2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnBinds]{Renaming and dependency analysis of bindings}
6 This module does renaming and dependency analysis on value bindings in
7 the abstract syntax. It does {\em not} do cycle-checks on class or
8 type-synonym declarations; those cannot be done at this stage because
9 they may be affected by renaming (which isn't fully worked out yet).
13 -- The above warning supression flag is a temporary kludge.
14 -- While working on this module you are encouraged to remove it and fix
15 -- any warnings in the module. See
16 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
19 module RnBinds (rnTopBinds, rnTopBindsLHS, rnTopBindsRHS, -- use these for top-level bindings
20 rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS, -- or these for local bindings
21 rnMethodBinds, renameSigs, mkSigTvFn,
22 rnMatchGroup, rnGRHSs,
26 #include "HsVersions.h"
28 import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts )
34 import RnTypes ( rnHsSigType, rnLHsType, rnHsTypeFVs,checkPrecMatch)
35 import RnPat (rnPatsAndThen_LocalRightwards, rnBindPat,
36 NameMaker, localRecNameMaker, topRecNameMaker, applyNameMaker,
39 import RnEnv ( lookupLocatedBndrRn,
40 lookupInstDeclBndr, newIPNameRn,
41 lookupLocatedSigOccRn, bindPatSigTyVarsFV,
42 bindLocalFixities, bindSigTyVarsFV,
43 warnUnusedLocalBinds, mapFvRn, extendTyVarEnvFVRn,
44 bindLocatedLocalsFV, bindLocalNames, bindLocalNamesFV,
45 bindLocalNamesFV_WithFixities,
47 checkDupAndShadowedRdrNames
49 import DynFlags ( DynFlag(..) )
50 import HscTypes (FixItem(..))
55 import PrelNames ( isUnboundName )
56 import RdrName ( RdrName, rdrNameOcc )
57 import SrcLoc ( Located(..), unLoc, noLoc )
58 import ListSetOps ( findDupsEq )
59 import BasicTypes ( RecFlag(..) )
60 import Digraph ( SCC(..), stronglyConnComp )
63 import Maybes ( orElse )
64 import Util ( filterOut )
65 import Monad ( foldM, unless )
68 -- ToDo: Put the annotations into the monad, so that they arrive in the proper
69 -- place and can be used when complaining.
71 The code tree received by the function @rnBinds@ contains definitions
72 in where-clauses which are all apparently mutually recursive, but which may
73 not really depend upon each other. For example, in the top level program
78 the definitions of @a@ and @y@ do not depend on each other at all.
79 Unfortunately, the typechecker cannot always check such definitions.
80 \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive
81 definitions. In Proceedings of the International Symposium on Programming,
82 Toulouse, pp. 217-39. LNCS 167. Springer Verlag.}
83 However, the typechecker usually can check definitions in which only the
84 strongly connected components have been collected into recursive bindings.
85 This is precisely what the function @rnBinds@ does.
87 ToDo: deal with case where a single monobinds binds the same variable
90 The vertag tag is a unique @Int@; the tags only need to be unique
91 within one @MonoBinds@, so that unique-Int plumbing is done explicitly
92 (heavy monad machinery not needed).
95 %************************************************************************
97 %* naming conventions *
99 %************************************************************************
101 \subsection[name-conventions]{Name conventions}
103 The basic algorithm involves walking over the tree and returning a tuple
104 containing the new tree plus its free variables. Some functions, such
105 as those walking polymorphic bindings (HsBinds) and qualifier lists in
106 list comprehensions (@Quals@), return the variables bound in local
107 environments. These are then used to calculate the free variables of the
108 expression evaluated in these environments.
110 Conventions for variable names are as follows:
113 new code is given a prime to distinguish it from the old.
116 a set of variables defined in @Exp@ is written @dvExp@
119 a set of variables free in @Exp@ is written @fvExp@
122 %************************************************************************
124 %* analysing polymorphic bindings (HsBindGroup, HsBind)
126 %************************************************************************
128 \subsubsection[dep-HsBinds]{Polymorphic bindings}
130 Non-recursive expressions are reconstructed without any changes at top
131 level, although their component expressions may have to be altered.
132 However, non-recursive expressions are currently not expected as
133 \Haskell{} programs, and this code should not be executed.
