2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnExpr]{Renaming of expressions}
6 Basically dependency analysis.
8 Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In
9 general, all of these functions return a renamed thing, and a set of
14 rnMatch, rnGRHSs, rnExpr, rnExprs, rnStmts,
18 #include "HsVersions.h"
20 import {-# SOURCE #-} RnSource ( rnSrcDecls, rnBindsAndThen, rnBinds )
22 -- RnSource imports RnBinds.rnTopMonoBinds, RnExpr.rnExpr
23 -- RnBinds imports RnExpr.rnMatch, etc
24 -- RnExpr imports [boot] RnSource.rnSrcDecls, RnSource.rnBinds
31 import RnTypes ( rnHsTypeFVs, rnPat, litFVs, rnOverLit, rnPatsAndThen,
32 dupFieldErr, precParseErr, sectionPrecErr, patSigErr )
33 import CmdLineOpts ( DynFlag(..), opt_IgnoreAsserts )
34 import BasicTypes ( Fixity(..), FixityDirection(..), IPName(..),
35 defaultFixity, negateFixity, compareFixity )
36 import PrelNames ( hasKey, assertIdKey,
38 cCallableClassName, cReturnableClassName,
40 splitName, fstName, sndName, ioDataConName,
41 replicatePName, mapPName, filterPName,
42 crossPName, zipPName, toPName,
43 enumFromToPName, enumFromThenToPName, assertErrorName,
44 negateName, qTyConName, monadNames, mfixName )
45 import RdrName ( RdrName )
46 import Name ( Name, nameOccName )
48 import UnicodeUtil ( stringToUtf8 )
49 import UniqFM ( isNullUFM )
50 import UniqSet ( emptyUniqSet )
51 import Util ( isSingleton )
52 import List ( intersectBy, unzip4 )
53 import ListSetOps ( removeDups )
59 ************************************************************************
63 ************************************************************************
66 rnMatch :: HsMatchContext RdrName -> RdrNameMatch -> RnM (RenamedMatch, FreeVars)
68 rnMatch ctxt match@(Match pats maybe_rhs_sig grhss)
69 = addSrcLoc (getMatchLoc match) $
71 -- Deal with the rhs type signature
72 bindPatSigTyVars rhs_sig_tys $
73 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
74 (case maybe_rhs_sig of
75 Nothing -> returnM (Nothing, emptyFVs)
76 Just ty | opt_GlasgowExts -> rnHsTypeFVs doc_sig ty `thenM` \ (ty', ty_fvs) ->
77 returnM (Just ty', ty_fvs)
78 | otherwise -> addErr (patSigErr ty) `thenM_`
79 returnM (Nothing, emptyFVs)
80 ) `thenM` \ (maybe_rhs_sig', ty_fvs) ->
83 rnPatsAndThen ctxt pats $ \ pats' ->
84 rnGRHSs grhss `thenM` \ (grhss', grhss_fvs) ->
86 returnM (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
87 -- The bindPatSigTyVars and rnPatsAndThen will remove the bound FVs
89 rhs_sig_tys = case maybe_rhs_sig of
92 doc_sig = text "In a result type-signature"
96 %************************************************************************
98 \subsubsection{Guarded right-hand sides (GRHSs)}
100 %************************************************************************
103 rnGRHSs :: RdrNameGRHSs -> RnM (RenamedGRHSs, FreeVars)
105 rnGRHSs (GRHSs grhss binds _)
106 = rnBindsAndThen binds $ \ binds' ->
107 mapFvRn rnGRHS grhss `thenM` \ (grhss', fvGRHSs) ->
108 returnM (GRHSs grhss' binds' placeHolderType, fvGRHSs)
110 rnGRHS (GRHS guarded locn)
112 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
113 checkM (opt_GlasgowExts || is_standard_guard guarded)
114 (addWarn (nonStdGuardErr guarded)) `thenM_`
116 rnStmts PatGuard guarded `thenM` \ (guarded', fvs) ->
117 returnM (GRHS guarded' locn, fvs)
119 -- Standard Haskell 1.4 guards are just a single boolean
120 -- expression, rather than a list of qualifiers as in the
122 is_standard_guard [ResultStmt _ _] = True
123 is_standard_guard [ExprStmt _ _ _, ResultStmt _ _] = True
124 is_standard_guard other = False
127 %************************************************************************
129 \subsubsection{Expressions}
131 %************************************************************************
134 rnExprs :: [RdrNameHsExpr] -> RnM ([RenamedHsExpr], FreeVars)
135 rnExprs ls = rnExprs' ls emptyUniqSet
137 rnExprs' [] acc = returnM ([], acc)
138 rnExprs' (expr:exprs) acc
139 = rnExpr expr `thenM` \ (expr', fvExpr) ->
141 -- Now we do a "seq" on the free vars because typically it's small
142 -- or empty, especially in very long lists of constants
144 acc' = acc `plusFV` fvExpr
146 (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) ->
147 returnM (expr':exprs', fvExprs)
