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 RnNames ( importsFromLocalDecls )
32 import RnTypes ( rnHsTypeFVs, rnPat, litFVs, rnOverLit, rnPatsAndThen,
33 dupFieldErr, precParseErr, sectionPrecErr, patSigErr, checkTupSize )
34 import CmdLineOpts ( DynFlag(..), opt_IgnoreAsserts )
35 import BasicTypes ( Fixity(..), FixityDirection(..), IPName(..),
36 defaultFixity, negateFixity, compareFixity )
37 import PrelNames ( hasKey, assertIdKey,
39 cCallableClassName, cReturnableClassName,
41 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
42 splitName, fstName, sndName, ioDataConName,
43 replicatePName, mapPName, filterPName,
44 crossPName, zipPName, toPName,
45 enumFromToPName, enumFromThenToPName, assertErrorName,
46 negateName, monadNames, mfixName )
47 import Name ( Name, nameOccName )
49 import UnicodeUtil ( stringToUtf8 )
50 import UniqFM ( isNullUFM )
51 import UniqSet ( emptyUniqSet )
52 import Util ( isSingleton, mapAndUnzip )
53 import List ( intersectBy, unzip4 )
54 import ListSetOps ( removeDups )
56 import SrcLoc ( noSrcLoc )
61 ************************************************************************
65 ************************************************************************
68 rnMatch :: HsMatchContext Name -> RdrNameMatch -> RnM (RenamedMatch, FreeVars)
70 rnMatch ctxt match@(Match pats maybe_rhs_sig grhss)
71 = addSrcLoc (getMatchLoc match) $
73 -- Deal with the rhs type signature
74 bindPatSigTyVarsFV rhs_sig_tys $
75 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
76 (case maybe_rhs_sig of
77 Nothing -> returnM (Nothing, emptyFVs)
78 Just ty | opt_GlasgowExts -> rnHsTypeFVs doc_sig ty `thenM` \ (ty', ty_fvs) ->
79 returnM (Just ty', ty_fvs)
80 | otherwise -> addErr (patSigErr ty) `thenM_`
81 returnM (Nothing, emptyFVs)
82 ) `thenM` \ (maybe_rhs_sig', ty_fvs) ->
85 rnPatsAndThen ctxt pats $ \ pats' ->
86 rnGRHSs ctxt grhss `thenM` \ (grhss', grhss_fvs) ->
88 returnM (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
89 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
91 rhs_sig_tys = case maybe_rhs_sig of
94 doc_sig = text "In a result type-signature"
98 %************************************************************************
100 \subsubsection{Guarded right-hand sides (GRHSs)}
102 %************************************************************************
105 rnGRHSs :: HsMatchContext Name -> RdrNameGRHSs -> RnM (RenamedGRHSs, FreeVars)
107 rnGRHSs ctxt (GRHSs grhss binds _)
108 = rnBindsAndThen binds $ \ binds' ->
109 mapFvRn (rnGRHS ctxt) grhss `thenM` \ (grhss', fvGRHSs) ->
110 returnM (GRHSs grhss' binds' placeHolderType, fvGRHSs)
112 rnGRHS ctxt (GRHS guarded locn)
114 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
115 checkM (opt_GlasgowExts || is_standard_guard guarded)
116 (addWarn (nonStdGuardErr guarded)) `thenM_`
118 rnStmts (PatGuard ctxt) guarded `thenM` \ (guarded', fvs) ->
119 returnM (GRHS guarded' locn, fvs)
121 -- Standard Haskell 1.4 guards are just a single boolean
122 -- expression, rather than a list of qualifiers as in the
124 is_standard_guard [ResultStmt _ _] = True
125 is_standard_guard [ExprStmt _ _ _, ResultStmt _ _] = True
126 is_standard_guard other = False
129 %************************************************************************
131 \subsubsection{Expressions}
133 %************************************************************************
136 rnExprs :: [RdrNameHsExpr] -> RnM ([RenamedHsExpr], FreeVars)
137 rnExprs ls = rnExprs' ls emptyUniqSet
139 rnExprs' [] acc = returnM ([], acc)
140 rnExprs' (expr:exprs) acc
141 = rnExpr expr `thenM` \ (expr', fvExpr) ->
143 -- Now we do a "seq" on the free vars because typically it's small
144 -- or empty, especially in very long lists of constants
146 acc' = acc `plusFV` fvExpr
148 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
149 returnM (expr':exprs', fvExprs)
151 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
152 grubby_seqNameSet ns result | isNullUFM ns = result
156 Variables. We look up the variable and return the resulting name.
159 rnExpr :: RdrNameHsExpr -> RnM (RenamedHsExpr, FreeVars)
162 = lookupOccRn v `thenM` \ name ->
163 if name `hasKey` assertIdKey && not opt_IgnoreAsserts then
164 -- We expand it to (GHC.Err.assertError location_string)
165 mkAssertErrorExpr `thenM` \ (e, fvs) ->
166 returnM (e, fvs `addOneFV` name)
167 -- Keep 'assert' as a free var, to ensure it's not reported as unused!
169 -- The normal case. Even if the Id was 'assert', if we are
170 -- ignoring assertions we leave it as GHC.Base.assert;
171 -- this function just ignores its first arg.
