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 -- 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
20 mkHsConApp, mkHsDictLet, mkHsApp,
21 hsLitType, hsLPatType, hsPatType,
22 mkHsAppTy, mkSimpleHsAlt,
23 nlHsIntLit, mkVanillaTuplePat,
25 mkArbitraryType, -- Put this elsewhere?
27 -- re-exported from TcMonad
28 TcId, TcIdSet, TcDictBinds,
30 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
34 #include "HsVersions.h"
37 import HsSyn -- oodles of it
63 %************************************************************************
65 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
67 %************************************************************************
69 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
70 then something is wrong.
72 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
73 -- A vanilla tuple pattern simply gets its type from its sub-patterns
74 mkVanillaTuplePat pats box
75 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
77 hsLPatType :: OutPat Id -> Type
78 hsLPatType (L _ pat) = hsPatType pat
80 hsPatType (ParPat pat) = hsLPatType pat
81 hsPatType (WildPat ty) = ty
82 hsPatType (VarPat var) = idType var
83 hsPatType (VarPatOut var _) = idType var
84 hsPatType (BangPat pat) = hsLPatType pat
85 hsPatType (LazyPat pat) = hsLPatType pat
86 hsPatType (LitPat lit) = hsLitType lit
87 hsPatType (AsPat var pat) = idType (unLoc var)
88 hsPatType (ViewPat expr pat ty) = ty
89 hsPatType (ListPat _ ty) = mkListTy ty
90 hsPatType (PArrPat _ ty) = mkPArrTy ty
91 hsPatType (TuplePat pats box ty) = ty
92 hsPatType (ConPatOut{ pat_ty = ty })= ty
93 hsPatType (SigPatOut pat ty) = ty
94 hsPatType (NPat lit _ _) = overLitType lit
95 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
96 hsPatType (CoPat _ _ ty) = ty
98 hsLitType :: HsLit -> TcType
99 hsLitType (HsChar c) = charTy
100 hsLitType (HsCharPrim c) = charPrimTy
101 hsLitType (HsString str) = stringTy
102 hsLitType (HsStringPrim s) = addrPrimTy
103 hsLitType (HsInt i) = intTy
104 hsLitType (HsIntPrim i) = intPrimTy
105 hsLitType (HsInteger i ty) = ty
106 hsLitType (HsRat _ ty) = ty
107 hsLitType (HsFloatPrim f) = floatPrimTy
108 hsLitType (HsDoublePrim d) = doublePrimTy
112 %************************************************************************
114 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
116 %************************************************************************
119 -- zonkId is used *during* typechecking just to zonk the Id's type
120 zonkId :: TcId -> TcM TcId
122 = zonkTcType (idType id) `thenM` \ ty' ->
123 returnM (Id.setIdType id ty')
126 The rest of the zonking is done *after* typechecking.
127 The main zonking pass runs over the bindings
129 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
130 b) convert unbound TcTyVar to Void
131 c) convert each TcId to an Id by zonking its type
133 The type variables are converted by binding mutable tyvars to immutable ones
134 and then zonking as normal.
136 The Ids are converted by binding them in the normal Tc envt; that
137 way we maintain sharing; eg an Id is zonked at its binding site and they
138 all occurrences of that Id point to the common zonked copy
140 It's all pretty boring stuff, because HsSyn is such a large type, and
141 the environment manipulation is tiresome.
144 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
145 (IdEnv Id) -- What variables are in scope
146 -- Maps an Id to its zonked version; both have the same Name
147 -- Is only consulted lazily; hence knot-tying
149 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
151 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
152 extendZonkEnv (ZonkEnv zonk_ty env) ids
153 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
155 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
156 extendZonkEnv1 (ZonkEnv zonk_ty env) id
157 = ZonkEnv zonk_ty (extendVarEnv env id id)
159 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
160 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
162 zonkEnvIds :: ZonkEnv -> [Id]
163 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
165 zonkIdOcc :: ZonkEnv -> TcId -> Id
166 -- Ids defined in this module should be in the envt;
167 -- ignore others. (Actually, data constructors are also
168 -- not LocalVars, even when locally defined, but that is fine.)