149 -- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq
150 grubby_seqNameSet ns result | isNullUFM ns = result
154 Variables. We look up the variable and return the resulting name.
157 rnExpr :: RdrNameHsExpr -> RnM (RenamedHsExpr, FreeVars)
160 = lookupOccRn v `thenM` \ name ->
161 if name `hasKey` assertIdKey && not opt_IgnoreAsserts then
162 -- We expand it to (GHC.Err.assertError location_string)
165 -- The normal case. Even if the Id was 'assert', if we are
166 -- ignoring assertions we leave it as GHC.Base.assert;
167 -- this function just ignores its first arg.
168 returnM (HsVar name, unitFV name)
171 = newIPName v `thenM` \ name ->
174 Linear _ -> mkFVs [splitName, fstName, sndName]
175 Dupable _ -> emptyFVs
177 returnM (HsIPVar name, fvs)
180 = litFVs lit `thenM` \ fvs ->
181 returnM (HsLit lit, fvs)
183 rnExpr (HsOverLit lit)
184 = rnOverLit lit `thenM` \ (lit', fvs) ->
185 returnM (HsOverLit lit', fvs)
188 = rnMatch LambdaExpr match `thenM` \ (match', fvMatch) ->
189 returnM (HsLam match', fvMatch)
191 rnExpr (HsApp fun arg)
192 = rnExpr fun `thenM` \ (fun',fvFun) ->
193 rnExpr arg `thenM` \ (arg',fvArg) ->
194 returnM (HsApp fun' arg', fvFun `plusFV` fvArg)
196 rnExpr (OpApp e1 op _ e2)
197 = rnExpr e1 `thenM` \ (e1', fv_e1) ->
198 rnExpr e2 `thenM` \ (e2', fv_e2) ->
199 rnExpr op `thenM` \ (op'@(HsVar op_name), fv_op) ->
202 -- When renaming code synthesised from "deriving" declarations
203 -- we're in Interface mode, and we should ignore fixity; assume
204 -- that the deriving code generator got the association correct
205 -- Don't even look up the fixity when in interface mode
206 getModeRn `thenM` \ mode ->
207 (if isInterfaceMode mode
208 then returnM (OpApp e1' op' defaultFixity e2')
209 else lookupFixityRn op_name `thenM` \ fixity ->
210 mkOpAppRn e1' op' fixity e2'
211 ) `thenM` \ final_e ->
214 fv_e1 `plusFV` fv_op `plusFV` fv_e2)
217 = rnExpr e `thenM` \ (e', fv_e) ->
218 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
219 mkNegAppRn e' neg_name `thenM` \ final_e ->
220 returnM (final_e, fv_e `plusFV` fv_neg)
223 = rnExpr e `thenM` \ (e', fvs_e) ->
224 returnM (HsPar e', fvs_e)
226 -- Template Haskell extensions
227 rnExpr (HsBracket br_body)
228 = checkGHCI (thErr "bracket") `thenM_`
229 rnBracket br_body `thenM` \ (body', fvs_e) ->
230 returnM (HsBracket body', fvs_e `addOneFV` qTyConName)
231 -- We use the Q tycon as a proxy to haul in all the smart
232 -- constructors; see the hack in RnIfaces
234 rnExpr (HsSplice n e)
235 = checkGHCI (thErr "splice") `thenM_`
236 getSrcLocM `thenM` \ loc ->
237 newLocalsRn [(n,loc)] `thenM` \ [n'] ->
238 rnExpr e `thenM` \ (e', fvs_e) ->
239 returnM (HsSplice n' e', fvs_e)
241 rnExpr section@(SectionL expr op)
242 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
243 rnExpr op `thenM` \ (op', fvs_op) ->
244 checkSectionPrec InfixL section op' expr' `thenM_`
245 returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr)
247 rnExpr section@(SectionR op expr)
248 = rnExpr op `thenM` \ (op', fvs_op) ->
249 rnExpr expr `thenM` \ (expr', fvs_expr) ->
250 checkSectionPrec InfixR section op' expr' `thenM_`
251 returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr)
253 rnExpr (HsCCall fun args may_gc is_casm _)
254 -- Check out the comment on RnIfaces.getNonWiredDataDecl about ccalls
255 = rnExprs args `thenM` \ (args', fvs_args) ->
256 returnM (HsCCall fun args' may_gc is_casm placeHolderType,
257 fvs_args `plusFV` mkFVs [cCallableClassName,
