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@(L _ (InlinePrag {})) = return prag
308 zonk_prag (L loc (SpecPrag expr ty ds inl))
309 = do { expr' <- zonkExpr env expr
310 ; ty' <- zonkTcTypeToType env ty
311 ; let ds' = zonkIdOccs env ds
312 ; return (L loc (SpecPrag expr' ty' ds' inl)) }
315 %************************************************************************
317 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
319 %************************************************************************
322 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
323 zonkMatchGroup env (MatchGroup ms ty)
324 = do { ms' <- mapM (zonkMatch env) ms
325 ; ty' <- zonkTcTypeToType env ty
326 ; return (MatchGroup ms' ty') }
328 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
329 zonkMatch env (L loc (Match pats _ grhss))
330 = do { (env1, new_pats) <- zonkPats env pats
331 ; new_grhss <- zonkGRHSs env1 grhss
332 ; return (L loc (Match new_pats Nothing new_grhss)) }
334 -------------------------------------------------------------------------
335 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
337 zonkGRHSs env (GRHSs grhss binds)
338 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
340 zonk_grhs (GRHS guarded rhs)
341 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
342 zonkLExpr env2 rhs `thenM` \ new_rhs ->
343 returnM (GRHS new_guarded new_rhs)
345 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
346 returnM (GRHSs new_grhss new_binds)
349 %************************************************************************
351 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
353 %************************************************************************
356 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
357 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
358 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
360 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
361 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
363 zonkExpr env (HsVar id)
364 = returnM (HsVar (zonkIdOcc env id))
366 zonkExpr env (HsIPVar id)
367 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
369 zonkExpr env (HsLit (HsRat f ty))
370 = zonkTcTypeToType env ty `thenM` \ new_ty ->
371 returnM (HsLit (HsRat f new_ty))
373 zonkExpr env (HsLit lit)
374 = returnM (HsLit lit)
376 zonkExpr env (HsOverLit lit)
377 = do { lit' <- zonkOverLit env lit
378 ; return (HsOverLit lit') }
380 zonkExpr env (HsLam matches)
381 = zonkMatchGroup env matches `thenM` \ new_matches ->
382 returnM (HsLam new_matches)
384 zonkExpr env (HsApp e1 e2)
385 = zonkLExpr env e1 `thenM` \ new_e1 ->
386 zonkLExpr env e2 `thenM` \ new_e2 ->
387 returnM (HsApp new_e1 new_e2)
389 zonkExpr env (HsBracketOut body bs)
390 = mappM zonk_b bs `thenM` \ bs' ->
391 returnM (HsBracketOut body bs')
393 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
396 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
397 returnM (HsSpliceE s)
399 zonkExpr env (OpApp e1 op fixity e2)
400 = zonkLExpr env e1 `thenM` \ new_e1 ->
401 zonkLExpr env op `thenM` \ new_op ->
402 zonkLExpr env e2 `thenM` \ new_e2 ->
403 returnM (OpApp new_e1 new_op fixity new_e2)
405 zonkExpr env (NegApp expr op)
406 = zonkLExpr env expr `thenM` \ new_expr ->
407 zonkExpr env op `thenM` \ new_op ->
408 returnM (NegApp new_expr new_op)
410 zonkExpr env (HsPar e)
411 = zonkLExpr env e `thenM` \new_e ->
412 returnM (HsPar new_e)
414 zonkExpr env (SectionL expr op)
415 = zonkLExpr env expr `thenM` \ new_expr ->
416 zonkLExpr env op `thenM` \ new_op ->
417 returnM (SectionL new_expr new_op)
419 zonkExpr env (SectionR op expr)
420 = zonkLExpr env op `thenM` \ new_op ->
421 zonkLExpr env expr `thenM` \ new_expr ->
422 returnM (SectionR new_op new_expr)
424 zonkExpr env (HsCase expr ms)
425 = zonkLExpr env expr `thenM` \ new_expr ->
426 zonkMatchGroup env ms `thenM` \ new_ms ->
427 returnM (HsCase new_expr new_ms)
429 zonkExpr env (HsIf e1 e2 e3)
430 = zonkLExpr env e1 `thenM` \ new_e1 ->
431 zonkLExpr env e2 `thenM` \ new_e2 ->
432 zonkLExpr env e3 `thenM` \ new_e3 ->
433 returnM (HsIf new_e1 new_e2 new_e3)
435 zonkExpr env (HsLet binds expr)
436 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
437 zonkLExpr new_env expr `thenM` \ new_expr ->
438 returnM (HsLet new_binds new_expr)
440 zonkExpr env (HsDo do_or_lc stmts body ty)
441 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
442 zonkLExpr new_env body `thenM` \ new_body ->
443 zonkTcTypeToType env ty `thenM` \ new_ty ->
444 returnM (HsDo (zonkDo env do_or_lc)
445 new_stmts new_body new_ty)
447 zonkExpr env (ExplicitList ty exprs)
448 = zonkTcTypeToType env ty `thenM` \ new_ty ->
