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 RnNames ( getLocalDeclBinders, extendRdrEnvRn )
38 import RnTypes ( rnHsTypeFVs,
39 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec)
40 import RnPat (rnQuasiQuote, rnOverLit, rnPatsAndThen_LocalRightwards, rnBindPat,
41 localRecNameMaker, rnLit,
42 rnHsRecFields_Con, rnHsRecFields_Update, checkTupSize)
43 import RdrName ( mkRdrUnqual )
44 import DynFlags ( DynFlag(..) )
45 import BasicTypes ( FixityDirection(..) )
46 import SrcLoc ( SrcSpan )
47 import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName,
48 loopAName, choiceAName, appAName, arrAName, composeAName, firstAName,
49 negateName, thenMName, bindMName, failMName, groupWithName )
51 import Name ( Name, nameOccName, nameModule, nameIsLocalOrFrom )
54 import RdrName ( RdrName, extendLocalRdrEnv, lookupLocalRdrEnv, hideSomeUnquals )
55 import LoadIface ( loadInterfaceForName )
56 import UniqSet ( isEmptyUniqSet, emptyUniqSet )
58 import Util ( isSingleton )
59 import ListSetOps ( removeDups )
60 import Maybes ( expectJust )
62 import SrcLoc ( Located(..), unLoc, getLoc, noLoc )
65 import List ( unzip4 )
72 thenM :: Monad a => a b -> (b -> a c) -> a c
75 thenM_ :: Monad a => a b -> a c -> a c
78 returnM :: Monad m => a -> m a
81 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
84 mappM_ :: (Monad m) => (a -> m b) -> [a] -> m ()
87 checkM :: Monad m => Bool -> m () -> m ()
91 %************************************************************************
93 \subsubsection{Expressions}
95 %************************************************************************
98 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
99 rnExprs ls = rnExprs' ls emptyUniqSet
101 rnExprs' [] acc = returnM ([], acc)
102 rnExprs' (expr:exprs) acc
103 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
105 -- Now we do a "seq" on the free vars because typically it's small
106 -- or empty, especially in very long lists of constants
108 acc' = acc `plusFV` fvExpr
110 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
111 returnM (expr':exprs', fvExprs)
113 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
114 grubby_seqNameSet ns result | isEmptyUniqSet ns = result
118 Variables. We look up the variable and return the resulting name.
121 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
122 rnLExpr = wrapLocFstM rnExpr
124 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
127 = do name <- lookupOccRn v
128 ignore_asserts <- doptM Opt_IgnoreAsserts
129 finish_var ignore_asserts name
131 finish_var ignore_asserts name
132 | ignore_asserts || not (name `hasKey` assertIdKey)
133 = return (HsVar name, unitFV name)
135 = do { (e, fvs) <- mkAssertErrorExpr
136 ; return (e, fvs `addOneFV` name) }
139 = newIPNameRn v `thenM` \ name ->
140 returnM (HsIPVar name, emptyFVs)
142 rnExpr (HsLit lit@(HsString s))
144 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
145 ; if opt_OverloadedStrings then
146 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
147 else -- Same as below
149 returnM (HsLit lit, emptyFVs)
154 returnM (HsLit lit, emptyFVs)
156 rnExpr (HsOverLit lit)
157 = rnOverLit lit `thenM` \ (lit', fvs) ->
158 returnM (HsOverLit lit', fvs)
160 rnExpr (HsApp fun arg)
161 = rnLExpr fun `thenM` \ (fun',fvFun) ->
162 rnLExpr arg `thenM` \ (arg',fvArg) ->
163 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
165 rnExpr (OpApp e1 op _ e2)
166 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
167 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
168 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
171 -- When renaming code synthesised from "deriving" declarations
172 -- we used to avoid fixity stuff, but we can't easily tell any
173 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
174 -- should prevent bad things happening.
175 lookupFixityRn op_name `thenM` \ fixity ->
176 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
179 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
182 = rnLExpr e `thenM` \ (e', fv_e) ->
183 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
184 mkNegAppRn e' neg_name `thenM` \ final_e ->
185 returnM (final_e, fv_e `plusFV` fv_neg)
188 = rnLExpr e `thenM` \ (e', fvs_e) ->
189 returnM (HsPar e', fvs_e)
191 -- Template Haskell extensions
192 -- Don't ifdef-GHCI them because we want to fail gracefully
193 -- (not with an rnExpr crash) in a stage-1 compiler.