135 Monomorphic bindings contain information that is returned in a tuple
136 (a @FlatMonoBinds@) containing:
140 a unique @Int@ that serves as the ``vertex tag'' for this binding.
143 the name of a function or the names in a pattern. These are a set
144 referred to as @dvLhs@, the defined variables of the left hand side.
147 the free variables of the body. These are referred to as @fvBody@.
150 the definition's actual code. This is referred to as just @code@.
153 The function @nonRecDvFv@ returns two sets of variables. The first is
154 the set of variables defined in the set of monomorphic bindings, while the
155 second is the set of free variables in those bindings.
157 The set of variables defined in a non-recursive binding is just the
158 union of all of them, as @union@ removes duplicates. However, the
159 free variables in each successive set of cumulative bindings is the
160 union of those in the previous set plus those of the newest binding after
161 the defined variables of the previous set have been removed.
163 @rnMethodBinds@ deals only with the declarations in class and
164 instance declarations. It expects only to see @FunMonoBind@s, and
165 it expects the global environment to contain bindings for the binders
166 (which are all class operations).
168 %************************************************************************
170 \subsubsection{ Top-level bindings}
172 %************************************************************************
175 -- for top-level bindings, we need to make top-level names,
176 -- so we have a different entry point than for local bindings
177 rnTopBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
178 -- these fixities need to be brought into scope with the names
179 -> HsValBinds RdrName
180 -> RnM (HsValBindsLR Name RdrName)
181 rnTopBindsLHS fix_env binds =
182 (uncurry $ rnValBindsLHSFromDoc (topRecNameMaker fix_env)) (bindersAndDoc binds) binds
184 rnTopBindsRHS :: [Name] -- the names bound by these binds
185 -> HsValBindsLR Name RdrName
186 -> RnM (HsValBinds Name, DefUses)
187 rnTopBindsRHS bound_names binds =
188 do { is_boot <- tcIsHsBoot
190 then rnTopBindsBoot binds
191 else rnValBindsRHSGen (\x -> x) -- don't trim free vars
195 -- wrapper if we don't need to do anything in between the left and right,
196 -- or anything else in the scope of the left
198 -- never used when there are fixity declarations
199 rnTopBinds :: HsValBinds RdrName
200 -> RnM (HsValBinds Name, DefUses)
202 do nl <- rnTopBindsLHS emptyUFM b
203 let bound_names = map unLoc (collectHsValBinders nl)
204 bindLocalNames bound_names $ rnTopBindsRHS bound_names nl
207 rnTopBindsBoot :: HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses)
208 -- A hs-boot file has no bindings.
209 -- Return a single HsBindGroup with empty binds and renamed signatures
210 rnTopBindsBoot (ValBindsIn mbinds sigs)
211 = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds)
212 ; sigs' <- renameSigs okHsBootSig sigs
213 ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) }
218 %*********************************************************
222 %*********************************************************
225 rnLocalBindsAndThen :: HsLocalBinds RdrName
226 -> (HsLocalBinds Name -> RnM (result, FreeVars))
227 -> RnM (result, FreeVars)
228 -- This version (a) assumes that the binding vars are *not* already in scope
229 -- (b) removes the binders from the free vars of the thing inside
230 -- The parser doesn't produce ThenBinds
231 rnLocalBindsAndThen EmptyLocalBinds thing_inside
232 = thing_inside EmptyLocalBinds
234 rnLocalBindsAndThen (HsValBinds val_binds) thing_inside
235 = rnValBindsAndThen val_binds $ \ val_binds' ->
236 thing_inside (HsValBinds val_binds')
238 rnLocalBindsAndThen (HsIPBinds binds) thing_inside = do
239 (binds',fv_binds) <- rnIPBinds binds
240 (thing, fvs_thing) <- thing_inside (HsIPBinds binds')
241 return (thing, fvs_thing `plusFV` fv_binds)
244 rnIPBinds (IPBinds ip_binds _no_dict_binds) = do
245 (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds
246 return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s)
248 rnIPBind (IPBind n expr) = do
249 name <- newIPNameRn n
250 (expr',fvExpr) <- rnLExpr expr
251 return (IPBind name expr', fvExpr)
255 %************************************************************************
259 %************************************************************************
262 -- wrapper for local binds
263 -- creates the documentation info and calls the helper below
264 rnValBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
265 -- these fixities need to be brought into scope with the names
266 -> HsValBinds RdrName
267 -> RnM (HsValBindsLR Name RdrName)
268 rnValBindsLHS fix_env binds =
269 let (boundNames,doc) = bindersAndDoc binds
270 in rnValBindsLHSFromDoc_Local boundNames doc fix_env binds
272 -- a helper used for local binds that does the duplicates check,
273 -- just so we don't forget to do it somewhere
274 rnValBindsLHSFromDoc_Local :: [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
275 -> SDoc -- doc string for dup names and shadowing
276 -> UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
277 -- these fixities need to be brought into scope with the names
278 -> HsValBinds RdrName
279 -> RnM (HsValBindsLR Name RdrName)
281 rnValBindsLHSFromDoc_Local boundNames doc fix_env binds = do
282 -- Do error checking: we need to check for dups here because we
283 -- don't don't bind all of the variables from the ValBinds at once
284 -- with bindLocatedLocals any more.
