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,
17 shortCutLit, hsOverLitName,
19 -- re-exported from TcMonad
20 TcId, TcIdSet, TcDictBinds,
22 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
26 #include "HsVersions.h"
29 import HsSyn -- oodles of it
56 thenM :: Monad a => a b -> (b -> a c) -> a c
59 thenM_ :: Monad a => a b -> a c -> a c
62 returnM :: Monad m => a -> m a
65 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
70 %************************************************************************
72 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
74 %************************************************************************
76 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
77 then something is wrong.
79 hsLPatType :: OutPat Id -> Type
80 hsLPatType (L _ pat) = hsPatType pat
82 hsPatType :: Pat Id -> Type
83 hsPatType (ParPat pat) = hsLPatType pat
84 hsPatType (WildPat ty) = ty
85 hsPatType (VarPat var) = idType var
86 hsPatType (VarPatOut var _) = idType var
87 hsPatType (BangPat pat) = hsLPatType pat
88 hsPatType (LazyPat pat) = hsLPatType pat
89 hsPatType (LitPat lit) = hsLitType lit
90 hsPatType (AsPat var _) = idType (unLoc var)
91 hsPatType (ViewPat _ _ ty) = ty
92 hsPatType (ListPat _ ty) = mkListTy ty
93 hsPatType (PArrPat _ ty) = mkPArrTy ty
94 hsPatType (TuplePat _ _ ty) = ty
95 hsPatType (ConPatOut { pat_ty = ty }) = ty
96 hsPatType (SigPatOut _ ty) = ty
97 hsPatType (NPat lit _ _) = overLitType lit
98 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
99 hsPatType (CoPat _ _ ty) = ty
100 hsPatType p = pprPanic "hsPatType" (ppr p)
102 hsLitType :: HsLit -> TcType
103 hsLitType (HsChar _) = charTy
104 hsLitType (HsCharPrim _) = charPrimTy
105 hsLitType (HsString _) = stringTy
106 hsLitType (HsStringPrim _) = addrPrimTy
107 hsLitType (HsInt _) = intTy
108 hsLitType (HsIntPrim _) = intPrimTy
109 hsLitType (HsWordPrim _) = wordPrimTy
110 hsLitType (HsInteger _ ty) = ty
111 hsLitType (HsRat _ ty) = ty
112 hsLitType (HsFloatPrim _) = floatPrimTy
113 hsLitType (HsDoublePrim _) = doublePrimTy
116 Overloaded literals. Here mainly becuase it uses isIntTy etc
119 shortCutLit :: OverLitVal -> TcType -> Maybe (HsExpr TcId)
120 shortCutLit (HsIntegral i) ty
121 | isIntTy ty && inIntRange i = Just (HsLit (HsInt i))
122 | isWordTy ty && inWordRange i = Just (mkLit wordDataCon (HsWordPrim i))
123 | isIntegerTy ty = Just (HsLit (HsInteger i ty))
124 | otherwise = shortCutLit (HsFractional (fromInteger i)) ty
125 -- The 'otherwise' case is important
126 -- Consider (3 :: Float). Syntactically it looks like an IntLit,
127 -- so we'll call shortCutIntLit, but of course it's a float
128 -- This can make a big difference for programs with a lot of
129 -- literals, compiled without -O
131 shortCutLit (HsFractional f) ty
132 | isFloatTy ty = Just (mkLit floatDataCon (HsFloatPrim f))
133 | isDoubleTy ty = Just (mkLit doubleDataCon (HsDoublePrim f))
134 | otherwise = Nothing
136 shortCutLit (HsIsString s) ty
137 | isStringTy ty = Just (HsLit (HsString s))
138 | otherwise = Nothing
140 mkLit :: DataCon -> HsLit -> HsExpr Id
141 mkLit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit)
143 ------------------------------
144 hsOverLitName :: OverLitVal -> Name
145 -- Get the canonical 'fromX' name for a particular OverLitVal
146 hsOverLitName (HsIntegral {}) = fromIntegerName
147 hsOverLitName (HsFractional {}) = fromRationalName
148 hsOverLitName (HsIsString {}) = fromStringName
151 %************************************************************************
153 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
155 %************************************************************************
158 -- zonkId is used *during* typechecking just to zonk the Id's type
159 zonkId :: TcId -> TcM TcId
161 = zonkTcType (idType id) `thenM` \ ty' ->
162 returnM (Id.setIdType id ty')
165 The rest of the zonking is done *after* typechecking.
166 The main zonking pass runs over the bindings
168 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
169 b) convert unbound TcTyVar to Void
170 c) convert each TcId to an Id by zonking its type
172 The type variables are converted by binding mutable tyvars to immutable ones
173 and then zonking as normal.
