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 UniqFM ( isNullUFM )
57 import UniqSet ( emptyUniqSet )
59 import Util ( isSingleton )
60 import ListSetOps ( removeDups )
61 import Maybes ( expectJust )
63 import SrcLoc ( Located(..), unLoc, getLoc, noLoc )
66 import List ( unzip4 )
70 %************************************************************************
72 \subsubsection{Expressions}
74 %************************************************************************
77 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
78 rnExprs ls = rnExprs' ls emptyUniqSet
80 rnExprs' [] acc = returnM ([], acc)
81 rnExprs' (expr:exprs) acc
82 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
84 -- Now we do a "seq" on the free vars because typically it's small
85 -- or empty, especially in very long lists of constants
87 acc' = acc `plusFV` fvExpr
89 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
90 returnM (expr':exprs', fvExprs)
92 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
93 grubby_seqNameSet ns result | isNullUFM ns = result
97 Variables. We look up the variable and return the resulting name.
100 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
101 rnLExpr = wrapLocFstM rnExpr
103 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
106 = do name <- lookupOccRn v
107 ignore_asserts <- doptM Opt_IgnoreAsserts
108 finish_var ignore_asserts name
110 finish_var ignore_asserts name
111 | ignore_asserts || not (name `hasKey` assertIdKey)
112 = return (HsVar name, unitFV name)
114 = do { (e, fvs) <- mkAssertErrorExpr
115 ; return (e, fvs `addOneFV` name) }
118 = newIPNameRn v `thenM` \ name ->
119 returnM (HsIPVar name, emptyFVs)
121 rnExpr (HsLit lit@(HsString s))
123 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
124 ; if opt_OverloadedStrings then
125 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
126 else -- Same as below
128 returnM (HsLit lit, emptyFVs)
133 returnM (HsLit lit, emptyFVs)
135 rnExpr (HsOverLit lit)
136 = rnOverLit lit `thenM` \ (lit', fvs) ->
137 returnM (HsOverLit lit', fvs)
139 rnExpr (HsApp fun arg)
140 = rnLExpr fun `thenM` \ (fun',fvFun) ->
141 rnLExpr arg `thenM` \ (arg',fvArg) ->
142 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
144 rnExpr (OpApp e1 op _ e2)
145 = rnLExpr e1 `thenM` \ (e1', fv_e1) ->
146 rnLExpr e2 `thenM` \ (e2', fv_e2) ->
147 rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) ->
150 -- When renaming code synthesised from "deriving" declarations
151 -- we used to avoid fixity stuff, but we can't easily tell any
152 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
153 -- should prevent bad things happening.
154 lookupFixityRn op_name `thenM` \ fixity ->
155 mkOpAppRn e1' op' fixity e2' `thenM` \ final_e ->
158 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
161 = rnLExpr e `thenM` \ (e', fv_e) ->
162 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
163 mkNegAppRn e' neg_name `thenM` \ final_e ->
164 returnM (final_e, fv_e `plusFV` fv_neg)
167 = rnLExpr e `thenM` \ (e', fvs_e) ->
168 returnM (HsPar e', fvs_e)
170 -- Template Haskell extensions
171 -- Don't ifdef-GHCI them because we want to fail gracefully
172 -- (not with an rnExpr crash) in a stage-1 compiler.
