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
43 import {- Kind parts of -} Type
58 %************************************************************************
60 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
62 %************************************************************************
64 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
65 then something is wrong.
67 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
68 -- A vanilla tuple pattern simply gets its type from its sub-patterns
69 mkVanillaTuplePat pats box
70 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
72 hsLPatType :: OutPat Id -> Type
73 hsLPatType (L _ pat) = hsPatType pat
75 hsPatType (ParPat pat) = hsLPatType pat
76 hsPatType (WildPat ty) = ty
77 hsPatType (VarPat var) = idType var
78 hsPatType (VarPatOut var _) = idType var
79 hsPatType (BangPat pat) = hsLPatType pat
80 hsPatType (LazyPat pat) = hsLPatType pat
81 hsPatType (LitPat lit) = hsLitType lit
82 hsPatType (AsPat var pat) = idType (unLoc var)
83 hsPatType (ListPat _ ty) = mkListTy ty
84 hsPatType (PArrPat _ ty) = mkPArrTy ty
85 hsPatType (TuplePat pats box ty) = ty
86 hsPatType (ConPatOut{ pat_ty = ty })= ty
87 hsPatType (SigPatOut pat ty) = ty
88 hsPatType (NPat lit _ _ ty) = ty
89 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
90 hsPatType (CoPat _ _ ty) = ty
91 hsPatType (DictPat ds ms) = case (ds ++ ms) of
94 ds -> mkTupleTy Boxed (length ds) (map idType ds)
97 hsLitType :: HsLit -> TcType
98 hsLitType (HsChar c) = charTy
99 hsLitType (HsCharPrim c) = charPrimTy
100 hsLitType (HsString str) = stringTy
101 hsLitType (HsStringPrim s) = addrPrimTy
102 hsLitType (HsInt i) = intTy
103 hsLitType (HsIntPrim i) = intPrimTy
104 hsLitType (HsInteger i ty) = ty
105 hsLitType (HsRat _ ty) = ty
106 hsLitType (HsFloatPrim f) = floatPrimTy
107 hsLitType (HsDoublePrim d) = doublePrimTy
111 %************************************************************************
113 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
115 %************************************************************************
118 -- zonkId is used *during* typechecking just to zonk the Id's type
119 zonkId :: TcId -> TcM TcId
121 = zonkTcType (idType id) `thenM` \ ty' ->
122 returnM (Id.setIdType id ty')
125 The rest of the zonking is done *after* typechecking.
126 The main zonking pass runs over the bindings
128 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
129 b) convert unbound TcTyVar to Void
130 c) convert each TcId to an Id by zonking its type
132 The type variables are converted by binding mutable tyvars to immutable ones
133 and then zonking as normal.
135 The Ids are converted by binding them in the normal Tc envt; that
136 way we maintain sharing; eg an Id is zonked at its binding site and they
137 all occurrences of that Id point to the common zonked copy
139 It's all pretty boring stuff, because HsSyn is such a large type, and
140 the environment manipulation is tiresome.
143 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
144 (IdEnv Id) -- What variables are in scope
145 -- Maps an Id to its zonked version; both have the same Name
146 -- Is only consulted lazily; hence knot-tying
148 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
150 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
151 extendZonkEnv (ZonkEnv zonk_ty env) ids
152 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
154 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
155 extendZonkEnv1 (ZonkEnv zonk_ty env) id
156 = ZonkEnv zonk_ty (extendVarEnv env id id)
158 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
159 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
161 zonkEnvIds :: ZonkEnv -> [Id]
162 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
164 zonkIdOcc :: ZonkEnv -> TcId -> Id
165 -- Ids defined in this module should be in the envt;
166 -- ignore others. (Actually, data constructors are also
167 -- not LocalVars, even when locally defined, but that is fine.)
168 -- (Also foreign-imported things aren't currently in the ZonkEnv;
169 -- that's ok because they don't need zonking.)
171 -- Actually, Template Haskell works in 'chunks' of declarations, and
172 -- an earlier chunk won't be in the 'env' that the zonking phase
173 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
174 -- zonked. There's no point in looking it up there (except for error
175 -- checking), and it's not conveniently to hand; hence the simple
176 -- 'orElse' case in the LocalVar branch.
178 -- Even without template splices, in module Main, the checking of
179 -- 'main' is done as a separate chunk.
