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,
18 mkArbitraryType, -- Put this elsewhere?
20 -- re-exported from TcMonad
21 TcId, TcIdSet, TcDictBinds,
23 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
27 #include "HsVersions.h"
30 import HsSyn -- oodles of it
56 %************************************************************************
58 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
60 %************************************************************************
62 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
63 then something is wrong.
65 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
66 -- A vanilla tuple pattern simply gets its type from its sub-patterns
67 mkVanillaTuplePat pats box
68 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
70 hsLPatType :: OutPat Id -> Type
71 hsLPatType (L _ pat) = hsPatType pat
73 hsPatType (ParPat pat) = hsLPatType pat
74 hsPatType (WildPat ty) = ty
75 hsPatType (VarPat var) = idType var
76 hsPatType (VarPatOut var _) = idType var
77 hsPatType (BangPat pat) = hsLPatType pat
78 hsPatType (LazyPat pat) = hsLPatType pat
79 hsPatType (LitPat lit) = hsLitType lit
80 hsPatType (AsPat var pat) = idType (unLoc var)
81 hsPatType (ListPat _ ty) = mkListTy ty
82 hsPatType (PArrPat _ ty) = mkPArrTy ty
83 hsPatType (TuplePat pats box ty) = ty
84 hsPatType (ConPatOut{ pat_ty = ty })= ty
85 hsPatType (SigPatOut pat ty) = ty
86 hsPatType (NPat lit _ _ ty) = ty
87 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
88 hsPatType (CoPat _ _ ty) = ty
90 hsLitType :: HsLit -> TcType
91 hsLitType (HsChar c) = charTy
92 hsLitType (HsCharPrim c) = charPrimTy
93 hsLitType (HsString str) = stringTy
94 hsLitType (HsStringPrim s) = addrPrimTy
95 hsLitType (HsInt i) = intTy
96 hsLitType (HsIntPrim i) = intPrimTy
97 hsLitType (HsInteger i ty) = ty
98 hsLitType (HsRat _ ty) = ty
99 hsLitType (HsFloatPrim f) = floatPrimTy
100 hsLitType (HsDoublePrim d) = doublePrimTy
104 %************************************************************************
106 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
108 %************************************************************************
111 -- zonkId is used *during* typechecking just to zonk the Id's type
112 zonkId :: TcId -> TcM TcId
114 = zonkTcType (idType id) `thenM` \ ty' ->
115 returnM (Id.setIdType id ty')
118 The rest of the zonking is done *after* typechecking.
119 The main zonking pass runs over the bindings
121 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
122 b) convert unbound TcTyVar to Void
123 c) convert each TcId to an Id by zonking its type
125 The type variables are converted by binding mutable tyvars to immutable ones
126 and then zonking as normal.
128 The Ids are converted by binding them in the normal Tc envt; that
129 way we maintain sharing; eg an Id is zonked at its binding site and they
130 all occurrences of that Id point to the common zonked copy
132 It's all pretty boring stuff, because HsSyn is such a large type, and
133 the environment manipulation is tiresome.
136 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
137 (IdEnv Id) -- What variables are in scope
138 -- Maps an Id to its zonked version; both have the same Name
139 -- Is only consulted lazily; hence knot-tying
141 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
143 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
144 extendZonkEnv (ZonkEnv zonk_ty env) ids
145 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
147 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
148 extendZonkEnv1 (ZonkEnv zonk_ty env) id
149 = ZonkEnv zonk_ty (extendVarEnv env id id)
151 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
152 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
154 zonkEnvIds :: ZonkEnv -> [Id]
155 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
157 zonkIdOcc :: ZonkEnv -> TcId -> Id
158 -- Ids defined in this module should be in the envt;
159 -- ignore others. (Actually, data constructors are also
160 -- not LocalVars, even when locally defined, but that is fine.)
161 -- (Also foreign-imported things aren't currently in the ZonkEnv;
162 -- that's ok because they don't need zonking.)
164 -- Actually, Template Haskell works in 'chunks' of declarations, and
165 -- an earlier chunk won't be in the 'env' that the zonking phase
166 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
167 -- zonked. There's no point in looking it up there (except for error
168 -- checking), and it's not conveniently to hand; hence the simple
169 -- 'orElse' case in the LocalVar branch.