285 checkDupAndShadowedRdrNames doc boundNames
287 -- (Note that we don't want to do this at the top level, since
288 -- sorting out duplicates and shadowing there happens elsewhere.
289 -- The behavior is even different. For example,
292 -- should not produce a shadowing warning (but it will produce
293 -- an ambiguity warning if you use f), but
295 -- g = let f = ... in f
297 rnValBindsLHSFromDoc (localRecNameMaker fix_env) boundNames doc binds
299 bindersAndDoc :: HsValBinds RdrName -> ([Located RdrName], SDoc)
300 bindersAndDoc binds =
302 -- the unrenamed bndrs for error checking and reporting
303 orig = collectHsValBinders binds
304 doc = text "In the binding group for:" <+> pprWithCommas ppr (map unLoc orig)
308 -- renames the left-hand sides
309 -- generic version used both at the top level and for local binds
310 -- does some error checking, but not what gets done elsewhere at the top level
311 rnValBindsLHSFromDoc :: NameMaker
312 -> [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
313 -> SDoc -- doc string for dup names and shadowing
314 -> HsValBinds RdrName
315 -> RnM (HsValBindsLR Name RdrName)
316 rnValBindsLHSFromDoc topP original_bndrs doc binds@(ValBindsIn mbinds sigs) = do
318 mbinds' <- mapBagM (rnBindLHS topP doc) mbinds
319 return $ ValBindsIn mbinds' sigs
321 -- assumes the LHS vars are in scope
322 -- general version used both from the top-level and for local things
324 -- does not bind the local fixity declarations
325 rnValBindsRHSGen :: (FreeVars -> FreeVars) -- for trimming free var sets
326 -- The trimming function trims the free vars we attach to a
327 -- binding so that it stays reasonably small
328 -> [Name] -- names bound by the LHSes
329 -> HsValBindsLR Name RdrName
330 -> RnM (HsValBinds Name, DefUses)
332 rnValBindsRHSGen trim bound_names binds@(ValBindsIn mbinds sigs) = do
334 sigs' <- rename_sigs sigs
336 binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds
337 let (anal_binds, anal_dus) = depAnalBinds binds_w_dus
338 (valbind', valbind'_dus) = (ValBindsOut anal_binds sigs',
339 usesOnly (hsSigsFVs sigs') `plusDU` anal_dus)
340 -- We do the check-sigs after renaming the bindings,
341 -- so that we have convenient access to the binders
342 check_sigs (okBindSig (duDefs anal_dus)) sigs'
343 return (valbind', valbind'_dus)
345 -- wrapper for local binds
347 -- the *client* of this function is responsible for checking for unused binders;
348 -- it doesn't (and can't: we don't have the thing inside the binds) happen here
350 -- the client is also responsible for bringing the fixities into scope
351 rnValBindsRHS :: [Name] -- names bound by the LHSes
352 -> HsValBindsLR Name RdrName
353 -> RnM (HsValBinds Name, DefUses)
354 rnValBindsRHS bound_names binds =
355 rnValBindsRHSGen (\ fvs -> -- only keep the names the names from this group
356 intersectNameSet (mkNameSet bound_names) fvs) bound_names binds
360 -- wrapper that does both the left- and right-hand sides
362 -- here there are no local fixity decls passed in;
363 -- the local fixity decls come from the ValBinds sigs
364 rnValBindsAndThen :: HsValBinds RdrName
365 -> (HsValBinds Name -> RnM (result, FreeVars))
366 -> RnM (result, FreeVars)
367 rnValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside =
369 (original_bndrs, doc) = bindersAndDoc binds
372 -- (A) create the local fixity environment
373 new_fixities <- makeMiniFixityEnv [L loc sig | L loc (FixSig sig) <- sigs]
375 -- (B) rename the LHSes