180 zonkIdOcc (ZonkEnv zonk_ty env) id
181 | isLocalVar id = lookupVarEnv env id `orElse` id
184 zonkIdOccs env ids = map (zonkIdOcc env) ids
186 -- zonkIdBndr is used *after* typechecking to get the Id's type
187 -- to its final form. The TyVarEnv give
188 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
190 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
191 returnM (Id.setIdType id ty')
193 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
194 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
196 zonkTopBndrs :: [TcId] -> TcM [Id]
197 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
202 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
203 zonkTopExpr e = zonkExpr emptyZonkEnv e
205 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
206 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
208 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
213 zonkTopDecls binds rules fords
214 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
215 -- Top level is implicitly recursive
216 ; rules' <- zonkRules env rules
217 ; fords' <- zonkForeignExports env fords
218 ; return (zonkEnvIds env, binds', fords', rules') }
220 ---------------------------------------------
221 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
222 zonkLocalBinds env EmptyLocalBinds
223 = return (env, EmptyLocalBinds)
225 zonkLocalBinds env (HsValBinds binds)
226 = do { (env1, new_binds) <- zonkValBinds env binds
227 ; return (env1, HsValBinds new_binds) }
229 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
230 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
232 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
234 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
235 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
237 zonk_ip_bind (IPBind n e)
238 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
239 zonkLExpr env e `thenM` \ e' ->
240 returnM (IPBind n' e')
243 ---------------------------------------------
244 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
245 zonkValBinds env bs@(ValBindsIn _ _)
246 = panic "zonkValBinds" -- Not in typechecker output
247 zonkValBinds env (ValBindsOut binds sigs)
248 = do { (env1, new_binds) <- go env binds
249 ; return (env1, ValBindsOut new_binds sigs) }
251 go env [] = return (env, [])
252 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
253 ; (env2, bs') <- go env1 bs
254 ; return (env2, (r,b'):bs') }
256 ---------------------------------------------
257 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
258 zonkRecMonoBinds env binds
259 = fixM (\ ~(_, new_binds) -> do
260 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
261 ; binds' <- zonkMonoBinds env1 binds
262 ; return (env1, binds') })
264 ---------------------------------------------
265 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
266 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
268 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
269 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
270 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
271 ; new_grhss <- zonkGRHSs env grhss
272 ; new_ty <- zonkTcTypeToType env ty
273 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
275 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
276 = zonkIdBndr env var `thenM` \ new_var ->
277 zonkLExpr env expr `thenM` \ new_expr ->
278 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
280 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
281 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
282 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
283 zonkMatchGroup env1 ms `thenM` \ new_ms ->
284 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
286 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
287 abs_exports = exports, abs_binds = val_binds })
288 = ASSERT( all isImmutableTyVar tyvars )
289 zonkIdBndrs env dicts `thenM` \ new_dicts ->
290 fixM (\ ~(new_val_binds, _) ->
292 env1 = extendZonkEnv env new_dicts
293 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
295 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
296 mappM (zonkExport env2) exports `thenM` \ new_exports ->
297 returnM (new_val_binds, new_exports)
298 ) `thenM` \ (new_val_bind, new_exports) ->
299 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
300 abs_exports = new_exports, abs_binds = new_val_bind })
302 zonkExport env (tyvars, global, local, prags)
303 -- The tyvars are already zonked
304 = zonkIdBndr env global `thenM` \ new_global ->
305 mapM zonk_prag prags `thenM` \ new_prags ->
306 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