194 rnExpr e@(HsBracket br_body)
195 = checkTH e "bracket" `thenM_`
196 rnBracket br_body `thenM` \ (body', fvs_e) ->
197 returnM (HsBracket body', fvs_e)
199 rnExpr e@(HsSpliceE splice)
200 = rnSplice splice `thenM` \ (splice', fvs) ->
201 returnM (HsSpliceE splice', fvs)
204 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
206 rnExpr e@(HsQuasiQuoteE qq)
207 = rnQuasiQuote qq `thenM` \ (qq', fvs_qq) ->
208 runQuasiQuoteExpr qq' `thenM` \ (L _ expr') ->
209 rnExpr expr' `thenM` \ (expr'', fvs_expr) ->
210 returnM (expr'', fvs_qq `plusFV` fvs_expr)
213 rnExpr section@(SectionL expr op)
214 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
215 rnLExpr op `thenM` \ (op', fvs_op) ->
216 checkSectionPrec InfixL section op' expr' `thenM_`
217 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
219 rnExpr section@(SectionR op expr)
220 = rnLExpr op `thenM` \ (op', fvs_op) ->
221 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
222 checkSectionPrec InfixR section op' expr' `thenM_`
223 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
225 rnExpr (HsCoreAnn ann expr)
226 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
227 returnM (HsCoreAnn ann expr', fvs_expr)
229 rnExpr (HsSCC lbl expr)
230 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
231 returnM (HsSCC lbl expr', fvs_expr)
232 rnExpr (HsTickPragma info expr)
233 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
234 returnM (HsTickPragma info expr', fvs_expr)
236 rnExpr (HsLam matches)
237 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
238 returnM (HsLam matches', fvMatch)
240 rnExpr (HsCase expr matches)
241 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
242 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
243 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
245 rnExpr (HsLet binds expr)
246 = rnLocalBindsAndThen binds $ \ binds' ->
247 rnLExpr expr `thenM` \ (expr',fvExpr) ->
248 returnM (HsLet binds' expr', fvExpr)
250 rnExpr e@(HsDo do_or_lc stmts body _)
251 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
253 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
255 rnExpr (ExplicitList _ exps)
256 = rnExprs exps `thenM` \ (exps', fvs) ->
257 returnM (ExplicitList placeHolderType exps', fvs)
259 rnExpr (ExplicitPArr _ exps)
260 = rnExprs exps `thenM` \ (exps', fvs) ->
261 returnM (ExplicitPArr placeHolderType exps', fvs)
263 rnExpr e@(ExplicitTuple exps boxity)
264 = checkTupSize (length exps) `thenM_`
265 rnExprs exps `thenM` \ (exps', fvs) ->
266 returnM (ExplicitTuple exps' boxity, fvs)
268 rnExpr (RecordCon con_id _ rbinds)
269 = do { conname <- lookupLocatedOccRn con_id
270 ; (rbinds', fvRbinds) <- rnHsRecFields_Con conname rnLExpr rbinds
271 ; return (RecordCon conname noPostTcExpr rbinds',
272 fvRbinds `addOneFV` unLoc conname) }
274 rnExpr (RecordUpd expr rbinds _ _ _)
275 = do { (expr', fvExpr) <- rnLExpr expr
276 ; (rbinds', fvRbinds) <- rnHsRecFields_Update rnLExpr rbinds
277 ; return (RecordUpd expr' rbinds' [] [] [],
278 fvExpr `plusFV` fvRbinds) }
280 rnExpr (ExprWithTySig expr pty)
281 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
282 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
284 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
286 doc = text "In an expression type signature"
288 rnExpr (HsIf p b1 b2)
289 = rnLExpr p `thenM` \ (p', fvP) ->
290 rnLExpr b1 `thenM` \ (b1', fvB1) ->
291 rnLExpr b2 `thenM` \ (b2', fvB2) ->
292 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
295 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
296 returnM (HsType t, fvT)
298 doc = text "In a type argument"
300 rnExpr (ArithSeq _ seq)
301 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
302 returnM (ArithSeq noPostTcExpr new_seq, fvs)
304 rnExpr (PArrSeq _ seq)
305 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
306 returnM (PArrSeq noPostTcExpr new_seq, fvs)