169 -- (Also foreign-imported things aren't currently in the ZonkEnv;
170 -- that's ok because they don't need zonking.)
172 -- Actually, Template Haskell works in 'chunks' of declarations, and
173 -- an earlier chunk won't be in the 'env' that the zonking phase
174 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
175 -- zonked. There's no point in looking it up there (except for error
176 -- checking), and it's not conveniently to hand; hence the simple
177 -- 'orElse' case in the LocalVar branch.
179 -- Even without template splices, in module Main, the checking of
180 -- 'main' is done as a separate chunk.
181 zonkIdOcc (ZonkEnv zonk_ty env) id
182 | isLocalVar id = lookupVarEnv env id `orElse` id
185 zonkIdOccs env ids = map (zonkIdOcc env) ids
187 -- zonkIdBndr is used *after* typechecking to get the Id's type
188 -- to its final form. The TyVarEnv give
189 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
191 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
192 returnM (Id.setIdType id ty')
194 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
195 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
197 zonkDictBndrs :: ZonkEnv -> [Var] -> TcM [Var]
198 -- "Dictionary" binders can be coercion variables or dictionary variables
199 zonkDictBndrs env ids = mappM (zonkDictBndr env) ids
201 zonkDictBndr env var | isTyVar var = return var
202 | otherwise = zonkIdBndr env var
204 zonkTopBndrs :: [TcId] -> TcM [Id]
205 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
210 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
211 zonkTopExpr e = zonkExpr emptyZonkEnv e
213 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
214 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
216 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
221 zonkTopDecls binds rules fords
222 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
223 -- Top level is implicitly recursive
224 ; rules' <- zonkRules env rules
225 ; fords' <- zonkForeignExports env fords
226 ; return (zonkEnvIds env, binds', fords', rules') }
228 ---------------------------------------------
229 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
230 zonkLocalBinds env EmptyLocalBinds
231 = return (env, EmptyLocalBinds)
233 zonkLocalBinds env (HsValBinds binds)
234 = do { (env1, new_binds) <- zonkValBinds env binds
235 ; return (env1, HsValBinds new_binds) }
237 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
238 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
240 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
242 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
243 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
245 zonk_ip_bind (IPBind n e)
246 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
247 zonkLExpr env e `thenM` \ e' ->
248 returnM (IPBind n' e')
251 ---------------------------------------------
252 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
253 zonkValBinds env bs@(ValBindsIn _ _)
254 = panic "zonkValBinds" -- Not in typechecker output
255 zonkValBinds env (ValBindsOut binds sigs)
256 = do { (env1, new_binds) <- go env binds
257 ; return (env1, ValBindsOut new_binds sigs) }
259 go env [] = return (env, [])
260 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
261 ; (env2, bs') <- go env1 bs
262 ; return (env2, (r,b'):bs') }
264 ---------------------------------------------
265 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
266 zonkRecMonoBinds env binds
267 = fixM (\ ~(_, new_binds) -> do
268 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
269 ; binds' <- zonkMonoBinds env1 binds
270 ; return (env1, binds') })
272 ---------------------------------------------
273 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
274 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
276 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
277 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
278 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
279 ; new_grhss <- zonkGRHSs env grhss
280 ; new_ty <- zonkTcTypeToType env ty
281 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
283 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
284 = zonkIdBndr env var `thenM` \ new_var ->
285 zonkLExpr env expr `thenM` \ new_expr ->
