedStmt]]
910 glomSegments ((defs,uses,fwds,stmt) : segs)
911 -- Actually stmts will always be a singleton
912 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
914 segs' = glomSegments segs
915 (extras, others) = grab uses segs'
916 (ds, us, fs, ss) = unzip4 extras
918 seg_defs = plusFVs ds `plusFV` defs
919 seg_uses = plusFVs us `plusFV` uses
920 seg_fwds = plusFVs fs `plusFV` fwds
921 seg_stmts = stmt : concat ss
923 grab :: NameSet -- The client
925 -> ([Segment a], -- Needed by the 'client'
926 [Segment a]) -- Not needed by the client
927 -- The result is simply a split of the input
929 = (reverse yeses, reverse noes)
931 (noes, yeses) = span not_needed (reverse dus)
932 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
935 ----------------------------------------------------
936 segsToStmts :: [Segment [RenamedStmt]] -> ([RenamedStmt], FreeVars)
938 segsToStmts [] = ([], emptyFVs)
939 segsToStmts ((defs, uses, fwds, ss) : segs)
940 = (new_stmt : later_stmts, later_uses `plusFV` uses)
942 (later_stmts, later_uses) = segsToStmts segs
943 new_stmt | non_rec = head ss
944 | otherwise = RecStmt ss (nameSetToList used_later) (nameSetToList fwds) []
946 non_rec = isSingleton ss && isEmptyNameSet fwds
947 used_later = defs `intersectNameSet` later_uses
948 -- The ones needed after the RecStmt
951 %************************************************************************
953 \subsubsection{Precedence Parsing}
955 %************************************************************************
957 @mkOpAppRn@ deals with operator fixities. The argument expressions
958 are assumed to be already correctly arranged. It needs the fixities
959 recorded in the OpApp nodes, because fixity info applies to the things
960 the programmer actually wrote, so you can't find it out from the Name.
962 Furthermore, the second argument is guaranteed not to be another
963 operator application. Why? Because the parser parses all
964 operator appications left-associatively, EXCEPT negation, which
965 we need to handle specially.
968 mkOpAppRn :: RenamedHsExpr -- Left operand; already rearranged
969 -> RenamedHsExpr -> Fixity -- Operator and fixity
970 -> RenamedHsExpr -- Right operand (not an OpApp, but might
974 ---------------------------
975 -- (e11 `op1` e12) `op2` e2
976 mkOpAppRn e1@(OpApp e11 op1 fix1 e12) op2 fix2 e2
978 = addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) `thenM_`
979 returnM (OpApp e1 op2 fix2 e2)
982 = mkOpAppRn e12 op2 fix2 e2 `thenM` \ new_e ->
983 returnM (OpApp e11 op1 fix1 new_e)
985 (nofix_error, associate_right) = compareFixity fix1 fix2
987 ---------------------------
988 -- (- neg_arg) `op` e2
989 mkOpAppRn e1@(NegApp neg_arg neg_name) op2 fix2 e2
991 = addErr (precParseErr (pp_prefix_minus,negateFixity) (ppr_op op2,fix2)) `thenM_`
992 returnM (OpApp e1 op2 fix2 e2)
995 = mkOpAppRn neg_arg op2 fix2 e2 `thenM` \ new_e ->
996 returnM (NegApp new_e neg_name)
998 (nofix_error, associate_right) = compareFixity negateFixity fix2
1000 ---------------------------
1001 -- e1 `op` - neg_arg
1002 mkOpAppRn e1 op1 fix1 e2@(NegApp neg_arg _) -- NegApp can occur on the right
1003 | not associate_right -- We *want* right association
1004 = addErr (precParseErr (ppr_op op1, fix1) (pp_prefix_minus, negateFixity)) `thenM_`
1005 returnM (OpApp e1 op1 fix1 e2)
1007 (_, associate_right) = compareFixity fix1 negateFixity
1009 ---------------------------
1011 mkOpAppRn e1 op fix e2 -- Default case, no rearrangment
1012 = ASSERT2( right_op_ok fix e2,
1013 ppr e1 $$ text "---" $$ ppr op $$ text "---" $$ ppr fix $$ text "---" $$ ppr e2
1015 returnM (OpApp e1 op fix e2)
1017 -- Parser left-associates everything, but
1018 -- derived instances may have correctly-associated things to