171 -- Even without template splices, in module Main, the checking of
172 -- 'main' is done as a separate chunk.
173 zonkIdOcc (ZonkEnv zonk_ty env) id
174 | isLocalVar id = lookupVarEnv env id `orElse` id
177 zonkIdOccs env ids = map (zonkIdOcc env) ids
179 -- zonkIdBndr is used *after* typechecking to get the Id's type
180 -- to its final form. The TyVarEnv give
181 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
183 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
184 returnM (Id.setIdType id ty')
186 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
187 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
189 zonkTopBndrs :: [TcId] -> TcM [Id]
190 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
195 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
196 zonkTopExpr e = zonkExpr emptyZonkEnv e
198 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
199 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
201 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
206 zonkTopDecls binds rules fords
207 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
208 -- Top level is implicitly recursive
209 ; rules' <- zonkRules env rules
210 ; fords' <- zonkForeignExports env fords
211 ; return (zonkEnvIds env, binds', fords', rules') }
213 ---------------------------------------------
214 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
215 zonkLocalBinds env EmptyLocalBinds
216 = return (env, EmptyLocalBinds)
218 zonkLocalBinds env (HsValBinds binds)
219 = do { (env1, new_binds) <- zonkValBinds env binds
220 ; return (env1, HsValBinds new_binds) }
222 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
223 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
225 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
227 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
228 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
230 zonk_ip_bind (IPBind n e)
231 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
232 zonkLExpr env e `thenM` \ e' ->
233 returnM (IPBind n' e')
236 ---------------------------------------------
237 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
238 zonkValBinds env bs@(ValBindsIn _ _)
239 = panic "zonkValBinds" -- Not in typechecker output
240 zonkValBinds env (ValBindsOut binds sigs)
241 = do { (env1, new_binds) <- go env binds
242 ; return (env1, ValBindsOut new_binds sigs) }
244 go env [] = return (env, [])
245 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
246 ; (env2, bs') <- go env1 bs
247 ; return (env2, (r,b'):bs') }
249 ---------------------------------------------
250 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
251 zonkRecMonoBinds env binds
252 = fixM (\ ~(_, new_binds) -> do
253 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
254 ; binds' <- zonkMonoBinds env1 binds
255 ; return (env1, binds') })
257 ---------------------------------------------
258 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
259 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
261 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
262 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
263 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
264 ; new_grhss <- zonkGRHSs env grhss
265 ; new_ty <- zonkTcTypeToType env ty
266 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
268 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
269 = zonkIdBndr env var `thenM` \ new_var ->
270 zonkLExpr env expr `thenM` \ new_expr ->
271 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
273 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
274 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
275 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
276 zonkMatchGroup env1 ms `thenM` \ new_ms ->
277 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
279 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
280 abs_exports = exports, abs_binds = val_binds })
281 = ASSERT( all isImmutableTyVar tyvars )
282 zonkIdBndrs env dicts `thenM` \ new_dicts ->
283 fixM (\ ~(new_val_binds, _) ->
285 env1 = extendZonkEnv env new_dicts
286 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
288 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
289 mappM (zonkExport env2) exports `thenM` \ new_exports ->
290 returnM (new_val_binds, new_exports)
291 ) `thenM` \ (new_val_bind, new_exports) ->
292 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
293 abs_exports = new_exports, abs_binds = new_val_bind })
295 zonkExport env (tyvars, global, local, prags)
296 -- The tyvars are already zonked
297 = zonkIdBndr env global `thenM` \ new_global ->