173 rnExpr e@(HsBracket br_body)
174 = checkTH e "bracket" `thenM_`
175 rnBracket br_body `thenM` \ (body', fvs_e) ->
176 returnM (HsBracket body', fvs_e)
178 rnExpr e@(HsSpliceE splice)
179 = rnSplice splice `thenM` \ (splice', fvs) ->
180 returnM (HsSpliceE splice', fvs)
183 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
185 rnExpr e@(HsQuasiQuoteE qq)
186 = rnQuasiQuote qq `thenM` \ (qq', fvs_qq) ->
187 runQuasiQuoteExpr qq' `thenM` \ (L _ expr') ->
188 rnExpr expr' `thenM` \ (expr'', fvs_expr) ->
189 returnM (expr'', fvs_qq `plusFV` fvs_expr)
192 rnExpr section@(SectionL expr op)
193 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
194 rnLExpr op `thenM` \ (op', fvs_op) ->
195 checkSectionPrec InfixL section op' expr' `thenM_`
196 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
198 rnExpr section@(SectionR op expr)
199 = rnLExpr op `thenM` \ (op', fvs_op) ->
200 rnLExpr expr `thenM` \ (expr', fvs_expr) ->
201 checkSectionPrec InfixR section op' expr' `thenM_`
202 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
204 rnExpr (HsCoreAnn ann expr)
205 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
206 returnM (HsCoreAnn ann expr', fvs_expr)
208 rnExpr (HsSCC lbl expr)
209 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
210 returnM (HsSCC lbl expr', fvs_expr)
211 rnExpr (HsTickPragma info expr)
212 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
213 returnM (HsTickPragma info expr', fvs_expr)
215 rnExpr (HsLam matches)
216 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
217 returnM (HsLam matches', fvMatch)
219 rnExpr (HsCase expr matches)
220 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
221 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
222 returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
224 rnExpr (HsLet binds expr)
225 = rnLocalBindsAndThen binds $ \ binds' ->
226 rnLExpr expr `thenM` \ (expr',fvExpr) ->
227 returnM (HsLet binds' expr', fvExpr)
229 rnExpr e@(HsDo do_or_lc stmts body _)
230 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
232 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
234 rnExpr (ExplicitList _ exps)
235 = rnExprs exps `thenM` \ (exps', fvs) ->
236 returnM (ExplicitList placeHolderType exps', fvs)
238 rnExpr (ExplicitPArr _ exps)
239 = rnExprs exps `thenM` \ (exps', fvs) ->
240 returnM (ExplicitPArr placeHolderType exps', fvs)
242 rnExpr e@(ExplicitTuple exps boxity)
243 = checkTupSize (length exps) `thenM_`
244 rnExprs exps `thenM` \ (exps', fvs) ->
245 returnM (ExplicitTuple exps' boxity, fvs)
247 rnExpr (RecordCon con_id _ rbinds)
248 = do { conname <- lookupLocatedOccRn con_id
249 ; (rbinds', fvRbinds) <- rnHsRecFields_Con conname rnLExpr rbinds
250 ; return (RecordCon conname noPostTcExpr rbinds',
251 fvRbinds `addOneFV` unLoc conname) }
253 rnExpr (RecordUpd expr rbinds _ _ _)
254 = do { (expr', fvExpr) <- rnLExpr expr
255 ; (rbinds', fvRbinds) <- rnHsRecFields_Update rnLExpr rbinds
256 ; return (RecordUpd expr' rbinds' [] [] [],
257 fvExpr `plusFV` fvRbinds) }
259 rnExpr (ExprWithTySig expr pty)
260 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
261 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
263 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
265 doc = text "In an expression type signature"
267 rnExpr (HsIf p b1 b2)
268 = rnLExpr p `thenM` \ (p', fvP) ->
269 rnLExpr b1 `thenM` \ (b1', fvB1) ->
270 rnLExpr b2 `thenM` \ (b2', fvB2) ->
271 returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
274 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
275 returnM (HsType t, fvT)
277 doc = text "In a type argument"
279 rnExpr (ArithSeq _ seq)
280 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
281 returnM (ArithSeq noPostTcExpr new_seq, fvs)
283 rnExpr (PArrSeq _ seq)
284 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
285 returnM (PArrSeq noPostTcExpr new_seq, fvs)
