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, var_inline = inl })
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, var_inline = inl })
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 (L loc (SpecPrag co_fn inl))
369 = do { (_, co_fn') <- zonkCoFn env co_fn
370 ; return (L loc (SpecPrag co_fn' inl)) }
373 %************************************************************************
375 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
377 %************************************************************************
380 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
381 zonkMatchGroup env (MatchGroup ms ty)
382 = do { ms' <- mapM (zonkMatch env) ms
383 ; ty' <- zonkTcTypeToType env ty
384 ; return (MatchGroup ms' ty') }
386 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
387 zonkMatch env (L loc (Match pats _ grhss))
388 = do { (env1, new_pats) <- zonkPats env pats
389 ; new_grhss <- zonkGRHSs env1 grhss
390 ; return (L loc (Match new_pats Nothing new_grhss)) }
392 -------------------------------------------------------------------------
393 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
395 zonkGRHSs env (GRHSs grhss binds)
396 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
398 zonk_grhs (GRHS guarded rhs)
399 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
400 zonkLExpr env2 rhs `thenM` \ new_rhs ->
401 returnM (GRHS new_guarded new_rhs)
403 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
404 returnM (GRHSs new_grhss new_binds)
407 %************************************************************************
409 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
411 %************************************************************************
414 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
415 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
416 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
418 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
419 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
421 zonkExpr env (HsVar id)
422 = returnM (HsVar (zonkIdOcc env id))
424 zonkExpr env (HsIPVar id)
425 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
427 zonkExpr env (HsLit (HsRat f ty))
428 = zonkTcTypeToType env ty `thenM` \ new_ty ->
429 returnM (HsLit (HsRat f new_ty))
431 zonkExpr _ (HsLit lit)
432 = returnM (HsLit lit)
434 zonkExpr env (HsOverLit lit)
435 = do { lit' <- zonkOverLit env lit
436 ; return (HsOverLit lit') }
438 zonkExpr env (HsLam matches)
439 = zonkMatchGroup env matches `thenM` \ new_matches ->
440 returnM (HsLam new_matches)
442 zonkExpr env (HsApp e1 e2)
443 = zonkLExpr env e1 `thenM` \ new_e1 ->
444 zonkLExpr env e2 `thenM` \ new_e2 ->
445 returnM (HsApp new_e1 new_e2)
447 zonkExpr env (HsBracketOut body bs)
448 = mappM zonk_b bs `thenM` \ bs' ->
449 returnM (HsBracketOut body bs')
451 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
454 zonkExpr _ (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
455 returnM (HsSpliceE s)
457 zonkExpr env (OpApp e1 op fixity e2)
458 = zonkLExpr env e1 `thenM` \ new_e1 ->
459 zonkLExpr env op `thenM` \ new_op ->
460 zonkLExpr env e2 `thenM` \ new_e2 ->
461 returnM (OpApp new_e1 new_op fixity new_e2)
463 zonkExpr env (NegApp expr op)
464 = zonkLExpr env expr `thenM` \ new_expr ->
465 zonkExpr env op `thenM` \ new_op ->
466 returnM (NegApp new_expr new_op)
468 zonkExpr env (HsPar e)
469 = zonkLExpr env e `thenM` \new_e ->
470 returnM (HsPar new_e)
472 zonkExpr env (SectionL expr op)
473 = zonkLExpr env expr `thenM` \ new_expr ->
474 zonkLExpr env op `thenM` \ new_op ->
475 returnM (SectionL new_expr new_op)
477 zonkExpr env (SectionR op expr)
478 = zonkLExpr env op `thenM` \ new_op ->
479 zonkLExpr env expr `thenM` \ new_expr ->
480 returnM (SectionR new_op new_expr)
482 zonkExpr env (ExplicitTuple tup_args boxed)
483 = do { new_tup_args <- mapM zonk_tup_arg tup_args
484 ; return (ExplicitTuple new_tup_args boxed) }
486 zonk_tup_arg (Present e) = do { e' <- zonkLExpr env e; return (Present e') }
487 zonk_tup_arg (Missing t) = do { t' <- zonkTcTypeToType env t; return (Missing t') }
489 zonkExpr env (HsCase expr ms)
490 = zonkLExpr env expr `thenM` \ new_expr ->
491 zonkMatchGroup env ms `thenM` \ new_ms ->
492 returnM (HsCase new_expr new_ms)
494 zonkExpr env (HsIf e1 e2 e3)
495 = zonkLExpr env e1 `thenM` \ new_e1 ->
496 zonkLExpr env e2 `thenM` \ new_e2 ->
497 zonkLExpr env e3 `thenM` \ new_e3 ->
498 returnM (HsIf new_e1 new_e2 new_e3)
500 zonkExpr env (HsLet binds expr)
501 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
502 zonkLExpr new_env expr `thenM` \ new_expr ->
503 returnM (HsLet new_binds new_expr)
505 zonkExpr env (HsDo do_or_lc stmts body ty)
506 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
507 zonkLExpr new_env body `thenM` \ new_body ->
508 zonkTcTypeToType env ty `thenM` \ new_ty ->
509 returnM (HsDo (zonkDo env do_or_lc)
510 new_stmts new_body new_ty)
512 zonkExpr env (ExplicitList ty exprs)
513 = zonkTcTypeToType env ty `thenM` \ new_ty ->
514 zonkLExprs env exprs `thenM` \ new_exprs ->
515 returnM (ExplicitList new_ty new_exprs)
517 zonkExpr env (ExplicitPArr ty exprs)
518 = zonkTcTypeToType env ty `thenM` \ new_ty ->
519 zonkLExprs env exprs `thenM` \ new_exprs ->
520 returnM (ExplicitPArr new_ty new_exprs)
