2 % (c) The University of Glasgow, 1996-2003
4 Functions over HsSyn specialised to RdrName.
9 extractHsRhoRdrTyVars, extractGenericPatTyVars,
12 mkHsIntegral, mkHsFractional, mkHsIsString,
13 mkHsDo, mkHsSplice, mkTopSpliceDecl,
14 mkClassDecl, mkTyData, mkTyFamily, mkTySynonym,
15 splitCon, mkInlinePragma,
16 mkRecConstrOrUpdate, -- HsExp -> [HsFieldUpdate] -> P HsExp
23 -- Stuff to do with Foreign declarations
27 mkExtName, -- RdrName -> CLabelString
28 mkGadtDecl, -- [Located RdrName] -> LHsType RdrName -> ConDecl RdrName
30 mkDeprecatedGadtRecordDecl,
32 -- Bunch of functions in the parser monad for
33 -- checking and constructing values
34 checkPrecP, -- Int -> P Int
35 checkContext, -- HsType -> P HsContext
36 checkPred, -- HsType -> P HsPred
37 checkTyVars, -- [LHsType RdrName] -> P ()
38 checkKindSigs, -- [LTyClDecl RdrName] -> P ()
39 checkInstType, -- HsType -> P HsType
40 checkPattern, -- HsExp -> P HsPat
42 checkPatterns, -- SrcLoc -> [HsExp] -> P [HsPat]
43 checkDo, -- [Stmt] -> P [Stmt]
44 checkMDo, -- [Stmt] -> P [Stmt]
45 checkValDef, -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl
46 checkValSig, -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl
51 import HsSyn -- Lots of it
52 import Class ( FunDep )
53 import TypeRep ( Kind )
54 import RdrName ( RdrName, isRdrTyVar, isRdrTc, mkUnqual, rdrNameOcc,
55 isRdrDataCon, isUnqual, getRdrName, setRdrNameSpace )
56 import BasicTypes ( maxPrecedence, Activation(..), RuleMatchInfo,
59 import TysWiredIn ( unitTyCon )
61 import OccName ( srcDataName, varName, isDataOcc, isTcOcc,
63 import PrelNames ( forall_tv_RDR )
66 import OrdList ( OrdList, fromOL )
67 import Bag ( Bag, emptyBag, consBag, foldrBag )
72 import Control.Applicative ((<$>))
74 import Text.ParserCombinators.ReadP as ReadP
75 import Data.List ( nubBy )
78 #include "HsVersions.h"
82 %************************************************************************
84 \subsection{A few functions over HsSyn at RdrName}
86 %************************************************************************
88 extractHsTyRdrNames finds the free variables of a HsType
89 It's used when making the for-alls explicit.
92 extractHsTyRdrTyVars :: LHsType RdrName -> [Located RdrName]
93 extractHsTyRdrTyVars ty = nubBy eqLocated (extract_lty ty [])
95 extractHsTysRdrTyVars :: [LHsType RdrName] -> [Located RdrName]
96 extractHsTysRdrTyVars ty = nubBy eqLocated (extract_ltys ty [])
98 extractHsRhoRdrTyVars :: LHsContext RdrName -> LHsType RdrName -> [Located RdrName]
99 -- This one takes the context and tau-part of a
100 -- sigma type and returns their free type variables
101 extractHsRhoRdrTyVars ctxt ty
102 = nubBy eqLocated $ extract_lctxt ctxt (extract_lty ty [])
104 extract_lctxt :: Located [LHsPred RdrName] -> [Located RdrName] -> [Located RdrName]
105 extract_lctxt ctxt acc = foldr (extract_pred . unLoc) acc (unLoc ctxt)
107 extract_pred :: HsPred RdrName -> [Located RdrName] -> [Located RdrName]
108 extract_pred (HsClassP _ tys) acc = extract_ltys tys acc
109 extract_pred (HsEqualP ty1 ty2) acc = extract_lty ty1 (extract_lty ty2 acc)
110 extract_pred (HsIParam _ ty ) acc = extract_lty ty acc
112 extract_ltys :: [LHsType RdrName] -> [Located RdrName] -> [Located RdrName]
113 extract_ltys tys acc = foldr extract_lty acc tys
115 extract_lty :: LHsType RdrName -> [Located RdrName] -> [Located RdrName]
116 extract_lty (L loc ty) acc
118 HsTyVar tv -> extract_tv loc tv acc
119 HsBangTy _ ty -> extract_lty ty acc
120 HsRecTy flds -> foldr (extract_lty . cd_fld_type) acc flds
121 HsAppTy ty1 ty2 -> extract_lty ty1 (extract_lty ty2 acc)
122 HsListTy ty -> extract_lty ty acc
123 HsPArrTy ty -> extract_lty ty acc
124 HsTupleTy _ tys -> extract_ltys tys acc
125 HsFunTy ty1 ty2 -> extract_lty ty1 (extract_lty ty2 acc)
126 HsPredTy p -> extract_pred p acc
127 HsOpTy ty1 (L loc tv) ty2 -> extract_tv loc tv (extract_lty ty1 (extract_lty ty2 acc))
128 HsParTy ty -> extract_lty ty acc
130 HsQuasiQuoteTy {} -> acc -- Quasi quotes mention no type variables
131 HsSpliceTy {} -> acc -- Type splices mention no type variables
132 HsKindSig ty _ -> extract_lty ty acc
133 HsForAllTy _ [] cx ty -> extract_lctxt cx (extract_lty ty acc)
134 HsForAllTy _ tvs cx ty -> acc ++ (filter ((`notElem` locals) . unLoc) $
135 extract_lctxt cx (extract_lty ty []))
137 locals = hsLTyVarNames tvs
138 HsDocTy ty _ -> extract_lty ty acc
140 extract_tv :: SrcSpan -> RdrName -> [Located RdrName] -> [Located RdrName]
141 extract_tv loc tv acc | isRdrTyVar tv = L loc tv : acc
144 extractGenericPatTyVars :: LHsBinds RdrName -> [Located RdrName]
145 -- Get the type variables out of the type patterns in a bunch of
146 -- possibly-generic bindings in a class declaration
147 extractGenericPatTyVars binds
148 = nubBy eqLocated (foldrBag get [] binds)
150 get (L _ (FunBind { fun_matches = MatchGroup ms _ })) acc = foldr (get_m.unLoc) acc ms
153 get_m (Match (L _ (TypePat ty) : _) _ _) acc = extract_lty ty acc
158 %************************************************************************
160 \subsection{Construction functions for Rdr stuff}
162 %************************************************************************
164 mkClassDecl builds a RdrClassDecl, filling in the names for tycon and datacon
165 by deriving them from the name of the class. We fill in the names for the
166 tycon and datacon corresponding to the class, by deriving them from the
167 name of the class itself. This saves recording the names in the interface
168 file (which would be equally good).