258 cReturnableClassName,
261 rnExpr (HsSCC lbl expr)
262 = rnExpr expr `thenM` \ (expr', fvs_expr) ->
263 returnM (HsSCC lbl expr', fvs_expr)
265 rnExpr (HsCase expr ms src_loc)
266 = addSrcLoc src_loc $
267 rnExpr expr `thenM` \ (new_expr, e_fvs) ->
268 mapFvRn (rnMatch CaseAlt) ms `thenM` \ (new_ms, ms_fvs) ->
269 returnM (HsCase new_expr new_ms src_loc, e_fvs `plusFV` ms_fvs)
271 rnExpr (HsLet binds expr)
272 = rnBindsAndThen binds $ \ binds' ->
273 rnExpr expr `thenM` \ (expr',fvExpr) ->
274 returnM (HsLet binds' expr', fvExpr)
276 rnExpr (HsWith expr binds is_with)
277 = warnIf is_with withWarning `thenM_`
278 rnExpr expr `thenM` \ (expr',fvExpr) ->
279 rnIPBinds binds `thenM` \ (binds',fvBinds) ->
280 returnM (HsWith expr' binds' is_with, fvExpr `plusFV` fvBinds)
282 rnExpr e@(HsDo do_or_lc stmts _ _ src_loc)
283 = addSrcLoc src_loc $
284 rnStmts do_or_lc stmts `thenM` \ (stmts', fvs) ->
286 -- Check the statement list ends in an expression
287 case last stmts' of {
288 ResultStmt _ _ -> returnM () ;
289 _ -> addErr (doStmtListErr "do" e)
292 -- Generate the rebindable syntax for the monad
293 mapAndUnzipM lookupSyntaxName
294 (syntax_names do_or_lc) `thenM` \ (monad_names', monad_fvs) ->
296 returnM (HsDo do_or_lc stmts' monad_names' placeHolderType src_loc,
297 fvs `plusFV` implicit_fvs do_or_lc `plusFV` plusFVs monad_fvs)
299 implicit_fvs PArrComp = mkFVs [replicatePName, mapPName, filterPName, crossPName, zipPName]
300 implicit_fvs ListComp = mkFVs [foldrName, buildName]
301 implicit_fvs DoExpr = emptyFVs
302 implicit_fvs MDoExpr = emptyFVs
304 syntax_names DoExpr = monadNames
305 syntax_names MDoExpr = monadNames ++ [mfixName]
306 syntax_names other = []
308 rnExpr (ExplicitList _ exps)
309 = rnExprs exps `thenM` \ (exps', fvs) ->
310 returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name)
312 rnExpr (ExplicitPArr _ exps)
313 = rnExprs exps `thenM` \ (exps', fvs) ->
314 returnM (ExplicitPArr placeHolderType exps',
315 fvs `addOneFV` toPName `addOneFV` parrTyCon_name)
317 rnExpr (ExplicitTuple exps boxity)
318 = rnExprs exps `thenM` \ (exps', fvs) ->
319 returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name)
321 tycon_name = tupleTyCon_name boxity (length exps)
323 rnExpr (RecordCon con_id rbinds)
324 = lookupOccRn con_id `thenM` \ conname ->
325 rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) ->
326 returnM (RecordCon conname rbinds', fvRbinds `addOneFV` conname)
328 rnExpr (RecordUpd expr rbinds)
329 = rnExpr expr `thenM` \ (expr', fvExpr) ->
330 rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) ->
331 returnM (RecordUpd expr' rbinds', fvExpr `plusFV` fvRbinds)
333 rnExpr (ExprWithTySig expr pty)
334 = rnExpr expr `thenM` \ (expr', fvExpr) ->
335 rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) ->
336 returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy)
338 doc = text "In an expression type signature"
340 rnExpr (HsIf p b1 b2 src_loc)
341 = addSrcLoc src_loc $
342 rnExpr p `thenM` \ (p', fvP) ->
343 rnExpr b1 `thenM` \ (b1', fvB1) ->
344 rnExpr b2 `thenM` \ (b2', fvB2) ->
345 returnM (HsIf p' b1' b2' src_loc, plusFVs [fvP, fvB1, fvB2])
348 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
349 returnM (HsType t, fvT)
351 doc = text "In a type argument"
353 rnExpr (ArithSeqIn seq)
354 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
355 returnM (ArithSeqIn new_seq, fvs `addOneFV` enumClassName)
357 rnExpr (PArrSeqIn seq)