172 returnM (HsVar name, unitFV name)
175 = newIPName v `thenM` \ name ->
178 Linear _ -> mkFVs [splitName, fstName, sndName]
179 Dupable _ -> emptyFVs
181 returnM (HsIPVar name, fvs)
184 = litFVs lit `thenM` \ fvs ->
185 returnM (HsLit lit, fvs)
187 rnExpr (HsOverLit lit)
188 = rnOverLit lit `thenM` \ (lit', fvs) ->
189 returnM (HsOverLit lit', fvs)
192 = rnMatch LambdaExpr match `thenM` \ (match', fvMatch) ->
193 returnM (HsLam match', fvMatch)
195 rnExpr (HsApp fun arg)
196 = rnExpr fun `thenM` \ (fun',fvFun) ->
197 rnExpr arg `thenM` \ (arg',fvArg) ->
198 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
200 rnExpr (OpApp e1 op _ e2)
201 = rnExpr e1 `thenM` \ (e1', fv_e1) ->
202 rnExpr e2 `thenM` \ (e2', fv_e2) ->
203 rnExpr op `thenM` \ (op'@(HsVar op_name), fv_op) ->
206 -- When renaming code synthesised from "deriving" declarations
207 -- we're in Interface mode, and we should ignore fixity; assume
208 -- that the deriving code generator got the association correct
209 -- Don't even look up the fixity when in interface mode
210 getModeRn `thenM` \ mode ->
211 (if isInterfaceMode mode
212 then returnM (OpApp e1' op' defaultFixity e2')
213 else lookupFixityRn op_name `thenM` \ fixity ->
214 mkOpAppRn e1' op' fixity e2'
215 ) `thenM` \ final_e ->
218 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
221 = rnExpr e `thenM` \ (e', fv_e) ->
222 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
223 mkNegAppRn e' neg_name `thenM` \ final_e ->
224 returnM (final_e, fv_e `plusFV` fv_neg)
227 = rnExpr e `thenM` \ (e', fvs_e) ->
228 returnM (HsPar e', fvs_e)
230 -- Template Haskell extensions
231 -- Don't ifdef-GHCI them because we want to fail gracefully
232 -- (not with an rnExpr crash) in a stage-1 compiler.
233 rnExpr e@(HsBracket br_body loc)
235 checkTH e "bracket" `thenM_`
236 rnBracket br_body `thenM` \ (body', fvs_e) ->
237 returnM (HsBracket body' loc, fvs_e `plusFV` thProxyName)
239 rnExpr e@(HsSplice n splice loc)
241 checkTH e "splice" `thenM_`
242 newLocalsRn [(n,loc)] `thenM` \ [n'] ->
243 rnExpr splice `thenM` \ (splice', fvs_e) ->
244 returnM (HsSplice n' splice' loc, fvs_e `plusFV` thProxyName)
246 rnExpr e@(HsReify (Reify flavour name))
247 = checkTH e "reify" `thenM_`
248 lookupGlobalOccRn name `thenM` \ name' ->
249 -- For now, we can only reify top-level things
250 returnM (HsReify (Reify flavour name'), unitFV name' `plusFV` thProxyName)
252 rnExpr section@(SectionL expr op)
253 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
254 rnExpr op `thenM` \ (op', fvs_op) ->
255 checkSectionPrec InfixL section op' expr' `thenM_`
256 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
258 rnExpr section@(SectionR op expr)
259 = rnExpr op `thenM` \ (op', fvs_op) ->
260 rnExpr expr `thenM` \ (expr', fvs_expr) ->
261 checkSectionPrec InfixR section op' expr' `thenM_`
262 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
264 rnExpr (HsCCall fun args may_gc is_casm _)
265 -- Check out the comment on RnIfaces.getNonWiredDataDecl about ccalls
266 = rnExprs args `thenM` \ (args', fvs_args) ->
267 returnM (HsCCall fun args' may_gc is_casm placeHolderType,
268 fvs_args `plusFV` mkFVs [cCallableClassName,
269 cReturnableClassName,
272 rnExpr (HsCoreAnn ann expr)
273 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
274 returnM (HsCoreAnn ann expr', fvs_expr)
276 rnExpr (HsSCC lbl expr)
277 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
278 returnM (HsSCC lbl expr', fvs_expr)
280 rnExpr (HsCase expr ms src_loc)
281 = addSrcLoc src_loc $
282 rnExpr expr `thenM` \ (new_expr, e_fvs) ->
283 mapFvRn (rnMatch CaseAlt) ms `thenM` \ (new_ms, ms_fvs) ->
284 returnM (HsCase new_expr new_ms src_loc, e_fvs `plusFV` ms_fvs)
286 rnExpr (HsLet binds expr)
287 = rnBindsAndThen binds $ \ binds' ->
288 rnExpr expr `thenM` \ (expr',fvExpr) ->
289 returnM (HsLet binds' expr', fvExpr)
291 rnExpr e@(HsDo do_or_lc stmts _ _ src_loc)
292 = addSrcLoc src_loc $
293 rnStmts do_or_lc stmts `thenM` \ (stmts', fvs) ->
295 -- Check the statement list ends in an expression
296 case last stmts' of {
297 ResultStmt _ _ -> returnM () ;
298 _ -> addErr (doStmtListErr do_or_lc e)
301 -- Generate the rebindable syntax for the monad
302 lookupSyntaxNames syntax_names `thenM` \ (syntax_names', monad_fvs) ->
304 returnM (HsDo do_or_lc stmts' syntax_names' placeHolderType src_loc,