286 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
288 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
289 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
290 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
291 zonkMatchGroup env1 ms `thenM` \ new_ms ->
292 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
294 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
295 abs_exports = exports, abs_binds = val_binds })
296 = ASSERT( all isImmutableTyVar tyvars )
297 zonkDictBndrs env dicts `thenM` \ new_dicts ->
298 fixM (\ ~(new_val_binds, _) ->
300 env1 = extendZonkEnv env new_dicts
301 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
303 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
304 mappM (zonkExport env2) exports `thenM` \ new_exports ->
305 returnM (new_val_binds, new_exports)
306 ) `thenM` \ (new_val_bind, new_exports) ->
307 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
308 abs_exports = new_exports, abs_binds = new_val_bind })
310 zonkExport env (tyvars, global, local, prags)
311 -- The tyvars are already zonked
312 = zonkIdBndr env global `thenM` \ new_global ->
313 mapM zonk_prag prags `thenM` \ new_prags ->
314 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
315 zonk_prag prag@(L _ (InlinePrag {})) = return prag
316 zonk_prag (L loc (SpecPrag expr ty inl))
317 = do { expr' <- zonkExpr env expr
318 ; ty' <- zonkTcTypeToType env ty
319 ; return (L loc (SpecPrag expr' ty' inl)) }
322 %************************************************************************
324 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
326 %************************************************************************
329 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
330 zonkMatchGroup env (MatchGroup ms ty)
331 = do { ms' <- mapM (zonkMatch env) ms
332 ; ty' <- zonkTcTypeToType env ty
333 ; return (MatchGroup ms' ty') }
335 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
336 zonkMatch env (L loc (Match pats _ grhss))
337 = do { (env1, new_pats) <- zonkPats env pats
338 ; new_grhss <- zonkGRHSs env1 grhss
339 ; return (L loc (Match new_pats Nothing new_grhss)) }
341 -------------------------------------------------------------------------
342 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
344 zonkGRHSs env (GRHSs grhss binds)
345 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
347 zonk_grhs (GRHS guarded rhs)
348 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
349 zonkLExpr env2 rhs `thenM` \ new_rhs ->
350 returnM (GRHS new_guarded new_rhs)
352 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
353 returnM (GRHSs new_grhss new_binds)
356 %************************************************************************
358 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
360 %************************************************************************
363 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
364 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
365 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
367 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
368 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
370 zonkExpr env (HsVar id)
371 = returnM (HsVar (zonkIdOcc env id))
373 zonkExpr env (HsIPVar id)
374 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
376 zonkExpr env (HsLit (HsRat f ty))
377 = zonkTcTypeToType env ty `thenM` \ new_ty ->
378 returnM (HsLit (HsRat f new_ty))
380 zonkExpr env (HsLit lit)
381 = returnM (HsLit lit)
383 zonkExpr env (HsOverLit lit)
384 = do { lit' <- zonkOverLit env lit
385 ; return (HsOverLit lit') }
387 zonkExpr env (HsLam matches)
388 = zonkMatchGroup env matches `thenM` \ new_matches ->
389 returnM (HsLam new_matches)
391 zonkExpr env (HsApp e1 e2)
392 = zonkLExpr env e1 `thenM` \ new_e1 ->
393 zonkLExpr env e2 `thenM` \ new_e2 ->
394 returnM (HsApp new_e1 new_e2)
396 zonkExpr env (HsBracketOut body bs)
397 = mappM zonk_b bs `thenM` \ bs' ->
398 returnM (HsBracketOut body bs')
400 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
403 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
404 returnM (HsSpliceE s)
406 zonkExpr env (OpApp e1 op fixity e2)
407 = zonkLExpr env e1 `thenM` \ new_e1 ->
408 zonkLExpr env op `thenM` \ new_op ->