449 zonkLExprs env exprs `thenM` \ new_exprs ->
450 returnM (ExplicitList new_ty new_exprs)
452 zonkExpr env (ExplicitPArr ty exprs)
453 = zonkTcTypeToType env ty `thenM` \ new_ty ->
454 zonkLExprs env exprs `thenM` \ new_exprs ->
455 returnM (ExplicitPArr new_ty new_exprs)
457 zonkExpr env (ExplicitTuple exprs boxed)
458 = zonkLExprs env exprs `thenM` \ new_exprs ->
459 returnM (ExplicitTuple new_exprs boxed)
461 zonkExpr env (RecordCon data_con con_expr rbinds)
462 = zonkExpr env con_expr `thenM` \ new_con_expr ->
463 zonkRbinds env rbinds `thenM` \ new_rbinds ->
464 returnM (RecordCon data_con new_con_expr new_rbinds)
466 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
467 = zonkLExpr env expr `thenM` \ new_expr ->
468 mapM (zonkTcTypeToType env) in_tys `thenM` \ new_in_tys ->
469 mapM (zonkTcTypeToType env) out_tys `thenM` \ new_out_tys ->
470 zonkRbinds env rbinds `thenM` \ new_rbinds ->
471 returnM (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys)
473 zonkExpr env (ExprWithTySigOut e ty)
474 = do { e' <- zonkLExpr env e
475 ; return (ExprWithTySigOut e' ty) }
477 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
479 zonkExpr env (ArithSeq expr info)
480 = zonkExpr env expr `thenM` \ new_expr ->
481 zonkArithSeq env info `thenM` \ new_info ->
482 returnM (ArithSeq new_expr new_info)
484 zonkExpr env (PArrSeq expr info)
485 = zonkExpr env expr `thenM` \ new_expr ->
486 zonkArithSeq env info `thenM` \ new_info ->
487 returnM (PArrSeq new_expr new_info)
489 zonkExpr env (HsSCC lbl expr)
490 = zonkLExpr env expr `thenM` \ new_expr ->
491 returnM (HsSCC lbl new_expr)
493 zonkExpr env (HsTickPragma info expr)
494 = zonkLExpr env expr `thenM` \ new_expr ->
495 returnM (HsTickPragma info new_expr)
497 -- hdaume: core annotations
498 zonkExpr env (HsCoreAnn lbl expr)
499 = zonkLExpr env expr `thenM` \ new_expr ->
500 returnM (HsCoreAnn lbl new_expr)
502 -- arrow notation extensions
503 zonkExpr env (HsProc pat body)
504 = do { (env1, new_pat) <- zonkPat env pat
505 ; new_body <- zonkCmdTop env1 body
506 ; return (HsProc new_pat new_body) }
508 zonkExpr env (HsArrApp e1 e2 ty ho rl)
509 = zonkLExpr env e1 `thenM` \ new_e1 ->
510 zonkLExpr env e2 `thenM` \ new_e2 ->
511 zonkTcTypeToType env ty `thenM` \ new_ty ->
512 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
514 zonkExpr env (HsArrForm op fixity args)
515 = zonkLExpr env op `thenM` \ new_op ->
516 mappM (zonkCmdTop env) args `thenM` \ new_args ->
517 returnM (HsArrForm new_op fixity new_args)
519 zonkExpr env (HsWrap co_fn expr)
520 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
521 zonkExpr env1 expr `thenM` \ new_expr ->
522 return (HsWrap new_co_fn new_expr)
524 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
526 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
527 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
529 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
530 = zonkLExpr env cmd `thenM` \ new_cmd ->
531 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
532 zonkTcTypeToType env ty `thenM` \ new_ty ->
533 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
534 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
536 -------------------------------------------------------------------------
537 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
538 zonkCoFn env WpHole = return (env, WpHole)
539 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
540 ; (env2, c2') <- zonkCoFn env1 c2
541 ; return (env2, WpCompose c1' c2') }
542 zonkCoFn env (WpCo co) = do { co' <- zonkTcTypeToType env co
543 ; return (env, WpCo co') }
544 zonkCoFn env (WpLam id) = do { id' <- zonkIdBndr env id
545 ; let env1 = extendZonkEnv1 env id'
546 ; return (env1, WpLam id') }
547 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
548 do { return (env, WpTyLam tv) }
549 zonkCoFn env (WpApp id) = do { return (env, WpApp (zonkIdOcc env id)) }
550 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
551 ; return (env, WpTyApp ty') }
552 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
553 ; return (env1, WpLet bs') }
556 -------------------------------------------------------------------------
557 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
558 -- Only used for 'do', so the only Ids are in a MDoExpr table
559 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
560 zonkDo env do_or_lc = do_or_lc
562 -------------------------------------------------------------------------
563 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
564 zonkOverLit env (HsIntegral i e)
565 = do { e' <- zonkExpr env e; return (HsIntegral i e') }