305 fvs `plusFV` implicit_fvs do_or_lc `plusFV` monad_fvs)
307 implicit_fvs PArrComp = mkFVs [replicatePName, mapPName, filterPName, crossPName, zipPName]
308 implicit_fvs ListComp = mkFVs [foldrName, buildName]
309 implicit_fvs DoExpr = emptyFVs
310 implicit_fvs MDoExpr = emptyFVs
312 syntax_names = case do_or_lc of
314 MDoExpr -> monadNames ++ [mfixName]
317 rnExpr (ExplicitList _ exps)
318 = rnExprs exps `thenM` \ (exps', fvs) ->
319 returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name)
321 rnExpr (ExplicitPArr _ exps)
322 = rnExprs exps `thenM` \ (exps', fvs) ->
323 returnM (ExplicitPArr placeHolderType exps',
324 fvs `addOneFV` toPName `addOneFV` parrTyCon_name)
326 rnExpr e@(ExplicitTuple exps boxity)
327 = checkTupSize tup_size `thenM_`
328 rnExprs exps `thenM` \ (exps', fvs) ->
329 returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name)
331 tup_size = length exps
332 tycon_name = tupleTyCon_name boxity tup_size
334 rnExpr (RecordCon con_id rbinds)
335 = lookupOccRn con_id `thenM` \ conname ->
336 rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) ->
337 returnM (RecordCon conname rbinds', fvRbinds `addOneFV` conname)
339 rnExpr (RecordUpd expr rbinds)
340 = rnExpr expr `thenM` \ (expr', fvExpr) ->
341 rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) ->
342 returnM (RecordUpd expr' rbinds', fvExpr `plusFV` fvRbinds)
344 rnExpr (ExprWithTySig expr pty)
345 = rnExpr expr `thenM` \ (expr', fvExpr) ->
346 rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) ->
347 returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy)
349 doc = text "In an expression type signature"
351 rnExpr (HsIf p b1 b2 src_loc)
352 = addSrcLoc src_loc $
353 rnExpr p `thenM` \ (p', fvP) ->
354 rnExpr b1 `thenM` \ (b1', fvB1) ->
355 rnExpr b2 `thenM` \ (b2', fvB2) ->
356 returnM (HsIf p' b1' b2' src_loc, plusFVs [fvP, fvB1, fvB2])
359 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
360 returnM (HsType t, fvT)
362 doc = text "In a type argument"
364 rnExpr (ArithSeqIn seq)
365 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
366 returnM (ArithSeqIn new_seq, fvs `addOneFV` enumClassName)
368 rnExpr (PArrSeqIn seq)
369 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
370 returnM (PArrSeqIn new_seq,
371 fvs `plusFV` mkFVs [enumFromToPName, enumFromThenToPName])
374 These three are pattern syntax appearing in expressions.
375 Since all the symbols are reservedops we can simply reject them.
376 We return a (bogus) EWildPat in each case.
379 rnExpr e@EWildPat = addErr (patSynErr e) `thenM_`
380 returnM (EWildPat, emptyFVs)
382 rnExpr e@(EAsPat _ _) = addErr (patSynErr e) `thenM_`
383 returnM (EWildPat, emptyFVs)
385 rnExpr e@(ELazyPat _) = addErr (patSynErr e) `thenM_`
386 returnM (EWildPat, emptyFVs)
389 %************************************************************************
393 %************************************************************************
396 rnExpr (HsProc pat body src_loc)
397 = addSrcLoc src_loc $
398 rnPatsAndThen ProcExpr [pat] $ \ [pat'] ->
399 rnCmdTop body `thenM` \ (body',fvBody) ->
400 returnM (HsProc pat' body' src_loc, fvBody)
402 rnExpr (HsArrApp arrow arg _ ho rtl srcloc)
403 = rnExpr arrow `thenM` \ (arrow',fvArrow) ->
404 rnExpr arg `thenM` \ (arg',fvArg) ->
405 returnM (HsArrApp arrow' arg' placeHolderType ho rtl srcloc,
406 fvArrow `plusFV` fvArg)
409 rnExpr (HsArrForm op (Just _) [arg1, arg2] srcloc)
410 = rnExpr op `thenM` \ (op'@(HsVar op_name),fv_op) ->
411 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
412 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
416 lookupFixityRn op_name `thenM` \ fixity ->
417 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
420 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
422 rnExpr (HsArrForm op fixity cmds srcloc)
423 = rnExpr op `thenM` \ (op',fvOp) ->
424 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
425 returnM (HsArrForm op' fixity cmds' srcloc,
426 fvOp `plusFV` fvCmds)
428 ---------------------------
429 -- Deal with fixity (cf mkOpAppRn for the method)
431 mkOpFormRn :: RenamedHsCmdTop -- Left operand; already rearranged
432 -> RenamedHsExpr -> Fixity -- Operator and fixity
433 -> RenamedHsCmdTop -- Right operand (not an infix)
436 ---------------------------