175 The Ids are converted by binding them in the normal Tc envt; that
176 way we maintain sharing; eg an Id is zonked at its binding site and they
177 all occurrences of that Id point to the common zonked copy
179 It's all pretty boring stuff, because HsSyn is such a large type, and
180 the environment manipulation is tiresome.
183 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
184 (IdEnv Id) -- What variables are in scope
185 -- Maps an Id to its zonked version; both have the same Name
186 -- Is only consulted lazily; hence knot-tying
188 emptyZonkEnv :: ZonkEnv
189 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
191 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
192 extendZonkEnv (ZonkEnv zonk_ty env) ids
193 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
195 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
196 extendZonkEnv1 (ZonkEnv zonk_ty env) id
197 = ZonkEnv zonk_ty (extendVarEnv env id id)
199 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
200 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
202 zonkEnvIds :: ZonkEnv -> [Id]
203 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
205 zonkIdOcc :: ZonkEnv -> TcId -> Id
206 -- Ids defined in this module should be in the envt;
207 -- ignore others. (Actually, data constructors are also
208 -- not LocalVars, even when locally defined, but that is fine.)
209 -- (Also foreign-imported things aren't currently in the ZonkEnv;
210 -- that's ok because they don't need zonking.)
212 -- Actually, Template Haskell works in 'chunks' of declarations, and
213 -- an earlier chunk won't be in the 'env' that the zonking phase
214 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
215 -- zonked. There's no point in looking it up there (except for error
216 -- checking), and it's not conveniently to hand; hence the simple
217 -- 'orElse' case in the LocalVar branch.
219 -- Even without template splices, in module Main, the checking of
220 -- 'main' is done as a separate chunk.
221 zonkIdOcc (ZonkEnv _zonk_ty env) id
222 | isLocalVar id = lookupVarEnv env id `orElse` id
225 zonkIdOccs :: ZonkEnv -> [TcId] -> [Id]
226 zonkIdOccs env ids = map (zonkIdOcc env) ids
228 -- zonkIdBndr is used *after* typechecking to get the Id's type
229 -- to its final form. The TyVarEnv give
230 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
232 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
233 returnM (Id.setIdType id ty')
235 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
236 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
238 zonkDictBndrs :: ZonkEnv -> [Var] -> TcM [Var]
239 -- "Dictionary" binders can be coercion variables or dictionary variables
240 zonkDictBndrs env ids = mappM (zonkDictBndr env) ids
242 zonkDictBndr :: ZonkEnv -> Var -> TcM Var
243 zonkDictBndr env var | isTyVar var = zonkTyVarBndr env var
244 | otherwise = zonkIdBndr env var
246 zonkTopBndrs :: [TcId] -> TcM [Id]
247 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
249 -- Zonk the kind of a non-TC tyvar in case it is a coercion variable (their
250 -- kind contains types).