170 Similarly for mkConDecl, mkClassOpSig and default-method names.
172 *** See "THE NAMING STORY" in HsDecls ****
175 mkClassDecl :: SrcSpan
176 -> Located (Maybe (LHsContext RdrName), LHsType RdrName)
177 -> Located [Located (FunDep RdrName)]
178 -> Located (OrdList (LHsDecl RdrName))
179 -> P (LTyClDecl RdrName)
181 mkClassDecl loc (L _ (mcxt, tycl_hdr)) fds where_cls
182 = do { let (binds, sigs, ats, docs) = cvBindsAndSigs (unLoc where_cls)
183 ; let cxt = fromMaybe (noLoc []) mcxt
184 ; (cls, tparams) <- checkTyClHdr tycl_hdr
185 ; tyvars <- checkTyVars tparams -- Only type vars allowed
187 ; return (L loc (ClassDecl { tcdCtxt = cxt, tcdLName = cls, tcdTyVars = tyvars,
188 tcdFDs = unLoc fds, tcdSigs = sigs, tcdMeths = binds,
189 tcdATs = ats, tcdDocs = docs })) }
193 -> Bool -- True <=> data family instance
194 -> Located (Maybe (LHsContext RdrName), LHsType RdrName)
196 -> [LConDecl RdrName]
197 -> Maybe [LHsType RdrName]
198 -> P (LTyClDecl RdrName)
199 mkTyData loc new_or_data is_family (L _ (mcxt, tycl_hdr)) ksig data_cons maybe_deriv
200 = do { (tc, tparams) <- checkTyClHdr tycl_hdr
202 ; checkDatatypeContext mcxt
203 ; let cxt = fromMaybe (noLoc []) mcxt
204 ; (tyvars, typats) <- checkTParams is_family tparams
205 ; return (L loc (TyData { tcdND = new_or_data, tcdCtxt = cxt, tcdLName = tc,
206 tcdTyVars = tyvars, tcdTyPats = typats,
208 tcdKindSig = ksig, tcdDerivs = maybe_deriv })) }
210 mkTySynonym :: SrcSpan
211 -> Bool -- True <=> type family instances
212 -> LHsType RdrName -- LHS
213 -> LHsType RdrName -- RHS
214 -> P (LTyClDecl RdrName)
215 mkTySynonym loc is_family lhs rhs
216 = do { (tc, tparams) <- checkTyClHdr lhs
217 ; (tyvars, typats) <- checkTParams is_family tparams
218 ; return (L loc (TySynonym tc tyvars typats rhs)) }
220 mkTyFamily :: SrcSpan
222 -> LHsType RdrName -- LHS
223 -> Maybe Kind -- Optional kind signature
224 -> P (LTyClDecl RdrName)
225 mkTyFamily loc flavour lhs ksig
226 = do { (tc, tparams) <- checkTyClHdr lhs
227 ; tyvars <- checkTyVars tparams
228 ; return (L loc (TyFamily flavour tc tyvars ksig)) }
230 mkTopSpliceDecl :: LHsExpr RdrName -> HsDecl RdrName
232 -- [pads| ... ] then return a QuasiQuoteD
233 -- $(e) then return a SpliceD
234 -- but if she wrote, say,
235 -- f x then behave as if she'd written $(f x)
237 mkTopSpliceDecl (L _ (HsQuasiQuoteE qq)) = QuasiQuoteD qq
238 mkTopSpliceDecl (L _ (HsSpliceE (HsSplice _ expr))) = SpliceD (SpliceDecl expr Explicit)
239 mkTopSpliceDecl other_expr = SpliceD (SpliceDecl other_expr Implicit)
242 %************************************************************************
244 \subsection[cvBinds-etc]{Converting to @HsBinds@, etc.}
246 %************************************************************************
248 Function definitions are restructured here. Each is assumed to be recursive
249 initially, and non recursive definitions are discovered by the dependency
254 -- | Groups together bindings for a single function
255 cvTopDecls :: OrdList (LHsDecl RdrName) -> [LHsDecl RdrName]
256 cvTopDecls decls = go (fromOL decls)
258 go :: [LHsDecl RdrName] -> [LHsDecl RdrName]
260 go (L l (ValD b) : ds) = L l' (ValD b') : go ds'
261 where (L l' b', ds') = getMonoBind (L l b) ds
262 go (d : ds) = d : go ds
264 -- Declaration list may only contain value bindings and signatures.