358 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
359 returnM (PArrSeqIn new_seq,
360 fvs `plusFV` mkFVs [enumFromToPName, enumFromThenToPName])
363 These three are pattern syntax appearing in expressions.
364 Since all the symbols are reservedops we can simply reject them.
365 We return a (bogus) EWildPat in each case.
368 rnExpr e@EWildPat = addErr (patSynErr e) `thenM_`
369 returnM (EWildPat, emptyFVs)
371 rnExpr e@(EAsPat _ _) = addErr (patSynErr e) `thenM_`
372 returnM (EWildPat, emptyFVs)
374 rnExpr e@(ELazyPat _) = addErr (patSynErr e) `thenM_`
375 returnM (EWildPat, emptyFVs)
378 %************************************************************************
382 %************************************************************************
385 rnArithSeq (From expr)
386 = rnExpr expr `thenM` \ (expr', fvExpr) ->
387 returnM (From expr', fvExpr)
389 rnArithSeq (FromThen expr1 expr2)
390 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
391 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
392 returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
394 rnArithSeq (FromTo expr1 expr2)
395 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
396 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
397 returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
399 rnArithSeq (FromThenTo expr1 expr2 expr3)
400 = rnExpr expr1 `thenM` \ (expr1', fvExpr1) ->
401 rnExpr expr2 `thenM` \ (expr2', fvExpr2) ->
402 rnExpr expr3 `thenM` \ (expr3', fvExpr3) ->
403 returnM (FromThenTo expr1' expr2' expr3',
404 plusFVs [fvExpr1, fvExpr2, fvExpr3])
408 %************************************************************************
410 \subsubsection{@Rbinds@s and @Rpats@s: in record expressions}
412 %************************************************************************
416 = mappM_ field_dup_err dup_fields `thenM_`
417 mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) ->
418 returnM (rbinds', fvRbind)
420 (_, dup_fields) = removeDups compare [ f | (f,_) <- rbinds ]
422 field_dup_err dups = addErr (dupFieldErr str dups)
424 rn_rbind (field, expr)
425 = lookupGlobalOccRn field `thenM` \ fieldname ->
426 rnExpr expr `thenM` \ (expr', fvExpr) ->
427 returnM ((fieldname, expr'), fvExpr `addOneFV` fieldname)
430 %************************************************************************
432 \subsubsection{@rnIPBinds@s: in implicit parameter bindings} *
434 %************************************************************************
437 rnIPBinds [] = returnM ([], emptyFVs)
438 rnIPBinds ((n, expr) : binds)
439 = newIPName n `thenM` \ name ->
440 rnExpr expr `thenM` \ (expr',fvExpr) ->
441 rnIPBinds binds `thenM` \ (binds',fvBinds) ->
442 returnM ((name, expr') : binds', fvExpr `plusFV` fvBinds)
446 %************************************************************************
448 Template Haskell brackets
450 %************************************************************************
453 rnBracket (ExpBr e) = rnExpr e `thenM` \ (e', fvs) ->
454 returnM (ExpBr e', fvs)
455 rnBracket (PatBr p) = rnPat p `thenM` \ (p', fvs) ->
456 returnM (PatBr p', fvs)
457 rnBracket (TypBr t) = rnHsTypeFVs doc t `thenM` \ (t', fvs) ->
458 returnM (TypBr t', fvs)
460 doc = ptext SLIT("In a Template-Haskell quoted type")
461 rnBracket (DecBr ds) = rnSrcDecls ds `thenM` \ (tcg_env, ds', fvs) ->
462 -- Discard the tcg_env; it contains the extended global RdrEnv
463 -- because there is no scope that these decls cover (yet!)
