2 % (c) The University of Glasgow 2006
3 % (c) The AQUA Project, Glasgow University, 1996-1998
6 TcHsSyn: Specialisations of the @HsSyn@ syntax for the typechecker
8 This module is an extension of @HsSyn@ syntax, for use in the type
13 mkHsConApp, mkHsDictLet, mkHsApp,
14 hsLitType, hsLPatType, hsPatType,
15 mkHsAppTy, mkSimpleHsAlt,
16 nlHsIntLit, mkVanillaTuplePat,
17 shortCutLit, hsOverLitName,
19 mkArbitraryType, -- Put this elsewhere?
21 -- re-exported from TcMonad
22 TcId, TcIdSet, TcDictBinds,
24 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
28 #include "HsVersions.h"
31 import HsSyn -- oodles of it
61 thenM :: Monad a => a b -> (b -> a c) -> a c
64 thenM_ :: Monad a => a b -> a c -> a c
67 returnM :: Monad m => a -> m a
70 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
75 %************************************************************************
77 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
79 %************************************************************************
81 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
82 then something is wrong.
84 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
85 -- A vanilla tuple pattern simply gets its type from its sub-patterns
86 mkVanillaTuplePat pats box
87 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
89 hsLPatType :: OutPat Id -> Type
90 hsLPatType (L _ pat) = hsPatType pat
92 hsPatType :: Pat Id -> Type
93 hsPatType (ParPat pat) = hsLPatType pat
94 hsPatType (WildPat ty) = ty
95 hsPatType (VarPat var) = idType var
96 hsPatType (VarPatOut var _) = idType var
97 hsPatType (BangPat pat) = hsLPatType pat
98 hsPatType (LazyPat pat) = hsLPatType pat
99 hsPatType (LitPat lit) = hsLitType lit
100 hsPatType (AsPat var _) = idType (unLoc var)
101 hsPatType (ViewPat _ _ ty) = ty
102 hsPatType (ListPat _ ty) = mkListTy ty
103 hsPatType (PArrPat _ ty) = mkPArrTy ty
104 hsPatType (TuplePat _ _ ty) = ty
105 hsPatType (ConPatOut { pat_ty = ty }) = ty
106 hsPatType (SigPatOut _ ty) = ty
107 hsPatType (NPat lit _ _) = overLitType lit
108 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
109 hsPatType (CoPat _ _ ty) = ty
110 hsPatType p = pprPanic "hsPatType" (ppr p)
112 hsLitType :: HsLit -> TcType
113 hsLitType (HsChar _) = charTy
114 hsLitType (HsCharPrim _) = charPrimTy
115 hsLitType (HsString _) = stringTy
116 hsLitType (HsStringPrim _) = addrPrimTy
117 hsLitType (HsInt _) = intTy
118 hsLitType (HsIntPrim _) = intPrimTy
119 hsLitType (HsWordPrim _) = wordPrimTy
120 hsLitType (HsInteger _ ty) = ty
121 hsLitType (HsRat _ ty) = ty
122 hsLitType (HsFloatPrim _) = floatPrimTy
123 hsLitType (HsDoublePrim _) = doublePrimTy
126 Overloaded literals. Here mainly becuase it uses isIntTy etc
129 shortCutLit :: OverLitVal -> TcType -> Maybe (HsExpr TcId)
130 shortCutLit (HsIntegral i) ty
131 | isIntTy ty && inIntRange i = Just (HsLit (HsInt i))
132 | isWordTy ty && inWordRange i = Just (mkLit wordDataCon (HsWordPrim i))
133 | isIntegerTy ty = Just (HsLit (HsInteger i ty))
134 | otherwise = shortCutLit (HsFractional (fromInteger i)) ty
135 -- The 'otherwise' case is important
136 -- Consider (3 :: Float). Syntactically it looks like an IntLit,
137 -- so we'll call shortCutIntLit, but of course it's a float
138 -- This can make a big difference for programs with a lot of
139 -- literals, compiled without -O
141 shortCutLit (HsFractional f) ty
142 | isFloatTy ty = Just (mkLit floatDataCon (HsFloatPrim f))
143 | isDoubleTy ty = Just (mkLit doubleDataCon (HsDoublePrim f))
144 | otherwise = Nothing
146 shortCutLit (HsIsString s) ty
147 | isStringTy ty = Just (HsLit (HsString s))
148 | otherwise = Nothing
150 mkLit :: DataCon -> HsLit -> HsExpr Id
151 mkLit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit)
153 ------------------------------
154 hsOverLitName :: OverLitVal -> Name
155 -- Get the canonical 'fromX' name for a particular OverLitVal
156 hsOverLitName (HsIntegral {}) = fromIntegerName
157 hsOverLitName (HsFractional {}) = fromRationalName
158 hsOverLitName (HsIsString {}) = fromStringName
161 %************************************************************************
163 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
165 %************************************************************************
168 -- zonkId is used *during* typechecking just to zonk the Id's type
169 zonkId :: TcId -> TcM TcId
171 = zonkTcType (idType id) `thenM` \ ty' ->
172 returnM (Id.setIdType id ty')