309 These three are pattern syntax appearing in expressions.
310 Since all the symbols are reservedops we can simply reject them.
311 We return a (bogus) EWildPat in each case.
314 rnExpr e@EWildPat = patSynErr e
315 rnExpr e@(EAsPat {}) = patSynErr e
316 rnExpr e@(EViewPat {}) = patSynErr e
317 rnExpr e@(ELazyPat {}) = patSynErr e
320 %************************************************************************
324 %************************************************************************
327 rnExpr (HsProc pat body)
329 rnPatsAndThen_LocalRightwards ProcExpr [pat] $ \ [pat'] ->
330 rnCmdTop body `thenM` \ (body',fvBody) ->
331 returnM (HsProc pat' body', fvBody)
333 rnExpr (HsArrApp arrow arg _ ho rtl)
334 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
335 rnLExpr arg `thenM` \ (arg',fvArg) ->
336 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
337 fvArrow `plusFV` fvArg)
339 select_arrow_scope tc = case ho of
340 HsHigherOrderApp -> tc
341 HsFirstOrderApp -> escapeArrowScope tc
344 rnExpr (HsArrForm op (Just _) [arg1, arg2])
345 = escapeArrowScope (rnLExpr op)
346 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
347 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
348 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
352 lookupFixityRn op_name `thenM` \ fixity ->
353 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
356 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
358 rnExpr (HsArrForm op fixity cmds)
359 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
360 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
361 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
363 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
368 %************************************************************************
372 %************************************************************************
375 rnCmdArgs [] = returnM ([], emptyFVs)
377 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
378 rnCmdArgs args `thenM` \ (args',fvArgs) ->
379 returnM (arg':args', fvArg `plusFV` fvArgs)
382 rnCmdTop = wrapLocFstM rnCmdTop'
384 rnCmdTop' (HsCmdTop cmd _ _ _)
385 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
387 cmd_names = [arrAName, composeAName, firstAName] ++
388 nameSetToList (methodNamesCmd (unLoc cmd'))
390 -- Generate the rebindable syntax for the monad
391 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
393 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
394 fvCmd `plusFV` cmd_fvs)
396 ---------------------------------------------------
397 -- convert OpApp's in a command context to HsArrForm's
399 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
400 convertOpFormsLCmd = fmap convertOpFormsCmd
402 convertOpFormsCmd :: HsCmd id -> HsCmd id
404 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
405 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
406 convertOpFormsCmd (OpApp c1 op fixity c2)
408 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
409 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
411 HsArrForm op (Just fixity) [arg1, arg2]
413 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
416 convertOpFormsCmd (HsCase exp matches)
417 = HsCase exp (convertOpFormsMatch matches)
419 convertOpFormsCmd (HsIf exp c1 c2)
420 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
422 convertOpFormsCmd (HsLet binds cmd)
423 = HsLet binds (convertOpFormsLCmd cmd)
425 convertOpFormsCmd (HsDo ctxt stmts body ty)
426 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
427 (convertOpFormsLCmd body) ty
429 -- Anything else is unchanged. This includes HsArrForm (already done),
430 -- things with no sub-commands, and illegal commands (which will be
431 -- caught by the type checker)
432 convertOpFormsCmd c = c
434 convertOpFormsStmt (BindStmt pat cmd _ _)
435 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
436 convertOpFormsStmt (ExprStmt cmd _ _)
437 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
438 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
439 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
440 convertOpFormsStmt stmt = stmt
442 convertOpFormsMatch (MatchGroup ms ty)
443 = MatchGroup (map (fmap convert) ms) ty
444 where convert (Match pat mty grhss)
445 = Match pat mty (convertOpFormsGRHSs grhss)
447 convertOpFormsGRHSs (GRHSs grhss binds)
448 = GRHSs (map convertOpFormsGRHS grhss) binds
450 convertOpFormsGRHS = fmap convert
452 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
454 ---------------------------------------------------
455 type CmdNeeds = FreeVars -- Only inhabitants are
456 -- appAName, choiceAName, loopAName
458 -- find what methods the Cmd needs (loop, choice, apply)
459 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
460 methodNamesLCmd = methodNamesCmd . unLoc
462 methodNamesCmd :: HsCmd Name -> CmdNeeds
464 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
466 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
468 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
470 methodNamesCmd (HsPar c) = methodNamesLCmd c
472 methodNamesCmd (HsIf p c1 c2)
473 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
475 methodNamesCmd (HsLet b c) = methodNamesLCmd c
477 methodNamesCmd (HsDo sc stmts body ty)
478 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
480 methodNamesCmd (HsApp c e) = methodNamesLCmd c
482 methodNamesCmd (HsLam match) = methodNamesMatch match
484 methodNamesCmd (HsCase scrut matches)
485 = methodNamesMatch matches `addOneFV` choiceAName
487 methodNamesCmd other = emptyFVs
488 -- Other forms can't occur in commands, but it's not convenient
489 -- to error here so we just do what's convenient.