464 returnM (DecBr ds', fvs)
467 %************************************************************************
469 \subsubsection{@Stmt@s: in @do@ expressions}
471 %************************************************************************
474 rnStmts :: HsStmtContext
476 -> RnM ([RenamedStmt], FreeVars)
478 rnStmts MDoExpr stmts = rnMDoStmts stmts
479 rnStmts ctxt stmts = rnNormalStmts ctxt stmts
481 rnNormalStmts :: HsStmtContext -> [RdrNameStmt] -> RnM ([RenamedStmt], FreeVars)
482 -- Used for cases *other* than recursive mdo
483 -- Implements nested scopes
485 rnNormalStmts ctxt (ExprStmt expr _ src_loc : stmts)
486 = addSrcLoc src_loc $
487 rnExpr expr `thenM` \ (expr', fv_expr) ->
488 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
489 returnM (ExprStmt expr' placeHolderType src_loc : stmts',
490 fv_expr `plusFV` fvs)
492 rnNormalStmts ctxt [ResultStmt expr src_loc]
493 = addSrcLoc src_loc $
494 rnExpr expr `thenM` \ (expr', fv_expr) ->
495 returnM ([ResultStmt expr' src_loc], fv_expr)
497 rnNormalStmts ctxt (BindStmt pat expr src_loc : stmts)
498 = addSrcLoc src_loc $
499 rnExpr expr `thenM` \ (expr', fv_expr) ->
500 -- The binders do not scope over the expression
502 rnPatsAndThen (StmtCtxt ctxt) [pat] $ \ [pat'] ->
503 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
504 returnM (BindStmt pat' expr' src_loc : stmts',
505 fv_expr `plusFV` fvs) -- fv_expr shouldn't really be filtered by
506 -- the rnPatsAndThen, but it does not matter
508 rnNormalStmts ctxt (LetStmt binds : stmts)
509 = rnBindsAndThen binds $ \ binds' ->
510 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
511 returnM (LetStmt binds' : stmts', fvs)
513 rnNormalStmts ctxt (ParStmt stmtss : stmts)
514 = mapFvRn (rnNormalStmts ctxt) stmtss `thenM` \ (stmtss', fv_stmtss) ->
516 bndrss = map collectStmtsBinders stmtss'
518 foldlM checkBndrs [] bndrss `thenM` \ new_binders ->
519 bindLocalNamesFV new_binders $
520 -- Note: binders are returned in scope order, so one may
521 -- shadow the next; e.g. x <- xs; x <- ys
522 rnNormalStmts ctxt stmts `thenM` \ (stmts', fvs) ->
523 returnM (ParStmtOut (bndrss `zip` stmtss') : stmts',
524 fv_stmtss `plusFV` fvs)
527 checkBndrs all_bndrs bndrs
528 = checkErr (null common) (err (head common)) `thenM_`
529 returnM (bndrs ++ all_bndrs)
531 common = intersectBy eqOcc all_bndrs bndrs
533 eqOcc n1 n2 = nameOccName n1 == nameOccName n2