409 zonkLExpr env e2 `thenM` \ new_e2 ->
410 returnM (OpApp new_e1 new_op fixity new_e2)
412 zonkExpr env (NegApp expr op)
413 = zonkLExpr env expr `thenM` \ new_expr ->
414 zonkExpr env op `thenM` \ new_op ->
415 returnM (NegApp new_expr new_op)
417 zonkExpr env (HsPar e)
418 = zonkLExpr env e `thenM` \new_e ->
419 returnM (HsPar new_e)
421 zonkExpr env (SectionL expr op)
422 = zonkLExpr env expr `thenM` \ new_expr ->
423 zonkLExpr env op `thenM` \ new_op ->
424 returnM (SectionL new_expr new_op)
426 zonkExpr env (SectionR op expr)
427 = zonkLExpr env op `thenM` \ new_op ->
428 zonkLExpr env expr `thenM` \ new_expr ->
429 returnM (SectionR new_op new_expr)
431 zonkExpr env (HsCase expr ms)
432 = zonkLExpr env expr `thenM` \ new_expr ->
433 zonkMatchGroup env ms `thenM` \ new_ms ->
434 returnM (HsCase new_expr new_ms)
436 zonkExpr env (HsIf e1 e2 e3)
437 = zonkLExpr env e1 `thenM` \ new_e1 ->
438 zonkLExpr env e2 `thenM` \ new_e2 ->
439 zonkLExpr env e3 `thenM` \ new_e3 ->
440 returnM (HsIf new_e1 new_e2 new_e3)
442 zonkExpr env (HsLet binds expr)
443 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
444 zonkLExpr new_env expr `thenM` \ new_expr ->
445 returnM (HsLet new_binds new_expr)
447 zonkExpr env (HsDo do_or_lc stmts body ty)
448 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
449 zonkLExpr new_env body `thenM` \ new_body ->
450 zonkTcTypeToType env ty `thenM` \ new_ty ->
451 returnM (HsDo (zonkDo env do_or_lc)
452 new_stmts new_body new_ty)
454 zonkExpr env (ExplicitList ty exprs)
455 = zonkTcTypeToType env ty `thenM` \ new_ty ->
456 zonkLExprs env exprs `thenM` \ new_exprs ->
457 returnM (ExplicitList new_ty new_exprs)
459 zonkExpr env (ExplicitPArr ty exprs)
460 = zonkTcTypeToType env ty `thenM` \ new_ty ->
461 zonkLExprs env exprs `thenM` \ new_exprs ->
462 returnM (ExplicitPArr new_ty new_exprs)
464 zonkExpr env (ExplicitTuple exprs boxed)
465 = zonkLExprs env exprs `thenM` \ new_exprs ->
466 returnM (ExplicitTuple new_exprs boxed)
468 zonkExpr env (RecordCon data_con con_expr rbinds)
469 = do { new_con_expr <- zonkExpr env con_expr
470 ; new_rbinds <- zonkRecFields env rbinds
471 ; return (RecordCon data_con new_con_expr new_rbinds) }
473 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
474 = do { new_expr <- zonkLExpr env expr
475 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
476 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
477 ; new_rbinds <- zonkRecFields env rbinds
478 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
480 zonkExpr env (ExprWithTySigOut e ty)
481 = do { e' <- zonkLExpr env e
482 ; return (ExprWithTySigOut e' ty) }
484 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
486 zonkExpr env (ArithSeq expr info)
487 = zonkExpr env expr `thenM` \ new_expr ->
488 zonkArithSeq env info `thenM` \ new_info ->
489 returnM (ArithSeq new_expr new_info)
491 zonkExpr env (PArrSeq expr info)
492 = zonkExpr env expr `thenM` \ new_expr ->
493 zonkArithSeq env info `thenM` \ new_info ->
494 returnM (PArrSeq new_expr new_info)
496 zonkExpr env (HsSCC lbl expr)
497 = zonkLExpr env expr `thenM` \ new_expr ->
498 returnM (HsSCC lbl new_expr)
500 zonkExpr env (HsTickPragma info expr)
501 = zonkLExpr env expr `thenM` \ new_expr ->
502 returnM (HsTickPragma info new_expr)
504 -- hdaume: core annotations
505 zonkExpr env (HsCoreAnn lbl expr)
506 = zonkLExpr env expr `thenM` \ new_expr ->
507 returnM (HsCoreAnn lbl new_expr)
509 -- arrow notation extensions
510 zonkExpr env (HsProc pat body)
511 = do { (env1, new_pat) <- zonkPat env pat
512 ; new_body <- zonkCmdTop env1 body
513 ; return (HsProc new_pat new_body) }
515 zonkExpr env (HsArrApp e1 e2 ty ho rl)
516 = zonkLExpr env e1 `thenM` \ new_e1 ->
517 zonkLExpr env e2 `thenM` \ new_e2 ->
518 zonkTcTypeToType env ty `thenM` \ new_ty ->
519 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
521 zonkExpr env (HsArrForm op fixity args)
522 = zonkLExpr env op `thenM` \ new_op ->
523 mappM (zonkCmdTop env) args `thenM` \ new_args ->
524 returnM (HsArrForm new_op fixity new_args)
526 zonkExpr env (HsWrap co_fn expr)
527 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
528 zonkExpr env1 expr `thenM` \ new_expr ->
529 return (HsWrap new_co_fn new_expr)
531 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