490 -- The type checker will complain later
492 ---------------------------------------------------
493 methodNamesMatch (MatchGroup ms _)
494 = plusFVs (map do_one ms)
496 do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss
498 -------------------------------------------------
500 methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss)
502 -------------------------------------------------
503 methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs
505 ---------------------------------------------------
506 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
508 ---------------------------------------------------
509 methodNamesLStmt = methodNamesStmt . unLoc
511 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
512 methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd
513 methodNamesStmt (RecStmt stmts _ _ _ _)
514 = methodNamesStmts stmts `addOneFV` loopAName
515 methodNamesStmt (LetStmt b) = emptyFVs
516 methodNamesStmt (ParStmt ss) = emptyFVs
517 methodNamesStmt (TransformStmt _ _ _) = emptyFVs
518 methodNamesStmt (GroupStmt _ _) = emptyFVs
519 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
520 -- here so we just do what's convenient
524 %************************************************************************
528 %************************************************************************
531 rnArithSeq (From expr)
532 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
533 returnM (From expr', fvExpr)
535 rnArithSeq (FromThen expr1 expr2)
536 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
537 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
538 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
540 rnArithSeq (FromTo expr1 expr2)
541 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
542 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
543 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
545 rnArithSeq (FromThenTo expr1 expr2 expr3)
546 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
547 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
548 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
549 returnM (FromThenTo expr1' expr2' expr3',
550 plusFVs [fvExpr1, fvExpr2, fvExpr3])
553 %************************************************************************
555 Template Haskell brackets
557 %************************************************************************
560 rnBracket (VarBr n) = do { name <- lookupOccRn n
561 ; this_mod <- getModule
562 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
563 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
564 ; return () } -- only way that is going to happen
565 ; returnM (VarBr name, unitFV name) }
567 msg = ptext SLIT("Need interface for Template Haskell quoted Name")
569 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
570 ; return (ExpBr e', fvs) }
572 rnBracket (PatBr p) = do { addErr (ptext SLIT("Tempate Haskell pattern brackets are not supported yet"));
575 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
576 ; return (TypBr t', fvs) }
578 doc = ptext SLIT("In a Template-Haskell quoted type")
579 rnBracket (DecBr group)
580 = do { gbl_env <- getGblEnv
582 ; let new_gbl_env = gbl_env { -- Set the module to thFAKE. The top-level names from the bracketed
583 -- declarations will go into the name cache, and we don't want them to
584 -- confuse the Names for the current module.
585 -- By using a pretend module, thFAKE, we keep them safely out of the way.
588 -- The emptyDUs is so that we just collect uses for this group alone
589 -- in the call to rnSrcDecls below
591 ; setGblEnv new_gbl_env $ do {
593 -- In this situation we want to *shadow* top-level bindings.
595 -- bar = [d| foo = 1 |]
596 -- If we don't shadow, we'll get an ambiguity complaint when we do
597 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
599 -- Furthermore, arguably if the splice does define foo, that should hide
600 -- any foo's further out
602 -- The shadowing is acheived by calling rnSrcDecls with True as the shadowing flag
603 ; (tcg_env, group') <- rnSrcDecls True group
605 -- Discard the tcg_env; it contains only extra info about fixity
606 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
609 %************************************************************************
611 \subsubsection{@Stmt@s: in @do@ expressions}
613 %************************************************************************
616 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
617 -> RnM (thing, FreeVars)
618 -> RnM (([LStmt Name], thing), FreeVars)
620 rnStmts (MDoExpr _) = rnMDoStmts
621 rnStmts ctxt = rnNormalStmts ctxt
623 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
624 -> RnM (thing, FreeVars)
625 -> RnM (([LStmt Name], thing), FreeVars)
626 -- Used for cases *other* than recursive mdo
627 -- Implements nested scopes
629 rnNormalStmts ctxt [] thing_inside
630 = do { (thing, fvs) <- thing_inside
631 ; return (([],thing), fvs) }
633 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
634 = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $
635 rnNormalStmts ctxt stmts thing_inside
636 ; return (((L loc stmt' : stmts'), thing), fvs) }
639 rnStmt :: HsStmtContext Name -> Stmt RdrName
640 -> RnM (thing, FreeVars)
641 -> RnM ((Stmt Name, thing), FreeVars)
643 rnStmt ctxt (ExprStmt expr _ _) thing_inside
644 = do { (expr', fv_expr) <- rnLExpr expr
645 ; (then_op, fvs1) <- lookupSyntaxName thenMName
646 ; (thing, fvs2) <- thing_inside
647 ; return ((ExprStmt expr' then_op placeHolderType, thing),
648 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
650 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
651 = do { (expr', fv_expr) <- rnLExpr expr
652 -- The binders do not scope over the expression
653 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
654 ; (fail_op, fvs2) <- lookupSyntaxName failMName
655 ; rnPatsAndThen_LocalRightwards (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
656 { (thing, fvs3) <- thing_inside
657 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
658 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
659 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
660 -- but it does not matter because the names are unique
662 rnStmt ctxt (LetStmt binds) thing_inside = do
663 checkErr (ok ctxt binds) (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds)
664 rnLocalBindsAndThen binds $ \binds' -> do
665 (thing, fvs) <- thing_inside
666 return ((LetStmt binds', thing), fvs)
668 -- We do not allow implicit-parameter bindings in a parallel
669 -- list comprehension. I'm not sure what it might mean.