534 err v = ptext SLIT("Duplicate binding in parallel list comprehension for:")
538 = bindLocalsRn doc (collectStmtsBinders stmts) $ \ _ ->
539 mappM rn_mdo_stmt stmts `thenM` \ segs ->
540 returnM (segsToStmts (glomSegments (addFwdRefs segs)))
542 doc = text "In a mdo-expression"
545 type Uses = NameSet -- Same as FreeVars really
546 type FwdRefs = NameSet
547 type Segment = (Defs,
548 Uses, -- May include defs
549 FwdRefs, -- A subset of uses that are
550 -- (a) used before they are bound in this segment, or
551 -- (b) used here, and bound in subsequent segments
554 ----------------------------------------------------
555 rn_mdo_stmt :: RdrNameStmt -> RnM Segment
556 -- Assumes all binders are already in scope
557 -- Turns each stmt into a singleton Stmt
559 rn_mdo_stmt (ExprStmt expr _ src_loc)
560 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
561 returnM (emptyNameSet, fvs, emptyNameSet,
562 [ExprStmt expr' placeHolderType src_loc])
564 rn_mdo_stmt (ResultStmt expr src_loc)
565 = addSrcLoc src_loc (rnExpr expr) `thenM` \ (expr', fvs) ->
566 returnM (emptyNameSet, fvs, emptyNameSet,
567 [ResultStmt expr' src_loc])
569 rn_mdo_stmt (BindStmt pat expr src_loc)
570 = addSrcLoc src_loc $
571 rnExpr expr `thenM` \ (expr', fv_expr) ->
572 rnPat pat `thenM` \ (pat', fv_pat) ->
574 bndrs = mkNameSet (collectPatBinders pat')
575 fvs = fv_expr `plusFV` fv_pat
577 returnM (bndrs, fvs, bndrs `intersectNameSet` fvs,
578 [BindStmt pat' expr' src_loc])
580 rn_mdo_stmt (LetStmt binds)
581 = rnBinds binds `thenM` \ (binds', fv_binds) ->
582 returnM (mkNameSet (collectHsBinders binds'),
583 fv_binds, emptyNameSet, [LetStmt binds'])
585 rn_mdo_stmt stmt@(ParStmt _) -- Syntactically illegal in mdo
586 = pprPanic "rn_mdo_stmt" (ppr stmt)
589 addFwdRefs :: [Segment] -> [Segment]
590 -- So far the segments only have forward refs *within* the Stmt
591 -- (which happens for bind: x <- ...x...)
592 -- This function adds the cross-seg fwd ref info
595 = fst (foldr mk_seg ([], emptyNameSet) pairs)
597 mk_seg (defs, uses, fwds, stmts) (segs, seg_defs)
598 = (new_seg : segs, all_defs)
600 new_seg = (defs, uses, new_fwds, stmts)
601 all_defs = seg_defs `unionNameSets` defs
602 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` seg_defs)
603 -- Add the downstream fwd refs here
605 ----------------------------------------------------
606 -- Breaking a recursive 'do' into segments
609 -- mdo { x <- ...y...