298 mapM zonk_prag prags `thenM` \ new_prags ->
299 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
300 zonk_prag prag@(L _ (InlinePrag {})) = return prag
301 zonk_prag (L loc (SpecPrag expr ty ds inl))
302 = do { expr' <- zonkExpr env expr
303 ; ty' <- zonkTcTypeToType env ty
304 ; let ds' = zonkIdOccs env ds
305 ; return (L loc (SpecPrag expr' ty' ds' inl)) }
308 %************************************************************************
310 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
312 %************************************************************************
315 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
316 zonkMatchGroup env (MatchGroup ms ty)
317 = do { ms' <- mapM (zonkMatch env) ms
318 ; ty' <- zonkTcTypeToType env ty
319 ; return (MatchGroup ms' ty') }
321 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
322 zonkMatch env (L loc (Match pats _ grhss))
323 = do { (env1, new_pats) <- zonkPats env pats
324 ; new_grhss <- zonkGRHSs env1 grhss
325 ; return (L loc (Match new_pats Nothing new_grhss)) }
327 -------------------------------------------------------------------------
328 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
330 zonkGRHSs env (GRHSs grhss binds)
331 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
333 zonk_grhs (GRHS guarded rhs)
334 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
335 zonkLExpr env2 rhs `thenM` \ new_rhs ->
336 returnM (GRHS new_guarded new_rhs)
338 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
339 returnM (GRHSs new_grhss new_binds)
342 %************************************************************************
344 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
346 %************************************************************************
349 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
350 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
351 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
353 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
354 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
356 zonkExpr env (HsVar id)
357 = returnM (HsVar (zonkIdOcc env id))
359 zonkExpr env (HsIPVar id)
360 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
362 zonkExpr env (HsLit (HsRat f ty))
363 = zonkTcTypeToType env ty `thenM` \ new_ty ->
364 returnM (HsLit (HsRat f new_ty))
366 zonkExpr env (HsLit lit)
367 = returnM (HsLit lit)
369 zonkExpr env (HsOverLit lit)
370 = do { lit' <- zonkOverLit env lit
371 ; return (HsOverLit lit') }
373 zonkExpr env (HsLam matches)
374 = zonkMatchGroup env matches `thenM` \ new_matches ->
375 returnM (HsLam new_matches)
377 zonkExpr env (HsApp e1 e2)
378 = zonkLExpr env e1 `thenM` \ new_e1 ->
379 zonkLExpr env e2 `thenM` \ new_e2 ->
380 returnM (HsApp new_e1 new_e2)
382 zonkExpr env (HsBracketOut body bs)
383 = mappM zonk_b bs `thenM` \ bs' ->
384 returnM (HsBracketOut body bs')
386 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
389 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
390 returnM (HsSpliceE s)
392 zonkExpr env (OpApp e1 op fixity e2)
393 = zonkLExpr env e1 `thenM` \ new_e1 ->
394 zonkLExpr env op `thenM` \ new_op ->
395 zonkLExpr env e2 `thenM` \ new_e2 ->
396 returnM (OpApp new_e1 new_op fixity new_e2)
398 zonkExpr env (NegApp expr op)
399 = zonkLExpr env expr `thenM` \ new_expr ->
400 zonkExpr env op `thenM` \ new_op ->
401 returnM (NegApp new_expr new_op)
403 zonkExpr env (HsPar e)
404 = zonkLExpr env e `thenM` \new_e ->
405 returnM (HsPar new_e)
407 zonkExpr env (SectionL expr op)
408 = zonkLExpr env expr `thenM` \ new_expr ->
409 zonkLExpr env op `thenM` \ new_op ->
410 returnM (SectionL new_expr new_op)
412 zonkExpr env (SectionR op expr)
413 = zonkLExpr env op `thenM` \ new_op ->
414 zonkLExpr env expr `thenM` \ new_expr ->
415 returnM (SectionR new_op new_expr)
417 zonkExpr env (HsCase expr ms)
418 = zonkLExpr env expr `thenM` \ new_expr ->
419 zonkMatchGroup env ms `thenM` \ new_ms ->
420 returnM (HsCase new_expr new_ms)
422 zonkExpr env (HsIf e1 e2 e3)
423 = zonkLExpr env e1 `thenM` \ new_e1 ->
424 zonkLExpr env e2 `thenM` \ new_e2 ->
425 zonkLExpr env e3 `thenM` \ new_e3 ->
426 returnM (HsIf new_e1 new_e2 new_e3)
428 zonkExpr env (HsLet binds expr)
429 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
430 zonkLExpr new_env expr `thenM` \ new_expr ->
431 returnM (HsLet new_binds new_expr)
433 zonkExpr env (HsDo do_or_lc stmts body ty)
434 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
435 zonkLExpr new_env body `thenM` \ new_body ->
436 zonkTcTypeToType env ty `thenM` \ new_ty ->
437 returnM (HsDo (zonkDo env do_or_lc)
438 new_stmts new_body new_ty)