252 zonkTyVarBndr :: ZonkEnv -> TyVar -> TcM TyVar
255 = do { kind <- zonkTcTypeToType env (tyVarKind tv)
256 ; return $ setTyVarKind tv kind
258 | otherwise = return tv
263 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
264 zonkTopExpr e = zonkExpr emptyZonkEnv e
266 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
267 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
269 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
274 zonkTopDecls binds rules fords
275 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
276 -- Top level is implicitly recursive
277 ; rules' <- zonkRules env rules
278 ; fords' <- zonkForeignExports env fords
279 ; return (zonkEnvIds env, binds', fords', rules') }
281 ---------------------------------------------
282 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
283 zonkLocalBinds env EmptyLocalBinds
284 = return (env, EmptyLocalBinds)
286 zonkLocalBinds env (HsValBinds binds)
287 = do { (env1, new_binds) <- zonkValBinds env binds
288 ; return (env1, HsValBinds new_binds) }
290 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
291 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
293 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
295 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
296 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
298 zonk_ip_bind (IPBind n e)
299 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
300 zonkLExpr env e `thenM` \ e' ->
301 returnM (IPBind n' e')
304 ---------------------------------------------
305 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
306 zonkValBinds _ (ValBindsIn _ _)
307 = panic "zonkValBinds" -- Not in typechecker output
308 zonkValBinds env (ValBindsOut binds sigs)
309 = do { (env1, new_binds) <- go env binds
310 ; return (env1, ValBindsOut new_binds sigs) }
312 go env [] = return (env, [])
313 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
314 ; (env2, bs') <- go env1 bs
315 ; return (env2, (r,b'):bs') }
317 ---------------------------------------------
318 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
319 zonkRecMonoBinds env binds
320 = fixM (\ ~(_, new_binds) -> do
321 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
322 ; binds' <- zonkMonoBinds env1 binds
323 ; return (env1, binds') })
325 ---------------------------------------------
326 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
327 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
329 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
330 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
331 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
332 ; new_grhss <- zonkGRHSs env grhss
333 ; new_ty <- zonkTcTypeToType env ty
334 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
336 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
337 = zonkIdBndr env var `thenM` \ new_var ->
338 zonkLExpr env expr `thenM` \ new_expr ->
339 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
341 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
342 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
343 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
344 zonkMatchGroup env1 ms `thenM` \ new_ms ->
345 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
347 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
348 abs_exports = exports, abs_binds = val_binds })
349 = ASSERT( all isImmutableTyVar tyvars )
350 zonkDictBndrs env dicts `thenM` \ new_dicts ->
351 fixM (\ ~(new_val_binds, _) ->
353 env1 = extendZonkEnv env new_dicts
354 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
356 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
357 mappM (zonkExport env2) exports `thenM` \ new_exports ->
358 returnM (new_val_binds, new_exports)
359 ) `thenM` \ (new_val_bind, new_exports) ->
360 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
361 abs_exports = new_exports, abs_binds = new_val_bind })
363 zonkExport env (tyvars, global, local, prags)
364 -- The tyvars are already zonked
365 = zonkIdBndr env global `thenM` \ new_global ->
366 mapM zonk_prag prags `thenM` \ new_prags ->
367 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
368 zonk_prag prag@(L _ (InlinePrag {})) = return prag
369 zonk_prag (L loc (SpecPrag expr ty inl))
370 = do { expr' <- zonkExpr env expr
371 ; ty' <- zonkTcTypeToType env ty
372 ; return (L loc (SpecPrag expr' ty' inl)) }