288 These three are pattern syntax appearing in expressions.
289 Since all the symbols are reservedops we can simply reject them.
290 We return a (bogus) EWildPat in each case.
293 rnExpr e@EWildPat = patSynErr e
294 rnExpr e@(EAsPat {}) = patSynErr e
295 rnExpr e@(EViewPat {}) = patSynErr e
296 rnExpr e@(ELazyPat {}) = patSynErr e
299 %************************************************************************
303 %************************************************************************
306 rnExpr (HsProc pat body)
308 rnPatsAndThen_LocalRightwards ProcExpr [pat] $ \ [pat'] ->
309 rnCmdTop body `thenM` \ (body',fvBody) ->
310 returnM (HsProc pat' body', fvBody)
312 rnExpr (HsArrApp arrow arg _ ho rtl)
313 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
314 rnLExpr arg `thenM` \ (arg',fvArg) ->
315 returnM (HsArrApp arrow' arg' placeHolderType ho rtl,
316 fvArrow `plusFV` fvArg)
318 select_arrow_scope tc = case ho of
319 HsHigherOrderApp -> tc
320 HsFirstOrderApp -> escapeArrowScope tc
323 rnExpr (HsArrForm op (Just _) [arg1, arg2])
324 = escapeArrowScope (rnLExpr op)
325 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
326 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
327 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
331 lookupFixityRn op_name `thenM` \ fixity ->
332 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
335 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
337 rnExpr (HsArrForm op fixity cmds)
338 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
339 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
340 returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
342 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
347 %************************************************************************
351 %************************************************************************
354 rnCmdArgs [] = returnM ([], emptyFVs)
356 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
357 rnCmdArgs args `thenM` \ (args',fvArgs) ->
358 returnM (arg':args', fvArg `plusFV` fvArgs)
361 rnCmdTop = wrapLocFstM rnCmdTop'
363 rnCmdTop' (HsCmdTop cmd _ _ _)
364 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
366 cmd_names = [arrAName, composeAName, firstAName] ++
367 nameSetToList (methodNamesCmd (unLoc cmd'))
369 -- Generate the rebindable syntax for the monad
370 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
372 returnM (HsCmdTop cmd' [] placeHolderType cmd_names',
373 fvCmd `plusFV` cmd_fvs)
375 ---------------------------------------------------
376 -- convert OpApp's in a command context to HsArrForm's
378 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
379 convertOpFormsLCmd = fmap convertOpFormsCmd
381 convertOpFormsCmd :: HsCmd id -> HsCmd id
383 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
384 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
385 convertOpFormsCmd (OpApp c1 op fixity c2)
387 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
388 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
390 HsArrForm op (Just fixity) [arg1, arg2]
392 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
395 convertOpFormsCmd (HsCase exp matches)
396 = HsCase exp (convertOpFormsMatch matches)
398 convertOpFormsCmd (HsIf exp c1 c2)
399 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
401 convertOpFormsCmd (HsLet binds cmd)
402 = HsLet binds (convertOpFormsLCmd cmd)
404 convertOpFormsCmd (HsDo ctxt stmts body ty)
405 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
406 (convertOpFormsLCmd body) ty
408 -- Anything else is unchanged. This includes HsArrForm (already done),
409 -- things with no sub-commands, and illegal commands (which will be
410 -- caught by the type checker)
411 convertOpFormsCmd c = c
413 convertOpFormsStmt (BindStmt pat cmd _ _)
414 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
415 convertOpFormsStmt (ExprStmt cmd _ _)
416 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
417 convertOpFormsStmt (RecStmt stmts lvs rvs es binds)
418 = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds
419 convertOpFormsStmt stmt = stmt
421 convertOpFormsMatch (MatchGroup ms ty)
422 = MatchGroup (map (fmap convert) ms) ty
423 where convert (Match pat mty grhss)
424 = Match pat mty (convertOpFormsGRHSs grhss)
426 convertOpFormsGRHSs (GRHSs grhss binds)
427 = GRHSs (map convertOpFormsGRHS grhss) binds
429 convertOpFormsGRHS = fmap convert
431 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
433 ---------------------------------------------------
434 type CmdNeeds = FreeVars -- Only inhabitants are
435 -- appAName, choiceAName, loopAName
437 -- find what methods the Cmd needs (loop, choice, apply)
438 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
439 methodNamesLCmd = methodNamesCmd . unLoc
441 methodNamesCmd :: HsCmd Name -> CmdNeeds
443 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
445 methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
447 methodNamesCmd cmd@(HsArrForm {}) = emptyFVs
449 methodNamesCmd (HsPar c) = methodNamesLCmd c
451 methodNamesCmd (HsIf p c1 c2)
452 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
454 methodNamesCmd (HsLet b c) = methodNamesLCmd c
456 methodNamesCmd (HsDo sc stmts body ty)
457 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
459 methodNamesCmd (HsApp c e) = methodNamesLCmd c
461 methodNamesCmd (HsLam match) = methodNamesMatch match
463 methodNamesCmd (HsCase scrut matches)
464 = methodNamesMatch matches `addOneFV` choiceAName
466 methodNamesCmd other = emptyFVs
467 -- Other forms can't occur in commands, but it's not convenient
468 -- to error here so we just do what's convenient.