440 zonkExpr env (ExplicitList ty exprs)
441 = zonkTcTypeToType env ty `thenM` \ new_ty ->
442 zonkLExprs env exprs `thenM` \ new_exprs ->
443 returnM (ExplicitList new_ty new_exprs)
445 zonkExpr env (ExplicitPArr ty exprs)
446 = zonkTcTypeToType env ty `thenM` \ new_ty ->
447 zonkLExprs env exprs `thenM` \ new_exprs ->
448 returnM (ExplicitPArr new_ty new_exprs)
450 zonkExpr env (ExplicitTuple exprs boxed)
451 = zonkLExprs env exprs `thenM` \ new_exprs ->
452 returnM (ExplicitTuple new_exprs boxed)
454 zonkExpr env (RecordCon data_con con_expr rbinds)
455 = do { new_con_expr <- zonkExpr env con_expr
456 ; new_rbinds <- zonkRecFields env rbinds
457 ; return (RecordCon data_con new_con_expr new_rbinds) }
459 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
460 = do { new_expr <- zonkLExpr env expr
461 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
462 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
463 ; new_rbinds <- zonkRecFields env rbinds
464 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
466 zonkExpr env (ExprWithTySigOut e ty)
467 = do { e' <- zonkLExpr env e
468 ; return (ExprWithTySigOut e' ty) }
470 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
472 zonkExpr env (ArithSeq expr info)
473 = zonkExpr env expr `thenM` \ new_expr ->
474 zonkArithSeq env info `thenM` \ new_info ->
475 returnM (ArithSeq new_expr new_info)
477 zonkExpr env (PArrSeq expr info)
478 = zonkExpr env expr `thenM` \ new_expr ->
479 zonkArithSeq env info `thenM` \ new_info ->
480 returnM (PArrSeq new_expr new_info)
482 zonkExpr env (HsSCC lbl expr)
483 = zonkLExpr env expr `thenM` \ new_expr ->
484 returnM (HsSCC lbl new_expr)
486 zonkExpr env (HsTickPragma info expr)
487 = zonkLExpr env expr `thenM` \ new_expr ->
488 returnM (HsTickPragma info new_expr)
490 -- hdaume: core annotations
491 zonkExpr env (HsCoreAnn lbl expr)
492 = zonkLExpr env expr `thenM` \ new_expr ->
493 returnM (HsCoreAnn lbl new_expr)
495 -- arrow notation extensions
496 zonkExpr env (HsProc pat body)
497 = do { (env1, new_pat) <- zonkPat env pat
498 ; new_body <- zonkCmdTop env1 body
499 ; return (HsProc new_pat new_body) }
501 zonkExpr env (HsArrApp e1 e2 ty ho rl)
502 = zonkLExpr env e1 `thenM` \ new_e1 ->
503 zonkLExpr env e2 `thenM` \ new_e2 ->
504 zonkTcTypeToType env ty `thenM` \ new_ty ->
505 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
507 zonkExpr env (HsArrForm op fixity args)
508 = zonkLExpr env op `thenM` \ new_op ->
509 mappM (zonkCmdTop env) args `thenM` \ new_args ->
510 returnM (HsArrForm new_op fixity new_args)
512 zonkExpr env (HsWrap co_fn expr)
513 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
514 zonkExpr env1 expr `thenM` \ new_expr ->
515 return (HsWrap new_co_fn new_expr)
517 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
519 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
520 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
522 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
523 = zonkLExpr env cmd `thenM` \ new_cmd ->
524 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
525 zonkTcTypeToType env ty `thenM` \ new_ty ->
526 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
527 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
529 -------------------------------------------------------------------------
530 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
531 zonkCoFn env WpHole = return (env, WpHole)
532 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
533 ; (env2, c2') <- zonkCoFn env1 c2
534 ; return (env2, WpCompose c1' c2') }
535 zonkCoFn env (WpCo co) = do { co' <- zonkTcTypeToType env co
536 ; return (env, WpCo co') }
537 zonkCoFn env (WpLam id) = do { id' <- zonkIdBndr env id
538 ; let env1 = extendZonkEnv1 env id'
539 ; return (env1, WpLam id') }
540 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
541 do { return (env, WpTyLam tv) }
542 zonkCoFn env (WpApp id) = do { return (env, WpApp (zonkIdOcc env id)) }
543 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
544 ; return (env, WpTyApp ty') }
545 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
546 ; return (env1, WpLet bs') }
549 -------------------------------------------------------------------------
550 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
551 -- Only used for 'do', so the only Ids are in a MDoExpr table
552 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
553 zonkDo env do_or_lc = do_or_lc
555 -------------------------------------------------------------------------
556 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
557 zonkOverLit env (HsIntegral i e)