375 %************************************************************************
377 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
379 %************************************************************************
382 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
383 zonkMatchGroup env (MatchGroup ms ty)
384 = do { ms' <- mapM (zonkMatch env) ms
385 ; ty' <- zonkTcTypeToType env ty
386 ; return (MatchGroup ms' ty') }
388 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
389 zonkMatch env (L loc (Match pats _ grhss))
390 = do { (env1, new_pats) <- zonkPats env pats
391 ; new_grhss <- zonkGRHSs env1 grhss
392 ; return (L loc (Match new_pats Nothing new_grhss)) }
394 -------------------------------------------------------------------------
395 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
397 zonkGRHSs env (GRHSs grhss binds)
398 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
400 zonk_grhs (GRHS guarded rhs)
401 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
402 zonkLExpr env2 rhs `thenM` \ new_rhs ->
403 returnM (GRHS new_guarded new_rhs)
405 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
406 returnM (GRHSs new_grhss new_binds)
409 %************************************************************************
411 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
413 %************************************************************************
416 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
417 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
418 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
420 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
421 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
423 zonkExpr env (HsVar id)
424 = returnM (HsVar (zonkIdOcc env id))
426 zonkExpr env (HsIPVar id)
427 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
429 zonkExpr env (HsLit (HsRat f ty))
430 = zonkTcTypeToType env ty `thenM` \ new_ty ->
431 returnM (HsLit (HsRat f new_ty))
433 zonkExpr _ (HsLit lit)
434 = returnM (HsLit lit)
436 zonkExpr env (HsOverLit lit)
437 = do { lit' <- zonkOverLit env lit
438 ; return (HsOverLit lit') }
440 zonkExpr env (HsLam matches)
441 = zonkMatchGroup env matches `thenM` \ new_matches ->
442 returnM (HsLam new_matches)
444 zonkExpr env (HsApp e1 e2)
445 = zonkLExpr env e1 `thenM` \ new_e1 ->
446 zonkLExpr env e2 `thenM` \ new_e2 ->
447 returnM (HsApp new_e1 new_e2)
449 zonkExpr env (HsBracketOut body bs)
450 = mappM zonk_b bs `thenM` \ bs' ->
451 returnM (HsBracketOut body bs')
453 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
456 zonkExpr _ (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
457 returnM (HsSpliceE s)
459 zonkExpr env (OpApp e1 op fixity e2)
460 = zonkLExpr env e1 `thenM` \ new_e1 ->
461 zonkLExpr env op `thenM` \ new_op ->
462 zonkLExpr env e2 `thenM` \ new_e2 ->
463 returnM (OpApp new_e1 new_op fixity new_e2)
465 zonkExpr env (NegApp expr op)
466 = zonkLExpr env expr `thenM` \ new_expr ->
467 zonkExpr env op `thenM` \ new_op ->
468 returnM (NegApp new_expr new_op)
470 zonkExpr env (HsPar e)
471 = zonkLExpr env e `thenM` \new_e ->
472 returnM (HsPar new_e)
474 zonkExpr env (SectionL expr op)
475 = zonkLExpr env expr `thenM` \ new_expr ->
476 zonkLExpr env op `thenM` \ new_op ->
477 returnM (SectionL new_expr new_op)
479 zonkExpr env (SectionR op expr)
480 = zonkLExpr env op `thenM` \ new_op ->
481 zonkLExpr env expr `thenM` \ new_expr ->
482 returnM (SectionR new_op new_expr)
484 zonkExpr env (ExplicitTuple tup_args boxed)
485 = do { new_tup_args <- mapM zonk_tup_arg tup_args
486 ; return (ExplicitTuple new_tup_args boxed) }
488 zonk_tup_arg (Present e) = do { e' <- zonkLExpr env e; return (Present e') }
489 zonk_tup_arg (Missing t) = do { t' <- zonkTcTypeToType env t; return (Missing t') }
491 zonkExpr env (HsCase expr ms)
492 = zonkLExpr env expr `thenM` \ new_expr ->
493 zonkMatchGroup env ms `thenM` \ new_ms ->
494 returnM (HsCase new_expr new_ms)
496 zonkExpr env (HsIf e1 e2 e3)
497 = zonkLExpr env e1 `thenM` \ new_e1 ->
498 zonkLExpr env e2 `thenM` \ new_e2 ->
499 zonkLExpr env e3 `thenM` \ new_e3 ->
500 returnM (HsIf new_e1 new_e2 new_e3)
502 zonkExpr env (HsLet binds expr)
503 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
504 zonkLExpr new_env expr `thenM` \ new_expr ->
505 returnM (HsLet new_binds new_expr)
507 zonkExpr env (HsDo do_or_lc stmts body ty)
