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 -- The above warning supression flag is a temporary kludge.
15 -- While working on this module you are encouraged to remove it and fix
16 -- any warnings in the module. See
17 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
21 rnLExpr, rnExpr, rnStmts
24 #include "HsVersions.h"
27 import {-# SOURCE #-} TcSplice( runQuasiQuoteExpr )
30 import RnSource ( rnSrcDecls, rnSplice, checkTH )
31 import RnBinds ( rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS,
32 rnMatchGroup, makeMiniFixityEnv)
36 import HscTypes ( availNames )
37 import RnTypes ( rnHsTypeFVs,
38 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec)
39 import RnPat (rnQuasiQuote, rnOverLit, rnPatsAndThen_LocalRightwards, rnBindPat,
40 localRecNameMaker, rnLit,
41 rnHsRecFields_Con, rnHsRecFields_Update, checkTupSize)
42 import RdrName ( mkRdrUnqual )
43 import DynFlags ( DynFlag(..) )
44 import BasicTypes ( FixityDirection(..) )
45 import SrcLoc ( SrcSpan )
46 import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName,
47 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
48 negateName, thenMName, bindMName, failMName, groupWithName )
50 import Name ( Name, nameOccName, nameModule, nameIsLocalOrFrom )
53 import RdrName ( RdrName, extendLocalRdrEnv, lookupLocalRdrEnv, hideSomeUnquals )
54 import LoadIface ( loadInterfaceForName )
55 import UniqSet ( isEmptyUniqSet, emptyUniqSet )
57 import Util ( isSingleton )
58 import ListSetOps ( removeDups )
59 import Maybes ( expectJust )
61 import SrcLoc ( Located(..), unLoc, getLoc, noLoc )
64 import List ( unzip4 )
71 thenM :: Monad a => a b -> (b -> a c) -> a c
74 thenM_ :: Monad a => a b -> a c -> a c
77 returnM :: Monad m => a -> m a
80 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
83 mappM_ :: (Monad m) => (a -> m b) -> [a] -> m ()
86 checkM :: Monad m => Bool -> m () -> m ()
90 %************************************************************************
92 \subsubsection{Expressions}
94 %************************************************************************
97 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
98 rnExprs ls = rnExprs' ls emptyUniqSet
100 rnExprs' [] acc = returnM ([], acc)
101 rnExprs' (expr:exprs) acc
102 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
104 -- Now we do a "seq" on the free vars because typically it's small
105 -- or empty, especially in very long lists of constants
107 acc' = acc `plusFV` fvExpr
109 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
110 returnM (expr':exprs', fvExprs)
112 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
113 grubby_seqNameSet ns result | isEmptyUniqSet ns = result
117 Variables. We look up the variable and return the resulting name.
120 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
121 rnLExpr = wrapLocFstM rnExpr
123 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
126 = do name <- lookupOccRn v
127 ignore_asserts <- doptM Opt_IgnoreAsserts
128 finish_var ignore_asserts name
130 finish_var ignore_asserts name
131 | ignore_asserts || not (name `hasKey` assertIdKey)
132 = return (HsVar name, unitFV name)
134 = do { (e, fvs) <- mkAssertErrorExpr
135 ; return (e, fvs `addOneFV` name) }
138 = newIPNameRn v `thenM` \ name ->
139 returnM (HsIPVar name, emptyFVs)
141 rnExpr (HsLit lit@(HsString s))
143 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
144 ; if opt_OverloadedStrings then
145 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
146 else -- Same as below
148 returnM (HsLit lit, emptyFVs)
153 returnM (HsLit lit, emptyFVs)
155 rnExpr (HsOverLit lit)
156 = rnOverLit lit `thenM` \ (lit', fvs) ->
157 returnM (HsOverLit lit', fvs)
159 rnExpr (HsApp fun arg)
160 = rnLExpr fun `thenM` \ (fun',fvFun) ->
161 rnLExpr arg `thenM` \ (arg',fvArg) ->
162 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
164 rnExpr (OpApp e1 op _ e2)
165 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
166 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
167 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
170 -- When renaming code synthesised from "deriving" declarations
171 -- we used to avoid fixity stuff, but we can't easily tell any
172 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
173 -- should prevent bad things happening.
174 lookupFixityRn op_name `thenM` \ fixity ->
175 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
178 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
181 = rnLExpr e `thenM` \ (e', fv_e) ->
182 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
183 mkNegAppRn e' neg_name `thenM` \ final_e ->
184 returnM (final_e, fv_e `plusFV` fv_neg)
187 = rnLExpr e `thenM` \ (e', fvs_e) ->
188 returnM (HsPar e', fvs_e)
190 -- Template Haskell extensions
191 -- Don't ifdef-GHCI them because we want to fail gracefully
192 -- (not with an rnExpr crash) in a stage-1 compiler.