265 cvBindGroup :: OrdList (LHsDecl RdrName) -> HsValBinds RdrName
267 = case cvBindsAndSigs binding of
268 (mbs, sigs, tydecls, _) -> ASSERT( null tydecls )
271 cvBindsAndSigs :: OrdList (LHsDecl RdrName)
272 -> (Bag (LHsBind RdrName), [LSig RdrName], [LTyClDecl RdrName], [LDocDecl])
273 -- Input decls contain just value bindings and signatures
274 -- and in case of class or instance declarations also
275 -- associated type declarations. They might also contain Haddock comments.
276 cvBindsAndSigs fb = go (fromOL fb)
278 go [] = (emptyBag, [], [], [])
279 go (L l (SigD s) : ds) = (bs, L l s : ss, ts, docs)
280 where (bs, ss, ts, docs) = go ds
281 go (L l (ValD b) : ds) = (b' `consBag` bs, ss, ts, docs)
282 where (b', ds') = getMonoBind (L l b) ds
283 (bs, ss, ts, docs) = go ds'
284 go (L l (TyClD t): ds) = (bs, ss, L l t : ts, docs)
285 where (bs, ss, ts, docs) = go ds
286 go (L l (DocD d) : ds) = (bs, ss, ts, (L l d) : docs)
287 where (bs, ss, ts, docs) = go ds
288 go (L _ d : _) = pprPanic "cvBindsAndSigs" (ppr d)
290 -----------------------------------------------------------------------------
291 -- Group function bindings into equation groups
293 getMonoBind :: LHsBind RdrName -> [LHsDecl RdrName]
294 -> (LHsBind RdrName, [LHsDecl RdrName])
295 -- Suppose (b',ds') = getMonoBind b ds
296 -- ds is a list of parsed bindings
297 -- b is a MonoBinds that has just been read off the front
299 -- Then b' is the result of grouping more equations from ds that
300 -- belong with b into a single MonoBinds, and ds' is the depleted
301 -- list of parsed bindings.
303 -- All Haddock comments between equations inside the group are
306 -- No AndMonoBinds or EmptyMonoBinds here; just single equations
308 getMonoBind (L loc1 (FunBind { fun_id = fun_id1@(L _ f1), fun_infix = is_infix1,
309 fun_matches = MatchGroup mtchs1 _ })) binds
311 = go is_infix1 mtchs1 loc1 binds []
313 go is_infix mtchs loc
314 (L loc2 (ValD (FunBind { fun_id = L _ f2, fun_infix = is_infix2,
315 fun_matches = MatchGroup mtchs2 _ })) : binds) _
316 | f1 == f2 = go (is_infix || is_infix2) (mtchs2 ++ mtchs)
317 (combineSrcSpans loc loc2) binds []
318 go is_infix mtchs loc (doc_decl@(L loc2 (DocD _)) : binds) doc_decls
319 = let doc_decls' = doc_decl : doc_decls
320 in go is_infix mtchs (combineSrcSpans loc loc2) binds doc_decls'
321 go is_infix mtchs loc binds doc_decls
322 = (L loc (makeFunBind fun_id1 is_infix (reverse mtchs)), (reverse doc_decls) ++ binds)
323 -- Reverse the final matches, to get it back in the right order
324 -- Do the same thing with the trailing doc comments
326 getMonoBind bind binds = (bind, binds)
328 has_args :: [LMatch RdrName] -> Bool
329 has_args [] = panic "RdrHsSyn:has_args"
330 has_args ((L _ (Match args _ _)) : _) = not (null args)
331 -- Don't group together FunBinds if they have
332 -- no arguments. This is necessary now that variable bindings
333 -- with no arguments are now treated as FunBinds rather
334 -- than pattern bindings (tests/rename/should_fail/rnfail002).
337 %************************************************************************
339 \subsection[PrefixToHS-utils]{Utilities for conversion}
341 %************************************************************************
345 -----------------------------------------------------------------------------
348 -- When parsing data declarations, we sometimes inadvertently parse
349 -- a constructor application as a type (eg. in data T a b = C a b `D` E a b)
350 -- This function splits up the type application, adds any pending
351 -- arguments, and converts the type constructor back into a data constructor.