437 -- (e11 `op1` e12) `op2` e2
438 mkOpFormRn a1@(HsCmdTop (HsArrForm op1 (Just fix1) [a11,a12] loc1) _ _ _) op2 fix2 a2
440 = addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) `thenM_`
441 returnM (HsArrForm op2 (Just fix2) [a1, a2] loc1)
444 = mkOpFormRn a12 op2 fix2 a2 `thenM` \ new_c ->
445 returnM (HsArrForm op1 (Just fix1)
446 [a11, HsCmdTop new_c [] placeHolderType []] loc1)
448 (nofix_error, associate_right) = compareFixity fix1 fix2
450 ---------------------------
452 mkOpFormRn arg1 op fix arg2 -- Default case, no rearrangment
453 = returnM (HsArrForm op (Just fix) [arg1, arg2] noSrcLoc)
458 %************************************************************************
462 %************************************************************************
465 rnCmdArgs [] = returnM ([], emptyFVs)
467 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
468 rnCmdArgs args `thenM` \ (args',fvArgs) ->
469 returnM (arg':args', fvArg `plusFV` fvArgs)
471 rnCmdTop (HsCmdTop cmd _ _ _)
472 = rnExpr (convertOpFormsCmd cmd) `thenM` \ (cmd', fvCmd) ->
474 cmd_names = [arrAName, composeAName, firstAName] ++
475 nameSetToList (methodNamesCmd cmd')
477 -- Generate the rebindable syntax for the monad
478 lookupSyntaxNames cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
480 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
481 fvCmd `plusFV` cmd_fvs)
483 ---------------------------------------------------
484 -- convert OpApp's in a command context to HsArrForm's
486 convertOpFormsCmd :: HsCmd id -> HsCmd id
488 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
490 convertOpFormsCmd (OpApp c1 op fixity c2)
492 arg1 = HsCmdTop (convertOpFormsCmd c1) [] placeHolderType []
493 arg2 = HsCmdTop (convertOpFormsCmd c2) [] placeHolderType []
495 HsArrForm op (Just fixity) [arg1, arg2] noSrcLoc
497 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsCmd c)
499 convertOpFormsCmd (HsCase exp matches locn)
500 = HsCase exp (map convertOpFormsMatch matches) locn
502 convertOpFormsCmd (HsIf exp c1 c2 locn)
503 = HsIf exp (convertOpFormsCmd c1) (convertOpFormsCmd c2) locn
505 convertOpFormsCmd (HsLet binds cmd)
506 = HsLet binds (convertOpFormsCmd cmd)
508 convertOpFormsCmd (HsDo ctxt stmts ids ty locn)
509 = HsDo ctxt (map convertOpFormsStmt stmts) ids ty locn
511 -- Anything else is unchanged. This includes HsArrForm (already done),
512 -- things with no sub-commands, and illegal commands (which will be
513 -- caught by the type checker)
514 convertOpFormsCmd c = c
516 convertOpFormsStmt (BindStmt pat cmd locn)
517 = BindStmt pat (convertOpFormsCmd cmd) locn
518 convertOpFormsStmt (ResultStmt cmd locn)
519 = ResultStmt (convertOpFormsCmd cmd) locn
520 convertOpFormsStmt (ExprStmt cmd ty locn)
521 = ExprStmt (convertOpFormsCmd cmd) ty locn
522 convertOpFormsStmt (RecStmt stmts lvs rvs es)
523 = RecStmt (map convertOpFormsStmt stmts) lvs rvs es
524 convertOpFormsStmt stmt = stmt
526 convertOpFormsMatch (Match pat mty grhss)
527 = Match pat mty (convertOpFormsGRHSs grhss)
529 convertOpFormsGRHSs (GRHSs grhss binds ty)
530 = GRHSs (map convertOpFormsGRHS grhss) binds ty
532 convertOpFormsGRHS (GRHS stmts locn)
534 (ResultStmt cmd locn') = last stmts
536 GRHS (init stmts ++ [ResultStmt (convertOpFormsCmd cmd) locn']) locn
538 ---------------------------------------------------
539 type CmdNeeds = FreeVars -- Only inhabitants are
540 -- appAName, choiceAName, loopAName
542 -- find what methods the Cmd needs (loop, choice, apply)
543 methodNamesCmd :: HsCmd Name -> CmdNeeds
545 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl _srcloc)
547 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl _srcloc)
549 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
551 methodNamesCmd (HsPar c) = methodNamesCmd c
553 methodNamesCmd (HsIf p c1 c2 loc)
554 = methodNamesCmd c1 `plusFV` methodNamesCmd c2 `addOneFV` choiceAName
556 methodNamesCmd (HsLet b c) = methodNamesCmd c
558 methodNamesCmd (HsDo sc stmts rbs ty loc) = methodNamesStmts stmts
560 methodNamesCmd (HsLam match) = methodNamesMatch match
562 methodNamesCmd (HsCase scrut matches loc)
563 = plusFVs (map methodNamesMatch matches) `addOneFV` choiceAName
565 methodNamesCmd other = emptyFVs
566 -- Other forms can't occur in commands, but it's not convenient
567 -- to error here so we just do what's convenient.