193 rnExpr e@(HsBracket br_body)
194 = checkTH e "bracket" `thenM_`
195 rnBracket br_body `thenM` \ (body', fvs_e) ->
196 returnM (HsBracket body', fvs_e)
198 rnExpr e@(HsSpliceE splice)
199 = rnSplice splice `thenM` \ (splice', fvs) ->
200 returnM (HsSpliceE splice', fvs)
203 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
205 rnExpr e@(HsQuasiQuoteE qq)
206 = rnQuasiQuote qq `thenM` \ (qq', fvs_qq) ->
207 runQuasiQuoteExpr qq' `thenM` \ (L _ expr') ->
208 rnExpr expr' `thenM` \ (expr'', fvs_expr) ->
209 returnM (expr'', fvs_qq `plusFV` fvs_expr)
212 rnExpr section@(SectionL expr op)
213 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
214 rnLExpr op `thenM` \ (op', fvs_op) ->
215 checkSectionPrec InfixL section op' expr' `thenM_`
216 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
218 rnExpr section@(SectionR op expr)
219 = rnLExpr op `thenM` \ (op', fvs_op) ->
220 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
221 checkSectionPrec InfixR section op' expr' `thenM_`
222 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
224 rnExpr (HsCoreAnn ann expr)
225 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
226 returnM (HsCoreAnn ann expr', fvs_expr)
228 rnExpr (HsSCC lbl expr)
229 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
230 returnM (HsSCC lbl expr', fvs_expr)
231 rnExpr (HsTickPragma info expr)
232 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
233 returnM (HsTickPragma info expr', fvs_expr)
235 rnExpr (HsLam matches)
236 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
237 returnM (HsLam matches', fvMatch)
239 rnExpr (HsCase expr matches)
240 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
241 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
242 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
244 rnExpr (HsLet binds expr)
245 = rnLocalBindsAndThen binds $ \ binds' ->
246 rnLExpr expr `thenM` \ (expr',fvExpr) ->
247 returnM (HsLet binds' expr', fvExpr)
249 rnExpr e@(HsDo do_or_lc stmts body _)
250 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
252 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
254 rnExpr (ExplicitList _ exps)
255 = rnExprs exps `thenM` \ (exps', fvs) ->
256 returnM (ExplicitList placeHolderType exps', fvs)
258 rnExpr (ExplicitPArr _ exps)
259 = rnExprs exps `thenM` \ (exps', fvs) ->
260 returnM (ExplicitPArr placeHolderType exps', fvs)
262 rnExpr e@(ExplicitTuple exps boxity)
263 = checkTupSize (length exps) `thenM_`
264 rnExprs exps `thenM` \ (exps', fvs) ->
265 returnM (ExplicitTuple exps' boxity, fvs)
267 rnExpr (RecordCon con_id _ rbinds)
268 = do { conname <- lookupLocatedOccRn con_id
269 ; (rbinds', fvRbinds) <- rnHsRecFields_Con conname rnLExpr rbinds
270 ; return (RecordCon conname noPostTcExpr rbinds',
271 fvRbinds `addOneFV` unLoc conname) }
273 rnExpr (RecordUpd expr rbinds _ _ _)
274 = do { (expr', fvExpr) <- rnLExpr expr
275 ; (rbinds', fvRbinds) <- rnHsRecFields_Update rnLExpr rbinds
276 ; return (RecordUpd expr' rbinds' [] [] [],
277 fvExpr `plusFV` fvRbinds) }
279 rnExpr (ExprWithTySig expr pty)
280 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
281 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
283 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
285 doc = text "In an expression type signature"
287 rnExpr (HsIf p b1 b2)
288 = rnLExpr p `thenM` \ (p', fvP) ->
289 rnLExpr b1 `thenM` \ (b1', fvB1) ->
290 rnLExpr b2 `thenM` \ (b2', fvB2) ->
291 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
294 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
295 returnM (HsType t, fvT)
297 doc = text "In a type argument"
299 rnExpr (ArithSeq _ seq)
300 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
301 returnM (ArithSeq noPostTcExpr new_seq, fvs)
303 rnExpr (PArrSeq _ seq)
304 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
305 returnM (PArrSeq noPostTcExpr new_seq, fvs)