1019 -- in the right operarand. So we just check that the right operand is OK
1020 right_op_ok fix1 (OpApp _ _ fix2 _)
1021 = not error_please && associate_right
1023 (error_please, associate_right) = compareFixity fix1 fix2
1024 right_op_ok fix1 other
1027 -- Parser initially makes negation bind more tightly than any other operator
1028 -- And "deriving" code should respect this (use HsPar if not)
1029 mkNegAppRn neg_arg neg_name
1030 = ASSERT( not_op_app neg_arg )
1031 returnM (NegApp neg_arg neg_name)
1033 not_op_app (OpApp _ _ _ _) = False
1034 not_op_app other = True
1038 checkPrecMatch :: Bool -> Name -> RenamedMatch -> RnM ()
1040 checkPrecMatch False fn match
1043 checkPrecMatch True op (Match (p1:p2:_) _ _)
1044 -- True indicates an infix lhs
1045 = -- See comments with rnExpr (OpApp ...) about "deriving"
1046 checkPrec op p1 False `thenM_`
1047 checkPrec op p2 True
1049 checkPrecMatch True op _ = panic "checkPrecMatch"
1051 checkPrec op (ConPatIn op1 (InfixCon _ _)) right
1052 = lookupFixityRn op `thenM` \ op_fix@(Fixity op_prec op_dir) ->
1053 lookupFixityRn op1 `thenM` \ op1_fix@(Fixity op1_prec op1_dir) ->
1055 inf_ok = op1_prec > op_prec ||
1056 (op1_prec == op_prec &&
1057 (op1_dir == InfixR && op_dir == InfixR && right ||
1058 op1_dir == InfixL && op_dir == InfixL && not right))
1060 info = (ppr_op op, op_fix)
1061 info1 = (ppr_op op1, op1_fix)
1062 (infol, infor) = if right then (info, info1) else (info1, info)
1064 checkErr inf_ok (precParseErr infol infor)
1066 checkPrec op pat right
1069 -- Check precedence of (arg op) or (op arg) respectively
1070 -- If arg is itself an operator application, then either
1071 -- (a) its precedence must be higher than that of op
1072 -- (b) its precedency & associativity must be the same as that of op
1073 checkSectionPrec direction section op arg
1075 OpApp _ op fix _ -> go_for_it (ppr_op op) fix
1076 NegApp _ _ -> go_for_it pp_prefix_minus negateFixity
1080 go_for_it pp_arg_op arg_fix@(Fixity arg_prec assoc)
1081 = lookupFixityRn op_name `thenM` \ op_fix@(Fixity op_prec _) ->
1082 checkErr (op_prec < arg_prec
1083 || op_prec == arg_prec && direction == assoc)
1084 (sectionPrecErr (ppr_op op_name, op_fix)
1085 (pp_arg_op, arg_fix) section)
1089 %************************************************************************
1091 \subsubsection{Assertion utils}
1093 %************************************************************************
1096 mkAssertErrorExpr :: RnM (RenamedHsExpr, FreeVars)
1097 -- Return an expression for (assertError "Foo.hs:27")
1099 = getSrcLocM `thenM` \ sloc ->
1101 expr = HsApp (HsVar assertErrorName) (HsLit msg)
1102 msg = HsStringPrim (mkFastString (stringToUtf8 (showSDoc (ppr sloc))))
1104 returnM (expr, emptyFVs)
1107 %************************************************************************
1109 \subsubsection{Errors}
1111 %************************************************************************
1114 ppr_op op = quotes (ppr op) -- Here, op can be a Name or a (Var n), where n is a Name
1115 pp_prefix_minus = ptext SLIT("prefix `-'")
1117 nonStdGuardErr guard
1119 SLIT("accepting non-standard pattern guards (-fglasgow-exts to suppress this message)")
1123 = sep [ptext SLIT("Pattern syntax in expression context:"),
1126 doStmtListErr do_or_lc e
1127 = sep [quotes (text binder_name) <+> ptext SLIT("statements must end in expression:"),
1130 binder_name = case do_or_lc of
1135 checkTH e what = returnM () -- OK
1137 checkTH e what -- Raise an error in a stage-1 compiler
1138 = addErr (vcat [ptext SLIT("Template Haskell") <+> text what <+>
1139 ptext SLIT("illegal in a stage-1 compiler"),
1143 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -fglasgow-exts"))
1146 = hang (ptext SLIT("Implicit-parameter bindings illegal in a parallel list comprehension:")) 4