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 ds inl))
317 = do { expr' <- zonkExpr env expr
318 ; ty' <- zonkTcTypeToType env ty
319 ; let ds' = zonkIdOccs env ds
320 ; return (L loc (SpecPrag expr' ty' ds' inl)) }
323 %************************************************************************
325 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
327 %************************************************************************
330 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
331 zonkMatchGroup env (MatchGroup ms ty)
332 = do { ms' <- mapM (zonkMatch env) ms
333 ; ty' <- zonkTcTypeToType env ty
334 ; return (MatchGroup ms' ty') }
336 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
337 zonkMatch env (L loc (Match pats _ grhss))
338 = do { (env1, new_pats) <- zonkPats env pats
339 ; new_grhss <- zonkGRHSs env1 grhss
340 ; return (L loc (Match new_pats Nothing new_grhss)) }
342 -------------------------------------------------------------------------
343 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
345 zonkGRHSs env (GRHSs grhss binds)
346 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
348 zonk_grhs (GRHS guarded rhs)
349 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
350 zonkLExpr env2 rhs `thenM` \ new_rhs ->
351 returnM (GRHS new_guarded new_rhs)
353 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
354 returnM (GRHSs new_grhss new_binds)
357 %************************************************************************
359 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
361 %************************************************************************
364 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
365 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
366 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
368 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
369 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
371 zonkExpr env (HsVar id)
372 = returnM (HsVar (zonkIdOcc env id))
374 zonkExpr env (HsIPVar id)
375 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
377 zonkExpr env (HsLit (HsRat f ty))
378 = zonkTcTypeToType env ty `thenM` \ new_ty ->
379 returnM (HsLit (HsRat f new_ty))
381 zonkExpr env (HsLit lit)
382 = returnM (HsLit lit)
384 zonkExpr env (HsOverLit lit)
385 = do { lit' <- zonkOverLit env lit
386 ; return (HsOverLit lit') }
388 zonkExpr env (HsLam matches)
389 = zonkMatchGroup env matches `thenM` \ new_matches ->
390 returnM (HsLam new_matches)
392 zonkExpr env (HsApp e1 e2)
393 = zonkLExpr env e1 `thenM` \ new_e1 ->
394 zonkLExpr env e2 `thenM` \ new_e2 ->
395 returnM (HsApp new_e1 new_e2)
397 zonkExpr env (HsBracketOut body bs)
398 = mappM zonk_b bs `thenM` \ bs' ->
399 returnM (HsBracketOut body bs')
401 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
404 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
405 returnM (HsSpliceE s)
407 zonkExpr env (OpApp e1 op fixity e2)
408 = zonkLExpr env e1 `thenM` \ new_e1 ->
409 zonkLExpr env op `thenM` \ new_op ->
410 zonkLExpr env e2 `thenM` \ new_e2 ->
411 returnM (OpApp new_e1 new_op fixity new_e2)
413 zonkExpr env (NegApp expr op)
414 = zonkLExpr env expr `thenM` \ new_expr ->
415 zonkExpr env op `thenM` \ new_op ->
416 returnM (NegApp new_expr new_op)
418 zonkExpr env (HsPar e)
419 = zonkLExpr env e `thenM` \new_e ->
420 returnM (HsPar new_e)
422 zonkExpr env (SectionL expr op)
423 = zonkLExpr env expr `thenM` \ new_expr ->
424 zonkLExpr env op `thenM` \ new_op ->
425 returnM (SectionL new_expr new_op)
427 zonkExpr env (SectionR op expr)
428 = zonkLExpr env op `thenM` \ new_op ->
429 zonkLExpr env expr `thenM` \ new_expr ->
430 returnM (SectionR new_op new_expr)
432 zonkExpr env (HsCase expr ms)
433 = zonkLExpr env expr `thenM` \ new_expr ->
434 zonkMatchGroup env ms `thenM` \ new_ms ->
435 returnM (HsCase new_expr new_ms)
437 zonkExpr env (HsIf e1 e2 e3)
438 = zonkLExpr env e1 `thenM` \ new_e1 ->
439 zonkLExpr env e2 `thenM` \ new_e2 ->
440 zonkLExpr env e3 `thenM` \ new_e3 ->
441 returnM (HsIf new_e1 new_e2 new_e3)
443 zonkExpr env (HsLet binds expr)
444 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
445 zonkLExpr new_env expr `thenM` \ new_expr ->
446 returnM (HsLet new_binds new_expr)
448 zonkExpr env (HsDo do_or_lc stmts body ty)
449 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
450 zonkLExpr new_env body `thenM` \ new_body ->
451 zonkTcTypeToType env ty `thenM` \ new_ty ->
452 returnM (HsDo (zonkDo env do_or_lc)
453 new_stmts new_body new_ty)
455 zonkExpr env (ExplicitList ty exprs)
456 = zonkTcTypeToType env ty `thenM` \ new_ty ->
457 zonkLExprs env exprs `thenM` \ new_exprs ->
458 returnM (ExplicitList new_ty new_exprs)
460 zonkExpr env (ExplicitPArr ty exprs)
461 = zonkTcTypeToType env ty `thenM` \ new_ty ->
462 zonkLExprs env exprs `thenM` \ new_exprs ->
463 returnM (ExplicitPArr new_ty new_exprs)
465 zonkExpr env (ExplicitTuple exprs boxed)
466 = zonkLExprs env exprs `thenM` \ new_exprs ->