307 zonk_prag prag@(InlinePrag {}) = return prag
308 zonk_prag (SpecPrag expr ty ds inl) = do { expr' <- zonkExpr env expr
309 ; ty' <- zonkTcTypeToType env ty
310 ; let ds' = zonkIdOccs env ds
311 ; return (SpecPrag expr' ty' ds' inl) }
314 %************************************************************************
316 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
318 %************************************************************************
321 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
322 zonkMatchGroup env (MatchGroup ms ty)
323 = do { ms' <- mapM (zonkMatch env) ms
324 ; ty' <- zonkTcTypeToType env ty
325 ; return (MatchGroup ms' ty') }
327 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
328 zonkMatch env (L loc (Match pats _ grhss))
329 = do { (env1, new_pats) <- zonkPats env pats
330 ; new_grhss <- zonkGRHSs env1 grhss
331 ; return (L loc (Match new_pats Nothing new_grhss)) }
333 -------------------------------------------------------------------------
334 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
336 zonkGRHSs env (GRHSs grhss binds)
337 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
339 zonk_grhs (GRHS guarded rhs)
340 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
341 zonkLExpr env2 rhs `thenM` \ new_rhs ->
342 returnM (GRHS new_guarded new_rhs)
344 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
345 returnM (GRHSs new_grhss new_binds)
348 %************************************************************************
350 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
352 %************************************************************************
355 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
356 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
357 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
359 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
360 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
362 zonkExpr env (HsVar id)
363 = returnM (HsVar (zonkIdOcc env id))
365 zonkExpr env (HsIPVar id)
366 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
368 zonkExpr env (HsLit (HsRat f ty))
369 = zonkTcTypeToType env ty `thenM` \ new_ty ->
370 returnM (HsLit (HsRat f new_ty))
372 zonkExpr env (HsLit lit)
373 = returnM (HsLit lit)
375 zonkExpr env (HsOverLit lit)
376 = do { lit' <- zonkOverLit env lit
377 ; return (HsOverLit lit') }
379 zonkExpr env (HsLam matches)
380 = zonkMatchGroup env matches `thenM` \ new_matches ->
381 returnM (HsLam new_matches)
383 zonkExpr env (HsApp e1 e2)
384 = zonkLExpr env e1 `thenM` \ new_e1 ->
385 zonkLExpr env e2 `thenM` \ new_e2 ->
386 returnM (HsApp new_e1 new_e2)
388 zonkExpr env (HsBracketOut body bs)
389 = mappM zonk_b bs `thenM` \ bs' ->
390 returnM (HsBracketOut body bs')
392 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
395 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
396 returnM (HsSpliceE s)
398 zonkExpr env (OpApp e1 op fixity e2)
399 = zonkLExpr env e1 `thenM` \ new_e1 ->
400 zonkLExpr env op `thenM` \ new_op ->
401 zonkLExpr env e2 `thenM` \ new_e2 ->
402 returnM (OpApp new_e1 new_op fixity new_e2)
404 zonkExpr env (NegApp expr op)
405 = zonkLExpr env expr `thenM` \ new_expr ->
406 zonkExpr env op `thenM` \ new_op ->
407 returnM (NegApp new_expr new_op)
409 zonkExpr env (HsPar e)
410 = zonkLExpr env e `thenM` \new_e ->
411 returnM (HsPar new_e)
413 zonkExpr env (SectionL expr op)
414 = zonkLExpr env expr `thenM` \ new_expr ->
415 zonkLExpr env op `thenM` \ new_op ->
416 returnM (SectionL new_expr new_op)
418 zonkExpr env (SectionR op expr)
419 = zonkLExpr env op `thenM` \ new_op ->
420 zonkLExpr env expr `thenM` \ new_expr ->
421 returnM (SectionR new_op new_expr)
423 zonkExpr env (HsCase expr ms)
424 = zonkLExpr env expr `thenM` \ new_expr ->
425 zonkMatchGroup env ms `thenM` \ new_ms ->
426 returnM (HsCase new_expr new_ms)
428 zonkExpr env (HsIf e1 e2 e3)
429 = zonkLExpr env e1 `thenM` \ new_e1 ->
430 zonkLExpr env e2 `thenM` \ new_e2 ->
431 zonkLExpr env e3 `thenM` \ new_e3 ->
432 returnM (HsIf new_e1 new_e2 new_e3)
434 zonkExpr env (HsLet binds expr)
435 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
436 zonkLExpr new_env expr `thenM` \ new_expr ->
437 returnM (HsLet new_binds new_expr)
439 zonkExpr env (HsDo do_or_lc stmts body ty)
440 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
441 zonkLExpr new_env body `thenM` \ new_body ->
442 zonkTcTypeToType env ty `thenM` \ new_ty ->
443 returnM (HsDo (zonkDo env do_or_lc)
444 new_stmts new_body new_ty)
446 zonkExpr env (ExplicitList ty exprs)
447 = zonkTcTypeToType env ty `thenM` \ new_ty ->