175 The rest of the zonking is done *after* typechecking.
176 The main zonking pass runs over the bindings
178 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
179 b) convert unbound TcTyVar to Void
180 c) convert each TcId to an Id by zonking its type
182 The type variables are converted by binding mutable tyvars to immutable ones
183 and then zonking as normal.
185 The Ids are converted by binding them in the normal Tc envt; that
186 way we maintain sharing; eg an Id is zonked at its binding site and they
187 all occurrences of that Id point to the common zonked copy
189 It's all pretty boring stuff, because HsSyn is such a large type, and
190 the environment manipulation is tiresome.
193 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
194 (IdEnv Id) -- What variables are in scope
195 -- Maps an Id to its zonked version; both have the same Name
196 -- Is only consulted lazily; hence knot-tying
198 emptyZonkEnv :: ZonkEnv
199 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
201 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
202 extendZonkEnv (ZonkEnv zonk_ty env) ids
203 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
205 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
206 extendZonkEnv1 (ZonkEnv zonk_ty env) id
207 = ZonkEnv zonk_ty (extendVarEnv env id id)
209 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
210 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
212 zonkEnvIds :: ZonkEnv -> [Id]
213 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
215 zonkIdOcc :: ZonkEnv -> TcId -> Id
216 -- Ids defined in this module should be in the envt;
217 -- ignore others. (Actually, data constructors are also
218 -- not LocalVars, even when locally defined, but that is fine.)
219 -- (Also foreign-imported things aren't currently in the ZonkEnv;
220 -- that's ok because they don't need zonking.)
222 -- Actually, Template Haskell works in 'chunks' of declarations, and
223 -- an earlier chunk won't be in the 'env' that the zonking phase
224 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
225 -- zonked. There's no point in looking it up there (except for error
226 -- checking), and it's not conveniently to hand; hence the simple
227 -- 'orElse' case in the LocalVar branch.
229 -- Even without template splices, in module Main, the checking of
230 -- 'main' is done as a separate chunk.
231 zonkIdOcc (ZonkEnv _zonk_ty env) id
232 | isLocalVar id = lookupVarEnv env id `orElse` id
235 zonkIdOccs :: ZonkEnv -> [TcId] -> [Id]
236 zonkIdOccs env ids = map (zonkIdOcc env) ids
238 -- zonkIdBndr is used *after* typechecking to get the Id's type
239 -- to its final form. The TyVarEnv give
240 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
242 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
243 returnM (Id.setIdType id ty')
245 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
246 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
248 zonkDictBndrs :: ZonkEnv -> [Var] -> TcM [Var]
249 -- "Dictionary" binders can be coercion variables or dictionary variables
250 zonkDictBndrs env ids = mappM (zonkDictBndr env) ids
252 zonkDictBndr :: ZonkEnv -> Var -> TcM Var
253 zonkDictBndr env var | isTyVar var = zonkTyVarBndr env var
254 | otherwise = zonkIdBndr env var
256 zonkTopBndrs :: [TcId] -> TcM [Id]
257 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
259 -- Zonk the kind of a non-TC tyvar in case it is a coercion variable (their
260 -- kind contains types).