467 returnM (ExplicitTuple new_exprs boxed)
469 zonkExpr env (RecordCon data_con con_expr rbinds)
470 = do { new_con_expr <- zonkExpr env con_expr
471 ; new_rbinds <- zonkRecFields env rbinds
472 ; return (RecordCon data_con new_con_expr new_rbinds) }
474 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
475 = do { new_expr <- zonkLExpr env expr
476 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
477 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
478 ; new_rbinds <- zonkRecFields env rbinds
479 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
481 zonkExpr env (ExprWithTySigOut e ty)
482 = do { e' <- zonkLExpr env e
483 ; return (ExprWithTySigOut e' ty) }
485 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
487 zonkExpr env (ArithSeq expr info)
488 = zonkExpr env expr `thenM` \ new_expr ->
489 zonkArithSeq env info `thenM` \ new_info ->
490 returnM (ArithSeq new_expr new_info)
492 zonkExpr env (PArrSeq expr info)
493 = zonkExpr env expr `thenM` \ new_expr ->
494 zonkArithSeq env info `thenM` \ new_info ->
495 returnM (PArrSeq new_expr new_info)
497 zonkExpr env (HsSCC lbl expr)
498 = zonkLExpr env expr `thenM` \ new_expr ->
499 returnM (HsSCC lbl new_expr)
501 zonkExpr env (HsTickPragma info expr)
502 = zonkLExpr env expr `thenM` \ new_expr ->
503 returnM (HsTickPragma info new_expr)
505 -- hdaume: core annotations
506 zonkExpr env (HsCoreAnn lbl expr)
507 = zonkLExpr env expr `thenM` \ new_expr ->
508 returnM (HsCoreAnn lbl new_expr)
510 -- arrow notation extensions
511 zonkExpr env (HsProc pat body)
512 = do { (env1, new_pat) <- zonkPat env pat
513 ; new_body <- zonkCmdTop env1 body
514 ; return (HsProc new_pat new_body) }
516 zonkExpr env (HsArrApp e1 e2 ty ho rl)
517 = zonkLExpr env e1 `thenM` \ new_e1 ->
518 zonkLExpr env e2 `thenM` \ new_e2 ->
519 zonkTcTypeToType env ty `thenM` \ new_ty ->
520 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
522 zonkExpr env (HsArrForm op fixity args)
523 = zonkLExpr env op `thenM` \ new_op ->
524 mappM (zonkCmdTop env) args `thenM` \ new_args ->
525 returnM (HsArrForm new_op fixity new_args)
527 zonkExpr env (HsWrap co_fn expr)
528 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
529 zonkExpr env1 expr `thenM` \ new_expr ->
530 return (HsWrap new_co_fn new_expr)
532 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
534 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
535 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
537 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
538 = zonkLExpr env cmd `thenM` \ new_cmd ->
539 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
540 zonkTcTypeToType env ty `thenM` \ new_ty ->
541 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
542 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
544 -------------------------------------------------------------------------
545 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
546 zonkCoFn env WpHole = return (env, WpHole)
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' <- zonkIdBndr 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 (LetStmt binds)
650 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
651 returnM (env1, LetStmt new_binds)
653 zonkStmt env (BindStmt pat expr bind_op fail_op)
654 = do { new_expr <- zonkLExpr env expr
655 ; (env1, new_pat) <- zonkPat env pat
656 ; new_bind <- zonkExpr env bind_op
657 ; new_fail <- zonkExpr env fail_op
658 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
661 -------------------------------------------------------------------------
662 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
663 zonkRecFields env (HsRecFields flds dd)
664 = do { flds' <- mappM zonk_rbind flds
665 ; return (HsRecFields flds' dd) }
668 = do { new_expr <- zonkLExpr env (hsRecFieldArg fld)
669 ; return (fld { hsRecFieldArg = new_expr }) }
670 -- Field selectors have declared types; hence no zonking
672 -------------------------------------------------------------------------
673 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
674 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
678 %************************************************************************
680 \subsection[BackSubst-Pats]{Patterns}
682 %************************************************************************
685 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
686 -- Extend the environment as we go, because it's possible for one
687 -- pattern to bind something that is used in another (inside or
689 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
691 zonk_pat env (ParPat p)
692 = do { (env', p') <- zonkPat env p
693 ; return (env', ParPat p') }
695 zonk_pat env (WildPat ty)
696 = do { ty' <- zonkTcTypeToType env ty
697 ; return (env, WildPat ty') }
699 zonk_pat env (VarPat v)
700 = do { v' <- zonkIdBndr env v
701 ; return (extendZonkEnv1 env v', VarPat v') }
703 zonk_pat env (VarPatOut v binds)
704 = do { v' <- zonkIdBndr env v
705 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