508 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
509 zonkLExpr new_env body `thenM` \ new_body ->
510 zonkTcTypeToType env ty `thenM` \ new_ty ->
511 returnM (HsDo (zonkDo env do_or_lc)
512 new_stmts new_body new_ty)
514 zonkExpr env (ExplicitList ty exprs)
515 = zonkTcTypeToType env ty `thenM` \ new_ty ->
516 zonkLExprs env exprs `thenM` \ new_exprs ->
517 returnM (ExplicitList new_ty new_exprs)
519 zonkExpr env (ExplicitPArr ty exprs)
520 = zonkTcTypeToType env ty `thenM` \ new_ty ->
521 zonkLExprs env exprs `thenM` \ new_exprs ->
522 returnM (ExplicitPArr new_ty new_exprs)
524 zonkExpr env (RecordCon data_con con_expr rbinds)
525 = do { new_con_expr <- zonkExpr env con_expr
526 ; new_rbinds <- zonkRecFields env rbinds
527 ; return (RecordCon data_con new_con_expr new_rbinds) }
529 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
530 = do { new_expr <- zonkLExpr env expr
531 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
532 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
533 ; new_rbinds <- zonkRecFields env rbinds
534 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
536 zonkExpr env (ExprWithTySigOut e ty)
537 = do { e' <- zonkLExpr env e
538 ; return (ExprWithTySigOut e' ty) }
540 zonkExpr _ (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
542 zonkExpr env (ArithSeq expr info)
543 = zonkExpr env expr `thenM` \ new_expr ->
544 zonkArithSeq env info `thenM` \ new_info ->
545 returnM (ArithSeq new_expr new_info)
547 zonkExpr env (PArrSeq expr info)
548 = zonkExpr env expr `thenM` \ new_expr ->
549 zonkArithSeq env info `thenM` \ new_info ->
550 returnM (PArrSeq new_expr new_info)
552 zonkExpr env (HsSCC lbl expr)
553 = zonkLExpr env expr `thenM` \ new_expr ->
554 returnM (HsSCC lbl new_expr)
556 zonkExpr env (HsTickPragma info expr)
557 = zonkLExpr env expr `thenM` \ new_expr ->
558 returnM (HsTickPragma info new_expr)
560 -- hdaume: core annotations
561 zonkExpr env (HsCoreAnn lbl expr)
562 = zonkLExpr env expr `thenM` \ new_expr ->
563 returnM (HsCoreAnn lbl new_expr)
565 -- arrow notation extensions
566 zonkExpr env (HsProc pat body)
567 = do { (env1, new_pat) <- zonkPat env pat
568 ; new_body <- zonkCmdTop env1 body
569 ; return (HsProc new_pat new_body) }
571 zonkExpr env (HsArrApp e1 e2 ty ho rl)
572 = zonkLExpr env e1 `thenM` \ new_e1 ->
573 zonkLExpr env e2 `thenM` \ new_e2 ->
574 zonkTcTypeToType env ty `thenM` \ new_ty ->
575 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
577 zonkExpr env (HsArrForm op fixity args)
578 = zonkLExpr env op `thenM` \ new_op ->
579 mappM (zonkCmdTop env) args `thenM` \ new_args ->
580 returnM (HsArrForm new_op fixity new_args)
582 zonkExpr env (HsWrap co_fn expr)
583 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
584 zonkExpr env1 expr `thenM` \ new_expr ->
585 return (HsWrap new_co_fn new_expr)
587 zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr)
589 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
590 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
592 zonk_cmd_top :: ZonkEnv -> HsCmdTop TcId -> TcM (HsCmdTop Id)
593 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
594 = zonkLExpr env cmd `thenM` \ new_cmd ->
595 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
596 zonkTcTypeToType env ty `thenM` \ new_ty ->
597 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
598 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
600 -------------------------------------------------------------------------
601 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
602 zonkCoFn env WpHole = return (env, WpHole)
603 zonkCoFn env WpInline = return (env, WpInline)
604 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
605 ; (env2, c2') <- zonkCoFn env1 c2
606 ; return (env2, WpCompose c1' c2') }
607 zonkCoFn env (WpCast co) = do { co' <- zonkTcTypeToType env co
608 ; return (env, WpCast co') }
609 zonkCoFn env (WpLam id) = do { id' <- zonkDictBndr env id
610 ; let env1 = extendZonkEnv1 env id'
611 ; return (env1, WpLam id') }
612 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
613 do { tv' <- zonkTyVarBndr env tv
614 ; return (env, WpTyLam tv') }
615 zonkCoFn env (WpApp v)
616 | isTcTyVar v = do { co <- zonkTcTyVar v
617 ; return (env, WpTyApp co) }
618 -- Yuk! A mutable coercion variable is a TcTyVar
619 -- not a CoVar, so don't use isCoVar!