448 zonkLExprs env exprs `thenM` \ new_exprs ->
449 returnM (ExplicitList new_ty new_exprs)
451 zonkExpr env (ExplicitPArr ty exprs)
452 = zonkTcTypeToType env ty `thenM` \ new_ty ->
453 zonkLExprs env exprs `thenM` \ new_exprs ->
454 returnM (ExplicitPArr new_ty new_exprs)
456 zonkExpr env (ExplicitTuple exprs boxed)
457 = zonkLExprs env exprs `thenM` \ new_exprs ->
458 returnM (ExplicitTuple new_exprs boxed)
460 zonkExpr env (RecordCon data_con con_expr rbinds)
461 = zonkExpr env con_expr `thenM` \ new_con_expr ->
462 zonkRbinds env rbinds `thenM` \ new_rbinds ->
463 returnM (RecordCon data_con new_con_expr new_rbinds)
465 zonkExpr env (RecordUpd expr rbinds in_ty out_ty)
466 = zonkLExpr env expr `thenM` \ new_expr ->
467 zonkTcTypeToType env in_ty `thenM` \ new_in_ty ->
468 zonkTcTypeToType env out_ty `thenM` \ new_out_ty ->
469 zonkRbinds env rbinds `thenM` \ new_rbinds ->
470 returnM (RecordUpd new_expr new_rbinds new_in_ty new_out_ty)
472 zonkExpr env (ExprWithTySigOut e ty)
473 = do { e' <- zonkLExpr env e
474 ; return (ExprWithTySigOut e' ty) }
476 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
478 zonkExpr env (ArithSeq expr info)
479 = zonkExpr env expr `thenM` \ new_expr ->
480 zonkArithSeq env info `thenM` \ new_info ->
481 returnM (ArithSeq new_expr new_info)
483 zonkExpr env (PArrSeq expr info)
484 = zonkExpr env expr `thenM` \ new_expr ->
485 zonkArithSeq env info `thenM` \ new_info ->
486 returnM (PArrSeq new_expr new_info)
488 zonkExpr env (HsSCC lbl expr)
489 = zonkLExpr env expr `thenM` \ new_expr ->
490 returnM (HsSCC lbl new_expr)
492 zonkExpr env (HsTickPragma info expr)
493 = zonkLExpr env expr `thenM` \ new_expr ->
494 returnM (HsTickPragma info new_expr)
496 -- hdaume: core annotations
497 zonkExpr env (HsCoreAnn lbl expr)
498 = zonkLExpr env expr `thenM` \ new_expr ->
499 returnM (HsCoreAnn lbl new_expr)
501 -- arrow notation extensions
502 zonkExpr env (HsProc pat body)
503 = do { (env1, new_pat) <- zonkPat env pat
504 ; new_body <- zonkCmdTop env1 body
505 ; return (HsProc new_pat new_body) }
507 zonkExpr env (HsArrApp e1 e2 ty ho rl)
508 = zonkLExpr env e1 `thenM` \ new_e1 ->
509 zonkLExpr env e2 `thenM` \ new_e2 ->
510 zonkTcTypeToType env ty `thenM` \ new_ty ->
511 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
513 zonkExpr env (HsArrForm op fixity args)
514 = zonkLExpr env op `thenM` \ new_op ->
515 mappM (zonkCmdTop env) args `thenM` \ new_args ->
516 returnM (HsArrForm new_op fixity new_args)
518 zonkExpr env (HsWrap co_fn expr)
519 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
520 zonkExpr env1 expr `thenM` \ new_expr ->
521 return (HsWrap new_co_fn new_expr)
523 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
525 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
526 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
528 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
529 = zonkLExpr env cmd `thenM` \ new_cmd ->
530 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
531 zonkTcTypeToType env ty `thenM` \ new_ty ->
532 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
533 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
535 -------------------------------------------------------------------------
536 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
537 zonkCoFn env WpHole = return (env, WpHole)
538 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
539 ; (env2, c2') <- zonkCoFn env1 c2
540 ; return (env2, WpCompose c1' c2') }
541 zonkCoFn env (WpCo co) = do { co' <- zonkTcTypeToType env co
542 ; return (env, WpCo co') }
543 zonkCoFn env (WpLam id) = do { id' <- zonkIdBndr env id
544 ; let env1 = extendZonkEnv1 env id'
545 ; return (env1, WpLam id') }
546 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
547 do { return (env, WpTyLam tv) }
548 zonkCoFn env (WpApp id) = do { return (env, WpApp (zonkIdOcc env id)) }
549 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
550 ; return (env, WpTyApp ty') }
551 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
552 ; return (env1, WpLet bs') }
555 -------------------------------------------------------------------------
556 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
557 -- Only used for 'do', so the only Ids are in a MDoExpr table
558 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
559 zonkDo env do_or_lc = do_or_lc
561 -------------------------------------------------------------------------
562 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
563 zonkOverLit env (HsIntegral i e)
564 = do { e' <- zonkExpr env e; return (HsIntegral i e') }
565 zonkOverLit env (HsFractional r e)