706 ; returnM (env', VarPatOut v' binds') }
708 zonk_pat env (LazyPat pat)
709 = do { (env', pat') <- zonkPat env pat
710 ; return (env', LazyPat pat') }
712 zonk_pat env (BangPat pat)
713 = do { (env', pat') <- zonkPat env pat
714 ; return (env', BangPat pat') }
716 zonk_pat env (AsPat (L loc v) pat)
717 = do { v' <- zonkIdBndr env v
718 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
719 ; return (env', AsPat (L loc v') pat') }
721 zonk_pat env (ViewPat expr pat ty)
722 = do { expr' <- zonkLExpr env expr
723 ; (env', pat') <- zonkPat env pat
724 ; return (env', ViewPat expr' pat' ty) }
726 zonk_pat env (ListPat pats ty)
727 = do { ty' <- zonkTcTypeToType env ty
728 ; (env', pats') <- zonkPats env pats
729 ; return (env', ListPat pats' ty') }
731 zonk_pat env (PArrPat pats ty)
732 = do { ty' <- zonkTcTypeToType env ty
733 ; (env', pats') <- zonkPats env pats
734 ; return (env', PArrPat pats' ty') }
736 zonk_pat env (TuplePat pats boxed ty)
737 = do { ty' <- zonkTcTypeToType env ty
738 ; (env', pats') <- zonkPats env pats
739 ; return (env', TuplePat pats' boxed ty') }
741 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
742 = ASSERT( all isImmutableTyVar (pat_tvs p) )
743 do { new_ty <- zonkTcTypeToType env ty
744 ; new_dicts <- zonkIdBndrs env dicts
745 ; let env1 = extendZonkEnv env new_dicts
746 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
747 ; (env', new_args) <- zonkConStuff env2 args
748 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
749 pat_binds = new_binds, pat_args = new_args }) }
751 zonk_pat env (LitPat lit) = return (env, LitPat lit)
753 zonk_pat env (SigPatOut pat ty)
754 = do { ty' <- zonkTcTypeToType env ty
755 ; (env', pat') <- zonkPat env pat
756 ; return (env', SigPatOut pat' ty') }
758 zonk_pat env (NPat lit mb_neg eq_expr)
759 = do { lit' <- zonkOverLit env lit
760 ; mb_neg' <- case mb_neg of
761 Nothing -> return Nothing
762 Just neg -> do { neg' <- zonkExpr env neg
763 ; return (Just neg') }
764 ; eq_expr' <- zonkExpr env eq_expr
765 ; return (env, NPat lit' mb_neg' eq_expr') }
767 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
768 = do { n' <- zonkIdBndr env n
769 ; lit' <- zonkOverLit env lit
770 ; e1' <- zonkExpr env e1
771 ; e2' <- zonkExpr env e2
772 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
774 zonk_pat env (CoPat co_fn pat ty)
775 = do { (env', co_fn') <- zonkCoFn env co_fn
776 ; (env'', pat') <- zonkPat env' (noLoc pat)
777 ; ty' <- zonkTcTypeToType env'' ty
778 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
780 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
782 ---------------------------
783 zonkConStuff env (PrefixCon pats)
784 = do { (env', pats') <- zonkPats env pats
785 ; return (env', PrefixCon pats') }
787 zonkConStuff env (InfixCon p1 p2)
788 = do { (env1, p1') <- zonkPat env p1
789 ; (env', p2') <- zonkPat env1 p2
790 ; return (env', InfixCon p1' p2') }
792 zonkConStuff env (RecCon (HsRecFields rpats dd))
793 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
794 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
795 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
796 -- Field selectors have declared types; hence no zonking
798 ---------------------------
799 zonkPats env [] = return (env, [])
800 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
801 ; (env', pats') <- zonkPats env1 pats
802 ; return (env', pat':pats') }
805 %************************************************************************
807 \subsection[BackSubst-Foreign]{Foreign exports}
809 %************************************************************************
813 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
814 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
816 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
817 zonkForeignExport env (ForeignExport i hs_ty spec) =
818 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
819 zonkForeignExport env for_imp
820 = returnM for_imp -- Foreign imports don't need zonking
824 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
825 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
827 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
828 zonkRule env (HsRule name act (vars::[RuleBndr TcId]) lhs fv_lhs rhs fv_rhs)
829 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
830 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
832 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
833 -- Type variables don't need an envt
834 -- They are bound through the mutable mechanism
836 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
837 -- We need to gather the type variables mentioned on the LHS so we can
838 -- quantify over them. Example:
844 -- {-# RULES "myrule" foo C = 1 #-}
846 -- After type checking the LHS becomes (foo a (C a))
847 -- and we do not want to zap the unbound tyvar 'a' to (), because
848 -- that limits the applicability of the rule. Instead, we
849 -- want to quantify over it!