308 These three are pattern syntax appearing in expressions.
309 Since all the symbols are reservedops we can simply reject them.
310 We return a (bogus) EWildPat in each case.
313 rnExpr e@EWildPat = patSynErr e
314 rnExpr e@(EAsPat {}) = patSynErr e
315 rnExpr e@(EViewPat {}) = patSynErr e
316 rnExpr e@(ELazyPat {}) = patSynErr e
319 %************************************************************************
323 %************************************************************************
326 rnExpr (HsProc pat body)
328 rnPatsAndThen_LocalRightwards ProcExpr [pat] $ \ [pat'] ->
329 rnCmdTop body `thenM` \ (body',fvBody) ->
330 returnM (HsProc pat' body', fvBody)
332 rnExpr (HsArrApp arrow arg _ ho rtl)
333 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
334 rnLExpr arg `thenM` \ (arg',fvArg) ->
335 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
336 fvArrow `plusFV` fvArg)
338 select_arrow_scope tc = case ho of
339 HsHigherOrderApp -> tc
340 HsFirstOrderApp -> escapeArrowScope tc
343 rnExpr (HsArrForm op (Just _) [arg1, arg2])
344 = escapeArrowScope (rnLExpr op)
345 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
346 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
347 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
351 lookupFixityRn op_name `thenM` \ fixity ->
352 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
355 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
357 rnExpr (HsArrForm op fixity cmds)
358 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
359 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
360 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
362 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
367 %************************************************************************
371 %************************************************************************
374 rnCmdArgs [] = returnM ([], emptyFVs)
376 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
377 rnCmdArgs args `thenM` \ (args',fvArgs) ->
378 returnM (arg':args', fvArg `plusFV` fvArgs)
381 rnCmdTop = wrapLocFstM rnCmdTop'
383 rnCmdTop' (HsCmdTop cmd _ _ _)
384 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
386 cmd_names = [arrAName, composeAName, firstAName] ++
387 nameSetToList (methodNamesCmd (unLoc cmd'))
389 -- Generate the rebindable syntax for the monad
390 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
392 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
393 fvCmd `plusFV` cmd_fvs)
395 ---------------------------------------------------
396 -- convert OpApp's in a command context to HsArrForm's
398 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
399 convertOpFormsLCmd = fmap convertOpFormsCmd
401 convertOpFormsCmd :: HsCmd id -> HsCmd id
403 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
404 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
405 convertOpFormsCmd (OpApp c1 op fixity c2)
407 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
408 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
410 HsArrForm op (Just fixity) [arg1, arg2]
412 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
414 convertOpFormsCmd (HsCase exp matches)
415 = HsCase exp (convertOpFormsMatch matches)
417 convertOpFormsCmd (HsIf exp c1 c2)
418 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
420 convertOpFormsCmd (HsLet binds cmd)
421 = HsLet binds (convertOpFormsLCmd cmd)
423 convertOpFormsCmd (HsDo ctxt stmts body ty)
424 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
425 (convertOpFormsLCmd body) ty
427 -- Anything else is unchanged. This includes HsArrForm (already done),
428 -- things with no sub-commands, and illegal commands (which will be
429 -- caught by the type checker)
430 convertOpFormsCmd c = c
432 convertOpFormsStmt (BindStmt pat cmd _ _)
433 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
434 convertOpFormsStmt (ExprStmt cmd _ _)
435 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
436 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
437 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
438 convertOpFormsStmt stmt = stmt
440 convertOpFormsMatch (MatchGroup ms ty)
441 = MatchGroup (map (fmap convert) ms) ty
442 where convert (Match pat mty grhss)
443 = Match pat mty (convertOpFormsGRHSs grhss)
445 convertOpFormsGRHSs (GRHSs grhss binds)
446 = GRHSs (map convertOpFormsGRHS grhss) binds
448 convertOpFormsGRHS = fmap convert
450 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
452 ---------------------------------------------------
453 type CmdNeeds = FreeVars -- Only inhabitants are
454 -- appAName, choiceAName, loopAName
456 -- find what methods the Cmd needs (loop, choice, apply)
457 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
458 methodNamesLCmd = methodNamesCmd . unLoc
460 methodNamesCmd :: HsCmd Name -> CmdNeeds
462 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
464 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
466 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
468 methodNamesCmd (HsPar c) = methodNamesLCmd c
470 methodNamesCmd (HsIf p c1 c2)
471 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
473 methodNamesCmd (HsLet b c) = methodNamesLCmd c
475 methodNamesCmd (HsDo sc stmts body ty)
476 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
478 methodNamesCmd (HsApp c e) = methodNamesLCmd c
480 methodNamesCmd (HsLam match) = methodNamesMatch match
482 methodNamesCmd (HsCase scrut matches)
483 = methodNamesMatch matches `addOneFV` choiceAName
485 methodNamesCmd other = emptyFVs
486 -- Other forms can't occur in commands, but it's not convenient
487 -- to error here so we just do what's convenient.