262 zonkTyVarBndr :: ZonkEnv -> TyVar -> TcM TyVar
265 = do { kind <- zonkTcTypeToType env (tyVarKind tv)
266 ; return $ setTyVarKind tv kind
268 | otherwise = return tv
273 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
274 zonkTopExpr e = zonkExpr emptyZonkEnv e
276 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
277 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
279 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
284 zonkTopDecls binds rules fords
285 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
286 -- Top level is implicitly recursive
287 ; rules' <- zonkRules env rules
288 ; fords' <- zonkForeignExports env fords
289 ; return (zonkEnvIds env, binds', fords', rules') }
291 ---------------------------------------------
292 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
293 zonkLocalBinds env EmptyLocalBinds
294 = return (env, EmptyLocalBinds)
296 zonkLocalBinds env (HsValBinds binds)
297 = do { (env1, new_binds) <- zonkValBinds env binds
298 ; return (env1, HsValBinds new_binds) }
300 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
301 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
303 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
305 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
306 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
308 zonk_ip_bind (IPBind n e)
309 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
310 zonkLExpr env e `thenM` \ e' ->
311 returnM (IPBind n' e')
314 ---------------------------------------------
315 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
316 zonkValBinds _ (ValBindsIn _ _)
317 = panic "zonkValBinds" -- Not in typechecker output
318 zonkValBinds env (ValBindsOut binds sigs)
319 = do { (env1, new_binds) <- go env binds
320 ; return (env1, ValBindsOut new_binds sigs) }
322 go env [] = return (env, [])
323 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
324 ; (env2, bs') <- go env1 bs
325 ; return (env2, (r,b'):bs') }
327 ---------------------------------------------
328 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
329 zonkRecMonoBinds env binds
330 = fixM (\ ~(_, new_binds) -> do
331 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
332 ; binds' <- zonkMonoBinds env1 binds
333 ; return (env1, binds') })
335 ---------------------------------------------
336 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
337 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
339 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
340 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
341 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
342 ; new_grhss <- zonkGRHSs env grhss
343 ; new_ty <- zonkTcTypeToType env ty
344 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
346 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
347 = zonkIdBndr env var `thenM` \ new_var ->
348 zonkLExpr env expr `thenM` \ new_expr ->
349 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
351 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
352 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
353 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
354 zonkMatchGroup env1 ms `thenM` \ new_ms ->
355 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
357 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
358 abs_exports = exports, abs_binds = val_binds })
359 = ASSERT( all isImmutableTyVar tyvars )
360 zonkDictBndrs env dicts `thenM` \ new_dicts ->
361 fixM (\ ~(new_val_binds, _) ->
363 env1 = extendZonkEnv env new_dicts
364 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
366 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
367 mappM (zonkExport env2) exports `thenM` \ new_exports ->
368 returnM (new_val_binds, new_exports)
369 ) `thenM` \ (new_val_bind, new_exports) ->
370 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
371 abs_exports = new_exports, abs_binds = new_val_bind })
373 zonkExport env (tyvars, global, local, prags)
374 -- The tyvars are already zonked
375 = zonkIdBndr env global `thenM` \ new_global ->
376 mapM zonk_prag prags `thenM` \ new_prags ->
377 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
378 zonk_prag prag@(L _ (InlinePrag {})) = return prag
379 zonk_prag (L loc (SpecPrag expr ty inl))
380 = do { expr' <- zonkExpr env expr
381 ; ty' <- zonkTcTypeToType env ty
382 ; return (L loc (SpecPrag expr' ty' inl)) }
385 %************************************************************************
387 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
389 %************************************************************************
392 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
393 zonkMatchGroup env (MatchGroup ms ty)
394 = do { ms' <- mapM (zonkMatch env) ms
395 ; ty' <- zonkTcTypeToType env ty
396 ; return (MatchGroup ms' ty') }
398 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
399 zonkMatch env (L loc (Match pats _ grhss))
400 = do { (env1, new_pats) <- zonkPats env pats