851 -- It's easiest to find the free tyvars here. Attempts to do so earlier
852 -- are tiresome, because (a) the data type is big and (b) finding the
853 -- free type vars of an expression is necessarily monadic operation.
854 -- (consider /\a -> f @ b, where b is side-effected to a)
856 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
857 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
859 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
861 final_bndrs :: [Located Var]
862 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
864 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
865 -- I hate this map RuleBndr stuff
867 zonk_bndr (RuleBndr v)
868 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
869 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
874 %************************************************************************
876 \subsection[BackSubst-Foreign]{Foreign exports}
878 %************************************************************************
881 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
882 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
884 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
885 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
887 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
888 -- This variant collects unbound type variables in a mutable variable
889 zonkTypeCollecting unbound_tv_set
890 = zonkType zonk_unbound_tyvar
892 zonk_unbound_tyvar tv
893 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
894 readMutVar unbound_tv_set `thenM` \ tv_set ->
895 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
896 return (mkTyVarTy tv')
898 zonkTypeZapping :: TcType -> TcM Type
899 -- This variant is used for everything except the LHS of rules
900 -- It zaps unbound type variables to (), or some other arbitrary type
902 = zonkType zonk_unbound_tyvar ty
904 -- Zonk a mutable but unbound type variable to an arbitrary type
905 -- We know it's unbound even though we don't carry an environment,
906 -- because at the binding site for a type variable we bind the
907 -- mutable tyvar to a fresh immutable one. So the mutable store
908 -- plays the role of an environment. If we come across a mutable
909 -- type variable that isn't so bound, it must be completely free.
910 zonk_unbound_tyvar tv = do { writeMetaTyVar tv ty; return ty }
912 ty = mkArbitraryType tv
915 -- When the type checker finds a type variable with no binding,
916 -- which means it can be instantiated with an arbitrary type, it
917 -- usually instantiates it to Void. Eg.
921 -- length Void (Nil Void)
923 -- But in really obscure programs, the type variable might have
924 -- a kind other than *, so we need to invent a suitably-kinded type.
928 -- List for kind *->*
929 -- Tuple for kind *->...*->*
931 -- which deals with most cases. (Previously, it only dealt with
934 -- In the other cases, it just makes up a TyCon with a suitable
935 -- kind. If this gets into an interface file, anyone reading that
936 -- file won't understand it. This is fixable (by making the client
937 -- of the interface file make up a TyCon too) but it is tiresome and
938 -- never happens, so I am leaving it
940 mkArbitraryType :: TcTyVar -> Type
941 -- Make up an arbitrary type whose kind is the same as the tyvar.
942 -- We'll use this to instantiate the (unbound) tyvar.
944 | liftedTypeKind `isSubKind` kind = anyPrimTy -- The vastly common case
945 | otherwise = mkTyConApp tycon []
948 (args,res) = splitKindFunTys kind
950 tycon | eqKind kind (tyConKind anyPrimTyCon1) -- *->*
951 = anyPrimTyCon1 -- No tuples this size
953 | all isLiftedTypeKind args && isLiftedTypeKind res
954 = tupleTyCon Boxed (length args) -- *-> ... ->*->*
955 -- Horrible hack to make less use of mkAnyPrimTyCon
958 = mkAnyPrimTyCon (getUnique tv) kind
959 -- Same name as the tyvar, apart from making it start with a colon (sigh)
960 -- I dread to think what will happen if this gets out into an
961 -- interface file. Catastrophe likely. Major sigh.