488 -- The type checker will complain later
490 ---------------------------------------------------
491 methodNamesMatch (MatchGroup ms _)
492 = plusFVs (map do_one ms)
494 do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss
496 -------------------------------------------------
498 methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss)
500 -------------------------------------------------
501 methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs
503 ---------------------------------------------------
504 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
506 ---------------------------------------------------
507 methodNamesLStmt = methodNamesStmt . unLoc
509 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
510 methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd
511 methodNamesStmt (RecStmt stmts _ _ _ _)
512 = methodNamesStmts stmts `addOneFV` loopAName
513 methodNamesStmt (LetStmt b) = emptyFVs
514 methodNamesStmt (ParStmt ss) = emptyFVs
515 methodNamesStmt (TransformStmt _ _ _) = emptyFVs
516 methodNamesStmt (GroupStmt _ _) = emptyFVs
517 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
518 -- here so we just do what's convenient
522 %************************************************************************
526 %************************************************************************
529 rnArithSeq (From expr)
530 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
531 returnM (From expr', fvExpr)
533 rnArithSeq (FromThen expr1 expr2)
534 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
535 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
536 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
538 rnArithSeq (FromTo expr1 expr2)
539 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
540 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
541 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
543 rnArithSeq (FromThenTo expr1 expr2 expr3)
544 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
545 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
546 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
547 returnM (FromThenTo expr1' expr2' expr3',
548 plusFVs [fvExpr1, fvExpr2, fvExpr3])
551 %************************************************************************
553 Template Haskell brackets
555 %************************************************************************
558 rnBracket (VarBr n) = do { name <- lookupOccRn n
559 ; this_mod <- getModule
560 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
561 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
562 ; return () } -- only way that is going to happen
563 ; returnM (VarBr name, unitFV name) }
565 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
567 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
568 ; return (ExpBr e', fvs) }
570 rnBracket (PatBr p) = do { addErr (ptext (sLit "Tempate Haskell pattern brackets are not supported yet"));
573 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
574 ; return (TypBr t', fvs) }
576 doc = ptext (sLit "In a Template-Haskell quoted type")
577 rnBracket (DecBr group)
578 = do { gbl_env <- getGblEnv
580 ; let new_gbl_env = gbl_env { -- Set the module to thFAKE. The top-level names from the bracketed
581 -- declarations will go into the name cache, and we don't want them to
582 -- confuse the Names for the current module.
583 -- By using a pretend module, thFAKE, we keep them safely out of the way.
586 -- The emptyDUs is so that we just collect uses for this group alone
587 -- in the call to rnSrcDecls below
589 ; setGblEnv new_gbl_env $ do {
591 -- In this situation we want to *shadow* top-level bindings.
593 -- bar = [d| foo = 1 |]
594 -- If we don't shadow, we'll get an ambiguity complaint when we do
595 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
597 -- Furthermore, arguably if the splice does define foo, that should hide
598 -- any foo's further out
600 -- The shadowing is acheived by calling rnSrcDecls with True as the shadowing flag
601 ; (tcg_env, group') <- rnSrcDecls True group
603 -- Discard the tcg_env; it contains only extra info about fixity
604 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
607 %************************************************************************
609 \subsubsection{@Stmt@s: in @do@ expressions}
611 %************************************************************************
614 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
615 -> RnM (thing, FreeVars)
616 -> RnM (([LStmt Name], thing), FreeVars)
618 rnStmts (MDoExpr _) = rnMDoStmts
619 rnStmts ctxt = rnNormalStmts ctxt
621 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
622 -> RnM (thing, FreeVars)
623 -> RnM (([LStmt Name], thing), FreeVars)
624 -- Used for cases *other* than recursive mdo
625 -- Implements nested scopes
627 rnNormalStmts ctxt [] thing_inside
628 = do { (thing, fvs) <- thing_inside
629 ; return (([],thing), fvs) }
631 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
632 = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $
633 rnNormalStmts ctxt stmts thing_inside
634 ; return (((L loc stmt' : stmts'), thing), fvs) }
637 rnStmt :: HsStmtContext Name -> Stmt RdrName
638 -> RnM (thing, FreeVars)
639 -> RnM ((Stmt Name, thing), FreeVars)
641 rnStmt ctxt (ExprStmt expr _ _) thing_inside
642 = do { (expr', fv_expr) <- rnLExpr expr
643 ; (then_op, fvs1) <- lookupSyntaxName thenMName
644 ; (thing, fvs2) <- thing_inside
645 ; return ((ExprStmt expr' then_op placeHolderType, thing),
646 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
648 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
649 = do { (expr', fv_expr) <- rnLExpr expr
650 -- The binders do not scope over the expression
651 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
652 ; (fail_op, fvs2) <- lookupSyntaxName failMName