533 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
534 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
536 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
537 = zonkLExpr env cmd `thenM` \ new_cmd ->
538 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
539 zonkTcTypeToType env ty `thenM` \ new_ty ->
540 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
541 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
543 -------------------------------------------------------------------------
544 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
545 zonkCoFn env WpHole = return (env, WpHole)
546 zonkCoFn env WpInline = return (env, WpInline)
547 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
548 ; (env2, c2') <- zonkCoFn env1 c2
549 ; return (env2, WpCompose c1' c2') }
550 zonkCoFn env (WpCo co) = do { co' <- zonkTcTypeToType env co
551 ; return (env, WpCo co') }
552 zonkCoFn env (WpLam id) = do { id' <- zonkDictBndr env id
553 ; let env1 = extendZonkEnv1 env id'
554 ; return (env1, WpLam id') }
555 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
556 do { return (env, WpTyLam tv) }
557 zonkCoFn env (WpApp id) = do { return (env, WpApp (zonkIdOcc env id)) }
558 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
559 ; return (env, WpTyApp ty') }
560 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
561 ; return (env1, WpLet bs') }
564 -------------------------------------------------------------------------
565 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
566 -- Only used for 'do', so the only Ids are in a MDoExpr table
567 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
568 zonkDo env do_or_lc = do_or_lc
570 -------------------------------------------------------------------------
571 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
574 zonkedStuff = do ty' <- zonkTcTypeToType env (overLitType ol)
575 e' <- zonkExpr env (overLitExpr ol)
577 ru f (x, y) = return (f x y)
580 (HsIntegral i _ _) -> ru (HsIntegral i) =<< zonkedStuff
581 (HsFractional r _ _) -> ru (HsFractional r) =<< zonkedStuff
582 (HsIsString s _ _) -> ru (HsIsString s) =<< zonkedStuff
584 -------------------------------------------------------------------------
585 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
587 zonkArithSeq env (From e)
588 = zonkLExpr env e `thenM` \ new_e ->
591 zonkArithSeq env (FromThen e1 e2)
592 = zonkLExpr env e1 `thenM` \ new_e1 ->
593 zonkLExpr env e2 `thenM` \ new_e2 ->
594 returnM (FromThen new_e1 new_e2)
596 zonkArithSeq env (FromTo e1 e2)
597 = zonkLExpr env e1 `thenM` \ new_e1 ->
598 zonkLExpr env e2 `thenM` \ new_e2 ->
599 returnM (FromTo new_e1 new_e2)
601 zonkArithSeq env (FromThenTo e1 e2 e3)
602 = zonkLExpr env e1 `thenM` \ new_e1 ->
603 zonkLExpr env e2 `thenM` \ new_e2 ->
604 zonkLExpr env e3 `thenM` \ new_e3 ->
605 returnM (FromThenTo new_e1 new_e2 new_e3)
608 -------------------------------------------------------------------------
609 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
610 zonkStmts env [] = return (env, [])
611 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
612 ; (env2, ss') <- zonkStmts env1 ss
613 ; return (env2, s' : ss') }
615 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
616 zonkStmt env (ParStmt stmts_w_bndrs)
617 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
619 new_binders = concat (map snd new_stmts_w_bndrs)
620 env1 = extendZonkEnv env new_binders
622 return (env1, ParStmt new_stmts_w_bndrs)
624 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
625 returnM (new_stmts, zonkIdOccs env1 bndrs)
627 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
628 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
630 env1 = extendZonkEnv env new_rvs
632 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
633 -- Zonk the ret-expressions in an envt that
634 -- has the polymorphic bindings in the envt
635 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
637 new_lvs = zonkIdOccs env2 lvs
638 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
640 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
641 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
643 zonkStmt env (ExprStmt expr then_op ty)