670 ok (ParStmtCtxt _) (HsIPBinds _) = False
673 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
675 rn_rec_stmts_and_then rec_stmts $ \ segs ->
676 thing_inside `thenM` \ (thing, fvs) ->
678 segs_w_fwd_refs = addFwdRefs segs
679 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
680 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
681 fwd_vars = nameSetToList (plusFVs fs)
683 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
685 returnM ((rec_stmt, thing), uses `plusFV` fvs)
687 doc = text "In a recursive do statement"
689 rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do
690 checkIsTransformableListComp ctxt
692 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
693 ((stmts', binders, (maybeByExpr', thing)), fvs) <-
694 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
695 (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr
696 (thing, fv_thing) <- thing_inside
698 return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing)
700 return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs)
702 rnMaybeLExpr Nothing = return (Nothing, emptyFVs)
703 rnMaybeLExpr (Just expr) = do
704 (expr', fv_expr) <- rnLExpr expr
705 return (Just expr', fv_expr)
707 rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do
708 checkIsTransformableListComp ctxt
710 -- We must rename the using expression in the context before the transform is begun
711 groupByClauseAction <-
712 case groupByClause of
713 GroupByNothing usingExpr -> do
714 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
715 (return . return) (GroupByNothing usingExpr', fv_usingExpr)
716 GroupBySomething eitherUsingExpr byExpr -> do
717 (eitherUsingExpr', fv_eitherUsingExpr) <-
718 case eitherUsingExpr of
719 Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName)
721 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
722 return (Left usingExpr', fv_usingExpr)
725 (byExpr', fv_byExpr) <- rnLExpr byExpr
726 return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr)
728 -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so
729 -- perhaps we could refactor this to use rnNormalStmts directly?
730 ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <-
731 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
732 (groupByClause', fv_groupByClause) <- groupByClauseAction
734 unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs
735 let binderMap = zip unshadowed_bndrs unshadowed_bndrs'
737 -- Bind the "thing" inside a context where we have REBOUND everything
738 -- bound by the statements before the group. This is necessary since after
739 -- the grouping the same identifiers actually have different meanings
740 -- i.e. they refer to lists not singletons!
741 (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside
743 -- We remove entries from the binder map that are not used in the thing_inside.
744 -- We can then use that usage information to ensure that the free variables do
745 -- not contain the things we just bound, but do contain the things we need to
746 -- make those bindings (i.e. the corresponding non-listy variables)
748 -- Note that we also retain those entries which have an old binder in our
749 -- own free variables (the using or by expression). This is because this map
750 -- is reused in the desugarer to create the type to bind from the statements
751 -- that occur before this one. If the binders we need are not in the map, they
752 -- will never get bound into our desugared expression and hence the simplifier
753 -- crashes as we refer to variables that don't exist!