353 splitCon :: LHsType RdrName
354 -> P (Located RdrName, HsConDeclDetails RdrName)
355 -- This gets given a "type" that should look like
357 -- or C { x::Int, y::Bool }
358 -- and returns the pieces
362 split (L _ (HsAppTy t u)) ts = split t (u : ts)
363 split (L l (HsTyVar tc)) ts = do data_con <- tyConToDataCon l tc
364 return (data_con, mk_rest ts)
365 split (L l _) _ = parseErrorSDoc l (text "parse error in constructor in data/newtype declaration:" <+> ppr ty)
367 mk_rest [L _ (HsRecTy flds)] = RecCon flds
368 mk_rest ts = PrefixCon ts
370 mkDeprecatedGadtRecordDecl :: SrcSpan
372 -> [ConDeclField RdrName]
374 -> P (LConDecl RdrName)
375 -- This one uses the deprecated syntax
376 -- C { x,y ::Int } :: T a b
377 -- We give it a RecCon details right away
378 mkDeprecatedGadtRecordDecl loc (L con_loc con) flds res_ty
379 = do { data_con <- tyConToDataCon con_loc con
380 ; return (L loc (ConDecl { con_old_rec = True
381 , con_name = data_con
382 , con_explicit = Implicit
385 , con_details = RecCon flds
386 , con_res = ResTyGADT res_ty
387 , con_doc = Nothing })) }
389 mkSimpleConDecl :: Located RdrName -> [LHsTyVarBndr RdrName]
390 -> LHsContext RdrName -> HsConDeclDetails RdrName
393 mkSimpleConDecl name qvars cxt details
394 = ConDecl { con_old_rec = False
396 , con_explicit = Explicit
399 , con_details = details
401 , con_doc = Nothing }
403 mkGadtDecl :: [Located RdrName]
404 -> LHsType RdrName -- Always a HsForAllTy
406 -- We allow C,D :: ty
407 -- and expand it as if it had been
409 -- (Just like type signatures in general.)
410 mkGadtDecl names (L _ (HsForAllTy imp qvars cxt tau))
411 = [mk_gadt_con name | name <- names]
413 (details, res_ty) -- See Note [Sorting out the result type]
415 L _ (HsFunTy (L _ (HsRecTy flds)) res_ty) -> (RecCon flds, res_ty)
416 _other -> (PrefixCon [], tau)
419 = ConDecl { con_old_rec = False
424 , con_details = details
425 , con_res = ResTyGADT res_ty
426 , con_doc = Nothing }
427 mkGadtDecl _ other_ty = pprPanic "mkGadtDecl" (ppr other_ty)
429 tyConToDataCon :: SrcSpan -> RdrName -> P (Located RdrName)
430 tyConToDataCon loc tc
431 | isTcOcc (rdrNameOcc tc)
432 = return (L loc (setRdrNameSpace tc srcDataName))
434 = parseErrorSDoc loc (msg $$ extra)
436 msg = text "Not a data constructor:" <+> quotes (ppr tc)
437 extra | tc == forall_tv_RDR
438 = text "Perhaps you intended to use -XExistentialQuantification"
442 Note [Sorting out the result type]
443 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
444 In a GADT declaration which is not a record, we put the whole constr
445 type into the ResTyGADT for now; the renamer will unravel it once it
446 has sorted out operator fixities. Consider for example
447 C :: a :*: b -> a :*: b -> a :+: b
448 Initially this type will parse as
449 a :*: (b -> (a :*: (b -> (a :+: b))))
451 so it's hard to split up the arguments until we've done the precedence
452 resolution (in the renamer) On the other hand, for a record
453 { x,y :: Int } -> a :*: b
454 there is no doubt. AND we need to sort records out so that
455 we can bring x,y into scope. So:
456 * For PrefixCon we keep all the args in the ResTyGADT
457 * For RecCon we do not
460 ----------------------------------------------------------------------------
461 -- Various Syntactic Checks
463 checkInstType :: LHsType RdrName -> P (LHsType RdrName)
464 checkInstType (L l t)
466 HsForAllTy exp tvs ctxt ty -> do
467 dict_ty <- checkDictTy ty
468 return (L l (HsForAllTy exp tvs ctxt dict_ty))
470 HsParTy ty -> checkInstType ty
472 ty -> do dict_ty <- checkDictTy (L l ty)
473 return (L l (HsForAllTy Implicit [] (noLoc []) dict_ty))
475 checkDictTy :: LHsType RdrName -> P (LHsType RdrName)
476 checkDictTy (L spn ty) = check ty []
478 check (HsTyVar tc) args | isRdrTc tc = done tc args
479 check (HsOpTy t1 (L _ tc) t2) args | isRdrTc tc = done tc (t1:t2:args)
480 check (HsAppTy l r) args = check (unLoc l) (r:args)
481 check (HsParTy t) args = check (unLoc t) args
482 check _ _ = parseError spn "Malformed instance header"
484 done tc args = return (L spn (HsPredTy (HsClassP tc args)))
486 checkTParams :: Bool -- Type/data family
488 -> P ([LHsTyVarBndr RdrName], Maybe [LHsType RdrName])
489 -- checkTParams checks the type parameters of a data/newtype declaration
490 -- There are two cases:
492 -- a) Vanilla data/newtype decl. In that case
493 -- - the type parameters should all be type variables
494 -- - they may have a kind annotation
496 -- b) Family data/newtype decl. In that case
497 -- - The type parameters may be arbitrary types
498 -- - We find the type-varaible binders by find the
499 -- free type vars of those types
500 -- - We make them all kind-sig-free binders (UserTyVar)
501 -- If there are kind sigs in the type parameters, they
502 -- will fix the binder's kind when we kind-check the
504 checkTParams is_family tparams
505 | not is_family -- Vanilla case (a)
506 = do { tyvars <- checkTyVars tparams
507 ; return (tyvars, Nothing) }
508 | otherwise -- Family case (b)
509 = do { let tyvars = userHsTyVarBndrs (extractHsTysRdrTyVars tparams)
510 ; return (tyvars, Just tparams) }
512 checkTyVars :: [LHsType RdrName] -> P [LHsTyVarBndr RdrName]
513 -- Check whether the given list of type parameters are all type variables
514 -- (possibly with a kind signature). If the second argument is `False',
515 -- only type variables are allowed and we raise an error on encountering a
516 -- non-variable; otherwise, we allow non-variable arguments and return the
517 -- entire list of parameters.