376 new_lhs <- rnValBindsLHSFromDoc_Local original_bndrs doc new_fixities binds
377 let bound_names = map unLoc $ collectHsValBinders new_lhs
379 -- and bring them (and their fixities) into scope
380 bindLocalNamesFV_WithFixities bound_names new_fixities $
381 warnUnusedLocalBinds bound_names $ do
383 -- (C) do the RHS and thing inside
384 (binds', dus) <- rnValBindsRHS bound_names new_lhs
385 (result, result_fvs) <- thing_inside binds'
388 -- the variables used in the val binds are:
389 -- (1) the uses of the binds
390 -- (2) the FVs of the thing-inside
391 all_uses = (duUses dus) `plusFV` result_fvs
392 -- duUses: It's important to return all the uses. Otherwise consider:
394 -- y = let p = x in 'x' -- NB: p not used
395 -- If we don't "see" the dependency of 'y' on 'x', we may put the
396 -- bindings in the wrong order, and the type checker will complain
397 -- that x isn't in scope
400 -- the bound names are pruned out of all_uses
401 -- by the bindLocalNamesFV call above
405 -- Process the fixity declarations, making a FastString -> (Located Fixity) map
406 -- (We keep the location around for reporting duplicate fixity declarations.)
408 -- Checks for duplicates, but not that only locally defined things are fixed.
409 -- Note: for local fixity declarations, duplicates would also be checked in
410 -- check_sigs below. But we also use this function at the top level.
411 makeMiniFixityEnv :: [LFixitySig RdrName]
412 -> RnM (UniqFM (Located Fixity)) -- key is the FastString of the OccName
413 -- of the fixity declaration it came from
415 makeMiniFixityEnv decls = foldlM add_one emptyUFM decls
417 add_one env (L loc (FixitySig (L name_loc name) fixity)) = do
418 { -- this fixity decl is a duplicate iff
419 -- the ReaderName's OccName's FastString is already in the env
420 -- (we only need to check the local fix_env because
421 -- definitions of non-local will be caught elsewhere)
422 let {occ = rdrNameOcc name;
423 curKey = occNameFS occ;
424 fix_item = L loc fixity};
426 case lookupUFM env curKey of
427 Nothing -> return $ addToUFM env curKey fix_item
428 Just (L loc' _) -> do
430 addLocErr (L name_loc name) (dupFixityDecl loc')
434 pprFixEnv :: NameEnv FixItem -> SDoc
436 = pprWithCommas (\ (FixItem n f) -> ppr f <+> ppr n)
439 dupFixityDecl loc rdr_name
440 = vcat [ptext SLIT("Multiple fixity declarations for") <+> quotes (ppr rdr_name),
441 ptext SLIT("also at ") <+> ppr loc]
443 ---------------------
445 -- renaming a single bind
447 rnBindLHS :: NameMaker
450 -- returns the renamed left-hand side,
451 -- and the FreeVars *of the LHS*
452 -- (i.e., any free variables of the pattern)
453 -> RnM (LHsBindLR Name RdrName)
455 rnBindLHS name_maker doc (L loc (PatBind { pat_lhs = pat,
458 pat_rhs_ty=pat_rhs_ty
460 = setSrcSpan loc $ do
461 -- we don't actually use the FV processing of rnPatsAndThen here
462 (pat',pat'_fvs) <- rnBindPat name_maker pat
463 return (L loc (PatBind { pat_lhs = pat',
465 -- we temporarily store the pat's FVs here;
466 -- gets updated to the FVs of the whole bind
467 -- when doing the RHS below
469 -- these will get ignored in the next pass,
470 -- when we rename the RHS
471 pat_rhs_ty = pat_rhs_ty }))
473 rnBindLHS name_maker doc (L loc (FunBind { fun_id = name@(L nameLoc _),
475 fun_matches = matches,
476 fun_co_fn = fun_co_fn,
481 do { (newname, _fvs) <- applyNameMaker name_maker name $ \ newname ->
482 return (newname, emptyFVs)