644 = zonkLExpr env expr `thenM` \ new_expr ->
645 zonkExpr env then_op `thenM` \ new_then ->
646 zonkTcTypeToType env ty `thenM` \ new_ty ->
647 returnM (env, ExprStmt new_expr new_then new_ty)
649 zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
650 = do { (env', stmts') <- zonkStmts env stmts
651 ; let binders' = zonkIdOccs env' binders
652 ; usingExpr' <- zonkLExpr env' usingExpr
653 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
654 ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
656 zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
657 = do { (env', stmts') <- zonkStmts env stmts
658 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
660 case groupByClause of
661 GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
662 GroupBySomething eitherUsingExpr byExpr -> do
663 eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
664 byExpr' <- zonkLExpr env' byExpr
665 return $ GroupBySomething eitherUsingExpr' byExpr'
667 ; let env'' = extendZonkEnv env' (map snd binderMap')
668 ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
670 mapEitherM f g x = do
672 Left a -> f a >>= (return . Left)
673 Right b -> g b >>= (return . Right)
675 zonkBinderMapEntry env (oldBinder, newBinder) = do
676 let oldBinder' = zonkIdOcc env oldBinder
677 newBinder' <- zonkIdBndr env newBinder
678 return (oldBinder', newBinder')
680 zonkStmt env (LetStmt binds)
681 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
682 returnM (env1, LetStmt new_binds)
684 zonkStmt env (BindStmt pat expr bind_op fail_op)
685 = do { new_expr <- zonkLExpr env expr
686 ; (env1, new_pat) <- zonkPat env pat
687 ; new_bind <- zonkExpr env bind_op
688 ; new_fail <- zonkExpr env fail_op
689 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
691 zonkMaybeLExpr env Nothing = return Nothing
692 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
695 -------------------------------------------------------------------------
696 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
697 zonkRecFields env (HsRecFields flds dd)
698 = do { flds' <- mappM zonk_rbind flds
699 ; return (HsRecFields flds' dd) }
702 = do { new_expr <- zonkLExpr env (hsRecFieldArg fld)
703 ; return (fld { hsRecFieldArg = new_expr }) }
704 -- Field selectors have declared types; hence no zonking
706 -------------------------------------------------------------------------
707 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
708 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
712 %************************************************************************
714 \subsection[BackSubst-Pats]{Patterns}
716 %************************************************************************
719 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
720 -- Extend the environment as we go, because it's possible for one
721 -- pattern to bind something that is used in another (inside or
723 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
725 zonk_pat env (ParPat p)
726 = do { (env', p') <- zonkPat env p
727 ; return (env', ParPat p') }
729 zonk_pat env (WildPat ty)
730 = do { ty' <- zonkTcTypeToType env ty
731 ; return (env, WildPat ty') }
733 zonk_pat env (VarPat v)
734 = do { v' <- zonkIdBndr env v
735 ; return (extendZonkEnv1 env v', VarPat v') }
737 zonk_pat env (VarPatOut v binds)
738 = do { v' <- zonkIdBndr env v
739 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
740 ; returnM (env', VarPatOut v' binds') }
742 zonk_pat env (LazyPat pat)
743 = do { (env', pat') <- zonkPat env pat
744 ; return (env', LazyPat pat') }
746 zonk_pat env (BangPat pat)
747 = do { (env', pat') <- zonkPat env pat
748 ; return (env', BangPat pat') }
750 zonk_pat env (AsPat (L loc v) pat)
751 = do { v' <- zonkIdBndr env v
752 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
753 ; return (env', AsPat (L loc v') pat') }
755 zonk_pat env (ViewPat expr pat ty)
756 = do { expr' <- zonkLExpr env expr
757 ; (env', pat') <- zonkPat env pat
758 ; return (env', ViewPat expr' pat' ty) }
760 zonk_pat env (ListPat pats ty)
761 = do { ty' <- zonkTcTypeToType env ty
762 ; (env', pats') <- zonkPats env pats
763 ; return (env', ListPat pats' ty') }
765 zonk_pat env (PArrPat pats ty)
766 = do { ty' <- zonkTcTypeToType env ty
767 ; (env', pats') <- zonkPats env pats