401 ; new_grhss <- zonkGRHSs env1 grhss
402 ; return (L loc (Match new_pats Nothing new_grhss)) }
404 -------------------------------------------------------------------------
405 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
407 zonkGRHSs env (GRHSs grhss binds)
408 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
410 zonk_grhs (GRHS guarded rhs)
411 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
412 zonkLExpr env2 rhs `thenM` \ new_rhs ->
413 returnM (GRHS new_guarded new_rhs)
415 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
416 returnM (GRHSs new_grhss new_binds)
419 %************************************************************************
421 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
423 %************************************************************************
426 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
427 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
428 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
430 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
431 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
433 zonkExpr env (HsVar id)
434 = returnM (HsVar (zonkIdOcc env id))
436 zonkExpr env (HsIPVar id)
437 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
439 zonkExpr env (HsLit (HsRat f ty))
440 = zonkTcTypeToType env ty `thenM` \ new_ty ->
441 returnM (HsLit (HsRat f new_ty))
443 zonkExpr _ (HsLit lit)
444 = returnM (HsLit lit)
446 zonkExpr env (HsOverLit lit)
447 = do { lit' <- zonkOverLit env lit
448 ; return (HsOverLit lit') }
450 zonkExpr env (HsLam matches)
451 = zonkMatchGroup env matches `thenM` \ new_matches ->
452 returnM (HsLam new_matches)
454 zonkExpr env (HsApp e1 e2)
455 = zonkLExpr env e1 `thenM` \ new_e1 ->
456 zonkLExpr env e2 `thenM` \ new_e2 ->
457 returnM (HsApp new_e1 new_e2)
459 zonkExpr env (HsBracketOut body bs)
460 = mappM zonk_b bs `thenM` \ bs' ->
461 returnM (HsBracketOut body bs')
463 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
466 zonkExpr _ (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
467 returnM (HsSpliceE s)
469 zonkExpr env (OpApp e1 op fixity e2)
470 = zonkLExpr env e1 `thenM` \ new_e1 ->
471 zonkLExpr env op `thenM` \ new_op ->
472 zonkLExpr env e2 `thenM` \ new_e2 ->
473 returnM (OpApp new_e1 new_op fixity new_e2)
475 zonkExpr env (NegApp expr op)
476 = zonkLExpr env expr `thenM` \ new_expr ->
477 zonkExpr env op `thenM` \ new_op ->
478 returnM (NegApp new_expr new_op)
480 zonkExpr env (HsPar e)
481 = zonkLExpr env e `thenM` \new_e ->
482 returnM (HsPar new_e)
484 zonkExpr env (SectionL expr op)
485 = zonkLExpr env expr `thenM` \ new_expr ->
486 zonkLExpr env op `thenM` \ new_op ->
487 returnM (SectionL new_expr new_op)
489 zonkExpr env (SectionR op expr)
490 = zonkLExpr env op `thenM` \ new_op ->
491 zonkLExpr env expr `thenM` \ new_expr ->
492 returnM (SectionR new_op new_expr)
494 zonkExpr env (HsCase expr ms)
495 = zonkLExpr env expr `thenM` \ new_expr ->
496 zonkMatchGroup env ms `thenM` \ new_ms ->
497 returnM (HsCase new_expr new_ms)
499 zonkExpr env (HsIf e1 e2 e3)
500 = zonkLExpr env e1 `thenM` \ new_e1 ->
501 zonkLExpr env e2 `thenM` \ new_e2 ->
502 zonkLExpr env e3 `thenM` \ new_e3 ->
503 returnM (HsIf new_e1 new_e2 new_e3)
505 zonkExpr env (HsLet binds expr)
506 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
507 zonkLExpr new_env expr `thenM` \ new_expr ->
508 returnM (HsLet new_binds new_expr)
510 zonkExpr env (HsDo do_or_lc stmts body ty)
511 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
512 zonkLExpr new_env body `thenM` \ new_body ->
513 zonkTcTypeToType env ty `thenM` \ new_ty ->
514 returnM (HsDo (zonkDo env do_or_lc)
515 new_stmts new_body new_ty)
517 zonkExpr env (ExplicitList ty exprs)
518 = zonkTcTypeToType env ty `thenM` \ new_ty ->
519 zonkLExprs env exprs `thenM` \ new_exprs ->
520 returnM (ExplicitList new_ty new_exprs)
522 zonkExpr env (ExplicitPArr ty exprs)
523 = zonkTcTypeToType env ty `thenM` \ new_ty ->
524 zonkLExprs env exprs `thenM` \ new_exprs ->
525 returnM (ExplicitPArr new_ty new_exprs)
527 zonkExpr env (ExplicitTuple exprs boxed)
528 = zonkLExprs env exprs `thenM` \ new_exprs ->
529 returnM (ExplicitTuple new_exprs boxed)
531 zonkExpr env (RecordCon data_con con_expr rbinds)
532 = do { new_con_expr <- zonkExpr env con_expr
533 ; new_rbinds <- zonkRecFields env rbinds
534 ; return (RecordCon data_con new_con_expr new_rbinds) }
536 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
537 = do { new_expr <- zonkLExpr env expr
538 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
539 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
540 ; new_rbinds <- zonkRecFields env rbinds
541 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
543 zonkExpr env (ExprWithTySigOut e ty)
544 = do { e' <- zonkLExpr env e
545 ; return (ExprWithTySigOut e' ty) }
547 zonkExpr _ (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
549 zonkExpr env (ArithSeq expr info)
550 = zonkExpr env expr `thenM` \ new_expr ->