616 -- Start at the tail { r <- x }
617 -- Now add the next one { z <- y ; r <- x }
618 -- Now add one more { q <- x ; z <- y ; r <- x }
619 -- Now one more... but this time we have to group a bunch into rec
620 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
621 -- Now one more, which we can add on without a rec
623 -- rec { y <- ...x... ; q <- x ; z <- y } ;
625 -- Finally we add the last one; since it mentions y we have to
626 -- glom it togeher with the first two groups
627 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
628 -- q <- x ; z <- y } ;
631 glomSegments :: [Segment] -> [Segment]
633 glomSegments [seg] = [seg]
634 glomSegments ((defs,uses,fwds,stmts) : segs)
635 -- Actually stmts will always be a singleton
636 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
638 segs' = glomSegments segs
639 (extras, others) = grab uses segs'
640 (ds, us, fs, ss) = unzip4 extras
642 seg_defs = plusFVs ds `plusFV` defs
643 seg_uses = plusFVs us `plusFV` uses
644 seg_fwds = plusFVs fs `plusFV` fwds
645 seg_stmts = stmts ++ concat ss
647 grab :: NameSet -- The client
649 -> ([Segment], -- Needed by the 'client'
650 [Segment]) -- Not needed by the client
651 -- The result is simply a split of the input
653 = (reverse yeses, reverse noes)
655 (noes, yeses) = span not_needed (reverse dus)
656 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
659 ----------------------------------------------------
660 segsToStmts :: [Segment] -> ([RenamedStmt], FreeVars)
662 segsToStmts [] = ([], emptyFVs)
663 segsToStmts ((defs, uses, fwds, ss) : segs)
664 = (new_stmt : later_stmts, later_uses `plusFV` uses)
666 (later_stmts, later_uses) = segsToStmts segs
667 new_stmt | non_rec = head ss
668 | otherwise = RecStmt rec_names ss
670 non_rec = isSingleton ss && isEmptyNameSet fwds
671 rec_names = nameSetToList (fwds `plusFV` (defs `intersectNameSet` later_uses))
672 -- The names for the fixpoint are
673 -- (a) the ones needed after the RecStmt
674 -- (b) the forward refs within the fixpoint
677 %************************************************************************
679 \subsubsection{Precedence Parsing}
681 %************************************************************************
683 @mkOpAppRn@ deals with operator fixities. The argument expressions
684 are assumed to be already correctly arranged. It needs the fixities
685 recorded in the OpApp nodes, because fixity info applies to the things
686 the programmer actually wrote, so you can't find it out from the Name.
688 Furthermore, the second argument is guaranteed not to be another
689 operator application. Why? Because the parser parses all
690 operator appications left-associatively, EXCEPT negation, which
691 we need to handle specially.
694 mkOpAppRn :: RenamedHsExpr -- Left operand; already rearranged
695 -> RenamedHsExpr -> Fixity -- Operator and fixity
696 -> RenamedHsExpr -- Right operand (not an OpApp, but might
700 ---------------------------
701 -- (e11 `op1` e12) `op2` e2
702 mkOpAppRn e1@(OpApp e11 op1 fix1 e12) op2 fix2 e2
704 = addErr (precParseErr (ppr_op op1,fix1) (ppr_op op2,fix2)) `thenM_`
705 returnM (OpApp e1 op2 fix2 e2)
708 = mkOpAppRn e12 op2 fix2 e2 `thenM` \ new_e ->
709 returnM (OpApp e11 op1 fix1 new_e)
711 (nofix_error, associate_right) = compareFixity fix1 fix2
713 ---------------------------
714 -- (- neg_arg) `op` e2
715 mkOpAppRn e1@(NegApp neg_arg neg_name) op2 fix2 e2
717 = addErr (precParseErr (pp_prefix_minus,negateFixity) (ppr_op op2,fix2)) `thenM_`
718 returnM (OpApp e1 op2 fix2 e2)
721 = mkOpAppRn neg_arg op2 fix2 e2 `thenM` \ new_e ->
722 returnM (NegApp new_e neg_name)
724 (nofix_error, associate_right) = compareFixity negateFixity fix2
726 ---------------------------
728 mkOpAppRn e1 op1 fix1 e2@(NegApp neg_arg _) -- NegApp can occur on the right
729 | not associate_right -- We *want* right association
730 = addErr (precParseErr (ppr_op op1, fix1) (pp_prefix_minus, negateFixity)) `thenM_`
731 returnM (OpApp e1 op1 fix1 e2)
733 (_, associate_right) = compareFixity fix1 negateFixity
735 ---------------------------
737 mkOpAppRn e1 op fix e2 -- Default case, no rearrangment
738 = ASSERT2( right_op_ok fix e2,
739 ppr e1 $$ text "---" $$ ppr op $$ text "---" $$ ppr fix $$ text "---" $$ ppr e2
741 returnM (OpApp e1 op fix e2)
743 -- Parser left-associates everything, but
744 -- derived instances may have correctly-associated things to
745 -- in the right operarand. So we just check that the right operand is OK
746 right_op_ok fix1 (OpApp _ _ fix2 _)
747 = not error_please && associate_right
749 (error_please, associate_right) = compareFixity fix1 fix2
750 right_op_ok fix1 other
753 -- Parser initially makes negation bind more tightly than any other operator
754 mkNegAppRn neg_arg neg_name
757 getModeRn `thenM` \ mode ->
758 ASSERT( not_op_app mode neg_arg )
760 returnM (NegApp neg_arg neg_name)
762 not_op_app SourceMode (OpApp _ _ _ _) = False
763 not_op_app mode other = True
767 checkPrecMatch :: Bool -> Name -> RenamedMatch -> RnM ()
769 checkPrecMatch False fn match
772 checkPrecMatch True op (Match (p1:p2:_) _ _)
773 -- True indicates an infix lhs
774 = getModeRn `thenM` \ mode ->
775 -- See comments with rnExpr (OpApp ...)