653 ; rnPatsAndThen_LocalRightwards (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
654 { (thing, fvs3) <- thing_inside
655 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
656 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
657 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
658 -- but it does not matter because the names are unique
660 rnStmt ctxt (LetStmt binds) thing_inside
661 = do { checkLetStmt ctxt binds
662 ; rnLocalBindsAndThen binds $ \binds' -> do
663 { (thing, fvs) <- thing_inside
664 ; return ((LetStmt binds', thing), fvs) } }
666 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
667 = do { checkRecStmt ctxt
668 ; rn_rec_stmts_and_then rec_stmts $ \ segs -> do
669 { (thing, fvs) <- thing_inside
671 segs_w_fwd_refs = addFwdRefs segs
672 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
673 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
674 fwd_vars = nameSetToList (plusFVs fs)
676 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
677 ; return ((rec_stmt, thing), uses `plusFV` fvs) } }
679 rnStmt ctxt (ParStmt segs) thing_inside
680 = do { checkParStmt ctxt
681 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
682 ; return ((ParStmt segs', thing), fvs) }
684 rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do
685 checkTransformStmt ctxt
687 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
688 ((stmts', binders, (maybeByExpr', thing)), fvs) <-
689 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
690 (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr
691 (thing, fv_thing) <- thing_inside
693 return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing)
695 return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs)
697 rnMaybeLExpr Nothing = return (Nothing, emptyFVs)
698 rnMaybeLExpr (Just expr) = do
699 (expr', fv_expr) <- rnLExpr expr
700 return (Just expr', fv_expr)
702 rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do
703 checkTransformStmt ctxt
705 -- We must rename the using expression in the context before the transform is begun
706 groupByClauseAction <-
707 case groupByClause of
708 GroupByNothing usingExpr -> do
709 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
710 (return . return) (GroupByNothing usingExpr', fv_usingExpr)
711 GroupBySomething eitherUsingExpr byExpr -> do
712 (eitherUsingExpr', fv_eitherUsingExpr) <-
713 case eitherUsingExpr of
714 Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName)
716 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
717 return (Left usingExpr', fv_usingExpr)
720 (byExpr', fv_byExpr) <- rnLExpr byExpr
721 return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr)
723 -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so
724 -- perhaps we could refactor this to use rnNormalStmts directly?
725 ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <-
726 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
727 (groupByClause', fv_groupByClause) <- groupByClauseAction
729 unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs
730 let binderMap = zip unshadowed_bndrs unshadowed_bndrs'
732 -- Bind the "thing" inside a context where we have REBOUND everything
733 -- bound by the statements before the group. This is necessary since after
734 -- the grouping the same identifiers actually have different meanings
735 -- i.e. they refer to lists not singletons!
736 (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside
738 -- We remove entries from the binder map that are not used in the thing_inside.
739 -- We can then use that usage information to ensure that the free variables do
740 -- not contain the things we just bound, but do contain the things we need to
741 -- make those bindings (i.e. the corresponding non-listy variables)
743 -- Note that we also retain those entries which have an old binder in our
744 -- own free variables (the using or by expression). This is because this map
745 -- is reused in the desugarer to create the type to bind from the statements
746 -- that occur before this one. If the binders we need are not in the map, they
747 -- will never get bound into our desugared expression and hence the simplifier
748 -- crashes as we refer to variables that don't exist!
749 let usedBinderMap = filter
750 (\(old_binder, new_binder) ->
751 (new_binder `elemNameSet` fv_thing) ||
752 (old_binder `elemNameSet` fv_groupByClause)) binderMap
753 (usedOldBinders, usedNewBinders) = unzip usedBinderMap
754 real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders)
756 return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing)
758 traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap)
759 return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs)
761 rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name
763 -> ([Name] -> RnM (thing, FreeVars))
764 -> RnM (([LStmt Name], [Name], thing), FreeVars)
765 rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do
766 ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do
767 -- Find the Names that are bound by stmts that
768 -- by assumption we have just renamed
769 local_env <- getLocalRdrEnv
771 stmts_binders = collectLStmtsBinders stmts
772 bndrs = map (expectJust "rnStmt"
773 . lookupLocalRdrEnv local_env
774 . unLoc) stmts_binders
776 -- If shadow, we'll look up (Unqual x) twice, getting
777 -- the second binding both times, which is the
779 unshadowed_bndrs = nub bndrs
781 -- Typecheck the thing inside, passing on all
782 -- the Names bound before it for its information
783 (thing, fvs) <- thing_inside unshadowed_bndrs
785 -- Figure out which of the bound names are used
786 -- after the statements we renamed
787 let used_bndrs = filter (`elemNameSet` fvs) bndrs
788 return ((used_bndrs, thing), fvs)
790 -- Flatten the tuple returned by the above call a bit!