551 zonkArithSeq env info `thenM` \ new_info ->
552 returnM (ArithSeq new_expr new_info)
554 zonkExpr env (PArrSeq expr info)
555 = zonkExpr env expr `thenM` \ new_expr ->
556 zonkArithSeq env info `thenM` \ new_info ->
557 returnM (PArrSeq new_expr new_info)
559 zonkExpr env (HsSCC lbl expr)
560 = zonkLExpr env expr `thenM` \ new_expr ->
561 returnM (HsSCC lbl new_expr)
563 zonkExpr env (HsTickPragma info expr)
564 = zonkLExpr env expr `thenM` \ new_expr ->
565 returnM (HsTickPragma info new_expr)
567 -- hdaume: core annotations
568 zonkExpr env (HsCoreAnn lbl expr)
569 = zonkLExpr env expr `thenM` \ new_expr ->
570 returnM (HsCoreAnn lbl new_expr)
572 -- arrow notation extensions
573 zonkExpr env (HsProc pat body)
574 = do { (env1, new_pat) <- zonkPat env pat
575 ; new_body <- zonkCmdTop env1 body
576 ; return (HsProc new_pat new_body) }
578 zonkExpr env (HsArrApp e1 e2 ty ho rl)
579 = zonkLExpr env e1 `thenM` \ new_e1 ->
580 zonkLExpr env e2 `thenM` \ new_e2 ->
581 zonkTcTypeToType env ty `thenM` \ new_ty ->
582 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
584 zonkExpr env (HsArrForm op fixity args)
585 = zonkLExpr env op `thenM` \ new_op ->
586 mappM (zonkCmdTop env) args `thenM` \ new_args ->
587 returnM (HsArrForm new_op fixity new_args)
589 zonkExpr env (HsWrap co_fn expr)
590 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
591 zonkExpr env1 expr `thenM` \ new_expr ->
592 return (HsWrap new_co_fn new_expr)
594 zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr)
596 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
597 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
599 zonk_cmd_top :: ZonkEnv -> HsCmdTop TcId -> TcM (HsCmdTop Id)
600 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
601 = zonkLExpr env cmd `thenM` \ new_cmd ->
602 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
603 zonkTcTypeToType env ty `thenM` \ new_ty ->
604 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
605 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
607 -------------------------------------------------------------------------
608 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
609 zonkCoFn env WpHole = return (env, WpHole)
610 zonkCoFn env WpInline = return (env, WpInline)
611 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
612 ; (env2, c2') <- zonkCoFn env1 c2
613 ; return (env2, WpCompose c1' c2') }
614 zonkCoFn env (WpCast co) = do { co' <- zonkTcTypeToType env co
615 ; return (env, WpCast co') }
616 zonkCoFn env (WpLam id) = do { id' <- zonkDictBndr env id
617 ; let env1 = extendZonkEnv1 env id'
618 ; return (env1, WpLam id') }
619 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
620 do { tv' <- zonkTyVarBndr env tv
621 ; return (env, WpTyLam tv') }
622 zonkCoFn env (WpApp v)
623 | isTcTyVar v = do { co <- zonkTcTyVar v
624 ; return (env, WpTyApp co) }
625 -- Yuk! A mutable coercion variable is a TcTyVar
626 -- not a CoVar, so don't use isCoVar!
627 -- Yuk! A WpApp can't hold the zonked type,
628 -- so we switch to WpTyApp
629 | otherwise = return (env, WpApp (zonkIdOcc env v))
630 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
631 ; return (env, WpTyApp ty') }
632 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
633 ; return (env1, WpLet bs') }
636 -------------------------------------------------------------------------
637 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
638 -- Only used for 'do', so the only Ids are in a MDoExpr table
639 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
640 zonkDo _ do_or_lc = do_or_lc
642 -------------------------------------------------------------------------
643 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
644 zonkOverLit env lit@(OverLit { ol_witness = e, ol_type = ty })
645 = do { ty' <- zonkTcTypeToType env ty
646 ; e' <- zonkExpr env e
647 ; return (lit { ol_witness = e', ol_type = ty' }) }
649 -------------------------------------------------------------------------
650 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
652 zonkArithSeq env (From e)
653 = zonkLExpr env e `thenM` \ new_e ->
656 zonkArithSeq env (FromThen e1 e2)
657 = zonkLExpr env e1 `thenM` \ new_e1 ->
658 zonkLExpr env e2 `thenM` \ new_e2 ->
659 returnM (FromThen new_e1 new_e2)
661 zonkArithSeq env (FromTo e1 e2)
662 = zonkLExpr env e1 `thenM` \ new_e1 ->
663 zonkLExpr env e2 `thenM` \ new_e2 ->
664 returnM (FromTo new_e1 new_e2)
666 zonkArithSeq env (FromThenTo e1 e2 e3)
667 = zonkLExpr env e1 `thenM` \ new_e1 ->
668 zonkLExpr env e2 `thenM` \ new_e2 ->
669 zonkLExpr env e3 `thenM` \ new_e3 ->
670 returnM (FromThenTo new_e1 new_e2 new_e3)
673 -------------------------------------------------------------------------
674 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
675 zonkStmts env [] = return (env, [])
676 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
677 ; (env2, ss') <- zonkStmts env1 ss
678 ; return (env2, s' : ss') }
680 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