754 let usedBinderMap = filter
755 (\(old_binder, new_binder) ->
756 (new_binder `elemNameSet` fv_thing) ||
757 (old_binder `elemNameSet` fv_groupByClause)) binderMap
758 (usedOldBinders, usedNewBinders) = unzip usedBinderMap
759 real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders)
761 return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing)
763 traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap)
764 return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs)
766 rnStmt ctxt (ParStmt segs) thing_inside
767 = do { parallel_list_comp <- doptM Opt_ParallelListComp
768 ; checkM parallel_list_comp parStmtErr
769 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
770 ; return ((ParStmt segs', thing), fvs) }
773 rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name
775 -> ([Name] -> RnM (thing, FreeVars))
776 -> RnM (([LStmt Name], [Name], thing), FreeVars)
777 rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do
778 ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do
779 -- Find the Names that are bound by stmts that
780 -- by assumption we have just renamed
781 local_env <- getLocalRdrEnv
783 stmts_binders = collectLStmtsBinders stmts
784 bndrs = map (expectJust "rnStmt"
785 . lookupLocalRdrEnv local_env
786 . unLoc) stmts_binders
788 -- If shadow, we'll look up (Unqual x) twice, getting
789 -- the second binding both times, which is the
791 unshadowed_bndrs = nub bndrs
793 -- Typecheck the thing inside, passing on all
794 -- the Names bound before it for its information
795 (thing, fvs) <- thing_inside unshadowed_bndrs
797 -- Figure out which of the bound names are used
798 -- after the statements we renamed
799 let used_bndrs = filter (`elemNameSet` fvs) bndrs
800 return ((used_bndrs, thing), fvs)
802 -- Flatten the tuple returned by the above call a bit!
803 return ((stmts', used_bndrs, inner_thing), fvs)
806 rnParallelStmts ctxt segs thing_inside = do
807 orig_lcl_env <- getLocalRdrEnv
808 go orig_lcl_env [] segs
810 go orig_lcl_env bndrs [] = do
811 let (bndrs', dups) = removeDups cmpByOcc bndrs
812 inner_env = extendLocalRdrEnv orig_lcl_env bndrs'
815 (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
816 return (([], thing), fvs)
818 go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do
819 ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do
820 -- Typecheck the thing inside, passing on all
821 -- the Names bound, but separately; revert the envt
822 setLocalRdrEnv orig_lcl_env $ do
823 go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs
825 let seg' = (stmts', bndrs)
826 return (((seg':segs'), thing), delListFromNameSet fvs bndrs)
828 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
829 dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
830 <+> quotes (ppr (head vs)))
833 checkIsTransformableListComp :: HsStmtContext Name -> RnM ()
834 checkIsTransformableListComp ctxt = do
835 -- Ensure we are really within a list comprehension because otherwise the
836 -- desugarer will break when we come to operate on a parallel array
837 checkM (notParallelArray ctxt) transformStmtOutsideListCompErr
839 -- Ensure the user has turned the correct flag on
840 transform_list_comp <- doptM Opt_TransformListComp
841 checkM transform_list_comp transformStmtErr
843 notParallelArray PArrComp = False
844 notParallelArray _ = True
849 %************************************************************************
851 \subsubsection{mdo expressions}
853 %************************************************************************
856 type FwdRefs = NameSet
857 type Segment stmts = (Defs,
858 Uses, -- May include defs
859 FwdRefs, -- A subset of uses that are
860 -- (a) used before they are bound in this segment, or
861 -- (b) used here, and bound in subsequent segments
862 stmts) -- Either Stmt or [Stmt]
865 ----------------------------------------------------
867 rnMDoStmts :: [LStmt RdrName]
868 -> RnM (thing, FreeVars)
869 -> RnM (([LStmt Name], thing), FreeVars)
870 rnMDoStmts stmts thing_inside
871 = -- Step1: Bring all the binders of the mdo into scope
872 -- (Remember that this also removes the binders from the
873 -- finally-returned free-vars.)
874 -- And rename each individual stmt, making a
875 -- singleton segment. At this stage the FwdRefs field
876 -- isn't finished: it's empty for all except a BindStmt
877 -- for which it's the fwd refs within the bind itself
878 -- (This set may not be empty, because we're in a recursive
880 rn_rec_stmts_and_then stmts $ \ segs -> do {
882 ; (thing, fvs_later) <- thing_inside
885 -- Step 2: Fill in the fwd refs.