620 -- Yuk! A WpApp can't hold the zonked type,
621 -- so we switch to WpTyApp
622 | otherwise = return (env, WpApp (zonkIdOcc env v))
623 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
624 ; return (env, WpTyApp ty') }
625 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
626 ; return (env1, WpLet bs') }
629 -------------------------------------------------------------------------
630 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
631 -- Only used for 'do', so the only Ids are in a MDoExpr table
632 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
633 zonkDo _ do_or_lc = do_or_lc
635 -------------------------------------------------------------------------
636 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
637 zonkOverLit env lit@(OverLit { ol_witness = e, ol_type = ty })
638 = do { ty' <- zonkTcTypeToType env ty
639 ; e' <- zonkExpr env e
640 ; return (lit { ol_witness = e', ol_type = ty' }) }
642 -------------------------------------------------------------------------
643 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
645 zonkArithSeq env (From e)
646 = zonkLExpr env e `thenM` \ new_e ->
649 zonkArithSeq env (FromThen e1 e2)
650 = zonkLExpr env e1 `thenM` \ new_e1 ->
651 zonkLExpr env e2 `thenM` \ new_e2 ->
652 returnM (FromThen new_e1 new_e2)
654 zonkArithSeq env (FromTo e1 e2)
655 = zonkLExpr env e1 `thenM` \ new_e1 ->
656 zonkLExpr env e2 `thenM` \ new_e2 ->
657 returnM (FromTo new_e1 new_e2)
659 zonkArithSeq env (FromThenTo e1 e2 e3)
660 = zonkLExpr env e1 `thenM` \ new_e1 ->
661 zonkLExpr env e2 `thenM` \ new_e2 ->
662 zonkLExpr env e3 `thenM` \ new_e3 ->
663 returnM (FromThenTo new_e1 new_e2 new_e3)
666 -------------------------------------------------------------------------
667 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
668 zonkStmts env [] = return (env, [])
669 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
670 ; (env2, ss') <- zonkStmts env1 ss
671 ; return (env2, s' : ss') }
673 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
674 zonkStmt env (ParStmt stmts_w_bndrs)
675 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
677 new_binders = concat (map snd new_stmts_w_bndrs)
678 env1 = extendZonkEnv env new_binders
680 return (env1, ParStmt new_stmts_w_bndrs)
682 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
683 returnM (new_stmts, zonkIdOccs env1 bndrs)
685 zonkStmt env (RecStmt { recS_stmts = segStmts, recS_later_ids = lvs, recS_rec_ids = rvs
686 , recS_ret_fn = ret_id, recS_mfix_fn = mfix_id, recS_bind_fn = bind_id
687 , recS_rec_rets = rets, recS_dicts = binds })
688 = do { new_rvs <- zonkIdBndrs env rvs
689 ; new_lvs <- zonkIdBndrs env lvs
690 ; new_ret_id <- zonkExpr env ret_id
691 ; new_mfix_id <- zonkExpr env mfix_id
692 ; new_bind_id <- zonkExpr env bind_id
693 ; let env1 = extendZonkEnv env new_rvs
694 ; (env2, new_segStmts) <- zonkStmts env1 segStmts
695 -- Zonk the ret-expressions in an envt that
696 -- has the polymorphic bindings in the envt
697 ; new_rets <- mapM (zonkExpr env2) rets
698 ; let env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
699 ; (env4, new_binds) <- zonkRecMonoBinds env3 binds
701 RecStmt { recS_stmts = new_segStmts, recS_later_ids = new_lvs
702 , recS_rec_ids = new_rvs, recS_ret_fn = new_ret_id
703 , recS_mfix_fn = new_mfix_id, recS_bind_fn = new_bind_id
704 , recS_rec_rets = new_rets, recS_dicts = new_binds }) }
706 zonkStmt env (ExprStmt expr then_op ty)
707 = zonkLExpr env expr `thenM` \ new_expr ->
708 zonkExpr env then_op `thenM` \ new_then ->
709 zonkTcTypeToType env ty `thenM` \ new_ty ->
710 returnM (env, ExprStmt new_expr new_then new_ty)
712 zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
713 = do { (env', stmts') <- zonkStmts env stmts
714 ; let binders' = zonkIdOccs env' binders
715 ; usingExpr' <- zonkLExpr env' usingExpr
716 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
717 ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
719 zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
720 = do { (env', stmts') <- zonkStmts env stmts
721 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
723 case groupByClause of
724 GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
725 GroupBySomething eitherUsingExpr byExpr -> do
726 eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
727 byExpr' <- zonkLExpr env' byExpr
728 return $ GroupBySomething eitherUsingExpr' byExpr'
730 ; let env'' = extendZonkEnv env' (map snd binderMap')
731 ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
733 mapEitherM f g x = do
735 Left a -> f a >>= (return . Left)
736 Right b -> g b >>= (return . Right)
738 zonkBinderMapEntry env (oldBinder, newBinder) = do
739 let oldBinder' = zonkIdOcc env oldBinder
740 newBinder' <- zonkIdBndr env newBinder
741 return (oldBinder', newBinder')
743 zonkStmt env (LetStmt binds)
744 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