681 zonkStmt env (ParStmt stmts_w_bndrs)
682 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
684 new_binders = concat (map snd new_stmts_w_bndrs)
685 env1 = extendZonkEnv env new_binders
687 return (env1, ParStmt new_stmts_w_bndrs)
689 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
690 returnM (new_stmts, zonkIdOccs env1 bndrs)
692 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
693 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
695 env1 = extendZonkEnv env new_rvs
697 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
698 -- Zonk the ret-expressions in an envt that
699 -- has the polymorphic bindings in the envt
700 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
702 new_lvs = zonkIdOccs env2 lvs
703 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
705 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
706 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
708 zonkStmt env (ExprStmt expr then_op ty)
709 = zonkLExpr env expr `thenM` \ new_expr ->
710 zonkExpr env then_op `thenM` \ new_then ->
711 zonkTcTypeToType env ty `thenM` \ new_ty ->
712 returnM (env, ExprStmt new_expr new_then new_ty)
714 zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
715 = do { (env', stmts') <- zonkStmts env stmts
716 ; let binders' = zonkIdOccs env' binders
717 ; usingExpr' <- zonkLExpr env' usingExpr
718 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
719 ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
721 zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
722 = do { (env', stmts') <- zonkStmts env stmts
723 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
725 case groupByClause of
726 GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
727 GroupBySomething eitherUsingExpr byExpr -> do
728 eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
729 byExpr' <- zonkLExpr env' byExpr
730 return $ GroupBySomething eitherUsingExpr' byExpr'
732 ; let env'' = extendZonkEnv env' (map snd binderMap')
733 ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
735 mapEitherM f g x = do
737 Left a -> f a >>= (return . Left)
738 Right b -> g b >>= (return . Right)
740 zonkBinderMapEntry env (oldBinder, newBinder) = do
741 let oldBinder' = zonkIdOcc env oldBinder
742 newBinder' <- zonkIdBndr env newBinder
743 return (oldBinder', newBinder')
745 zonkStmt env (LetStmt binds)
746 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
747 returnM (env1, LetStmt new_binds)
749 zonkStmt env (BindStmt pat expr bind_op fail_op)
750 = do { new_expr <- zonkLExpr env expr
751 ; (env1, new_pat) <- zonkPat env pat
752 ; new_bind <- zonkExpr env bind_op
753 ; new_fail <- zonkExpr env fail_op
754 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
756 zonkMaybeLExpr :: ZonkEnv -> Maybe (LHsExpr TcId) -> TcM (Maybe (LHsExpr Id))
757 zonkMaybeLExpr _ Nothing = return Nothing
758 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
761 -------------------------------------------------------------------------
762 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
763 zonkRecFields env (HsRecFields flds dd)
764 = do { flds' <- mappM zonk_rbind flds
765 ; return (HsRecFields flds' dd) }
768 = do { new_id <- wrapLocM (zonkIdBndr env) (hsRecFieldId fld)
769 ; new_expr <- zonkLExpr env (hsRecFieldArg fld)
770 ; return (fld { hsRecFieldId = new_id, hsRecFieldArg = new_expr }) }
772 -------------------------------------------------------------------------
773 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
774 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
778 %************************************************************************
780 \subsection[BackSubst-Pats]{Patterns}
782 %************************************************************************
785 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
786 -- Extend the environment as we go, because it's possible for one
787 -- pattern to bind something that is used in another (inside or
789 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
791 zonk_pat :: ZonkEnv -> Pat TcId -> TcM (ZonkEnv, Pat Id)
792 zonk_pat env (ParPat p)
793 = do { (env', p') <- zonkPat env p
794 ; return (env', ParPat p') }
796 zonk_pat env (WildPat ty)
797 = do { ty' <- zonkTcTypeToType env ty
798 ; return (env, WildPat ty') }
800 zonk_pat env (VarPat v)
801 = do { v' <- zonkIdBndr env v
802 ; return (extendZonkEnv1 env v', VarPat v') }
804 zonk_pat env (VarPatOut v binds)
805 = do { v' <- zonkIdBndr env v
806 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
807 ; returnM (env', VarPatOut v' binds') }
809 zonk_pat env (LazyPat pat)
810 = do { (env', pat') <- zonkPat env pat
811 ; return (env', LazyPat pat') }
813 zonk_pat env (BangPat pat)
814 = do { (env', pat') <- zonkPat env pat
815 ; return (env', BangPat pat') }
817 zonk_pat env (AsPat (L loc v) pat)
818 = do { v' <- zonkIdBndr env v
819 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
820 ; return (env', AsPat (L loc v') pat') }