518 checkTyVars tparms = mapM chk tparms
520 -- Check that the name space is correct!
521 chk (L l (HsKindSig (L _ (HsTyVar tv)) k))
522 | isRdrTyVar tv = return (L l (KindedTyVar tv k))
523 chk (L l (HsTyVar tv))
524 | isRdrTyVar tv = return (L l (UserTyVar tv placeHolderKind))
526 parseError l "Type found where type variable expected"
528 checkDatatypeContext :: Maybe (LHsContext RdrName) -> P ()
529 checkDatatypeContext Nothing = return ()
530 checkDatatypeContext (Just (L loc _))
531 = do allowed <- extension datatypeContextsEnabled
533 parseError loc "Illegal datatype context (use -XDatatypeContexts)"
535 checkTyClHdr :: LHsType RdrName
536 -> P (Located RdrName, -- the head symbol (type or class name)
537 [LHsType RdrName]) -- parameters of head symbol
538 -- Well-formedness check and decomposition of type and class heads.
539 -- Decomposes T ty1 .. tyn into (T, [ty1, ..., tyn])
540 -- Int :*: Bool into (:*:, [Int, Bool])
541 -- returning the pieces
545 goL (L l ty) acc = go l ty acc
547 go l (HsTyVar tc) acc
548 | isRdrTc tc = return (L l tc, acc)
550 go _ (HsOpTy t1 ltc@(L _ tc) t2) acc
551 | isRdrTc tc = return (ltc, t1:t2:acc)
552 go _ (HsParTy ty) acc = goL ty acc
553 go _ (HsAppTy t1 t2) acc = goL t1 (t2:acc)
554 go l _ _ = parseError l "Malformed head of type or class declaration"
556 -- Check that associated type declarations of a class are all kind signatures.
558 checkKindSigs :: [LTyClDecl RdrName] -> P ()
559 checkKindSigs = mapM_ check
562 | isFamilyDecl tydecl
563 || isSynDecl tydecl = return ()
565 parseError l "Type declaration in a class must be a kind signature or synonym default"
567 checkContext :: LHsType RdrName -> P (LHsContext RdrName)
571 check (HsTupleTy _ ts) -- (Eq a, Ord b) shows up as a tuple type
572 = do ctx <- mapM checkPred ts
575 check (HsParTy ty) -- to be sure HsParTy doesn't get into the way
578 check (HsTyVar t) -- Empty context shows up as a unit type ()
579 | t == getRdrName unitTyCon = return (L l [])
582 = do p <- checkPred (L l t)
586 checkPred :: LHsType RdrName -> P (LHsPred RdrName)
587 -- Watch out.. in ...deriving( Show )... we use checkPred on
588 -- the list of partially applied predicates in the deriving,
589 -- so there can be zero args.
590 checkPred (L spn (HsPredTy (HsIParam n ty)))
591 = return (L spn (HsIParam n ty))
595 checkl (L l ty) args = check l ty args
597 check _loc (HsPredTy pred@(HsEqualP _ _))
599 = return $ L spn pred
600 check _loc (HsTyVar t) args | not (isRdrTyVar t)
601 = return (L spn (HsClassP t args))
602 check _loc (HsAppTy l r) args = checkl l (r:args)
603 check _loc (HsOpTy l (L loc tc) r) args = check loc (HsTyVar tc) (l:r:args)
604 check _loc (HsParTy t) args = checkl t args
605 check loc _ _ = parseError loc
606 "malformed class assertion"
608 ---------------------------------------------------------------------------
609 -- Checking statements in a do-expression
610 -- We parse do { e1 ; e2 ; }
611 -- as [ExprStmt e1, ExprStmt e2]
612 -- checkDo (a) checks that the last thing is an ExprStmt
613 -- (b) returns it separately
614 -- same comments apply for mdo as well
616 checkDo, checkMDo :: SrcSpan -> [LStmt RdrName] -> P ([LStmt RdrName], LHsExpr RdrName)
618 checkDo = checkDoMDo "a " "'do'"
619 checkMDo = checkDoMDo "an " "'mdo'"
621 checkDoMDo :: String -> String -> SrcSpan -> [LStmt RdrName] -> P ([LStmt RdrName], LHsExpr RdrName)
622 checkDoMDo _ nm loc [] = parseError loc ("Empty " ++ nm ++ " construct")
623 checkDoMDo pre nm _ ss = do
626 check [] = panic "RdrHsSyn:checkDoMDo"
627 check [L _ (ExprStmt e _ _)] = return ([], e)
628 check [L l _] = parseError l ("The last statement in " ++ pre ++ nm ++
629 " construct must be an expression")
634 -- -------------------------------------------------------------------------
635 -- Checking Patterns.