483 ; return (L loc (FunBind { fun_id = L nameLoc newname,
485 fun_matches = matches,
486 -- we temporatily store the LHS's FVs (empty in this case) here
487 -- gets updated when doing the RHS below
489 -- everything else will get ignored in the next pass
490 fun_co_fn = fun_co_fn,
494 -- assumes the left-hands-side vars are in scope
495 rnBind :: (Name -> [Name]) -- Signature tyvar function
496 -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars
497 -> LHsBindLR Name RdrName
498 -> RnM (LHsBind Name, [Name], Uses)
499 rnBind sig_fn trim (L loc (PatBind { pat_lhs = pat,
501 -- pat fvs were stored here while processing the LHS
504 do {let bndrs = collectPatBinders pat
506 ; (grhss', fvs) <- rnGRHSs PatBindRhs grhss
507 -- No scoped type variables for pattern bindings
509 ; return (L loc (PatBind { pat_lhs = pat,
511 pat_rhs_ty = placeHolderType,
512 bind_fvs = trim fvs }),
513 bndrs, pat_fvs `plusFV` fvs) }
517 (L loc (FunBind { fun_id = name,
519 fun_matches = matches,
523 -- invariant: no free vars here when it's a FunBind
525 do { let plain_name = unLoc name
527 ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
528 -- bindSigTyVars tests for Opt_ScopedTyVars
529 rnMatchGroup (FunRhs plain_name inf) matches
531 ; checkPrecMatch inf plain_name matches'
533 ; return (L loc (FunBind { fun_id = name,
535 fun_matches = matches',
537 fun_co_fn = idHsWrapper,
538 fun_tick = Nothing }),
542 ---------------------
543 depAnalBinds :: Bag (LHsBind Name, [Name], Uses)
544 -> ([(RecFlag, LHsBinds Name)], DefUses)
545 -- Dependency analysis; this is important so that
546 -- unused-binding reporting is accurate
547 depAnalBinds binds_w_dus
548 = (map get_binds sccs, map get_du sccs)
550 sccs = stronglyConnComp edges
552 keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..]
554 edges = [ (node, key, [key | n <- nameSetToList uses,
555 Just key <- [lookupNameEnv key_map n] ])
556 | (node@(_,_,uses), key) <- keyd_nodes ]
558 key_map :: NameEnv Int -- Which binding it comes from
559 key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes
562 get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind)
563 get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,d,u) <- binds_w_dus])
565 get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses)
566 get_du (CyclicSCC binds_w_dus) = (Just defs, uses)
568 defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs]
569 uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus]
572 ---------------------
573 -- Bind the top-level forall'd type variables in the sigs.
576 -- The 'a' scopes over the rhs
578 -- NB: there'll usually be just one (for a function binding)
579 -- but if there are many, one may shadow the rest; too bad!
580 -- e.g x :: [a] -> [a]
583 -- In e, 'a' will be in scope, and it'll be the one from 'y'!
585 mkSigTvFn :: [LSig Name] -> (Name -> [Name])
586 -- Return a lookup function that maps an Id Name to the names
587 -- of the type variables that should scope over its body..
589 = \n -> lookupNameEnv env n `orElse` []
591 env :: NameEnv [Name]
592 env = mkNameEnv [ (name, map hsLTyVarName ltvs)
593 | L _ (TypeSig (L _ name)
594 (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs]
595 -- Note the pattern-match on "Explicit"; we only bind
596 -- type variables from signatures with an explicit top-level for-all
600 @rnMethodBinds@ is used for the method bindings of a class and an instance
601 declaration. Like @rnBinds@ but without dependency analysis.