469 -- The type checker will complain later
471 ---------------------------------------------------
472 methodNamesMatch (MatchGroup ms _)
473 = plusFVs (map do_one ms)
475 do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss
477 -------------------------------------------------
479 methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss)
481 -------------------------------------------------
482 methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs
484 ---------------------------------------------------
485 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
487 ---------------------------------------------------
488 methodNamesLStmt = methodNamesStmt . unLoc
490 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
491 methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd
492 methodNamesStmt (RecStmt stmts _ _ _ _)
493 = methodNamesStmts stmts `addOneFV` loopAName
494 methodNamesStmt (LetStmt b) = emptyFVs
495 methodNamesStmt (ParStmt ss) = emptyFVs
496 methodNamesStmt (TransformStmt _ _ _) = emptyFVs
497 methodNamesStmt (GroupStmt _ _) = emptyFVs
498 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
499 -- here so we just do what's convenient
503 %************************************************************************
507 %************************************************************************
510 rnArithSeq (From expr)
511 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
512 returnM (From expr', fvExpr)
514 rnArithSeq (FromThen expr1 expr2)
515 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
516 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
517 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
519 rnArithSeq (FromTo expr1 expr2)
520 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
521 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
522 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
524 rnArithSeq (FromThenTo expr1 expr2 expr3)
525 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
526 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
527 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
528 returnM (FromThenTo expr1' expr2' expr3',
529 plusFVs [fvExpr1, fvExpr2, fvExpr3])
532 %************************************************************************
534 Template Haskell brackets
536 %************************************************************************
539 rnBracket (VarBr n) = do { name <- lookupOccRn n
540 ; this_mod <- getModule
541 ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
542 do { loadInterfaceForName msg name -- home interface is loaded, and this is the
543 ; return () } -- only way that is going to happen
544 ; returnM (VarBr name, unitFV name) }
546 msg = ptext SLIT("Need interface for Template Haskell quoted Name")
548 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
549 ; return (ExpBr e', fvs) }
551 rnBracket (PatBr p) = do { addErr (ptext SLIT("Tempate Haskell pattern brackets are not supported yet"));
554 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
555 ; return (TypBr t', fvs) }
557 doc = ptext SLIT("In a Template-Haskell quoted type")
558 rnBracket (DecBr group)
559 = do { gbl_env <- getGblEnv
561 ; let new_gbl_env = gbl_env { -- Set the module to thFAKE. The top-level names from the bracketed
562 -- declarations will go into the name cache, and we don't want them to
563 -- confuse the Names for the current module.
564 -- By using a pretend module, thFAKE, we keep them safely out of the way.
567 -- The emptyDUs is so that we just collect uses for this group alone
568 -- in the call to rnSrcDecls below
570 ; setGblEnv new_gbl_env $ do {
572 -- In this situation we want to *shadow* top-level bindings.
574 -- bar = [d| foo = 1 |]
575 -- If we don't shadow, we'll get an ambiguity complaint when we do
576 -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo'
578 -- Furthermore, arguably if the splice does define foo, that should hide
579 -- any foo's further out
581 -- The shadowing is acheived by calling rnSrcDecls with True as the shadowing flag
582 ; (tcg_env, group') <- rnSrcDecls True group
584 -- Discard the tcg_env; it contains only extra info about fixity
585 ; return (DecBr group', allUses (tcg_dus tcg_env)) } }
588 %************************************************************************
590 \subsubsection{@Stmt@s: in @do@ expressions}
592 %************************************************************************
595 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
596 -> RnM (thing, FreeVars)
597 -> RnM (([LStmt Name], thing), FreeVars)
599 rnStmts (MDoExpr _) = rnMDoStmts
600 rnStmts ctxt = rnNormalStmts ctxt
602 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
603 -> RnM (thing, FreeVars)
604 -> RnM (([LStmt Name], thing), FreeVars)
605 -- Used for cases *other* than recursive mdo
606 -- Implements nested scopes
608 rnNormalStmts ctxt [] thing_inside
609 = do { (thing, fvs) <- thing_inside
610 ; return (([],thing), fvs) }
612 rnNormalStmts ctxt (L loc stmt : stmts) thing_inside
613 = do { ((stmt', (stmts', thing)), fvs) <- rnStmt ctxt stmt $
614 rnNormalStmts ctxt stmts thing_inside
615 ; return (((L loc stmt' : stmts'), thing), fvs) }
618 rnStmt :: HsStmtContext Name -> Stmt RdrName
619 -> RnM (thing, FreeVars)
620 -> RnM ((Stmt Name, thing), FreeVars)
622 rnStmt ctxt (ExprStmt expr _ _) thing_inside
623 = do { (expr', fv_expr) <- rnLExpr expr
624 ; (then_op, fvs1) <- lookupSyntaxName thenMName
625 ; (thing, fvs2) <- thing_inside
626 ; return ((ExprStmt expr' then_op placeHolderType, thing),
627 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
629 rnStmt ctxt (BindStmt pat expr _ _) thing_inside
630 = do { (expr', fv_expr) <- rnLExpr expr
631 -- The binders do not scope over the expression
632 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
633 ; (fail_op, fvs2) <- lookupSyntaxName failMName
634 ; rnPatsAndThen_LocalRightwards (StmtCtxt ctxt) [pat] $ \ [pat'] -> do
635 { (thing, fvs3) <- thing_inside
636 ; return ((BindStmt pat' expr' bind_op fail_op, thing),
637 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
638 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
639 -- but it does not matter because the names are unique
641 rnStmt ctxt (LetStmt binds) thing_inside = do
642 checkErr (ok ctxt binds) (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds)
643 rnLocalBindsAndThen binds $ \binds' -> do
644 (thing, fvs) <- thing_inside
645 return ((LetStmt binds', thing), fvs)
647 -- We do not allow implicit-parameter bindings in a parallel
648 -- list comprehension. I'm not sure what it might mean.