886 -- The segments are all singletons, but their fwd-ref
887 -- field mentions all the things used by the segment
888 -- that are bound after their use
889 segs_w_fwd_refs = addFwdRefs segs
891 -- Step 3: Group together the segments to make bigger segments
892 -- Invariant: in the result, no segment uses a variable
893 -- bound in a later segment
894 grouped_segs = glomSegments segs_w_fwd_refs
896 -- Step 4: Turn the segments into Stmts
897 -- Use RecStmt when and only when there are fwd refs
898 -- Also gather up the uses from the end towards the
899 -- start, so we can tell the RecStmt which things are
900 -- used 'after' the RecStmt
901 (stmts', fvs) = segsToStmts grouped_segs fvs_later
903 ; return ((stmts', thing), fvs) }
905 doc = text "In a recursive mdo-expression"
907 ---------------------------------------------
909 -- wrapper that does both the left- and right-hand sides
910 rn_rec_stmts_and_then :: [LStmt RdrName]
911 -- assumes that the FreeVars returned includes
912 -- the FreeVars of the Segments
913 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
915 rn_rec_stmts_and_then s cont = do
916 -- (A) make the mini fixity env for all of the stmts
917 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
920 new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
922 -- bring them and their fixities into scope
923 let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
924 bindLocalNamesFV_WithFixities bound_names fix_env $
925 warnUnusedLocalBinds bound_names $ do
927 -- (C) do the right-hand-sides and thing-inside
928 segs <- rn_rec_stmts bound_names new_lhs_and_fv
932 -- get all the fixity decls in any Let stmt
933 collectRecStmtsFixities l =
934 foldr (\ s -> \acc -> case s of
935 (L loc (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
936 foldr (\ sig -> \ acc -> case sig of
937 (L loc (FixSig s)) -> (L loc s) : acc
943 rn_rec_stmt_lhs :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
944 -- these fixities need to be brought into scope with the names
946 -- rename LHS, and return its FVs
947 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
948 -- so we don't bother to compute it accurately in the other cases
949 -> RnM [(LStmtLR Name RdrName, FreeVars)]
951 rn_rec_stmt_lhs fix_env (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
952 -- this is actually correct
955 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
957 -- should the ctxt be MDo instead?
958 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
959 return [(L loc (BindStmt pat' expr a b),
962 rn_rec_stmt_lhs fix_env (L loc (LetStmt binds@(HsIPBinds _)))
963 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
966 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
967 = do binds' <- rnValBindsLHS fix_env binds
968 return [(L loc (LetStmt (HsValBinds binds')),
969 -- Warning: this is bogus; see function invariant
973 rn_rec_stmt_lhs fix_env (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
974 = rn_rec_stmts_lhs fix_env stmts
976 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
977 = pprPanic "rn_rec_stmt" (ppr stmt)
979 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo
980 = pprPanic "rn_rec_stmt" (ppr stmt)
982 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo
983 = pprPanic "rn_rec_stmt" (ppr stmt)
985 rn_rec_stmts_lhs :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
986 -- these fixities need to be brought into scope with the names
988 -> RnM [(LStmtLR Name RdrName, FreeVars)]
989 rn_rec_stmts_lhs fix_env stmts =
990 let boundNames = collectLStmtsBinders stmts
991 doc = text "In a recursive mdo-expression"
993 -- First do error checking: we need to check for dups here because we
994 -- don't bind all of the variables from the Stmt at once
995 -- with bindLocatedLocals.
996 checkDupRdrNames doc boundNames
997 mappM (rn_rec_stmt_lhs fix_env) stmts `thenM` \ ls -> returnM (concat ls)
1002 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
1003 -- Rename a Stmt that is inside a RecStmt (or mdo)
1004 -- Assumes all binders are already in scope
1005 -- Turns each stmt into a singleton Stmt
1006 rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _)) _
1007 = rnLExpr expr `thenM` \ (expr', fvs) ->
1008 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
1009 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
1010 L loc (ExprStmt expr' then_op placeHolderType))]
1012 rn_rec_stmt all_bndrs (L loc (BindStmt pat' expr _ _)) fv_pat
1013 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
1014 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
1015 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
1017 bndrs = mkNameSet (collectPatBinders pat')
1018 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
1020 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
1021 L loc (BindStmt pat' expr' bind_op fail_op))]
1023 rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _))) _
1024 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
1027 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
1028 (binds', du_binds) <-
1029 -- fixities and unused are handled above in rn_rec_stmts_and_then
1030 rnValBindsRHS all_bndrs binds'
1031 returnM [(duDefs du_binds, duUses du_binds,
1032 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1034 -- no RecStmt case becuase they get flattened above when doing the LHSes
1035 rn_rec_stmt all_bndrs stmt@(L loc (RecStmt stmts _ _ _ _)) _
1036 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1038 rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo
1039 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1041 rn_rec_stmt all_bndrs stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo
1042 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1044 rn_rec_stmt all_bndrs stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo
1045 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1047 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1048 rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1049 returnM (concat segs_s)
1051 ---------------------------------------------
1052 addFwdRefs :: [Segment a] -> [Segment a]
1053 -- So far the segments only have forward refs *within* the Stmt
1054 -- (which happens for bind: x <- ...x...)