566 = do { e' <- zonkExpr env e; return (HsFractional r e') }
567 zonkOverLit env (HsIsString s e)
568 = do { e' <- zonkExpr env e; return (HsIsString s e') }
570 -------------------------------------------------------------------------
571 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
573 zonkArithSeq env (From e)
574 = zonkLExpr env e `thenM` \ new_e ->
577 zonkArithSeq env (FromThen e1 e2)
578 = zonkLExpr env e1 `thenM` \ new_e1 ->
579 zonkLExpr env e2 `thenM` \ new_e2 ->
580 returnM (FromThen new_e1 new_e2)
582 zonkArithSeq env (FromTo e1 e2)
583 = zonkLExpr env e1 `thenM` \ new_e1 ->
584 zonkLExpr env e2 `thenM` \ new_e2 ->
585 returnM (FromTo new_e1 new_e2)
587 zonkArithSeq env (FromThenTo e1 e2 e3)
588 = zonkLExpr env e1 `thenM` \ new_e1 ->
589 zonkLExpr env e2 `thenM` \ new_e2 ->
590 zonkLExpr env e3 `thenM` \ new_e3 ->
591 returnM (FromThenTo new_e1 new_e2 new_e3)
594 -------------------------------------------------------------------------
595 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
596 zonkStmts env [] = return (env, [])
597 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
598 ; (env2, ss') <- zonkStmts env1 ss
599 ; return (env2, s' : ss') }
601 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
602 zonkStmt env (ParStmt stmts_w_bndrs)
603 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
605 new_binders = concat (map snd new_stmts_w_bndrs)
606 env1 = extendZonkEnv env new_binders
608 return (env1, ParStmt new_stmts_w_bndrs)
610 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
611 returnM (new_stmts, zonkIdOccs env1 bndrs)
613 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
614 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
616 env1 = extendZonkEnv env new_rvs
618 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
619 -- Zonk the ret-expressions in an envt that
620 -- has the polymorphic bindings in the envt
621 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
623 new_lvs = zonkIdOccs env2 lvs
624 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
626 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
627 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
629 zonkStmt env (ExprStmt expr then_op ty)
630 = zonkLExpr env expr `thenM` \ new_expr ->
631 zonkExpr env then_op `thenM` \ new_then ->
632 zonkTcTypeToType env ty `thenM` \ new_ty ->
633 returnM (env, ExprStmt new_expr new_then new_ty)
635 zonkStmt env (LetStmt binds)
636 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
637 returnM (env1, LetStmt new_binds)
639 zonkStmt env (BindStmt pat expr bind_op fail_op)
640 = do { new_expr <- zonkLExpr env expr
641 ; (env1, new_pat) <- zonkPat env pat
642 ; new_bind <- zonkExpr env bind_op
643 ; new_fail <- zonkExpr env fail_op
644 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
647 -------------------------------------------------------------------------
648 zonkRbinds :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds Id)
650 zonkRbinds env rbinds
651 = mappM zonk_rbind rbinds
653 zonk_rbind (field, expr)
654 = zonkLExpr env expr `thenM` \ new_expr ->
655 returnM (fmap (zonkIdOcc env) field, new_expr)
657 -------------------------------------------------------------------------
658 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
659 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
663 %************************************************************************
665 \subsection[BackSubst-Pats]{Patterns}
667 %************************************************************************
670 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
671 -- Extend the environment as we go, because it's possible for one
672 -- pattern to bind something that is used in another (inside or
674 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
676 zonk_pat env (ParPat p)
677 = do { (env', p') <- zonkPat env p
678 ; return (env', ParPat p') }
680 zonk_pat env (WildPat ty)
681 = do { ty' <- zonkTcTypeToType env ty
682 ; return (env, WildPat ty') }
684 zonk_pat env (VarPat v)
685 = do { v' <- zonkIdBndr env v
686 ; return (extendZonkEnv1 env v', VarPat v') }
688 zonk_pat env (VarPatOut v binds)
689 = do { v' <- zonkIdBndr env v
690 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
691 ; returnM (env', VarPatOut v' binds') }
693 zonk_pat env (LazyPat pat)
694 = do { (env', pat') <- zonkPat env pat
695 ; return (env', LazyPat pat') }
697 zonk_pat env (BangPat pat)
698 = do { (env', pat') <- zonkPat env pat
699 ; return (env', BangPat pat') }
701 zonk_pat env (AsPat (L loc v) pat)
702 = do { v' <- zonkIdBndr env v