558 = do { e' <- zonkExpr env e; return (HsIntegral i e') }
559 zonkOverLit env (HsFractional r e)
560 = do { e' <- zonkExpr env e; return (HsFractional r e') }
561 zonkOverLit env (HsIsString s e)
562 = do { e' <- zonkExpr env e; return (HsIsString s e') }
564 -------------------------------------------------------------------------
565 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
567 zonkArithSeq env (From e)
568 = zonkLExpr env e `thenM` \ new_e ->
571 zonkArithSeq env (FromThen e1 e2)
572 = zonkLExpr env e1 `thenM` \ new_e1 ->
573 zonkLExpr env e2 `thenM` \ new_e2 ->
574 returnM (FromThen new_e1 new_e2)
576 zonkArithSeq env (FromTo e1 e2)
577 = zonkLExpr env e1 `thenM` \ new_e1 ->
578 zonkLExpr env e2 `thenM` \ new_e2 ->
579 returnM (FromTo new_e1 new_e2)
581 zonkArithSeq env (FromThenTo e1 e2 e3)
582 = zonkLExpr env e1 `thenM` \ new_e1 ->
583 zonkLExpr env e2 `thenM` \ new_e2 ->
584 zonkLExpr env e3 `thenM` \ new_e3 ->
585 returnM (FromThenTo new_e1 new_e2 new_e3)
588 -------------------------------------------------------------------------
589 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
590 zonkStmts env [] = return (env, [])
591 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
592 ; (env2, ss') <- zonkStmts env1 ss
593 ; return (env2, s' : ss') }
595 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
596 zonkStmt env (ParStmt stmts_w_bndrs)
597 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
599 new_binders = concat (map snd new_stmts_w_bndrs)
600 env1 = extendZonkEnv env new_binders
602 return (env1, ParStmt new_stmts_w_bndrs)
604 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
605 returnM (new_stmts, zonkIdOccs env1 bndrs)
607 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
608 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
610 env1 = extendZonkEnv env new_rvs
612 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
613 -- Zonk the ret-expressions in an envt that
614 -- has the polymorphic bindings in the envt
615 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
617 new_lvs = zonkIdOccs env2 lvs
618 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
620 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
621 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
623 zonkStmt env (ExprStmt expr then_op ty)
624 = zonkLExpr env expr `thenM` \ new_expr ->
625 zonkExpr env then_op `thenM` \ new_then ->
626 zonkTcTypeToType env ty `thenM` \ new_ty ->
627 returnM (env, ExprStmt new_expr new_then new_ty)
629 zonkStmt env (LetStmt binds)
630 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
631 returnM (env1, LetStmt new_binds)
633 zonkStmt env (BindStmt pat expr bind_op fail_op)
634 = do { new_expr <- zonkLExpr env expr
635 ; (env1, new_pat) <- zonkPat env pat
636 ; new_bind <- zonkExpr env bind_op
637 ; new_fail <- zonkExpr env fail_op
638 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
641 -------------------------------------------------------------------------
642 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
643 zonkRecFields env (HsRecFields flds dd)
644 = do { flds' <- mappM zonk_rbind flds
645 ; return (HsRecFields flds' dd) }
648 = do { new_expr <- zonkLExpr env (hsRecFieldArg fld)
649 ; return (fld { hsRecFieldArg = new_expr }) }
650 -- Field selectors have declared types; hence no zonking
652 -------------------------------------------------------------------------
653 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
654 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
658 %************************************************************************
660 \subsection[BackSubst-Pats]{Patterns}
662 %************************************************************************
665 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
666 -- Extend the environment as we go, because it's possible for one
667 -- pattern to bind something that is used in another (inside or
669 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
671 zonk_pat env (ParPat p)
672 = do { (env', p') <- zonkPat env p
673 ; return (env', ParPat p') }
675 zonk_pat env (WildPat ty)
676 = do { ty' <- zonkTcTypeToType env ty
677 ; return (env, WildPat ty') }
679 zonk_pat env (VarPat v)
680 = do { v' <- zonkIdBndr env v
681 ; return (extendZonkEnv1 env v', VarPat v') }
683 zonk_pat env (VarPatOut v binds)
684 = do { v' <- zonkIdBndr env v
685 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
686 ; returnM (env', VarPatOut v' binds') }
688 zonk_pat env (LazyPat pat)
689 = do { (env', pat') <- zonkPat env pat
690 ; return (env', LazyPat pat') }
692 zonk_pat env (BangPat pat)