649 ok (ParStmtCtxt _) (HsIPBinds _) = False
652 rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside
654 rn_rec_stmts_and_then rec_stmts $ \ segs ->
655 thing_inside `thenM` \ (thing, fvs) ->
657 segs_w_fwd_refs = addFwdRefs segs
658 (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs
659 later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs)
660 fwd_vars = nameSetToList (plusFVs fs)
662 rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds
664 returnM ((rec_stmt, thing), uses `plusFV` fvs)
666 doc = text "In a recursive do statement"
668 rnStmt ctxt (TransformStmt (stmts, _) usingExpr maybeByExpr) thing_inside = do
669 checkIsTransformableListComp ctxt
671 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
672 ((stmts', binders, (maybeByExpr', thing)), fvs) <-
673 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
674 (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr
675 (thing, fv_thing) <- thing_inside
677 return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing)
679 return ((TransformStmt (stmts', binders) usingExpr' maybeByExpr', thing), fv_usingExpr `plusFV` fvs)
681 rnMaybeLExpr Nothing = return (Nothing, emptyFVs)
682 rnMaybeLExpr (Just expr) = do
683 (expr', fv_expr) <- rnLExpr expr
684 return (Just expr', fv_expr)
686 rnStmt ctxt (GroupStmt (stmts, _) groupByClause) thing_inside = do
687 checkIsTransformableListComp ctxt
689 -- We must rename the using expression in the context before the transform is begun
690 groupByClauseAction <-
691 case groupByClause of
692 GroupByNothing usingExpr -> do
693 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
694 (return . return) (GroupByNothing usingExpr', fv_usingExpr)
695 GroupBySomething eitherUsingExpr byExpr -> do
696 (eitherUsingExpr', fv_eitherUsingExpr) <-
697 case eitherUsingExpr of
698 Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName)
700 (usingExpr', fv_usingExpr) <- rnLExpr usingExpr
701 return (Left usingExpr', fv_usingExpr)
704 (byExpr', fv_byExpr) <- rnLExpr byExpr
705 return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr)
707 -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so
708 -- perhaps we could refactor this to use rnNormalStmts directly?
709 ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <-
710 rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do
711 (groupByClause', fv_groupByClause) <- groupByClauseAction
713 unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs
714 let binderMap = zip unshadowed_bndrs unshadowed_bndrs'
716 -- Bind the "thing" inside a context where we have REBOUND everything
717 -- bound by the statements before the group. This is necessary since after
718 -- the grouping the same identifiers actually have different meanings
719 -- i.e. they refer to lists not singletons!
720 (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside
722 -- We remove entries from the binder map that are not used in the thing_inside.
723 -- We can then use that usage information to ensure that the free variables do
724 -- not contain the things we just bound, but do contain the things we need to
725 -- make those bindings (i.e. the corresponding non-listy variables)
727 -- Note that we also retain those entries which have an old binder in our
728 -- own free variables (the using or by expression). This is because this map
729 -- is reused in the desugarer to create the type to bind from the statements
730 -- that occur before this one. If the binders we need are not in the map, they
731 -- will never get bound into our desugared expression and hence the simplifier
732 -- crashes as we refer to variables that don't exist!