776 if isInterfaceMode mode
778 else checkPrec op p1 False `thenM_`
781 checkPrecMatch True op _ = panic "checkPrecMatch"
783 checkPrec op (ConPatIn op1 (InfixCon _ _)) right
784 = lookupFixityRn op `thenM` \ op_fix@(Fixity op_prec op_dir) ->
785 lookupFixityRn op1 `thenM` \ op1_fix@(Fixity op1_prec op1_dir) ->
787 inf_ok = op1_prec > op_prec ||
788 (op1_prec == op_prec &&
789 (op1_dir == InfixR && op_dir == InfixR && right ||
790 op1_dir == InfixL && op_dir == InfixL && not right))
792 info = (ppr_op op, op_fix)
793 info1 = (ppr_op op1, op1_fix)
794 (infol, infor) = if right then (info, info1) else (info1, info)
796 checkErr inf_ok (precParseErr infol infor)
798 checkPrec op pat right
801 -- Check precedence of (arg op) or (op arg) respectively
802 -- If arg is itself an operator application, then either
803 -- (a) its precedence must be higher than that of op
804 -- (b) its precedency & associativity must be the same as that of op
805 checkSectionPrec direction section op arg
807 OpApp _ op fix _ -> go_for_it (ppr_op op) fix
808 NegApp _ _ -> go_for_it pp_prefix_minus negateFixity
812 go_for_it pp_arg_op arg_fix@(Fixity arg_prec assoc)
813 = lookupFixityRn op_name `thenM` \ op_fix@(Fixity op_prec _) ->
814 checkErr (op_prec < arg_prec
815 || op_prec == arg_prec && direction == assoc)
816 (sectionPrecErr (ppr_op op_name, op_fix)
817 (pp_arg_op, arg_fix) section)
821 %************************************************************************
823 \subsubsection{Assertion utils}
825 %************************************************************************
828 mkAssertErrorExpr :: RnM (RenamedHsExpr, FreeVars)
829 -- Return an expression for (assertError "Foo.hs:27")
831 = getSrcLocM `thenM` \ sloc ->
833 expr = HsApp (HsVar assertErrorName) (HsLit msg)
834 msg = HsStringPrim (mkFastString (stringToUtf8 (showSDoc (ppr sloc))))
836 returnM (expr, unitFV assertErrorName)
839 %************************************************************************
841 \subsubsection{Errors}
843 %************************************************************************
846 ppr_op op = quotes (ppr op) -- Here, op can be a Name or a (Var n), where n is a Name
847 pp_prefix_minus = ptext SLIT("prefix `-'")
851 SLIT("accepting non-standard pattern guards (-fglasgow-exts to suppress this message)")
855 = sep [ptext SLIT("Pattern syntax in expression context:"),
859 = sep [quotes (text name) <+> ptext SLIT("statements must end in expression:"),
863 = ptext SLIT("Template Haskell") <+> text what <+>
864 ptext SLIT("illegal in a stage-1 compiler")
868 = sep [quotes (ptext SLIT("with")),
869 ptext SLIT("is deprecated, use"),
870 quotes (ptext SLIT("let")),
871 ptext SLIT("instead")]