568 -- The type checker will complain later
570 ---------------------------------------------------
571 methodNamesMatch (Match pats sig_ty grhss) = methodNamesGRHSs grhss
573 -------------------------------------------------
574 methodNamesGRHSs (GRHSs grhss binds ty) = plusFVs (map methodNamesGRHS grhss)
576 -------------------------------------------------
577 methodNamesGRHS (GRHS stmts loc) = methodNamesStmt (last stmts)
579 ---------------------------------------------------
580 methodNamesStmts stmts = plusFVs (map methodNamesStmt stmts)
582 ---------------------------------------------------
583 methodNamesStmt (ResultStmt cmd loc) = methodNamesCmd cmd
584 methodNamesStmt (ExprStmt cmd ty loc) = methodNamesCmd cmd
585 methodNamesStmt (BindStmt pat cmd loc) = methodNamesCmd cmd
586 methodNamesStmt (RecStmt stmts lvs rvs es)
587 = methodNamesStmts stmts `addOneFV` loopAName
588 methodNamesStmt (LetStmt b) = emptyFVs
589 methodNamesStmt (ParStmt ss) = emptyFVs
590 -- ParStmt can't occur in commands, but it's not convenient to error
591 -- here so we just do what's convenient
595 %************************************************************************
599 %************************************************************************
602 rnArithSeq (From expr)
603 = rnExpr expr `thenM` \ (expr', fvExpr) ->
604 returnM (From expr', fvExpr)
606 rnArithSeq (FromThen expr1 expr2)
607 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
608 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
609 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
611 rnArithSeq (FromTo expr1 expr2)
612 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
613 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
614 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
616 rnArithSeq (FromThenTo expr1 expr2 expr3)
617 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
618 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
619 rnExpr expr3 `thenM` \ (expr3', fvExpr3) ->
620 returnM (FromThenTo expr1' expr2' expr3',
621 plusFVs [fvExpr1, fvExpr2, fvExpr3])
625 %************************************************************************
627 \subsubsection{@Rbinds@s and @Rpats@s: in record expressions}
629 %************************************************************************
633 = mappM_ field_dup_err dup_fields `thenM_`
634 mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) ->
635 returnM (rbinds', fvRbind)
637 (_, dup_fields) = removeDups compare [ f | (f,_) <- rbinds ]
639 field_dup_err dups = addErr (dupFieldErr str dups)
641 rn_rbind (field, expr)
642 = lookupGlobalOccRn field `thenM` \ fieldname ->
643 rnExpr expr `thenM` \ (expr', fvExpr) ->
644 returnM ((fieldname, expr'), fvExpr `addOneFV` fieldname)
647 %************************************************************************
649 Template Haskell brackets
651 %************************************************************************
654 rnBracket (ExpBr e) = rnExpr e `thenM` \ (e', fvs) ->
655 returnM (ExpBr e', fvs)
656 rnBracket (PatBr p) = rnPat p `thenM` \ (p', fvs) ->
657 returnM (PatBr p', fvs)
658 rnBracket (TypBr t) = rnHsTypeFVs doc t `thenM` \ (t', fvs) ->
659 returnM (TypBr t', fvs)
661 doc = ptext SLIT("In a Template-Haskell quoted type")
662 rnBracket (DecBr group)
663 = importsFromLocalDecls group `thenM` \ (rdr_env, avails) ->
664 -- Discard avails (not useful here)
666 updGblEnv (\gbl -> gbl { tcg_rdr_env = rdr_env `plusGlobalRdrEnv` tcg_rdr_env gbl }) $
668 rnSrcDecls group `thenM` \ (tcg_env, group', dus) ->
669 -- Discard the tcg_env; it contains only extra info about fixity
671 returnM (DecBr group', duUses dus `minusNameSet` duDefs dus)
674 %************************************************************************
676 \subsubsection{@Stmt@s: in @do@ expressions}
678 %************************************************************************
681 rnStmts :: HsStmtContext Name -> [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
683 rnStmts MDoExpr stmts = rnMDoStmts stmts
684 rnStmts ctxt stmts = rnNormalStmts ctxt stmts
686 rnNormalStmts :: HsStmtContext Name -> [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
687 -- Used for cases *other* than recursive mdo
688 -- Implements nested scopes
690 rnNormalStmts ctxt [] = returnM ([], emptyFVs)
691 -- Happens at the end of the sub-lists of a ParStmts
693 rnNormalStmts ctxt (ExprStmt expr _ src_loc : stmts)
694 = addSrcLoc src_loc $
695 rnExpr expr `thenM` \ (expr', fv_expr) ->
696 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
697 returnM (ExprStmt expr' placeHolderType src_loc : stmts',
698 fv_expr `plusFV` fvs)
700 rnNormalStmts ctxt [ResultStmt expr src_loc]
701 = addSrcLoc src_loc $
702 rnExpr expr `thenM` \ (expr', fv_expr) ->
703 returnM ([ResultStmt expr' src_loc], fv_expr)
705 rnNormalStmts ctxt (BindStmt pat expr src_loc : stmts)
706 = addSrcLoc src_loc $
707 rnExpr expr `thenM` \ (expr', fv_expr) ->
708 -- The binders do not scope over the expression
710 rnPatsAndThen (StmtCtxt ctxt) [pat] $ \ [pat'] ->
711 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
712 returnM (BindStmt pat' expr' src_loc : stmts',
713 fv_expr `plusFV` fvs) -- fv_expr shouldn't really be filtered by
714 -- the rnPatsAndThen, but it does not matter
716 rnNormalStmts ctxt (LetStmt binds : stmts)
717 = checkErr (ok ctxt binds) (badIpBinds binds) `thenM_`
718 rnBindsAndThen binds ( \ binds' ->
719 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
720 returnM (LetStmt binds' : stmts', fvs))
722 -- We do not allow implicit-parameter bindings in a parallel
723 -- list comprehension. I'm not sure what it might mean.