637 -- We parse patterns as expressions and check for valid patterns below,
638 -- converting the expression into a pattern at the same time.
640 checkPattern :: LHsExpr RdrName -> P (LPat RdrName)
641 checkPattern e = checkLPat e
643 checkPatterns :: [LHsExpr RdrName] -> P [LPat RdrName]
644 checkPatterns es = mapM checkPattern es
646 checkLPat :: LHsExpr RdrName -> P (LPat RdrName)
647 checkLPat e@(L l _) = checkPat l e []
649 checkPat :: SrcSpan -> LHsExpr RdrName -> [LPat RdrName] -> P (LPat RdrName)
650 checkPat loc (L l (HsVar c)) args
651 | isRdrDataCon c = return (L loc (ConPatIn (L l c) (PrefixCon args)))
652 checkPat loc e args -- OK to let this happen even if bang-patterns
653 -- are not enabled, because there is no valid
654 -- non-bang-pattern parse of (C ! e)
655 | Just (e', args') <- splitBang e
656 = do { args'' <- checkPatterns args'
657 ; checkPat loc e' (args'' ++ args) }
658 checkPat loc (L _ (HsApp f x)) args
659 = do { x <- checkLPat x; checkPat loc f (x:args) }
660 checkPat loc (L _ e) []
661 = do { pState <- getPState
662 ; p <- checkAPat (dflags pState) loc e
667 checkAPat :: DynFlags -> SrcSpan -> HsExpr RdrName -> P (Pat RdrName)
668 checkAPat dynflags loc e = case e of
669 EWildPat -> return (WildPat placeHolderType)
670 HsVar x -> return (VarPat x)
671 HsLit l -> return (LitPat l)
673 -- Overloaded numeric patterns (e.g. f 0 x = x)
674 -- Negation is recorded separately, so that the literal is zero or +ve
675 -- NB. Negative *primitive* literals are already handled by the lexer
676 HsOverLit pos_lit -> return (mkNPat pos_lit Nothing)
677 NegApp (L _ (HsOverLit pos_lit)) _
678 -> return (mkNPat pos_lit (Just noSyntaxExpr))
680 SectionR (L _ (HsVar bang)) e -- (! x)
682 -> do { bang_on <- extension bangPatEnabled
683 ; if bang_on then checkLPat e >>= (return . BangPat)
684 else parseError loc "Illegal bang-pattern (use -XBangPatterns)" }
686 ELazyPat e -> checkLPat e >>= (return . LazyPat)
687 EAsPat n e -> checkLPat e >>= (return . AsPat n)
688 -- view pattern is well-formed if the pattern is
689 EViewPat expr patE -> checkLPat patE >>= (return . (\p -> ViewPat expr p placeHolderType))
690 ExprWithTySig e t -> do e <- checkLPat e
691 -- Pattern signatures are parsed as sigtypes,
692 -- but they aren't explicit forall points. Hence
693 -- we have to remove the implicit forall here.
695 L _ (HsForAllTy Implicit _ (L _ []) ty) -> ty
697 return (SigPatIn e t')
700 OpApp (L nloc (HsVar n)) (L _ (HsVar plus)) _
701 (L _ (HsOverLit lit@(OverLit {ol_val = HsIntegral {}})))
702 | dopt Opt_NPlusKPatterns dynflags && (plus == plus_RDR)
703 -> return (mkNPlusKPat (L nloc n) lit)
705 OpApp l op _fix r -> do l <- checkLPat l
708 L cl (HsVar c) | isDataOcc (rdrNameOcc c)
709 -> return (ConPatIn (L cl c) (InfixCon l r))
712 HsPar e -> checkLPat e >>= (return . ParPat)
713 ExplicitList _ es -> do ps <- mapM checkLPat es
714 return (ListPat ps placeHolderType)
715 ExplicitPArr _ es -> do ps <- mapM checkLPat es
716 return (PArrPat ps placeHolderType)
719 | all tupArgPresent es -> do ps <- mapM checkLPat [e | Present e <- es]
720 return (TuplePat ps b placeHolderType)
721 | otherwise -> parseError loc "Illegal tuple section in pattern"
723 RecordCon c _ (HsRecFields fs dd)
724 -> do fs <- mapM checkPatField fs
725 return (ConPatIn c (RecCon (HsRecFields fs dd)))
726 HsQuasiQuoteE q -> return (QuasiQuotePat q)
728 HsType ty -> return (TypePat ty)
731 placeHolderPunRhs :: LHsExpr RdrName
732 -- The RHS of a punned record field will be filled in by the renamer
733 -- It's better not to make it an error, in case we want to print it when debugging
734 placeHolderPunRhs = noLoc (HsVar pun_RDR)
736 plus_RDR, bang_RDR, pun_RDR :: RdrName
737 plus_RDR = mkUnqual varName (fsLit "+") -- Hack
738 bang_RDR = mkUnqual varName (fsLit "!") -- Hack
739 pun_RDR = mkUnqual varName (fsLit "pun-right-hand-side")
741 checkPatField :: HsRecField RdrName (LHsExpr RdrName) -> P (HsRecField RdrName (LPat RdrName))
742 checkPatField fld = do { p <- checkLPat (hsRecFieldArg fld)
743 ; return (fld { hsRecFieldArg = p }) }
745 patFail :: SrcSpan -> P a
746 patFail loc = parseError loc "Parse error in pattern"
749 ---------------------------------------------------------------------------
750 -- Check Equation Syntax
752 checkValDef :: LHsExpr RdrName
753 -> Maybe (LHsType RdrName)
754 -> Located (GRHSs RdrName)
755 -> P (HsBind RdrName)
757 checkValDef lhs (Just sig) grhss
758 -- x :: ty = rhs parses as a *pattern* binding
759 = checkPatBind (L (combineLocs lhs sig) (ExprWithTySig lhs sig)) grhss
761 checkValDef lhs opt_sig grhss
762 = do { mb_fun <- isFunLhs lhs
764 Just (fun, is_infix, pats) -> checkFunBind (getLoc lhs)
765 fun is_infix pats opt_sig grhss
766 Nothing -> checkPatBind lhs grhss }
768 checkFunBind :: SrcSpan
772 -> Maybe (LHsType RdrName)
773 -> Located (GRHSs RdrName)
774 -> P (HsBind RdrName)
775 checkFunBind lhs_loc fun is_infix pats opt_sig (L rhs_span grhss)
776 = do ps <- checkPatterns pats
777 let match_span = combineSrcSpans lhs_loc rhs_span
778 return (makeFunBind fun is_infix [L match_span (Match ps opt_sig grhss)])
779 -- The span of the match covers the entire equation.