566 zonkOverLit env (HsFractional r e)
567 = do { e' <- zonkExpr env e; return (HsFractional r e') }
568 zonkOverLit env (HsIsString s e)
569 = do { e' <- zonkExpr env e; return (HsIsString s e') }
571 -------------------------------------------------------------------------
572 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
574 zonkArithSeq env (From e)
575 = zonkLExpr env e `thenM` \ new_e ->
578 zonkArithSeq env (FromThen e1 e2)
579 = zonkLExpr env e1 `thenM` \ new_e1 ->
580 zonkLExpr env e2 `thenM` \ new_e2 ->
581 returnM (FromThen new_e1 new_e2)
583 zonkArithSeq env (FromTo e1 e2)
584 = zonkLExpr env e1 `thenM` \ new_e1 ->
585 zonkLExpr env e2 `thenM` \ new_e2 ->
586 returnM (FromTo new_e1 new_e2)
588 zonkArithSeq env (FromThenTo e1 e2 e3)
589 = zonkLExpr env e1 `thenM` \ new_e1 ->
590 zonkLExpr env e2 `thenM` \ new_e2 ->
591 zonkLExpr env e3 `thenM` \ new_e3 ->
592 returnM (FromThenTo new_e1 new_e2 new_e3)
595 -------------------------------------------------------------------------
596 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
597 zonkStmts env [] = return (env, [])
598 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
599 ; (env2, ss') <- zonkStmts env1 ss
600 ; return (env2, s' : ss') }
602 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
603 zonkStmt env (ParStmt stmts_w_bndrs)
604 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
606 new_binders = concat (map snd new_stmts_w_bndrs)
607 env1 = extendZonkEnv env new_binders
609 return (env1, ParStmt new_stmts_w_bndrs)
611 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
612 returnM (new_stmts, zonkIdOccs env1 bndrs)
614 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
615 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
617 env1 = extendZonkEnv env new_rvs
619 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
620 -- Zonk the ret-expressions in an envt that
621 -- has the polymorphic bindings in the envt
622 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
624 new_lvs = zonkIdOccs env2 lvs
625 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
627 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
628 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
630 zonkStmt env (ExprStmt expr then_op ty)
631 = zonkLExpr env expr `thenM` \ new_expr ->
632 zonkExpr env then_op `thenM` \ new_then ->
633 zonkTcTypeToType env ty `thenM` \ new_ty ->
634 returnM (env, ExprStmt new_expr new_then new_ty)
636 zonkStmt env (LetStmt binds)
637 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
638 returnM (env1, LetStmt new_binds)
640 zonkStmt env (BindStmt pat expr bind_op fail_op)
641 = do { new_expr <- zonkLExpr env expr
642 ; (env1, new_pat) <- zonkPat env pat
643 ; new_bind <- zonkExpr env bind_op
644 ; new_fail <- zonkExpr env fail_op
645 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
648 -------------------------------------------------------------------------
649 zonkRbinds :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds Id)
651 zonkRbinds env (HsRecordBinds rbinds)
652 = mappM zonk_rbind rbinds >>= return . HsRecordBinds
654 zonk_rbind (field, expr)
655 = zonkLExpr env expr `thenM` \ new_expr ->
656 returnM (fmap (zonkIdOcc env) field, new_expr)
658 -------------------------------------------------------------------------
659 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
660 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
664 %************************************************************************
666 \subsection[BackSubst-Pats]{Patterns}
668 %************************************************************************
671 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
672 -- Extend the environment as we go, because it's possible for one
673 -- pattern to bind something that is used in another (inside or
675 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
677 zonk_pat env (ParPat p)
678 = do { (env', p') <- zonkPat env p
679 ; return (env', ParPat p') }
681 zonk_pat env (WildPat ty)
682 = do { ty' <- zonkTcTypeToType env ty
683 ; return (env, WildPat ty') }
685 zonk_pat env (VarPat v)
686 = do { v' <- zonkIdBndr env v
687 ; return (extendZonkEnv1 env v', VarPat v') }
689 zonk_pat env (VarPatOut v binds)
690 = do { v' <- zonkIdBndr env v
691 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
692 ; returnM (env', VarPatOut v' binds') }
694 zonk_pat env (LazyPat pat)
695 = do { (env', pat') <- zonkPat env pat
696 ; return (env', LazyPat pat') }
698 zonk_pat env (BangPat pat)
699 = do { (env', pat') <- zonkPat env pat
700 ; return (env', BangPat pat') }
702 zonk_pat env (AsPat (L loc v) pat)
703 = do { v' <- zonkIdBndr env v