733 let usedBinderMap = filter
734 (\(old_binder, new_binder) ->
735 (new_binder `elemNameSet` fv_thing) ||
736 (old_binder `elemNameSet` fv_groupByClause)) binderMap
737 (usedOldBinders, usedNewBinders) = unzip usedBinderMap
738 real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders)
740 return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing)
742 traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap)
743 return ((GroupStmt (stmts', usedBinderMap) groupByClause', thing), fvs)
745 rnStmt ctxt (ParStmt segs) thing_inside
746 = do { parallel_list_comp <- doptM Opt_ParallelListComp
747 ; checkM parallel_list_comp parStmtErr
748 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
749 ; return ((ParStmt segs', thing), fvs) }
752 rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name
754 -> ([Name] -> RnM (thing, FreeVars))
755 -> RnM (([LStmt Name], [Name], thing), FreeVars)
756 rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do
757 ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do
758 -- Find the Names that are bound by stmts that
759 -- by assumption we have just renamed
760 local_env <- getLocalRdrEnv
762 stmts_binders = collectLStmtsBinders stmts
763 bndrs = map (expectJust "rnStmt"
764 . lookupLocalRdrEnv local_env
765 . unLoc) stmts_binders
767 -- If shadow, we'll look up (Unqual x) twice, getting
768 -- the second binding both times, which is the
770 unshadowed_bndrs = nub bndrs
772 -- Typecheck the thing inside, passing on all
773 -- the Names bound before it for its information
774 (thing, fvs) <- thing_inside unshadowed_bndrs
776 -- Figure out which of the bound names are used
777 -- after the statements we renamed
778 let used_bndrs = filter (`elemNameSet` fvs) bndrs
779 return ((used_bndrs, thing), fvs)
781 -- Flatten the tuple returned by the above call a bit!
782 return ((stmts', used_bndrs, inner_thing), fvs)
785 rnParallelStmts ctxt segs thing_inside = do
786 orig_lcl_env <- getLocalRdrEnv
787 go orig_lcl_env [] segs
789 go orig_lcl_env bndrs [] = do
790 let (bndrs', dups) = removeDups cmpByOcc bndrs
791 inner_env = extendLocalRdrEnv orig_lcl_env bndrs'
794 (thing, fvs) <- setLocalRdrEnv inner_env thing_inside
795 return (([], thing), fvs)
797 go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do
798 ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do
799 -- Typecheck the thing inside, passing on all
800 -- the Names bound, but separately; revert the envt
801 setLocalRdrEnv orig_lcl_env $ do
802 go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs
804 let seg' = (stmts', bndrs)
805 return (((seg':segs'), thing), delListFromNameSet fvs bndrs)
807 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
808 dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:")
809 <+> quotes (ppr (head vs)))
812 checkIsTransformableListComp :: HsStmtContext Name -> RnM ()
813 checkIsTransformableListComp ctxt = do
814 -- Ensure we are really within a list comprehension because otherwise the
815 -- desugarer will break when we come to operate on a parallel array
816 checkM (notParallelArray ctxt) transformStmtOutsideListCompErr
818 -- Ensure the user has turned the correct flag on
819 transform_list_comp <- doptM Opt_TransformListComp
820 checkM transform_list_comp transformStmtErr
822 notParallelArray PArrComp = False
823 notParallelArray _ = True
828 %************************************************************************
830 \subsubsection{mdo expressions}
832 %************************************************************************
835 type FwdRefs = NameSet
836 type Segment stmts = (Defs,
837 Uses, -- May include defs
838 FwdRefs, -- A subset of uses that are
839 -- (a) used before they are bound in this segment, or
840 -- (b) used here, and bound in subsequent segments
841 stmts) -- Either Stmt or [Stmt]
844 ----------------------------------------------------
846 rnMDoStmts :: [LStmt RdrName]
847 -> RnM (thing, FreeVars)
848 -> RnM (([LStmt Name], thing), FreeVars)
849 rnMDoStmts stmts thing_inside
850 = -- Step1: Bring all the binders of the mdo into scope
851 -- (Remember that this also removes the binders from the
852 -- finally-returned free-vars.)
853 -- And rename each individual stmt, making a
854 -- singleton segment. At this stage the FwdRefs field
855 -- isn't finished: it's empty for all except a BindStmt
856 -- for which it's the fwd refs within the bind itself
857 -- (This set may not be empty, because we're in a recursive
859 rn_rec_stmts_and_then stmts $ \ segs -> do {
861 ; (thing, fvs_later) <- thing_inside
864 -- Step 2: Fill in the fwd refs.