791 return ((stmts', used_bndrs, inner_thing), fvs)
794 rnParallelStmts ctxt segs thing_inside = do
795 orig_lcl_env <- getLocalRdrEnv
796 go orig_lcl_env [] segs
798 go orig_lcl_env bndrs [] = do
799 let (bndrs', dups) = removeDups cmpByOcc bndrs
800 inner_env = extendLocalRdrEnv orig_lcl_env bndrs'
803 (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
804 return (([], thing), fvs)
806 go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do
807 ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do
808 -- Typecheck the thing inside, passing on all
809 -- the Names bound, but separately; revert the envt
810 setLocalRdrEnv orig_lcl_env $ do
811 go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs
813 let seg' = (stmts', bndrs)
814 return (((seg':segs'), thing), delListFromNameSet fvs bndrs)
816 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
817 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
818 <+> quotes (ppr (head vs)))
822 %************************************************************************
824 \subsubsection{mdo expressions}
826 %************************************************************************
829 type FwdRefs = NameSet
830 type Segment stmts = (Defs,
831 Uses, -- May include defs
832 FwdRefs, -- A subset of uses that are
833 -- (a) used before they are bound in this segment, or
834 -- (b) used here, and bound in subsequent segments
835 stmts) -- Either Stmt or [Stmt]
838 ----------------------------------------------------
840 rnMDoStmts :: [LStmt RdrName]
841 -> RnM (thing, FreeVars)
842 -> RnM (([LStmt Name], thing), FreeVars)
843 rnMDoStmts stmts thing_inside
844 = -- Step1: Bring all the binders of the mdo into scope
845 -- (Remember that this also removes the binders from the
846 -- finally-returned free-vars.)
847 -- And rename each individual stmt, making a
848 -- singleton segment. At this stage the FwdRefs field
849 -- isn't finished: it's empty for all except a BindStmt
850 -- for which it's the fwd refs within the bind itself
851 -- (This set may not be empty, because we're in a recursive
853 rn_rec_stmts_and_then stmts $ \ segs -> do {
855 ; (thing, fvs_later) <- thing_inside
858 -- Step 2: Fill in the fwd refs.
859 -- The segments are all singletons, but their fwd-ref
860 -- field mentions all the things used by the segment
861 -- that are bound after their use
862 segs_w_fwd_refs = addFwdRefs segs
864 -- Step 3: Group together the segments to make bigger segments
865 -- Invariant: in the result, no segment uses a variable
866 -- bound in a later segment
867 grouped_segs = glomSegments segs_w_fwd_refs
869 -- Step 4: Turn the segments into Stmts
870 -- Use RecStmt when and only when there are fwd refs
871 -- Also gather up the uses from the end towards the
872 -- start, so we can tell the RecStmt which things are
873 -- used 'after' the RecStmt
874 (stmts', fvs) = segsToStmts grouped_segs fvs_later
876 ; return ((stmts', thing), fvs) }
878 doc = text "In a recursive mdo-expression"
880 ---------------------------------------------
882 -- wrapper that does both the left- and right-hand sides
883 rn_rec_stmts_and_then :: [LStmt RdrName]
884 -- assumes that the FreeVars returned includes
885 -- the FreeVars of the Segments
886 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
888 rn_rec_stmts_and_then s cont
889 = do { -- (A) Make the mini fixity env for all of the stmts
890 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
893 ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
895 -- ...bring them and their fixities into scope
896 ; let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
897 ; bindLocalNamesFV_WithFixities bound_names fix_env $ do
899 -- (C) do the right-hand-sides and thing-inside
900 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
901 ; (res, fvs) <- cont segs
902 ; warnUnusedLocalBinds bound_names fvs
903 ; return (res, fvs) }}
905 -- get all the fixity decls in any Let stmt
906 collectRecStmtsFixities l =
907 foldr (\ s -> \acc -> case s of
908 (L loc (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
909 foldr (\ sig -> \ acc -> case sig of
910 (L loc (FixSig s)) -> (L loc s) : acc
916 rn_rec_stmt_lhs :: MiniFixityEnv
918 -- rename LHS, and return its FVs
919 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
920 -- so we don't bother to compute it accurately in the other cases
921 -> RnM [(LStmtLR Name RdrName, FreeVars)]
923 rn_rec_stmt_lhs fix_env (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
924 -- this is actually correct
927 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
929 -- should the ctxt be MDo instead?