704 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
705 ; return (env', AsPat (L loc v') pat') }
707 zonk_pat env (ListPat pats ty)
708 = do { ty' <- zonkTcTypeToType env ty
709 ; (env', pats') <- zonkPats env pats
710 ; return (env', ListPat pats' ty') }
712 zonk_pat env (PArrPat pats ty)
713 = do { ty' <- zonkTcTypeToType env ty
714 ; (env', pats') <- zonkPats env pats
715 ; return (env', PArrPat pats' ty') }
717 zonk_pat env (TuplePat pats boxed ty)
718 = do { ty' <- zonkTcTypeToType env ty
719 ; (env', pats') <- zonkPats env pats
720 ; return (env', TuplePat pats' boxed ty') }
722 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
723 = ASSERT( all isImmutableTyVar (pat_tvs p) )
724 do { new_ty <- zonkTcTypeToType env ty
725 ; new_dicts <- zonkIdBndrs env dicts
726 ; let env1 = extendZonkEnv env new_dicts
727 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
728 ; (env', new_args) <- zonkConStuff env2 args
729 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
730 pat_binds = new_binds, pat_args = new_args }) }
732 zonk_pat env (LitPat lit) = return (env, LitPat lit)
734 zonk_pat env (SigPatOut pat ty)
735 = do { ty' <- zonkTcTypeToType env ty
736 ; (env', pat') <- zonkPat env pat
737 ; return (env', SigPatOut pat' ty') }
739 zonk_pat env (NPat lit mb_neg eq_expr ty)
740 = do { lit' <- zonkOverLit env lit
741 ; mb_neg' <- case mb_neg of
742 Nothing -> return Nothing
743 Just neg -> do { neg' <- zonkExpr env neg
744 ; return (Just neg') }
745 ; eq_expr' <- zonkExpr env eq_expr
746 ; ty' <- zonkTcTypeToType env ty
747 ; return (env, NPat lit' mb_neg' eq_expr' ty') }
749 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
750 = do { n' <- zonkIdBndr env n
751 ; lit' <- zonkOverLit env lit
752 ; e1' <- zonkExpr env e1
753 ; e2' <- zonkExpr env e2
754 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
756 zonk_pat env (DictPat ds ms)
757 = do { ds' <- zonkIdBndrs env ds
758 ; ms' <- zonkIdBndrs env ms
759 ; return (extendZonkEnv env (ds' ++ ms'), DictPat ds' ms') }
761 zonk_pat env (CoPat co_fn pat ty)
762 = do { (env', co_fn') <- zonkCoFn env co_fn
763 ; (env'', pat') <- zonkPat env' (noLoc pat)
764 ; ty' <- zonkTcTypeToType env'' ty
765 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
767 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
769 ---------------------------
770 zonkConStuff env (PrefixCon pats)
771 = do { (env', pats') <- zonkPats env pats
772 ; return (env', PrefixCon pats') }
774 zonkConStuff env (InfixCon p1 p2)
775 = do { (env1, p1') <- zonkPat env p1
776 ; (env', p2') <- zonkPat env1 p2
777 ; return (env', InfixCon p1' p2') }
779 zonkConStuff env (RecCon rpats)
780 = do { let (fields, pats) = unzip [ (f, p) | HsRecField f p _ <- rpats ]
781 ; (env', pats') <- zonkPats env pats
782 ; let recCon = RecCon [ mkRecField f p | (f, p) <- zip fields pats' ]
783 ; returnM (env', recCon) }
785 ---------------------------
786 zonkPats env [] = return (env, [])
787 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
788 ; (env', pats') <- zonkPats env1 pats
789 ; return (env', pat':pats') }
792 %************************************************************************
794 \subsection[BackSubst-Foreign]{Foreign exports}
796 %************************************************************************
800 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
801 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
803 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
804 zonkForeignExport env (ForeignExport i hs_ty spec) =
805 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
806 zonkForeignExport env for_imp
807 = returnM for_imp -- Foreign imports don't need zonking
811 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
812 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
814 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
815 zonkRule env (HsRule name act (vars::[RuleBndr TcId]) lhs fv_lhs rhs fv_rhs)
816 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
817 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
819 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
820 -- Type variables don't need an envt
821 -- They are bound through the mutable mechanism
823 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
824 -- We need to gather the type variables mentioned on the LHS so we can
825 -- quantify over them. Example:
831 -- {-# RULES "myrule" foo C = 1 #-}
833 -- After type checking the LHS becomes (foo a (C a))
834 -- and we do not want to zap the unbound tyvar 'a' to (), because
835 -- that limits the applicability of the rule. Instead, we
836 -- want to quantify over it!