768 ; return (env', PArrPat pats' ty') }
770 zonk_pat env (TuplePat pats boxed ty)
771 = do { ty' <- zonkTcTypeToType env ty
772 ; (env', pats') <- zonkPats env pats
773 ; return (env', TuplePat pats' boxed ty') }
775 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
776 = ASSERT( all isImmutableTyVar (pat_tvs p) )
777 do { new_ty <- zonkTcTypeToType env ty
778 ; new_dicts <- zonkDictBndrs env dicts
779 ; let env1 = extendZonkEnv env new_dicts
780 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
781 ; (env', new_args) <- zonkConStuff env2 args
782 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
783 pat_binds = new_binds, pat_args = new_args }) }
785 zonk_pat env (LitPat lit) = return (env, LitPat lit)
787 zonk_pat env (SigPatOut pat ty)
788 = do { ty' <- zonkTcTypeToType env ty
789 ; (env', pat') <- zonkPat env pat
790 ; return (env', SigPatOut pat' ty') }
792 zonk_pat env (NPat lit mb_neg eq_expr)
793 = do { lit' <- zonkOverLit env lit
794 ; mb_neg' <- case mb_neg of
795 Nothing -> return Nothing
796 Just neg -> do { neg' <- zonkExpr env neg
797 ; return (Just neg') }
798 ; eq_expr' <- zonkExpr env eq_expr
799 ; return (env, NPat lit' mb_neg' eq_expr') }
801 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
802 = do { n' <- zonkIdBndr env n
803 ; lit' <- zonkOverLit env lit
804 ; e1' <- zonkExpr env e1
805 ; e2' <- zonkExpr env e2
806 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
808 zonk_pat env (CoPat co_fn pat ty)
809 = do { (env', co_fn') <- zonkCoFn env co_fn
810 ; (env'', pat') <- zonkPat env' (noLoc pat)
811 ; ty' <- zonkTcTypeToType env'' ty
812 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
814 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
816 ---------------------------
817 zonkConStuff env (PrefixCon pats)
818 = do { (env', pats') <- zonkPats env pats
819 ; return (env', PrefixCon pats') }
821 zonkConStuff env (InfixCon p1 p2)
822 = do { (env1, p1') <- zonkPat env p1
823 ; (env', p2') <- zonkPat env1 p2
824 ; return (env', InfixCon p1' p2') }
826 zonkConStuff env (RecCon (HsRecFields rpats dd))
827 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
828 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
829 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
830 -- Field selectors have declared types; hence no zonking
832 ---------------------------
833 zonkPats env [] = return (env, [])
834 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
835 ; (env', pats') <- zonkPats env1 pats
836 ; return (env', pat':pats') }
839 %************************************************************************
841 \subsection[BackSubst-Foreign]{Foreign exports}
843 %************************************************************************
847 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
848 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
850 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
851 zonkForeignExport env (ForeignExport i hs_ty spec) =
852 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
853 zonkForeignExport env for_imp
854 = returnM for_imp -- Foreign imports don't need zonking
858 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
859 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
861 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
862 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
863 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
864 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
866 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
867 -- Type variables don't need an envt
868 -- They are bound through the mutable mechanism
870 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
871 -- We need to gather the type variables mentioned on the LHS so we can
872 -- quantify over them. Example:
878 -- {-# RULES "myrule" foo C = 1 #-}
880 -- After type checking the LHS becomes (foo a (C a))
881 -- and we do not want to zap the unbound tyvar 'a' to (), because
882 -- that limits the applicability of the rule. Instead, we
883 -- want to quantify over it!
885 -- It's easiest to find the free tyvars here. Attempts to do so earlier
886 -- are tiresome, because (a) the data type is big and (b) finding the
887 -- free type vars of an expression is necessarily monadic operation.