1055 -- This function adds the cross-seg fwd ref info
1058 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1060 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1061 = (new_seg : segs, all_defs)
1063 new_seg = (defs, uses, new_fwds, stmts)
1064 all_defs = later_defs `unionNameSets` defs
1065 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1066 -- Add the downstream fwd refs here
1068 ----------------------------------------------------
1069 -- Glomming the singleton segments of an mdo into
1070 -- minimal recursive groups.
1072 -- At first I thought this was just strongly connected components, but
1073 -- there's an important constraint: the order of the stmts must not change.
1076 -- mdo { x <- ...y...
1083 -- Here, the first stmt mention 'y', which is bound in the third.
1084 -- But that means that the innocent second stmt (p <- z) gets caught
1085 -- up in the recursion. And that in turn means that the binding for
1086 -- 'z' has to be included... and so on.
1088 -- Start at the tail { r <- x }
1089 -- Now add the next one { z <- y ; r <- x }
1090 -- Now add one more { q <- x ; z <- y ; r <- x }
1091 -- Now one more... but this time we have to group a bunch into rec
1092 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1093 -- Now one more, which we can add on without a rec
1095 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1097 -- Finally we add the last one; since it mentions y we have to
1098 -- glom it togeher with the first two groups
1099 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1100 -- q <- x ; z <- y } ;
1103 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1105 glomSegments [] = []
1106 glomSegments ((defs,uses,fwds,stmt) : segs)
1107 -- Actually stmts will always be a singleton
1108 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1110 segs' = glomSegments segs
1111 (extras, others) = grab uses segs'
1112 (ds, us, fs, ss) = unzip4 extras
1114 seg_defs = plusFVs ds `plusFV` defs
1115 seg_uses = plusFVs us `plusFV` uses
1116 seg_fwds = plusFVs fs `plusFV` fwds
1117 seg_stmts = stmt : concat ss
1119 grab :: NameSet -- The client
1121 -> ([Segment a], -- Needed by the 'client'
1122 [Segment a]) -- Not needed by the client
1123 -- The result is simply a split of the input
1125 = (reverse yeses, reverse noes)
1127 (noes, yeses) = span not_needed (reverse dus)
1128 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1131 ----------------------------------------------------
1132 segsToStmts :: [Segment [LStmt Name]]
1133 -> FreeVars -- Free vars used 'later'
1134 -> ([LStmt Name], FreeVars)
1136 segsToStmts [] fvs_later = ([], fvs_later)
1137 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
1138 = ASSERT( not (null ss) )
1139 (new_stmt : later_stmts, later_uses `plusFV` uses)
1141 (later_stmts, later_uses) = segsToStmts segs fvs_later
1142 new_stmt | non_rec = head ss
1143 | otherwise = L (getLoc (head ss)) $
1144 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
1147 non_rec = isSingleton ss && isEmptyNameSet fwds
1148 used_later = defs `intersectNameSet` later_uses
1149 -- The ones needed after the RecStmt
1152 %************************************************************************
1154 \subsubsection{Assertion utils}
1156 %************************************************************************
1159 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1160 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
1162 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
1163 -- Return an expression for (assertError "Foo.hs:27")
1165 = getSrcSpanM `thenM` \ sloc ->
1167 expr = HsApp (L sloc (HsVar assertErrorName))
1168 (L sloc (srcSpanPrimLit sloc))
1170 returnM (expr, emptyFVs)
1173 %************************************************************************
1175 \subsubsection{Errors}
1177 %************************************************************************
1180 patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context:"),
1182 ; return (EWildPat, emptyFVs) }
1185 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -XParallelListComp"))
1187 transformStmtErr = addErr (ptext SLIT("Illegal transform or grouping list comprehension: use -XTransformListComp"))
1188 transformStmtOutsideListCompErr = addErr (ptext SLIT("Currently you may only use transform or grouping comprehensions within list comprehensions, not parallel array comprehensions"))
1190 badIpBinds what binds
1191 = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what)