822 zonk_pat env (ViewPat expr pat ty)
823 = do { expr' <- zonkLExpr env expr
824 ; (env', pat') <- zonkPat env pat
825 ; ty' <- zonkTcTypeToType env ty
826 ; return (env', ViewPat expr' pat' ty') }
828 zonk_pat env (ListPat pats ty)
829 = do { ty' <- zonkTcTypeToType env ty
830 ; (env', pats') <- zonkPats env pats
831 ; return (env', ListPat pats' ty') }
833 zonk_pat env (PArrPat pats ty)
834 = do { ty' <- zonkTcTypeToType env ty
835 ; (env', pats') <- zonkPats env pats
836 ; return (env', PArrPat pats' ty') }
838 zonk_pat env (TuplePat pats boxed ty)
839 = do { ty' <- zonkTcTypeToType env ty
840 ; (env', pats') <- zonkPats env pats
841 ; return (env', TuplePat pats' boxed ty') }
843 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
844 = ASSERT( all isImmutableTyVar (pat_tvs p) )
845 do { new_ty <- zonkTcTypeToType env ty
846 ; new_dicts <- zonkDictBndrs env dicts
847 ; let env1 = extendZonkEnv env new_dicts
848 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
849 ; (env', new_args) <- zonkConStuff env2 args
850 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
851 pat_binds = new_binds, pat_args = new_args }) }
853 zonk_pat env (LitPat lit) = return (env, LitPat lit)
855 zonk_pat env (SigPatOut pat ty)
856 = do { ty' <- zonkTcTypeToType env ty
857 ; (env', pat') <- zonkPat env pat
858 ; return (env', SigPatOut pat' ty') }
860 zonk_pat env (NPat lit mb_neg eq_expr)
861 = do { lit' <- zonkOverLit env lit
862 ; mb_neg' <- case mb_neg of
863 Nothing -> return Nothing
864 Just neg -> do { neg' <- zonkExpr env neg
865 ; return (Just neg') }
866 ; eq_expr' <- zonkExpr env eq_expr
867 ; return (env, NPat lit' mb_neg' eq_expr') }
869 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
870 = do { n' <- zonkIdBndr env n
871 ; lit' <- zonkOverLit env lit
872 ; e1' <- zonkExpr env e1
873 ; e2' <- zonkExpr env e2
874 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
876 zonk_pat env (CoPat co_fn pat ty)
877 = do { (env', co_fn') <- zonkCoFn env co_fn
878 ; (env'', pat') <- zonkPat env' (noLoc pat)
879 ; ty' <- zonkTcTypeToType env'' ty
880 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
882 zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat)
884 ---------------------------
885 zonkConStuff :: ZonkEnv
886 -> HsConDetails (OutPat TcId) (HsRecFields id (OutPat TcId))
888 HsConDetails (OutPat Id) (HsRecFields id (OutPat Id)))
889 zonkConStuff env (PrefixCon pats)
890 = do { (env', pats') <- zonkPats env pats
891 ; return (env', PrefixCon pats') }
893 zonkConStuff env (InfixCon p1 p2)
894 = do { (env1, p1') <- zonkPat env p1
895 ; (env', p2') <- zonkPat env1 p2
896 ; return (env', InfixCon p1' p2') }
898 zonkConStuff env (RecCon (HsRecFields rpats dd))
899 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
900 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
901 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
902 -- Field selectors have declared types; hence no zonking
904 ---------------------------
905 zonkPats :: ZonkEnv -> [OutPat TcId] -> TcM (ZonkEnv, [OutPat Id])
906 zonkPats env [] = return (env, [])
907 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
908 ; (env', pats') <- zonkPats env1 pats
909 ; return (env', pat':pats') }
912 %************************************************************************
914 \subsection[BackSubst-Foreign]{Foreign exports}
916 %************************************************************************
920 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
921 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
923 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
924 zonkForeignExport env (ForeignExport i _hs_ty spec) =
925 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
926 zonkForeignExport _ for_imp
927 = returnM for_imp -- Foreign imports don't need zonking
931 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
932 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
934 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
935 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
936 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
937 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
939 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
940 -- Type variables don't need an envt
941 -- They are bound through the mutable mechanism
943 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
944 -- We need to gather the type variables mentioned on the LHS so we can
945 -- quantify over them. Example:
951 -- {-# RULES "myrule" foo C = 1 #-}
953 -- After type checking the LHS becomes (foo a (C a))
954 -- and we do not want to zap the unbound tyvar 'a' to (), because
955 -- that limits the applicability of the rule. Instead, we
956 -- want to quantify over it!
958 -- It's easiest to find the free tyvars here. Attempts to do so earlier
959 -- are tiresome, because (a) the data type is big and (b) finding the
960 -- free type vars of an expression is necessarily monadic operation.