780 -- That isn't quite right, but it'll do for now.
782 makeFunBind :: Located id -> Bool -> [LMatch id] -> HsBind id
783 -- Like HsUtils.mkFunBind, but we need to be able to set the fixity too
784 makeFunBind fn is_infix ms
785 = FunBind { fun_id = fn, fun_infix = is_infix, fun_matches = mkMatchGroup ms,
786 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames, fun_tick = Nothing }
788 checkPatBind :: LHsExpr RdrName
789 -> Located (GRHSs RdrName)
790 -> P (HsBind RdrName)
791 checkPatBind lhs (L _ grhss)
792 = do { lhs <- checkPattern lhs
793 ; return (PatBind lhs grhss placeHolderType placeHolderNames) }
799 checkValSig (L l (HsVar v)) ty
800 | isUnqual v && not (isDataOcc (rdrNameOcc v))
801 = return (TypeSig (L l v) ty)
802 checkValSig lhs@(L l _) ty
803 = parseErrorSDoc l ((text "Invalid type signature:" <+>
804 ppr lhs <+> text "::" <+> ppr ty)
807 hint = if looks_like_foreign lhs
808 then "Perhaps you meant to use -XForeignFunctionInterface?"
809 else "Should be of form <variable> :: <type>"
810 -- A common error is to forget the ForeignFunctionInterface flag
811 -- so check for that, and suggest. cf Trac #3805
812 -- Sadly 'foreign import' still barfs 'parse error' because 'import' is a keyword
813 looks_like_foreign (L _ (HsVar v)) = v == foreign_RDR
814 looks_like_foreign (L _ (HsApp lhs _)) = looks_like_foreign lhs
815 looks_like_foreign _ = False
817 foreign_RDR = mkUnqual varName (fsLit "foreign")
822 -- The parser left-associates, so there should
823 -- not be any OpApps inside the e's
824 splitBang :: LHsExpr RdrName -> Maybe (LHsExpr RdrName, [LHsExpr RdrName])
825 -- Splits (f ! g a b) into (f, [(! g), a, b])
826 splitBang (L loc (OpApp l_arg bang@(L _ (HsVar op)) _ r_arg))
827 | op == bang_RDR = Just (l_arg, L loc (SectionR bang arg1) : argns)
829 (arg1,argns) = split_bang r_arg []
830 split_bang (L _ (HsApp f e)) es = split_bang f (e:es)
831 split_bang e es = (e,es)
832 splitBang _ = Nothing
834 isFunLhs :: LHsExpr RdrName
835 -> P (Maybe (Located RdrName, Bool, [LHsExpr RdrName]))
836 -- A variable binding is parsed as a FunBind.
837 -- Just (fun, is_infix, arg_pats) if e is a function LHS
839 -- The whole LHS is parsed as a single expression.
840 -- Any infix operators on the LHS will parse left-associatively
842 -- will parse (rather strangely) as
844 -- It's up to isFunLhs to sort out the mess
850 go (L loc (HsVar f)) es
851 | not (isRdrDataCon f) = return (Just (L loc f, False, es))
852 go (L _ (HsApp f e)) es = go f (e:es)
853 go (L _ (HsPar e)) es@(_:_) = go e es
855 -- For infix function defns, there should be only one infix *function*
856 -- (though there may be infix *datacons* involved too). So we don't
857 -- need fixity info to figure out which function is being defined.
858 -- a `K1` b `op` c `K2` d
860 -- (a `K1` b) `op` (c `K2` d)
861 -- The renamer checks later that the precedences would yield such a parse.
863 -- There is a complication to deal with bang patterns.
865 -- ToDo: what about this?
866 -- x + 1 `op` y = ...
868 go e@(L loc (OpApp l (L loc' (HsVar op)) fix r)) es
869 | Just (e',es') <- splitBang e
870 = do { bang_on <- extension bangPatEnabled
871 ; if bang_on then go e' (es' ++ es)
872 else return (Just (L loc' op, True, (l:r:es))) }
873 -- No bangs; behave just like the next case
874 | not (isRdrDataCon op) -- We have found the function!