888 -- (consider /\a -> f @ b, where b is side-effected to a)
890 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
891 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
893 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
895 final_bndrs :: [Located Var]
896 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
898 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
899 -- I hate this map RuleBndr stuff
901 zonk_bndr (RuleBndr v)
902 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
903 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
908 %************************************************************************
910 \subsection[BackSubst-Foreign]{Foreign exports}
912 %************************************************************************
915 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
916 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
918 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
919 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
921 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
922 -- This variant collects unbound type variables in a mutable variable
923 zonkTypeCollecting unbound_tv_set
924 = zonkType zonk_unbound_tyvar
926 zonk_unbound_tyvar tv
927 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
928 readMutVar unbound_tv_set `thenM` \ tv_set ->
929 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
930 return (mkTyVarTy tv')
932 zonkTypeZapping :: TcType -> TcM Type
933 -- This variant is used for everything except the LHS of rules
934 -- It zaps unbound type variables to (), or some other arbitrary type
936 = zonkType zonk_unbound_tyvar ty
938 -- Zonk a mutable but unbound type variable to an arbitrary type
939 -- We know it's unbound even though we don't carry an environment,
940 -- because at the binding site for a type variable we bind the
941 -- mutable tyvar to a fresh immutable one. So the mutable store
942 -- plays the role of an environment. If we come across a mutable
943 -- type variable that isn't so bound, it must be completely free.
944 zonk_unbound_tyvar tv = do { ty <- mkArbitraryType warn tv
945 ; writeMetaTyVar tv ty
948 warn span msg = setSrcSpan span (addWarnTc msg)
951 {- Note [Strangely-kinded void TyCons]
952 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
953 See Trac #959 for more examples
955 When the type checker finds a type variable with no binding, which
956 means it can be instantiated with an arbitrary type, it usually
957 instantiates it to Void. Eg.
961 length Void (Nil Void)
963 But in really obscure programs, the type variable might have a kind
964 other than *, so we need to invent a suitably-kinded type.
969 Tuple for kind *->...*->*
971 which deals with most cases. (Previously, it only dealt with
974 In the other cases, it just makes up a TyCon with a suitable kind. If
975 this gets into an interface file, anyone reading that file won't
976 understand it. This is fixable (by making the client of the interface
977 file make up a TyCon too) but it is tiresome and never happens, so I
980 Meanwhile I have now fixed GHC to emit a civilized warning.
983 mkArbitraryType :: (SrcSpan -> SDoc -> TcRnIf g l a) -- How to complain
985 -> TcRnIf g l Type -- Used by desugarer too
986 -- Make up an arbitrary type whose kind is the same as the tyvar.
987 -- We'll use this to instantiate the (unbound) tyvar.
989 -- Also used by the desugarer; hence the (tiresome) parameter
990 -- to use when generating a warning
991 mkArbitraryType warn tv
992 | liftedTypeKind `isSubKind` kind -- The vastly common case
994 | eqKind kind (tyConKind anyPrimTyCon1) -- *->*
995 = return (mkTyConApp anyPrimTyCon1 []) -- No tuples this size
996 | all isLiftedTypeKind args -- *-> ... ->*->*
997 , isLiftedTypeKind res -- Horrible hack to make less use
998 = return (mkTyConApp tup_tc []) -- of mkAnyPrimTyCon
1000 = do { warn (getSrcSpan tv) msg
1001 ; return (mkTyConApp (mkAnyPrimTyCon (getUnique tv) kind) []) }
1002 -- Same name as the tyvar, apart from making it start with a colon (sigh)
1003 -- I dread to think what will happen if this gets out into an
1004 -- interface file. Catastrophe likely. Major sigh.
1007 (args,res) = splitKindFunTys kind
1008 tup_tc = tupleTyCon Boxed (length args)
1010 msg = vcat [ hang (ptext SLIT("Inventing strangely-kinded Any TyCon"))
1011 2 (ptext SLIT("of kind") <+> quotes (ppr kind))
1012 , nest 2 (ptext SLIT("from an instantiation of type variable") <+> quotes (ppr tv))
1013 , ptext SLIT("This warning can be suppressed by a type signature fixing") <+> quotes (ppr tv)
1014 , nest 2 (ptext SLIT("but is harmless without -O (and usually harmless anyway)."))
1015 , ptext SLIT("See http://hackage.haskell.org/trac/ghc/ticket/959 for details") ]