961 -- (consider /\a -> f @ b, where b is side-effected to a)
963 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
964 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
966 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
968 final_bndrs :: [Located Var]
969 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
971 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
972 -- I hate this map RuleBndr stuff
974 zonk_bndr (RuleBndr v)
975 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
976 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
978 zonk_bndr (RuleBndrSig {}) = panic "zonk_bndr RuleBndrSig"
982 %************************************************************************
984 \subsection[BackSubst-Foreign]{Foreign exports}
986 %************************************************************************
989 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
990 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
992 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
993 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
995 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
996 -- This variant collects unbound type variables in a mutable variable
997 zonkTypeCollecting unbound_tv_set
998 = zonkType zonk_unbound_tyvar
1000 zonk_unbound_tyvar tv
1001 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
1002 readMutVar unbound_tv_set `thenM` \ tv_set ->
1003 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
1004 return (mkTyVarTy tv')
1006 zonkTypeZapping :: TcType -> TcM Type
1007 -- This variant is used for everything except the LHS of rules
1008 -- It zaps unbound type variables to (), or some other arbitrary type
1010 = zonkType zonk_unbound_tyvar ty
1012 -- Zonk a mutable but unbound type variable to an arbitrary type
1013 -- We know it's unbound even though we don't carry an environment,
1014 -- because at the binding site for a type variable we bind the
1015 -- mutable tyvar to a fresh immutable one. So the mutable store
1016 -- plays the role of an environment. If we come across a mutable
1017 -- type variable that isn't so bound, it must be completely free.
1018 zonk_unbound_tyvar tv = do { ty <- mkArbitraryType warn tv
1019 ; writeMetaTyVar tv ty
1022 warn span msg = setSrcSpan span (addWarnTc msg)
1025 {- Note [Strangely-kinded void TyCons]
1026 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1027 See Trac #959 for more examples
1029 When the type checker finds a type variable with no binding, which
1030 means it can be instantiated with an arbitrary type, it usually
1031 instantiates it to Void. Eg.
1035 length Void (Nil Void)
1037 But in really obscure programs, the type variable might have a kind
1038 other than *, so we need to invent a suitably-kinded type.
1043 Tuple for kind *->...*->*
1045 which deals with most cases. (Previously, it only dealt with
1048 In the other cases, it just makes up a TyCon with a suitable kind. If
1049 this gets into an interface file, anyone reading that file won't
1050 understand it. This is fixable (by making the client of the interface
1051 file make up a TyCon too) but it is tiresome and never happens, so I
1054 Meanwhile I have now fixed GHC to emit a civilized warning.
1057 mkArbitraryType :: (SrcSpan -> SDoc -> TcRnIf g l a) -- How to complain
1059 -> TcRnIf g l Type -- Used by desugarer too
1060 -- Make up an arbitrary type whose kind is the same as the tyvar.
1061 -- We'll use this to instantiate the (unbound) tyvar.
1063 -- Also used by the desugarer; hence the (tiresome) parameter
1064 -- to use when generating a warning
1065 mkArbitraryType warn tv
1066 | liftedTypeKind `isSubKind` kind -- The vastly common case
1068 | eqKind kind (tyConKind anyPrimTyCon1) -- @*->*@
1069 = return (mkTyConApp anyPrimTyCon1 []) -- No tuples this size
1070 | all isLiftedTypeKind args -- @*-> ... ->*->*@
1071 , isLiftedTypeKind res -- Horrible hack to make less use
1072 = return (mkTyConApp tup_tc []) -- of mkAnyPrimTyCon
1074 = do { warn (getSrcSpan tv) msg
1075 ; return (mkTyConApp (mkAnyPrimTyCon (getUnique tv) kind) []) }
1076 -- Same name as the tyvar, apart from making it start with a colon (sigh)
1077 -- I dread to think what will happen if this gets out into an
1078 -- interface file. Catastrophe likely. Major sigh.
1081 (args,res) = splitKindFunTys kind
1082 tup_tc = tupleTyCon Boxed (length args)
1084 msg = vcat [ hang (ptext (sLit "Inventing strangely-kinded Any TyCon"))
1085 2 (ptext (sLit "of kind") <+> quotes (ppr kind))
1086 , nest 2 (ptext (sLit "from an instantiation of type variable") <+> quotes (ppr tv))
1087 , ptext (sLit "This warning can be suppressed by a type signature fixing") <+> quotes (ppr tv)
1088 , nest 2 (ptext (sLit "but is harmless without -O (and usually harmless anyway)."))
1089 , ptext (sLit "See http://hackage.haskell.org/trac/ghc/ticket/959 for details") ]