693 = do { (env', pat') <- zonkPat env pat
694 ; return (env', BangPat pat') }
696 zonk_pat env (AsPat (L loc v) pat)
697 = do { v' <- zonkIdBndr env v
698 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
699 ; return (env', AsPat (L loc v') pat') }
701 zonk_pat env (ListPat pats ty)
702 = do { ty' <- zonkTcTypeToType env ty
703 ; (env', pats') <- zonkPats env pats
704 ; return (env', ListPat pats' ty') }
706 zonk_pat env (PArrPat pats ty)
707 = do { ty' <- zonkTcTypeToType env ty
708 ; (env', pats') <- zonkPats env pats
709 ; return (env', PArrPat pats' ty') }
711 zonk_pat env (TuplePat pats boxed ty)
712 = do { ty' <- zonkTcTypeToType env ty
713 ; (env', pats') <- zonkPats env pats
714 ; return (env', TuplePat pats' boxed ty') }
716 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
717 = ASSERT( all isImmutableTyVar (pat_tvs p) )
718 do { new_ty <- zonkTcTypeToType env ty
719 ; new_dicts <- zonkIdBndrs env dicts
720 ; let env1 = extendZonkEnv env new_dicts
721 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
722 ; (env', new_args) <- zonkConStuff env2 args
723 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
724 pat_binds = new_binds, pat_args = new_args }) }
726 zonk_pat env (LitPat lit) = return (env, LitPat lit)
728 zonk_pat env (SigPatOut pat ty)
729 = do { ty' <- zonkTcTypeToType env ty
730 ; (env', pat') <- zonkPat env pat
731 ; return (env', SigPatOut pat' ty') }
733 zonk_pat env (NPat lit mb_neg eq_expr ty)
734 = do { lit' <- zonkOverLit env lit
735 ; mb_neg' <- case mb_neg of
736 Nothing -> return Nothing
737 Just neg -> do { neg' <- zonkExpr env neg
738 ; return (Just neg') }
739 ; eq_expr' <- zonkExpr env eq_expr
740 ; ty' <- zonkTcTypeToType env ty
741 ; return (env, NPat lit' mb_neg' eq_expr' ty') }
743 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
744 = do { n' <- zonkIdBndr env n
745 ; lit' <- zonkOverLit env lit
746 ; e1' <- zonkExpr env e1
747 ; e2' <- zonkExpr env e2
748 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
750 zonk_pat env (CoPat co_fn pat ty)
751 = do { (env', co_fn') <- zonkCoFn env co_fn
752 ; (env'', pat') <- zonkPat env' (noLoc pat)
753 ; ty' <- zonkTcTypeToType env'' ty
754 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
756 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
758 ---------------------------
759 zonkConStuff env (PrefixCon pats)
760 = do { (env', pats') <- zonkPats env pats
761 ; return (env', PrefixCon pats') }
763 zonkConStuff env (InfixCon p1 p2)
764 = do { (env1, p1') <- zonkPat env p1
765 ; (env', p2') <- zonkPat env1 p2
766 ; return (env', InfixCon p1' p2') }
768 zonkConStuff env (RecCon (HsRecFields rpats dd))
769 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
770 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
771 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
772 -- Field selectors have declared types; hence no zonking
774 ---------------------------
775 zonkPats env [] = return (env, [])
776 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
777 ; (env', pats') <- zonkPats env1 pats
778 ; return (env', pat':pats') }
781 %************************************************************************
783 \subsection[BackSubst-Foreign]{Foreign exports}
785 %************************************************************************
789 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
790 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
792 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
793 zonkForeignExport env (ForeignExport i hs_ty spec) =
794 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
795 zonkForeignExport env for_imp
796 = returnM for_imp -- Foreign imports don't need zonking
800 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
801 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
803 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
804 zonkRule env (HsRule name act (vars::[RuleBndr TcId]) lhs fv_lhs rhs fv_rhs)
805 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
806 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
808 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
809 -- Type variables don't need an envt
810 -- They are bound through the mutable mechanism
812 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
813 -- We need to gather the type variables mentioned on the LHS so we can
814 -- quantify over them. Example:
820 -- {-# RULES "myrule" foo C = 1 #-}
822 -- After type checking the LHS becomes (foo a (C a))
823 -- and we do not want to zap the unbound tyvar 'a' to (), because
824 -- that limits the applicability of the rule. Instead, we
825 -- want to quantify over it!