724 ok (ParStmtCtxt _) (IPBinds _ _) = False
727 rnNormalStmts ctxt (ParStmt stmtss : stmts)
728 = doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
729 checkM opt_GlasgowExts parStmtErr `thenM_`
730 mapFvRn rn_branch stmtss `thenM` \ (stmtss', fv_stmtss) ->
732 bndrss :: [[Name]] -- NB: Name, not RdrName
733 bndrss = map collectStmtsBinders stmtss'
734 (bndrs, dups) = removeDups cmpByOcc (concat bndrss)
736 mappM dupErr dups `thenM` \ _ ->
737 bindLocalNamesFV bndrs $
738 -- Note: binders are returned in scope order, so one may
739 -- shadow the next; e.g. x <- xs; x <- ys
740 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
742 -- Cut down the exported binders to just the ones neede in the body
744 used_bndrs_s = map (filter (`elemNameSet` fvs)) bndrss
746 returnM (ParStmt (stmtss' `zip` used_bndrs_s) : stmts',
747 fv_stmtss `plusFV` fvs)
750 rn_branch (stmts, _) = rnNormalStmts (ParStmtCtxt ctxt) stmts
752 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
753 dupErr (v:_) = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
756 rnNormalStmts ctxt (RecStmt rec_stmts _ _ _ : stmts)
757 = bindLocalsRn doc (collectStmtsBinders rec_stmts) $ \ _ ->
758 rn_rec_stmts rec_stmts `thenM` \ segs ->
759 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
761 segs_w_fwd_refs = addFwdRefs segs
762 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
763 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
764 fwd_vars = nameSetToList (plusFVs fs)
767 returnM (RecStmt rec_stmts' later_vars fwd_vars [] : stmts', uses `plusFV` fvs)
769 doc = text "In a recursive do statement"
773 %************************************************************************
775 \subsubsection{mdo expressions}
777 %************************************************************************
780 type FwdRefs = NameSet
781 type Segment stmts = (Defs,
782 Uses, -- May include defs
783 FwdRefs, -- A subset of uses that are
784 -- (a) used before they are bound in this segment, or
785 -- (b) used here, and bound in subsequent segments
786 stmts) -- Either Stmt or [Stmt]
789 ----------------------------------------------------
790 rnMDoStmts :: [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
792 = -- Step1: bring all the binders of the mdo into scope
793 -- Remember that this also removes the binders from the
794 -- finally-returned free-vars
795 bindLocalsRn doc (collectStmtsBinders stmts) $ \ _ ->
797 -- Step 2: Rename each individual stmt, making a
798 -- singleton segment. At this stage the FwdRefs field
799 -- isn't finished: it's empty for all except a BindStmt
800 -- for which it's the fwd refs within the bind itself
801 -- (This set may not be empty, because we're in a recursive
803 rn_rec_stmts stmts `thenM` \ segs ->
805 -- Step 3: Fill in the fwd refs.
806 -- The segments are all singletons, but their fwd-ref
807 -- field mentions all the things used by the segment
808 -- that are bound after their use
809 segs_w_fwd_refs = addFwdRefs segs
811 -- Step 4: Group together the segments to make bigger segments
812 -- Invariant: in the result, no segment uses a variable
813 -- bound in a later segment
814 grouped_segs = glomSegments segs_w_fwd_refs
816 -- Step 5: Turn the segments into Stmts
817 -- Use RecStmt when and only when there are fwd refs
818 -- Also gather up the uses from the end towards the
819 -- start, so we can tell the RecStmt which things are
820 -- used 'after' the RecStmt
821 stmts_w_fvs = segsToStmts grouped_segs
825 doc = text "In a mdo-expression"
828 ----------------------------------------------------
829 rn_rec_stmt :: RdrNameStmt -> RnM [Segment RenamedStmt]
830 -- Rename a Stmt that is inside a RecStmt (or mdo)
831 -- Assumes all binders are already in scope
832 -- Turns each stmt into a singleton Stmt
834 rn_rec_stmt (ExprStmt expr _ src_loc)
835 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
836 returnM [(emptyNameSet, fvs, emptyNameSet,
837 ExprStmt expr' placeHolderType src_loc)]
839 rn_rec_stmt (ResultStmt expr src_loc)
840 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
841 returnM [(emptyNameSet, fvs, emptyNameSet,
842 ResultStmt expr' src_loc)]
844 rn_rec_stmt (BindStmt pat expr src_loc)
845 = addSrcLoc src_loc $
846 rnExpr expr `thenM` \ (expr', fv_expr) ->
847 rnPat pat `thenM` \ (pat', fv_pat) ->
849 bndrs = mkNameSet (collectPatBinders pat')
850 fvs = fv_expr `plusFV` fv_pat
852 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
853 BindStmt pat' expr' src_loc)]
855 rn_rec_stmt (LetStmt binds)
856 = rnBinds binds `thenM` \ (binds', du_binds) ->
857 returnM [(duDefs du_binds, duUses du_binds,
858 emptyNameSet, LetStmt binds')]
860 rn_rec_stmt (RecStmt stmts _ _ _) -- Flatten Rec inside Rec
863 rn_rec_stmt stmt@(ParStmt _) -- Syntactically illegal in mdo
864 = pprPanic "rn_rec_stmt" (ppr stmt)
866 ---------------------------------------------
867 rn_rec_stmts :: [RdrNameStmt] -> RnM [Segment RenamedStmt]
868 rn_rec_stmts stmts = mappM rn_rec_stmt stmts `thenM` \ segs_s ->
869 returnM (concat segs_s)
872 ---------------------------------------------
873 addFwdRefs :: [Segment a] -> [Segment a]
874 -- So far the segments only have forward refs *within* the Stmt
875 -- (which happens for bind: x <- ...x...)