838 -- It's easiest to find the free tyvars here. Attempts to do so earlier
839 -- are tiresome, because (a) the data type is big and (b) finding the
840 -- free type vars of an expression is necessarily monadic operation.
841 -- (consider /\a -> f @ b, where b is side-effected to a)
843 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
844 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
846 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
848 final_bndrs :: [Located Var]
849 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
851 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
852 -- I hate this map RuleBndr stuff
854 zonk_bndr (RuleBndr v)
855 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
856 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
861 %************************************************************************
863 \subsection[BackSubst-Foreign]{Foreign exports}
865 %************************************************************************
868 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
869 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
871 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
872 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
874 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
875 -- This variant collects unbound type variables in a mutable variable
876 zonkTypeCollecting unbound_tv_set
877 = zonkType zonk_unbound_tyvar
879 zonk_unbound_tyvar tv
880 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
881 readMutVar unbound_tv_set `thenM` \ tv_set ->
882 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
883 return (mkTyVarTy tv')
885 zonkTypeZapping :: TcType -> TcM Type
886 -- This variant is used for everything except the LHS of rules
887 -- It zaps unbound type variables to (), or some other arbitrary type
889 = zonkType zonk_unbound_tyvar ty
891 -- Zonk a mutable but unbound type variable to an arbitrary type
892 -- We know it's unbound even though we don't carry an environment,
893 -- because at the binding site for a type variable we bind the
894 -- mutable tyvar to a fresh immutable one. So the mutable store
895 -- plays the role of an environment. If we come across a mutable
896 -- type variable that isn't so bound, it must be completely free.
897 zonk_unbound_tyvar tv = do { writeMetaTyVar tv ty; return ty }
899 ty = mkArbitraryType tv
902 -- When the type checker finds a type variable with no binding,
903 -- which means it can be instantiated with an arbitrary type, it
904 -- usually instantiates it to Void. Eg.
908 -- length Void (Nil Void)
910 -- But in really obscure programs, the type variable might have
911 -- a kind other than *, so we need to invent a suitably-kinded type.
915 -- List for kind *->*
916 -- Tuple for kind *->...*->*
918 -- which deals with most cases. (Previously, it only dealt with
921 -- In the other cases, it just makes up a TyCon with a suitable
922 -- kind. If this gets into an interface file, anyone reading that
923 -- file won't understand it. This is fixable (by making the client
924 -- of the interface file make up a TyCon too) but it is tiresome and
925 -- never happens, so I am leaving it
927 mkArbitraryType :: TcTyVar -> Type
928 -- Make up an arbitrary type whose kind is the same as the tyvar.
929 -- We'll use this to instantiate the (unbound) tyvar.
931 | liftedTypeKind `isSubKind` kind = anyPrimTy -- The vastly common case
932 | otherwise = mkTyConApp tycon []
935 (args,res) = splitKindFunTys kind
937 tycon | eqKind kind (tyConKind anyPrimTyCon1) -- *->*
938 = anyPrimTyCon1 -- No tuples this size
940 | all isLiftedTypeKind args && isLiftedTypeKind res
941 = tupleTyCon Boxed (length args) -- *-> ... ->*->*
942 -- Horrible hack to make less use of mkAnyPrimTyCon
945 = mkAnyPrimTyCon (getUnique tv) kind
946 -- Same name as the tyvar, apart from making it start with a colon (sigh)
947 -- I dread to think what will happen if this gets out into an
948 -- interface file. Catastrophe likely. Major sigh.