875 = return (Just (L loc' op, True, (l:r:es)))
876 | otherwise -- Infix data con; keep going
877 = do { mb_l <- go l es
879 Just (op', True, j : k : es')
880 -> return (Just (op', True, j : op_app : es'))
882 op_app = L loc (OpApp k (L loc' (HsVar op)) fix r)
883 _ -> return Nothing }
884 go _ _ = return Nothing
886 ---------------------------------------------------------------------------
887 -- Miscellaneous utilities
889 checkPrecP :: Located Int -> P Int
891 | 0 <= i && i <= maxPrecedence = return i
892 | otherwise = parseError l "Precedence out of range"
897 -> ([HsRecField RdrName (LHsExpr RdrName)], Bool)
898 -> P (HsExpr RdrName)
900 mkRecConstrOrUpdate (L l (HsVar c)) _ (fs,dd) | isRdrDataCon c
901 = return (RecordCon (L l c) noPostTcExpr (mk_rec_fields fs dd))
902 mkRecConstrOrUpdate exp loc (fs,dd)
903 | null fs = parseError loc "Empty record update"
904 | otherwise = return (RecordUpd exp (mk_rec_fields fs dd) [] [] [])
906 mk_rec_fields :: [HsRecField id arg] -> Bool -> HsRecFields id arg
907 mk_rec_fields fs False = HsRecFields { rec_flds = fs, rec_dotdot = Nothing }
908 mk_rec_fields fs True = HsRecFields { rec_flds = fs, rec_dotdot = Just (length fs) }
910 mkInlinePragma :: Maybe Activation -> RuleMatchInfo -> Bool -> InlinePragma
911 -- The Maybe is because the user can omit the activation spec (and usually does)
912 mkInlinePragma mb_act match_info inl
913 = InlinePragma { inl_inline = inl
916 , inl_rule = match_info }
920 Nothing | inl -> AlwaysActive
921 | otherwise -> NeverActive
922 -- If no specific phase is given then:
923 -- NOINLINE => NeverActive
926 -----------------------------------------------------------------------------
927 -- utilities for foreign declarations
929 -- construct a foreign import declaration
931 mkImport :: CCallConv
933 -> (Located FastString, Located RdrName, LHsType RdrName)
934 -> P (HsDecl RdrName)
935 mkImport cconv safety (L loc entity, v, ty)
936 | cconv == PrimCallConv = do
937 let funcTarget = CFunction (StaticTarget entity Nothing)
938 importSpec = CImport PrimCallConv safety nilFS funcTarget
939 return (ForD (ForeignImport v ty importSpec))
942 case parseCImport cconv safety (mkExtName (unLoc v)) (unpackFS entity) of
943 Nothing -> parseError loc "Malformed entity string"
944 Just importSpec -> return (ForD (ForeignImport v ty importSpec))
946 -- the string "foo" is ambigous: either a header or a C identifier. The
947 -- C identifier case comes first in the alternatives below, so we pick
949 parseCImport :: CCallConv -> Safety -> FastString -> String
950 -> Maybe ForeignImport
951 parseCImport cconv safety nm str =
952 listToMaybe $ map fst $ filter (null.snd) $
958 string "dynamic" >> return (mk nilFS (CFunction DynamicTarget)),
959 string "wrapper" >> return (mk nilFS CWrapper),
960 optional (string "static" >> skipSpaces) >>
961 (mk nilFS <$> cimp nm) +++
962 (do h <- munch1 hdr_char; skipSpaces; mk (mkFastString h) <$> cimp nm)
967 mk = CImport cconv safety
969 hdr_char c = not (isSpace c) -- header files are filenames, which can contain
970 -- pretty much any char (depending on the platform),
971 -- so just accept any non-space character
972 id_char c = isAlphaNum c || c == '_'
974 cimp nm = (ReadP.char '&' >> skipSpaces >> CLabel <$> cid)
975 +++ ((\c -> CFunction (StaticTarget c Nothing)) <$> cid)
978 (do c <- satisfy (\c -> isAlpha c || c == '_')
979 cs <- many (satisfy id_char)
980 return (mkFastString (c:cs)))
983 -- construct a foreign export declaration
985 mkExport :: CCallConv
986 -> (Located FastString, Located RdrName, LHsType RdrName)
987 -> P (HsDecl RdrName)
988 mkExport cconv (L _ entity, v, ty) = return $
989 ForD (ForeignExport v ty (CExport (CExportStatic entity' cconv)))
991 entity' | nullFS entity = mkExtName (unLoc v)
994 -- Supplying the ext_name in a foreign decl is optional; if it
995 -- isn't there, the Haskell name is assumed. Note that no transformation
996 -- of the Haskell name is then performed, so if you foreign export (++),
997 -- it's external name will be "++". Too bad; it's important because we don't
998 -- want z-encoding (e.g. names with z's in them shouldn't be doubled)
1000 mkExtName :: RdrName -> CLabelString
1001 mkExtName rdrNm = mkFastString (occNameString (rdrNameOcc rdrNm))
1005 -----------------------------------------------------------------------------
1009 parseError :: SrcSpan -> String -> P a
1010 parseError span s = parseErrorSDoc span (text s)
1012 parseErrorSDoc :: SrcSpan -> SDoc -> P a
1013 parseErrorSDoc span s = failSpanMsgP span s