876 -- This function adds the cross-seg fwd ref info
879 = fst (foldr mk_seg ([], emptyNameSet) pairs)
881 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
882 = (new_seg : segs, all_defs)
884 new_seg = (defs, uses, new_fwds, stmts)
885 all_defs = later_defs `unionNameSets` defs
886 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
887 -- Add the downstream fwd refs here
889 ----------------------------------------------------
890 -- Glomming the singleton segments of an mdo into
891 -- minimal recursive groups.
893 -- At first I thought this was just strongly connected components, but
894 -- there's an important constraint: the order of the stmts must not change.
897 -- mdo { x <- ...y...
904 -- Here, the first stmt mention 'y', which is bound in the third.
905 -- But that means that the innocent second stmt (p <- z) gets caught
906 -- up in the recursion. And that in turn means that the binding for
907 -- 'z' has to be included... and so on.
909 -- Start at the tail { r <- x }
910 -- Now add the next one { z <- y ; r <- x }
911 -- Now add one more { q <- x ; z <- y ; r <- x }
912 -- Now one more... but this time we have to group a bunch into rec
913 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
914 -- Now one more, which we can add on without a rec
916 -- rec { y <- ...x... ; q <- x ; z <- y } ;
918 -- Finally we add the last one; since it mentions y we have to
919 -- glom it togeher with the first two groups
920 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
921 -- q <- x ; z <- y } ;
924 glomSegments :: [Segment RenamedStmt] -> [Segment [RenamedStmt]]
927 glomSegments ((defs,uses,fwds,stmt) : segs)
928 -- Actually stmts will always be a singleton
929 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
931 segs' = glomSegments segs
932 (extras, others) = grab uses segs'
933 (ds, us, fs, ss) = unzip4 extras
935 seg_defs = plusFVs ds `plusFV` defs
936 seg_uses = plusFVs us `plusFV` uses
937 seg_fwds = plusFVs fs `plusFV` fwds
938 seg_stmts = stmt : concat ss
940 grab :: NameSet -- The client
942 -> ([Segment a], -- Needed by the 'client'
943 [Segment a]) -- Not needed by the client
944 -- The result is simply a split of the input
946 = (reverse yeses, reverse noes)
948 (noes, yeses) = span not_needed (reverse dus)
949 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
952 ----------------------------------------------------
953 segsToStmts :: [Segment [RenamedStmt]] -> ([RenamedStmt], FreeVars)
955 segsToStmts [] = ([], emptyFVs)
956 segsToStmts ((defs, uses, fwds, ss) : segs)
957 = (new_stmt : later_stmts, later_uses `plusFV` uses)
959 (later_stmts, later_uses) = segsToStmts segs
960 new_stmt | non_rec = head ss
961 | otherwise = RecStmt ss (nameSetToList used_later) (nameSetToList fwds) []
963 non_rec = isSingleton ss && isEmptyNameSet fwds
964 used_later = defs `intersectNameSet` later_uses
965 -- The ones needed after the RecStmt
968 %************************************************************************
970 \subsubsection{Precedence Parsing}
972 %************************************************************************
974 @mkOpAppRn@ deals with operator fixities. The argument expressions
975 are assumed to be already correctly arranged. It needs the fixities
976 recorded in the OpApp nodes, because fixity info applies to the things
977 the programmer actually wrote, so you can't find it out from the Name.
979 Furthermore, the second argument is guaranteed not to be another
980 operator application. Why? Because the parser parses all
981 operator appications left-associatively, EXCEPT negation, which
982 we need to handle specially.