703 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
704 ; return (env', AsPat (L loc v') pat') }
706 zonk_pat env (ListPat pats ty)
707 = do { ty' <- zonkTcTypeToType env ty
708 ; (env', pats') <- zonkPats env pats
709 ; return (env', ListPat pats' ty') }
711 zonk_pat env (PArrPat pats ty)
712 = do { ty' <- zonkTcTypeToType env ty
713 ; (env', pats') <- zonkPats env pats
714 ; return (env', PArrPat pats' ty') }
716 zonk_pat env (TuplePat pats boxed ty)
717 = do { ty' <- zonkTcTypeToType env ty
718 ; (env', pats') <- zonkPats env pats
719 ; return (env', TuplePat pats' boxed ty') }
721 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
722 = ASSERT( all isImmutableTyVar (pat_tvs p) )
723 do { new_ty <- zonkTcTypeToType env ty
724 ; new_dicts <- zonkIdBndrs env dicts
725 ; let env1 = extendZonkEnv env new_dicts
726 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
727 ; (env', new_args) <- zonkConStuff env2 args
728 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
729 pat_binds = new_binds, pat_args = new_args }) }
731 zonk_pat env (LitPat lit) = return (env, LitPat lit)
733 zonk_pat env (SigPatOut pat ty)
734 = do { ty' <- zonkTcTypeToType env ty
735 ; (env', pat') <- zonkPat env pat
736 ; return (env', SigPatOut pat' ty') }
738 zonk_pat env (NPat lit mb_neg eq_expr ty)
739 = do { lit' <- zonkOverLit env lit
740 ; mb_neg' <- case mb_neg of
741 Nothing -> return Nothing
742 Just neg -> do { neg' <- zonkExpr env neg
743 ; return (Just neg') }
744 ; eq_expr' <- zonkExpr env eq_expr
745 ; ty' <- zonkTcTypeToType env ty
746 ; return (env, NPat lit' mb_neg' eq_expr' ty') }
748 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
749 = do { n' <- zonkIdBndr env n
750 ; lit' <- zonkOverLit env lit
751 ; e1' <- zonkExpr env e1
752 ; e2' <- zonkExpr env e2
753 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
755 zonk_pat env (DictPat ds ms)
756 = do { ds' <- zonkIdBndrs env ds
757 ; ms' <- zonkIdBndrs env ms
758 ; return (extendZonkEnv env (ds' ++ ms'), DictPat ds' ms') }
760 zonk_pat env (CoPat co_fn pat ty)
761 = do { (env', co_fn') <- zonkCoFn env co_fn
762 ; (env'', pat') <- zonkPat env' (noLoc pat)
763 ; ty' <- zonkTcTypeToType env'' ty
764 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
766 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
768 ---------------------------
769 zonkConStuff env (PrefixCon pats)
770 = do { (env', pats') <- zonkPats env pats
771 ; return (env', PrefixCon pats') }
773 zonkConStuff env (InfixCon p1 p2)
774 = do { (env1, p1') <- zonkPat env p1
775 ; (env', p2') <- zonkPat env1 p2
776 ; return (env', InfixCon p1' p2') }
778 zonkConStuff env (RecCon rpats)
779 = do { let (fields, pats) = unzip [ (f, p) | HsRecField f p _ <- rpats ]
780 ; (env', pats') <- zonkPats env pats
781 ; let recCon = RecCon [ mkRecField f p | (f, p) <- zip fields pats' ]
782 ; returnM (env', recCon) }
784 ---------------------------
785 zonkPats env [] = return (env, [])
786 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
787 ; (env', pats') <- zonkPats env1 pats
788 ; return (env', pat':pats') }
791 %************************************************************************
793 \subsection[BackSubst-Foreign]{Foreign exports}
795 %************************************************************************
799 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
800 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
802 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
803 zonkForeignExport env (ForeignExport i hs_ty spec) =
804 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
805 zonkForeignExport env for_imp
806 = returnM for_imp -- Foreign imports don't need zonking
810 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
811 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
813 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
814 zonkRule env (HsRule name act (vars::[RuleBndr TcId]) lhs fv_lhs rhs fv_rhs)
815 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
816 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
818 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
819 -- Type variables don't need an envt
820 -- They are bound through the mutable mechanism
822 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
823 -- We need to gather the type variables mentioned on the LHS so we can
824 -- quantify over them. Example:
830 -- {-# RULES "myrule" foo C = 1 #-}
832 -- After type checking the LHS becomes (foo a (C a))
833 -- and we do not want to zap the unbound tyvar 'a' to (), because
834 -- that limits the applicability of the rule. Instead, we
835 -- want to quantify over it!