930 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
931 return [(L loc (BindStmt pat' expr a b),
934 rn_rec_stmt_lhs fix_env (L loc (LetStmt binds@(HsIPBinds _)))
935 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
938 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
939 = do binds' <- rnValBindsLHS fix_env binds
940 return [(L loc (LetStmt (HsValBinds binds')),
941 -- Warning: this is bogus; see function invariant
945 rn_rec_stmt_lhs fix_env (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
946 = rn_rec_stmts_lhs fix_env stmts
948 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
949 = pprPanic "rn_rec_stmt" (ppr stmt)
951 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo
952 = pprPanic "rn_rec_stmt" (ppr stmt)
954 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo
955 = pprPanic "rn_rec_stmt" (ppr stmt)
957 rn_rec_stmts_lhs :: MiniFixityEnv
959 -> RnM [(LStmtLR Name RdrName, FreeVars)]
960 rn_rec_stmts_lhs fix_env stmts =
961 let boundNames = collectLStmtsBinders stmts
962 doc = text "In a recursive mdo-expression"
964 -- First do error checking: we need to check for dups here because we
965 -- don't bind all of the variables from the Stmt at once
966 -- with bindLocatedLocals.
967 checkDupRdrNames doc boundNames
968 mappM (rn_rec_stmt_lhs fix_env) stmts `thenM` \ ls -> returnM (concat ls)
973 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
974 -- Rename a Stmt that is inside a RecStmt (or mdo)
975 -- Assumes all binders are already in scope
976 -- Turns each stmt into a singleton Stmt
977 rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _)) _
978 = rnLExpr expr `thenM` \ (expr', fvs) ->
979 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
980 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
981 L loc (ExprStmt expr' then_op placeHolderType))]
983 rn_rec_stmt all_bndrs (L loc (BindStmt pat' expr _ _)) fv_pat
984 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
985 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
986 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
988 bndrs = mkNameSet (collectPatBinders pat')
989 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
991 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
992 L loc (BindStmt pat' expr' bind_op fail_op))]
994 rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _))) _
995 = do { addErr (badIpBinds (ptext (sLit "an mdo expression")) binds)
998 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
999 (binds', du_binds) <-
1000 -- fixities and unused are handled above in rn_rec_stmts_and_then
1001 rnValBindsRHS all_bndrs binds'
1002 returnM [(duDefs du_binds, duUses du_binds,
1003 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1005 -- no RecStmt case becuase they get flattened above when doing the LHSes
1006 rn_rec_stmt all_bndrs stmt@(L loc (RecStmt stmts _ _ _ _)) _
1007 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1009 rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo
1010 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1012 rn_rec_stmt all_bndrs stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo
1013 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1015 rn_rec_stmt all_bndrs stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo
1016 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1018 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1019 rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1020 returnM (concat segs_s)
1022 ---------------------------------------------
1023 addFwdRefs :: [Segment a] -> [Segment a]
1024 -- So far the segments only have forward refs *within* the Stmt
1025 -- (which happens for bind: x <- ...x...)
1026 -- This function adds the cross-seg fwd ref info
1029 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1031 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1032 = (new_seg : segs, all_defs)
1034 new_seg = (defs, uses, new_fwds, stmts)
1035 all_defs = later_defs `unionNameSets` defs
1036 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1037 -- Add the downstream fwd refs here
1039 ----------------------------------------------------
1040 -- Glomming the singleton segments of an mdo into
1041 -- minimal recursive groups.
1043 -- At first I thought this was just strongly connected components, but
1044 -- there's an important constraint: the order of the stmts must not change.
1047 -- mdo { x <- ...y...
1054 -- Here, the first stmt mention 'y', which is bound in the third.
1055 -- But that means that the innocent second stmt (p <- z) gets caught
1056 -- up in the recursion. And that in turn means that the binding for
1057 -- 'z' has to be included... and so on.