745 returnM (env1, LetStmt new_binds)
747 zonkStmt env (BindStmt pat expr bind_op fail_op)
748 = do { new_expr <- zonkLExpr env expr
749 ; (env1, new_pat) <- zonkPat env pat
750 ; new_bind <- zonkExpr env bind_op
751 ; new_fail <- zonkExpr env fail_op
752 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
754 zonkMaybeLExpr :: ZonkEnv -> Maybe (LHsExpr TcId) -> TcM (Maybe (LHsExpr Id))
755 zonkMaybeLExpr _ Nothing = return Nothing
756 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
759 -------------------------------------------------------------------------
760 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
761 zonkRecFields env (HsRecFields flds dd)
762 = do { flds' <- mappM zonk_rbind flds
763 ; return (HsRecFields flds' dd) }
766 = do { new_id <- wrapLocM (zonkIdBndr env) (hsRecFieldId fld)
767 ; new_expr <- zonkLExpr env (hsRecFieldArg fld)
768 ; return (fld { hsRecFieldId = new_id, hsRecFieldArg = new_expr }) }
770 -------------------------------------------------------------------------
771 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
772 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
776 %************************************************************************
778 \subsection[BackSubst-Pats]{Patterns}
780 %************************************************************************
783 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
784 -- Extend the environment as we go, because it's possible for one
785 -- pattern to bind something that is used in another (inside or
787 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
789 zonk_pat :: ZonkEnv -> Pat TcId -> TcM (ZonkEnv, Pat Id)
790 zonk_pat env (ParPat p)
791 = do { (env', p') <- zonkPat env p
792 ; return (env', ParPat p') }
794 zonk_pat env (WildPat ty)
795 = do { ty' <- zonkTcTypeToType env ty
796 ; return (env, WildPat ty') }
798 zonk_pat env (VarPat v)
799 = do { v' <- zonkIdBndr env v
800 ; return (extendZonkEnv1 env v', VarPat v') }
802 zonk_pat env (VarPatOut v binds)
803 = do { v' <- zonkIdBndr env v
804 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
805 ; returnM (env', VarPatOut v' binds') }
807 zonk_pat env (LazyPat pat)
808 = do { (env', pat') <- zonkPat env pat
809 ; return (env', LazyPat pat') }
811 zonk_pat env (BangPat pat)
812 = do { (env', pat') <- zonkPat env pat
813 ; return (env', BangPat pat') }
815 zonk_pat env (AsPat (L loc v) pat)
816 = do { v' <- zonkIdBndr env v
817 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
818 ; return (env', AsPat (L loc v') pat') }
820 zonk_pat env (ViewPat expr pat ty)
821 = do { expr' <- zonkLExpr env expr
822 ; (env', pat') <- zonkPat env pat
823 ; ty' <- zonkTcTypeToType env ty
824 ; return (env', ViewPat expr' pat' ty') }
826 zonk_pat env (ListPat pats ty)
827 = do { ty' <- zonkTcTypeToType env ty
828 ; (env', pats') <- zonkPats env pats
829 ; return (env', ListPat pats' ty') }
831 zonk_pat env (PArrPat pats ty)
832 = do { ty' <- zonkTcTypeToType env ty
833 ; (env', pats') <- zonkPats env pats
834 ; return (env', PArrPat pats' ty') }
836 zonk_pat env (TuplePat pats boxed ty)
837 = do { ty' <- zonkTcTypeToType env ty
838 ; (env', pats') <- zonkPats env pats
839 ; return (env', TuplePat pats' boxed ty') }
841 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
842 = ASSERT( all isImmutableTyVar (pat_tvs p) )
843 do { new_ty <- zonkTcTypeToType env ty
844 ; new_dicts <- zonkDictBndrs env dicts
845 ; let env1 = extendZonkEnv env new_dicts
846 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
847 ; (env', new_args) <- zonkConStuff env2 args
848 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
849 pat_binds = new_binds, pat_args = new_args }) }
851 zonk_pat env (LitPat lit) = return (env, LitPat lit)
853 zonk_pat env (SigPatOut pat ty)
854 = do { ty' <- zonkTcTypeToType env ty
855 ; (env', pat') <- zonkPat env pat
856 ; return (env', SigPatOut pat' ty') }
858 zonk_pat env (NPat lit mb_neg eq_expr)
859 = do { lit' <- zonkOverLit env lit
860 ; mb_neg' <- case mb_neg of
861 Nothing -> return Nothing
862 Just neg -> do { neg' <- zonkExpr env neg
863 ; return (Just neg') }
864 ; eq_expr' <- zonkExpr env eq_expr
865 ; return (env, NPat lit' mb_neg' eq_expr') }
867 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
868 = do { n' <- zonkIdBndr env n
869 ; lit' <- zonkOverLit env lit
870 ; e1' <- zonkExpr env e1
871 ; e2' <- zonkExpr env e2
872 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
874 zonk_pat env (CoPat co_fn pat ty)
875 = do { (env', co_fn') <- zonkCoFn env co_fn
876 ; (env'', pat') <- zonkPat env' (noLoc pat)
877 ; ty' <- zonkTcTypeToType env'' ty
878 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
880 zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat)
882 ---------------------------
883 zonkConStuff :: ZonkEnv
884 -> HsConDetails (OutPat TcId) (HsRecFields id (OutPat TcId))