827 -- It's easiest to find the free tyvars here. Attempts to do so earlier
828 -- are tiresome, because (a) the data type is big and (b) finding the
829 -- free type vars of an expression is necessarily monadic operation.
830 -- (consider /\a -> f @ b, where b is side-effected to a)
832 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
833 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
835 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
837 final_bndrs :: [Located Var]
838 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
840 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
841 -- I hate this map RuleBndr stuff
843 zonk_bndr (RuleBndr v)
844 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
845 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
850 %************************************************************************
852 \subsection[BackSubst-Foreign]{Foreign exports}
854 %************************************************************************
857 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
858 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
860 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
861 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
863 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
864 -- This variant collects unbound type variables in a mutable variable
865 zonkTypeCollecting unbound_tv_set
866 = zonkType zonk_unbound_tyvar
868 zonk_unbound_tyvar tv
869 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
870 readMutVar unbound_tv_set `thenM` \ tv_set ->
871 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
872 return (mkTyVarTy tv')
874 zonkTypeZapping :: TcType -> TcM Type
875 -- This variant is used for everything except the LHS of rules
876 -- It zaps unbound type variables to (), or some other arbitrary type
878 = zonkType zonk_unbound_tyvar ty
880 -- Zonk a mutable but unbound type variable to an arbitrary type
881 -- We know it's unbound even though we don't carry an environment,
882 -- because at the binding site for a type variable we bind the
883 -- mutable tyvar to a fresh immutable one. So the mutable store
884 -- plays the role of an environment. If we come across a mutable
885 -- type variable that isn't so bound, it must be completely free.
886 zonk_unbound_tyvar tv = do { writeMetaTyVar tv ty; return ty }
888 ty = mkArbitraryType tv
891 -- When the type checker finds a type variable with no binding,
892 -- which means it can be instantiated with an arbitrary type, it
893 -- usually instantiates it to Void. Eg.
897 -- length Void (Nil Void)
899 -- But in really obscure programs, the type variable might have
900 -- a kind other than *, so we need to invent a suitably-kinded type.
904 -- List for kind *->*
905 -- Tuple for kind *->...*->*
907 -- which deals with most cases. (Previously, it only dealt with
910 -- In the other cases, it just makes up a TyCon with a suitable
911 -- kind. If this gets into an interface file, anyone reading that
912 -- file won't understand it. This is fixable (by making the client
913 -- of the interface file make up a TyCon too) but it is tiresome and
914 -- never happens, so I am leaving it
916 mkArbitraryType :: TcTyVar -> Type
917 -- Make up an arbitrary type whose kind is the same as the tyvar.
918 -- We'll use this to instantiate the (unbound) tyvar.
920 | liftedTypeKind `isSubKind` kind = anyPrimTy -- The vastly common case
921 | otherwise = mkTyConApp tycon []
924 (args,res) = splitKindFunTys kind
926 tycon | eqKind kind (tyConKind anyPrimTyCon1) -- *->*
927 = anyPrimTyCon1 -- No tuples this size
929 | all isLiftedTypeKind args && isLiftedTypeKind res
930 = tupleTyCon Boxed (length args) -- *-> ... ->*->*
931 -- Horrible hack to make less use of mkAnyPrimTyCon
934 = mkAnyPrimTyCon (getUnique tv) kind
935 -- Same name as the tyvar, apart from making it start with a colon (sigh)
936 -- I dread to think what will happen if this gets out into an
937 -- interface file. Catastrophe likely. Major sigh.