603 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
604 That's crucial when dealing with an instance decl:
606 instance Foo (T a) where
609 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
610 and unless @op@ occurs we won't treat the type signature of @op@ in the class
611 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
612 in many ways the @op@ in an instance decl is just like an occurrence, not
616 rnMethodBinds :: Name -- Class name
617 -> (Name -> [Name]) -- Signature tyvar function
618 -> [Name] -- Names for generic type variables
620 -> RnM (LHsBinds Name, FreeVars)
622 rnMethodBinds cls sig_fn gen_tyvars binds
623 = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
624 where do_one (binds,fvs) bind = do
625 (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
626 return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
628 rnMethodBind cls sig_fn gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf,
629 fun_matches = MatchGroup matches _ }))
630 = setSrcSpan loc $ do
631 sel_name <- lookupInstDeclBndr cls name
632 let plain_name = unLoc sel_name
633 -- We use the selector name as the binder
635 bindSigTyVarsFV (sig_fn plain_name) $ do
636 (new_matches, fvs) <- mapFvRn (rn_match plain_name) matches
638 new_group = MatchGroup new_matches placeHolderType
640 checkPrecMatch inf plain_name new_group
641 return (unitBag (L loc (FunBind {
642 fun_id = sel_name, fun_infix = inf,
643 fun_matches = new_group,
644 bind_fvs = fvs, fun_co_fn = idHsWrapper,
645 fun_tick = Nothing })),
646 fvs `addOneFV` plain_name)
647 -- The 'fvs' field isn't used for method binds
649 -- Truly gruesome; bring into scope the correct members of the generic
650 -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
651 rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _))
652 = extendTyVarEnvFVRn gen_tvs $
653 rnMatch (FunRhs sel_name inf) match
655 tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
656 gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
658 rn_match sel_name match = rnMatch (FunRhs sel_name inf) match
661 -- Can't handle method pattern-bindings which bind multiple methods.
662 rnMethodBind cls sig_fn gen_tyvars mbind@(L loc (PatBind other_pat _ _ _)) = do
663 addLocErr mbind methodBindErr
664 return (emptyBag, emptyFVs)
669 %************************************************************************
671 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
673 %************************************************************************
675 @renameSigs@ checks for:
677 \item more than one sig for one thing;
678 \item signatures given for things not bound here;
679 \item with suitably flaggery, that all top-level things have type signatures.
682 At the moment we don't gather free-var info from the types in
683 signatures. We'd only need this if we wanted to report unused tyvars.
686 renameSigs :: (LSig Name -> Bool) -> [LSig RdrName] -> RnM [LSig Name]
687 -- Renames the signatures and performs error checks
688 renameSigs ok_sig sigs
689 = do { sigs' <- rename_sigs sigs
690 ; check_sigs ok_sig sigs'
693 ----------------------
694 rename_sigs :: [LSig RdrName] -> RnM [LSig Name]
695 rename_sigs sigs = mapM (wrapLocM renameSig) sigs
697 ----------------------
698 check_sigs :: (LSig Name -> Bool) -> [LSig Name] -> RnM ()
699 -- Used for class and instance decls, as well as regular bindings
700 check_sigs ok_sig sigs = do
701 -- Check for (a) duplicate signatures
702 -- (b) signatures for things not in this group = do
703 traceRn (text "SIGS" <+> ppr sigs)
704 mapM_ unknownSigErr (filter (not . ok_sig) sigs')
705 mapM_ dupSigDeclErr (findDupsEq eqHsSig sigs')
707 -- Don't complain about an unbound name again
708 sigs' = filterOut bad_name sigs
709 bad_name sig = case sigName sig of
710 Just n -> isUnboundName n
713 -- We use lookupLocatedSigOccRn in the signatures, which is a little bit unsatisfactory
714 -- because this won't work for:
715 -- instance Foo T where
718 -- We'll just rename the INLINE prag to refer to whatever other 'op'
719 -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.)
720 -- Doesn't seem worth much trouble to sort this.
722 renameSig :: Sig RdrName -> RnM (Sig Name)
723 -- FixitSig is renamed elsewhere.