886 HsConDetails (OutPat Id) (HsRecFields id (OutPat Id)))
887 zonkConStuff env (PrefixCon pats)
888 = do { (env', pats') <- zonkPats env pats
889 ; return (env', PrefixCon pats') }
891 zonkConStuff env (InfixCon p1 p2)
892 = do { (env1, p1') <- zonkPat env p1
893 ; (env', p2') <- zonkPat env1 p2
894 ; return (env', InfixCon p1' p2') }
896 zonkConStuff env (RecCon (HsRecFields rpats dd))
897 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
898 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
899 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
900 -- Field selectors have declared types; hence no zonking
902 ---------------------------
903 zonkPats :: ZonkEnv -> [OutPat TcId] -> TcM (ZonkEnv, [OutPat Id])
904 zonkPats env [] = return (env, [])
905 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
906 ; (env', pats') <- zonkPats env1 pats
907 ; return (env', pat':pats') }
910 %************************************************************************
912 \subsection[BackSubst-Foreign]{Foreign exports}
914 %************************************************************************
918 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
919 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
921 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
922 zonkForeignExport env (ForeignExport i _hs_ty spec) =
923 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
924 zonkForeignExport _ for_imp
925 = returnM for_imp -- Foreign imports don't need zonking
929 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
930 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
932 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
933 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
934 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
935 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
937 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
938 -- Type variables don't need an envt
939 -- They are bound through the mutable mechanism
941 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
942 -- We need to gather the type variables mentioned on the LHS so we can
943 -- quantify over them. Example:
949 -- {-# RULES "myrule" foo C = 1 #-}
951 -- After type checking the LHS becomes (foo a (C a))
952 -- and we do not want to zap the unbound tyvar 'a' to (), because
953 -- that limits the applicability of the rule. Instead, we
954 -- want to quantify over it!
956 -- It's easiest to find the free tyvars here. Attempts to do so earlier
957 -- are tiresome, because (a) the data type is big and (b) finding the
958 -- free type vars of an expression is necessarily monadic operation.
959 -- (consider /\a -> f @ b, where b is side-effected to a)
961 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
962 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
964 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
966 final_bndrs :: [Located Var]
967 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
969 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
970 -- I hate this map RuleBndr stuff
972 zonk_bndr (RuleBndr v)
973 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
974 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
976 zonk_bndr (RuleBndrSig {}) = panic "zonk_bndr RuleBndrSig"
980 %************************************************************************
982 \subsection[BackSubst-Foreign]{Foreign exports}
984 %************************************************************************
987 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
988 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
990 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
991 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
993 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
994 -- This variant collects unbound type variables in a mutable variable
995 zonkTypeCollecting unbound_tv_set
996 = zonkType zonk_unbound_tyvar
998 zonk_unbound_tyvar tv
999 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
1000 readMutVar unbound_tv_set `thenM` \ tv_set ->
1001 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
1002 return (mkTyVarTy tv')
1004 zonkTypeZapping :: TcType -> TcM Type
1005 -- This variant is used for everything except the LHS of rules
1006 -- It zaps unbound type variables to (), or some other arbitrary type
1008 = zonkType zonk_unbound_tyvar ty
1010 -- Zonk a mutable but unbound type variable to an arbitrary type
1011 -- We know it's unbound even though we don't carry an environment,
1012 -- because at the binding site for a type variable we bind the
1013 -- mutable tyvar to a fresh immutable one. So the mutable store
1014 -- plays the role of an environment. If we come across a mutable
1015 -- type variable that isn't so bound, it must be completely free.
1016 zonk_unbound_tyvar tv = do { let ty = anyTypeOfKind (tyVarKind tv)
1017 ; writeMetaTyVar tv ty