985 mkOpAppRn :: RenamedHsExpr -- Left operand; already rearranged
986 -> RenamedHsExpr -> Fixity -- Operator and fixity
987 -> RenamedHsExpr -- Right operand (not an OpApp, but might
991 ---------------------------
992 -- (e11 `op1` e12) `op2` e2
993 mkOpAppRn e1@(OpApp e11 op1 fix1 e12) op2 fix2 e2
995 = addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) `thenM_`
996 returnM (OpApp e1 op2 fix2 e2)
999 = mkOpAppRn e12 op2 fix2 e2 `thenM` \ new_e ->
1000 returnM (OpApp e11 op1 fix1 new_e)
1002 (nofix_error, associate_right) = compareFixity fix1 fix2
1004 ---------------------------
1005 -- (- neg_arg) `op` e2
1006 mkOpAppRn e1@(NegApp neg_arg neg_name) op2 fix2 e2
1008 = addErr (precParseErr (pp_prefix_minus,negateFixity) (ppr_op op2,fix2)) `thenM_`
1009 returnM (OpApp e1 op2 fix2 e2)
1012 = mkOpAppRn neg_arg op2 fix2 e2 `thenM` \ new_e ->
1013 returnM (NegApp new_e neg_name)
1015 (nofix_error, associate_right) = compareFixity negateFixity fix2
1017 ---------------------------
1018 -- e1 `op` - neg_arg
1019 mkOpAppRn e1 op1 fix1 e2@(NegApp neg_arg _) -- NegApp can occur on the right
1020 | not associate_right -- We *want* right association
1021 = addErr (precParseErr (ppr_op op1, fix1) (pp_prefix_minus, negateFixity)) `thenM_`
1022 returnM (OpApp e1 op1 fix1 e2)
1024 (_, associate_right) = compareFixity fix1 negateFixity
1026 ---------------------------
1028 mkOpAppRn e1 op fix e2 -- Default case, no rearrangment
1029 = ASSERT2( right_op_ok fix e2,
1030 ppr e1 $$ text "---" $$ ppr op $$ text "---" $$ ppr fix $$ text "---" $$ ppr e2
1032 returnM (OpApp e1 op fix e2)
1034 -- Parser left-associates everything, but
1035 -- derived instances may have correctly-associated things to
1036 -- in the right operarand. So we just check that the right operand is OK
1037 right_op_ok fix1 (OpApp _ _ fix2 _)
1038 = not error_please && associate_right
1040 (error_please, associate_right) = compareFixity fix1 fix2
1041 right_op_ok fix1 other
1044 -- Parser initially makes negation bind more tightly than any other operator
1045 mkNegAppRn neg_arg neg_name
1048 getModeRn `thenM` \ mode ->
1049 ASSERT( not_op_app mode neg_arg )
1051 returnM (NegApp neg_arg neg_name)
1053 not_op_app SourceMode (OpApp _ _ _ _) = False
1054 not_op_app mode other = True
1058 checkPrecMatch :: Bool -> Name -> RenamedMatch -> RnM ()
1060 checkPrecMatch False fn match
1063 checkPrecMatch True op (Match (p1:p2:_) _ _)
1064 -- True indicates an infix lhs
1065 = getModeRn `thenM` \ mode ->
1066 -- See comments with rnExpr (OpApp ...)
1067 if isInterfaceMode mode
1069 else checkPrec op p1 False `thenM_`
1070 checkPrec op p2 True
1072 checkPrecMatch True op _ = panic "checkPrecMatch"
1074 checkPrec op (ConPatIn op1 (InfixCon _ _)) right
1075 = lookupFixityRn op `thenM` \ op_fix@(Fixity op_prec op_dir) ->
1076 lookupFixityRn op1 `thenM` \ op1_fix@(Fixity op1_prec op1_dir) ->
1078 inf_ok = op1_prec > op_prec ||
1079 (op1_prec == op_prec &&
1080 (op1_dir == InfixR && op_dir == InfixR && right ||
1081 op1_dir == InfixL && op_dir == InfixL && not right))
1083 info = (ppr_op op, op_fix)
1084 info1 = (ppr_op op1, op1_fix)
1085 (infol, infor) = if right then (info, info1) else (info1, info)
1087 checkErr inf_ok (precParseErr infol infor)
1089 checkPrec op pat right
1092 -- Check precedence of (arg op) or (op arg) respectively
1093 -- If arg is itself an operator application, then either
1094 -- (a) its precedence must be higher than that of op
1095 -- (b) its precedency & associativity must be the same as that of op
1096 checkSectionPrec direction section op arg
1098 OpApp _ op fix _ -> go_for_it (ppr_op op) fix
1099 NegApp _ _ -> go_for_it pp_prefix_minus negateFixity
1103 go_for_it pp_arg_op arg_fix@(Fixity arg_prec assoc)
1104 = lookupFixityRn op_name `thenM` \ op_fix@(Fixity op_prec _) ->
1105 checkErr (op_prec < arg_prec
1106 || op_prec == arg_prec && direction == assoc)
1107 (sectionPrecErr (ppr_op op_name, op_fix)
1108 (pp_arg_op, arg_fix) section)
1112 %************************************************************************
1114 \subsubsection{Assertion utils}
1116 %************************************************************************
1119 mkAssertErrorExpr :: RnM (RenamedHsExpr, FreeVars)
1120 -- Return an expression for (assertError "Foo.hs:27")
1122 = getSrcLocM `thenM` \ sloc ->
1124 expr = HsApp (HsVar assertErrorName) (HsLit msg)
1125 msg = HsStringPrim (mkFastString (stringToUtf8 (showSDoc (ppr sloc))))
1127 returnM (expr, unitFV assertErrorName)
1130 %************************************************************************
1132 \subsubsection{Errors}
1134 %************************************************************************
1137 ppr_op op = quotes (ppr op) -- Here, op can be a Name or a (Var n), where n is a Name
1138 pp_prefix_minus = ptext SLIT("prefix `-'")
1140 nonStdGuardErr guard
1142 SLIT("accepting non-standard pattern guards (-fglasgow-exts to suppress this message)")
1146 = sep [ptext SLIT("Pattern syntax in expression context:"),
1149 doStmtListErr do_or_lc e
1150 = sep [quotes (text binder_name) <+> ptext SLIT("statements must end in expression:"),
1153 binder_name = case do_or_lc of
1158 checkTH e what = returnM () -- OK
1160 checkTH e what -- Raise an error in a stage-1 compiler
1161 = addErr (vcat [ptext SLIT("Template Haskell") <+> text what <+>
1162 ptext SLIT("illegal in a stage-1 compiler"),
1166 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -fglagow-exts"))
1169 = hang (ptext SLIT("Implicit-parameter bindings illegal in a parallel list comprehension:")) 4