724 renameSig (TypeSig v ty) = do
725 new_v <- lookupLocatedSigOccRn v
726 new_ty <- rnHsSigType (quotes (ppr v)) ty
727 return (TypeSig new_v new_ty)
729 renameSig (SpecInstSig ty) = do
730 new_ty <- rnLHsType (text "A SPECIALISE instance pragma") ty
731 return (SpecInstSig new_ty)
733 renameSig (SpecSig v ty inl) = do
734 new_v <- lookupLocatedSigOccRn v
735 new_ty <- rnHsSigType (quotes (ppr v)) ty
736 return (SpecSig new_v new_ty inl)
738 renameSig (InlineSig v s) = do
739 new_v <- lookupLocatedSigOccRn v
740 return (InlineSig new_v s)
742 renameSig (FixSig (FixitySig v f)) = do
743 new_v <- lookupLocatedSigOccRn v
744 return (FixSig (FixitySig new_v f))
748 ************************************************************************
752 ************************************************************************
755 rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars)
756 rnMatchGroup ctxt (MatchGroup ms _) = do
757 (new_ms, ms_fvs) <- mapFvRn (rnMatch ctxt) ms
758 return (MatchGroup new_ms placeHolderType, ms_fvs)
760 rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
761 rnMatch ctxt = wrapLocFstM (rnMatch' ctxt)
763 rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss)
765 -- Deal with the rhs type signature
766 bindPatSigTyVarsFV rhs_sig_tys $ do
767 opt_PatternSignatures <- doptM Opt_PatternSignatures
768 (maybe_rhs_sig', ty_fvs) <-
769 case maybe_rhs_sig of
770 Nothing -> return (Nothing, emptyFVs)
771 Just ty | opt_PatternSignatures -> do (ty', ty_fvs) <- rnHsTypeFVs doc_sig ty
772 return (Just ty', ty_fvs)
773 | otherwise -> do addLocErr ty patSigErr
774 return (Nothing, emptyFVs)
776 -- Now the main event
777 -- note that there are no local ficity decls for matches
778 rnPatsAndThen_LocalRightwards ctxt pats $ \ pats' -> do
779 (grhss', grhss_fvs) <- rnGRHSs ctxt grhss
781 return (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
782 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
784 rhs_sig_tys = case maybe_rhs_sig of
787 doc_sig = text "In a result type-signature"
791 %************************************************************************
793 \subsubsection{Guarded right-hand sides (GRHSs)}
795 %************************************************************************
798 rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars)
800 rnGRHSs ctxt (GRHSs grhss binds)
801 = rnLocalBindsAndThen binds $ \ binds' -> do
802 (grhss', fvGRHSs) <- mapFvRn (rnGRHS ctxt) grhss
803 return (GRHSs grhss' binds', fvGRHSs)
805 rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars)
806 rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt)
808 rnGRHS' ctxt (GRHS guards rhs)
809 = do { pattern_guards_allowed <- doptM Opt_PatternGuards
810 ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $
813 ; unless (pattern_guards_allowed || is_standard_guard guards')
814 (addWarn (nonStdGuardErr guards'))
816 ; return (GRHS guards' rhs', fvs) }
818 -- Standard Haskell 1.4 guards are just a single boolean
819 -- expression, rather than a list of qualifiers as in the
821 is_standard_guard [] = True
822 is_standard_guard [L _ (ExprStmt _ _ _)] = True
823 is_standard_guard other = False
826 %************************************************************************
828 \subsection{Error messages}
830 %************************************************************************
833 dupSigDeclErr sigs@(L loc sig : _)
835 vcat [ptext SLIT("Duplicate") <+> what_it_is <> colon,
836 nest 2 (vcat (map ppr_sig sigs))]
838 what_it_is = hsSigDoc sig
839 ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig
841 unknownSigErr (L loc sig)
842 = do { mod <- getModule
844 vcat [sep [ptext SLIT("Misplaced") <+> what_it_is <> colon, ppr sig],
845 extra_stuff mod sig] }
847 what_it_is = hsSigDoc sig
848 extra_stuff mod (TypeSig (L _ n) _)
849 | nameIsLocalOrFrom mod n
850 = ptext SLIT("The type signature must be given where")
851 <+> quotes (ppr n) <+> ptext SLIT("is declared")
853 = ptext SLIT("You cannot give a type signature for an imported value")
855 extra_stuff mod other = empty
858 = hang (ptext SLIT("Pattern bindings (except simple variables) not allowed in instance declarations"))
861 bindsInHsBootFile mbinds
862 = hang (ptext SLIT("Bindings in hs-boot files are not allowed"))
865 nonStdGuardErr guards
866 = hang (ptext SLIT("accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
867 4 (interpp'SP guards)