837 -- It's easiest to find the free tyvars here. Attempts to do so earlier
838 -- are tiresome, because (a) the data type is big and (b) finding the
839 -- free type vars of an expression is necessarily monadic operation.
840 -- (consider /\a -> f @ b, where b is side-effected to a)
842 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
843 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
845 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
847 final_bndrs :: [Located Var]
848 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
850 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
851 -- I hate this map RuleBndr stuff
853 zonk_bndr (RuleBndr v)
854 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
855 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
860 %************************************************************************
862 \subsection[BackSubst-Foreign]{Foreign exports}
864 %************************************************************************
867 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
868 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
870 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
871 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
873 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
874 -- This variant collects unbound type variables in a mutable variable
875 zonkTypeCollecting unbound_tv_set
876 = zonkType zonk_unbound_tyvar
878 zonk_unbound_tyvar tv
879 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
880 readMutVar unbound_tv_set `thenM` \ tv_set ->
881 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
882 return (mkTyVarTy tv')
884 zonkTypeZapping :: TcType -> TcM Type
885 -- This variant is used for everything except the LHS of rules
886 -- It zaps unbound type variables to (), or some other arbitrary type
888 = zonkType zonk_unbound_tyvar ty
890 -- Zonk a mutable but unbound type variable to an arbitrary type
891 -- We know it's unbound even though we don't carry an environment,
892 -- because at the binding site for a type variable we bind the
893 -- mutable tyvar to a fresh immutable one. So the mutable store
894 -- plays the role of an environment. If we come across a mutable
895 -- type variable that isn't so bound, it must be completely free.
896 zonk_unbound_tyvar tv = do { writeMetaTyVar tv ty; return ty }
898 ty = mkArbitraryType tv
901 -- When the type checker finds a type variable with no binding,
902 -- which means it can be instantiated with an arbitrary type, it
903 -- usually instantiates it to Void. Eg.
907 -- length Void (Nil Void)
909 -- But in really obscure programs, the type variable might have
910 -- a kind other than *, so we need to invent a suitably-kinded type.
914 -- List for kind *->*
915 -- Tuple for kind *->...*->*
917 -- which deals with most cases. (Previously, it only dealt with
920 -- In the other cases, it just makes up a TyCon with a suitable
921 -- kind. If this gets into an interface file, anyone reading that
922 -- file won't understand it. This is fixable (by making the client
923 -- of the interface file make up a TyCon too) but it is tiresome and
924 -- never happens, so I am leaving it
926 mkArbitraryType :: TcTyVar -> Type
927 -- Make up an arbitrary type whose kind is the same as the tyvar.
928 -- We'll use this to instantiate the (unbound) tyvar.
930 | liftedTypeKind `isSubKind` kind = anyPrimTy -- The vastly common case
931 | otherwise = mkTyConApp tycon []
934 (args,res) = splitKindFunTys kind
936 tycon | eqKind kind (tyConKind anyPrimTyCon1) -- *->*
937 = anyPrimTyCon1 -- No tuples this size
939 | all isLiftedTypeKind args && isLiftedTypeKind res
940 = tupleTyCon Boxed (length args) -- *-> ... ->*->*
941 -- Horrible hack to make less use of mkAnyPrimTyCon
944 = mkAnyPrimTyCon (getUnique tv) kind
945 -- Same name as the tyvar, apart from making it start with a colon (sigh)
946 -- I dread to think what will happen if this gets out into an
947 -- interface file. Catastrophe likely. Major sigh.