865 -- The segments are all singletons, but their fwd-ref
866 -- field mentions all the things used by the segment
867 -- that are bound after their use
868 segs_w_fwd_refs = addFwdRefs segs
870 -- Step 3: Group together the segments to make bigger segments
871 -- Invariant: in the result, no segment uses a variable
872 -- bound in a later segment
873 grouped_segs = glomSegments segs_w_fwd_refs
875 -- Step 4: Turn the segments into Stmts
876 -- Use RecStmt when and only when there are fwd refs
877 -- Also gather up the uses from the end towards the
878 -- start, so we can tell the RecStmt which things are
879 -- used 'after' the RecStmt
880 (stmts', fvs) = segsToStmts grouped_segs fvs_later
882 ; return ((stmts', thing), fvs) }
884 doc = text "In a recursive mdo-expression"
886 ---------------------------------------------
888 -- wrapper that does both the left- and right-hand sides
889 rn_rec_stmts_and_then :: [LStmt RdrName]
890 -- assumes that the FreeVars returned includes
891 -- the FreeVars of the Segments
892 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
894 rn_rec_stmts_and_then s cont = do
895 -- (A) make the mini fixity env for all of the stmts
896 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
899 new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
901 -- bring them and their fixities into scope
902 let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv)
903 bindLocalNamesFV_WithFixities bound_names fix_env $
904 warnUnusedLocalBinds bound_names $ do
906 -- (C) do the right-hand-sides and thing-inside
907 segs <- rn_rec_stmts bound_names new_lhs_and_fv
911 -- get all the fixity decls in any Let stmt
912 collectRecStmtsFixities l =
913 foldr (\ s -> \acc -> case s of
914 (L loc (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
915 foldr (\ sig -> \ acc -> case sig of
916 (L loc (FixSig s)) -> (L loc s) : acc
922 rn_rec_stmt_lhs :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
923 -- these fixities need to be brought into scope with the names
925 -- rename LHS, and return its FVs
926 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
927 -- so we don't bother to compute it accurately in the other cases
928 -> RnM [(LStmtLR Name RdrName, FreeVars)]
930 rn_rec_stmt_lhs fix_env (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
931 -- this is actually correct
934 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
936 -- should the ctxt be MDo instead?
937 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
938 return [(L loc (BindStmt pat' expr a b),
941 rn_rec_stmt_lhs fix_env (L loc (LetStmt binds@(HsIPBinds _)))
942 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
945 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
946 = do binds' <- rnValBindsLHS fix_env binds
947 return [(L loc (LetStmt (HsValBinds binds')),
948 -- Warning: this is bogus; see function invariant
952 rn_rec_stmt_lhs fix_env (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec
953 = rn_rec_stmts_lhs fix_env stmts
955 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
956 = pprPanic "rn_rec_stmt" (ppr stmt)
958 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo
959 = pprPanic "rn_rec_stmt" (ppr stmt)
961 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo
962 = pprPanic "rn_rec_stmt" (ppr stmt)
964 rn_rec_stmts_lhs :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
965 -- these fixities need to be brought into scope with the names
967 -> RnM [(LStmtLR Name RdrName, FreeVars)]
968 rn_rec_stmts_lhs fix_env stmts =
969 let boundNames = collectLStmtsBinders stmts
970 doc = text "In a recursive mdo-expression"
972 -- First do error checking: we need to check for dups here because we
973 -- don't bind all of the variables from the Stmt at once
974 -- with bindLocatedLocals.
975 checkDupRdrNames doc boundNames
976 mappM (rn_rec_stmt_lhs fix_env) stmts `thenM` \ ls -> returnM (concat ls)
981 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
982 -- Rename a Stmt that is inside a RecStmt (or mdo)
983 -- Assumes all binders are already in scope
984 -- Turns each stmt into a singleton Stmt
985 rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _)) _
986 = rnLExpr expr `thenM` \ (expr', fvs) ->
987 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
988 returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
989 L loc (ExprStmt expr' then_op placeHolderType))]
991 rn_rec_stmt all_bndrs (L loc (BindStmt pat' expr _ _)) fv_pat
992 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
993 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
994 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
996 bndrs = mkNameSet (collectPatBinders pat')
997 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
999 returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs,
1000 L loc (BindStmt pat' expr' bind_op fail_op))]
1002 rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _))) _
1003 = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds)
1006 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
1007 (binds', du_binds) <-
1008 -- fixities and unused are handled above in rn_rec_stmts_and_then
1009 rnValBindsRHS all_bndrs binds'
1010 returnM [(duDefs du_binds, duUses du_binds,
1011 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1013 -- no RecStmt case becuase they get flattened above when doing the LHSes
1014 rn_rec_stmt all_bndrs stmt@(L loc (RecStmt stmts _ _ _ _)) _
1015 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1017 rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) _ -- Syntactically illegal in mdo
1018 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1020 rn_rec_stmt all_bndrs stmt@(L _ (TransformStmt _ _ _)) _ -- Syntactically illegal in mdo
1021 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1023 rn_rec_stmt all_bndrs stmt@(L _ (GroupStmt _ _)) _ -- Syntactically illegal in mdo
1024 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1026 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1027 rn_rec_stmts bndrs stmts = mappM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1028 returnM (concat segs_s)
1030 ---------------------------------------------
1031 addFwdRefs :: [Segment a] -> [Segment a]
1032 -- So far the segments only have forward refs *within* the Stmt
1033 -- (which happens for bind: x <- ...x...)