1059 -- Start at the tail { r <- x }
1060 -- Now add the next one { z <- y ; r <- x }
1061 -- Now add one more { q <- x ; z <- y ; r <- x }
1062 -- Now one more... but this time we have to group a bunch into rec
1063 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1064 -- Now one more, which we can add on without a rec
1066 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1068 -- Finally we add the last one; since it mentions y we have to
1069 -- glom it togeher with the first two groups
1070 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1071 -- q <- x ; z <- y } ;
1074 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1076 glomSegments [] = []
1077 glomSegments ((defs,uses,fwds,stmt) : segs)
1078 -- Actually stmts will always be a singleton
1079 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1081 segs' = glomSegments segs
1082 (extras, others) = grab uses segs'
1083 (ds, us, fs, ss) = unzip4 extras
1085 seg_defs = plusFVs ds `plusFV` defs
1086 seg_uses = plusFVs us `plusFV` uses
1087 seg_fwds = plusFVs fs `plusFV` fwds
1088 seg_stmts = stmt : concat ss
1090 grab :: NameSet -- The client
1092 -> ([Segment a], -- Needed by the 'client'
1093 [Segment a]) -- Not needed by the client
1094 -- The result is simply a split of the input
1096 = (reverse yeses, reverse noes)
1098 (noes, yeses) = span not_needed (reverse dus)
1099 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1102 ----------------------------------------------------
1103 segsToStmts :: [Segment [LStmt Name]]
1104 -> FreeVars -- Free vars used 'later'
1105 -> ([LStmt Name], FreeVars)
1107 segsToStmts [] fvs_later = ([], fvs_later)
1108 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
1109 = ASSERT( not (null ss) )
1110 (new_stmt : later_stmts, later_uses `plusFV` uses)
1112 (later_stmts, later_uses) = segsToStmts segs fvs_later
1113 new_stmt | non_rec = head ss
1114 | otherwise = L (getLoc (head ss)) $
1115 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
1118 non_rec = isSingleton ss && isEmptyNameSet fwds
1119 used_later = defs `intersectNameSet` later_uses
1120 -- The ones needed after the RecStmt
1123 %************************************************************************
1125 \subsubsection{Assertion utils}
1127 %************************************************************************
1130 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1131 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
1133 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
1134 -- Return an expression for (assertError "Foo.hs:27")
1136 = getSrcSpanM `thenM` \ sloc ->
1138 expr = HsApp (L sloc (HsVar assertErrorName))
1139 (L sloc (srcSpanPrimLit sloc))
1141 returnM (expr, emptyFVs)
1144 %************************************************************************
1146 \subsubsection{Errors}
1148 %************************************************************************
1152 ----------------------
1153 -- Checking when a particular Stmt is ok
1154 checkLetStmt :: HsStmtContext Name -> HsLocalBinds RdrName -> RnM ()
1155 checkLetStmt (ParStmtCtxt _) (HsIPBinds binds) = addErr (badIpBinds (ptext (sLit "a parallel list comprehension:")) binds)
1156 checkLetStmt _ctxt _binds = return ()
1157 -- We do not allow implicit-parameter bindings in a parallel
1158 -- list comprehension. I'm not sure what it might mean.
1161 checkRecStmt :: HsStmtContext Name -> RnM ()
1162 checkRecStmt (MDoExpr {}) = return () -- Recursive stmt ok in 'mdo'
1163 checkRecStmt (DoExpr {}) = return () -- ..and in 'do' but only because of arrows:
1164 -- proc x -> do { ...rec... }
1165 -- We don't have enough context to distinguish this situation here
1166 -- so we leave it to the type checker
1167 checkRecStmt ctxt = addErr msg
1169 msg = ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt
1172 checkParStmt :: HsStmtContext Name -> RnM ()
1174 = do { parallel_list_comp <- doptM Opt_ParallelListComp
1175 ; checkErr parallel_list_comp msg }
1177 msg = ptext (sLit "Illegal parallel list comprehension: use -XParallelListComp")
1180 checkTransformStmt :: HsStmtContext Name -> RnM ()
1181 checkTransformStmt ListComp -- Ensure we are really within a list comprehension because otherwise the
1182 -- desugarer will break when we come to operate on a parallel array
1183 = do { transform_list_comp <- doptM Opt_TransformListComp
1184 ; checkErr transform_list_comp msg }
1186 msg = ptext (sLit "Illegal transform or grouping list comprehension: use -XTransformListComp")
1187 checkTransformStmt (ParStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1188 checkTransformStmt (TransformStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1189 checkTransformStmt ctxt = addErr msg
1191 msg = ptext (sLit "Illegal transform or grouping in") <+> pprStmtContext ctxt
1194 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1196 ; return (EWildPat, emptyFVs) }
1198 badIpBinds what binds
1199 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)