1034 -- This function adds the cross-seg fwd ref info
1037 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1039 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1040 = (new_seg : segs, all_defs)
1042 new_seg = (defs, uses, new_fwds, stmts)
1043 all_defs = later_defs `unionNameSets` defs
1044 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1045 -- Add the downstream fwd refs here
1047 ----------------------------------------------------
1048 -- Glomming the singleton segments of an mdo into
1049 -- minimal recursive groups.
1051 -- At first I thought this was just strongly connected components, but
1052 -- there's an important constraint: the order of the stmts must not change.
1055 -- mdo { x <- ...y...
1062 -- Here, the first stmt mention 'y', which is bound in the third.
1063 -- But that means that the innocent second stmt (p <- z) gets caught
1064 -- up in the recursion. And that in turn means that the binding for
1065 -- 'z' has to be included... and so on.
1067 -- Start at the tail { r <- x }
1068 -- Now add the next one { z <- y ; r <- x }
1069 -- Now add one more { q <- x ; z <- y ; r <- x }
1070 -- Now one more... but this time we have to group a bunch into rec
1071 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1072 -- Now one more, which we can add on without a rec
1074 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1076 -- Finally we add the last one; since it mentions y we have to
1077 -- glom it togeher with the first two groups
1078 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1079 -- q <- x ; z <- y } ;
1082 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1084 glomSegments [] = []
1085 glomSegments ((defs,uses,fwds,stmt) : segs)
1086 -- Actually stmts will always be a singleton
1087 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1089 segs' = glomSegments segs
1090 (extras, others) = grab uses segs'
1091 (ds, us, fs, ss) = unzip4 extras
1093 seg_defs = plusFVs ds `plusFV` defs
1094 seg_uses = plusFVs us `plusFV` uses
1095 seg_fwds = plusFVs fs `plusFV` fwds
1096 seg_stmts = stmt : concat ss
1098 grab :: NameSet -- The client
1100 -> ([Segment a], -- Needed by the 'client'
1101 [Segment a]) -- Not needed by the client
1102 -- The result is simply a split of the input
1104 = (reverse yeses, reverse noes)
1106 (noes, yeses) = span not_needed (reverse dus)
1107 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1110 ----------------------------------------------------
1111 segsToStmts :: [Segment [LStmt Name]]
1112 -> FreeVars -- Free vars used 'later'
1113 -> ([LStmt Name], FreeVars)
1115 segsToStmts [] fvs_later = ([], fvs_later)
1116 segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later
1117 = ASSERT( not (null ss) )
1118 (new_stmt : later_stmts, later_uses `plusFV` uses)
1120 (later_stmts, later_uses) = segsToStmts segs fvs_later
1121 new_stmt | non_rec = head ss
1122 | otherwise = L (getLoc (head ss)) $
1123 RecStmt ss (nameSetToList used_later) (nameSetToList fwds)
1126 non_rec = isSingleton ss && isEmptyNameSet fwds
1127 used_later = defs `intersectNameSet` later_uses
1128 -- The ones needed after the RecStmt
1131 %************************************************************************
1133 \subsubsection{Assertion utils}
1135 %************************************************************************
1138 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1139 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDoc (ppr span))))
1141 mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars)
1142 -- Return an expression for (assertError "Foo.hs:27")
1144 = getSrcSpanM `thenM` \ sloc ->
1146 expr = HsApp (L sloc (HsVar assertErrorName))
1147 (L sloc (srcSpanPrimLit sloc))
1149 returnM (expr, emptyFVs)
1152 %************************************************************************
1154 \subsubsection{Errors}
1156 %************************************************************************
1159 patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context:"),
1161 ; return (EWildPat, emptyFVs) }
1164 parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -XParallelListComp"))
1166 transformStmtErr = addErr (ptext SLIT("Illegal transform or grouping list comprehension: use -XTransformListComp"))
1167 transformStmtOutsideListCompErr = addErr (ptext SLIT("Currently you may only use transform or grouping comprehensions within list comprehensions, not parallel array comprehensions"))
1169 badIpBinds what binds
1170 = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what)