522 zonkExpr env (RecordCon data_con con_expr rbinds)
523 = do { new_con_expr <- zonkExpr env con_expr
524 ; new_rbinds <- zonkRecFields env rbinds
525 ; return (RecordCon data_con new_con_expr new_rbinds) }
527 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
528 = do { new_expr <- zonkLExpr env expr
529 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
530 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
531 ; new_rbinds <- zonkRecFields env rbinds
532 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
534 zonkExpr env (ExprWithTySigOut e ty)
535 = do { e' <- zonkLExpr env e
536 ; return (ExprWithTySigOut e' ty) }
538 zonkExpr _ (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
540 zonkExpr env (ArithSeq expr info)
541 = zonkExpr env expr `thenM` \ new_expr ->
542 zonkArithSeq env info `thenM` \ new_info ->
543 returnM (ArithSeq new_expr new_info)
545 zonkExpr env (PArrSeq expr info)
546 = zonkExpr env expr `thenM` \ new_expr ->
547 zonkArithSeq env info `thenM` \ new_info ->
548 returnM (PArrSeq new_expr new_info)
550 zonkExpr env (HsSCC lbl expr)
551 = zonkLExpr env expr `thenM` \ new_expr ->
552 returnM (HsSCC lbl new_expr)
554 zonkExpr env (HsTickPragma info expr)
555 = zonkLExpr env expr `thenM` \ new_expr ->
556 returnM (HsTickPragma info new_expr)
558 -- hdaume: core annotations
559 zonkExpr env (HsCoreAnn lbl expr)
560 = zonkLExpr env expr `thenM` \ new_expr ->
561 returnM (HsCoreAnn lbl new_expr)
563 -- arrow notation extensions
564 zonkExpr env (HsProc pat body)
565 = do { (env1, new_pat) <- zonkPat env pat
566 ; new_body <- zonkCmdTop env1 body
567 ; return (HsProc new_pat new_body) }
569 zonkExpr env (HsArrApp e1 e2 ty ho rl)
570 = zonkLExpr env e1 `thenM` \ new_e1 ->
571 zonkLExpr env e2 `thenM` \ new_e2 ->
572 zonkTcTypeToType env ty `thenM` \ new_ty ->
573 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
575 zonkExpr env (HsArrForm op fixity args)
576 = zonkLExpr env op `thenM` \ new_op ->
577 mappM (zonkCmdTop env) args `thenM` \ new_args ->
578 returnM (HsArrForm new_op fixity new_args)
580 zonkExpr env (HsWrap co_fn expr)
581 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
582 zonkExpr env1 expr `thenM` \ new_expr ->
583 return (HsWrap new_co_fn new_expr)
585 zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr)
587 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
588 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
590 zonk_cmd_top :: ZonkEnv -> HsCmdTop TcId -> TcM (HsCmdTop Id)
591 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
592 = zonkLExpr env cmd `thenM` \ new_cmd ->
593 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
594 zonkTcTypeToType env ty `thenM` \ new_ty ->
595 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
596 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
598 -------------------------------------------------------------------------
599 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
600 zonkCoFn env WpHole = return (env, WpHole)
601 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
602 ; (env2, c2') <- zonkCoFn env1 c2
603 ; return (env2, WpCompose c1' c2') }
604 zonkCoFn env (WpCast co) = do { co' <- zonkTcTypeToType env co
605 ; return (env, WpCast co') }
606 zonkCoFn env (WpLam id) = do { id' <- zonkDictBndr env id
607 ; let env1 = extendZonkEnv1 env id'
608 ; return (env1, WpLam id') }
609 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
610 do { tv' <- zonkTyVarBndr env tv
611 ; return (env, WpTyLam tv') }
612 zonkCoFn env (WpApp v)
613 | isTcTyVar v = do { co <- zonkTcTyVar v
614 ; return (env, WpTyApp co) }
615 -- Yuk! A mutable coercion variable is a TcTyVar
616 -- not a CoVar, so don't use isCoVar!
617 -- Yuk! A WpApp can't hold the zonked type,
618 -- so we switch to WpTyApp
619 | otherwise = return (env, WpApp (zonkIdOcc env v))
620 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
621 ; return (env, WpTyApp ty') }
622 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
623 ; return (env1, WpLet bs') }
626 -------------------------------------------------------------------------
627 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
628 -- Only used for 'do', so the only Ids are in a MDoExpr table
629 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
630 zonkDo _ do_or_lc = do_or_lc
632 -------------------------------------------------------------------------
633 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
634 zonkOverLit env lit@(OverLit { ol_witness = e, ol_type = ty })
635 = do { ty' <- zonkTcTypeToType env ty
636 ; e' <- zonkExpr env e
637 ; return (lit { ol_witness = e', ol_type = ty' }) }
639 -------------------------------------------------------------------------
640 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
642 zonkArithSeq env (From e)
643 = zonkLExpr env e `thenM` \ new_e ->
646 zonkArithSeq env (FromThen e1 e2)
647 = zonkLExpr env e1 `thenM` \ new_e1 ->
648 zonkLExpr env e2 `thenM` \ new_e2 ->
649 returnM (FromThen new_e1 new_e2)
651 zonkArithSeq env (FromTo e1 e2)
652 = zonkLExpr env e1 `thenM` \ new_e1 ->
653 zonkLExpr env e2 `thenM` \ new_e2 ->
654 returnM (FromTo new_e1 new_e2)
656 zonkArithSeq env (FromThenTo e1 e2 e3)
657 = zonkLExpr env e1 `thenM` \ new_e1 ->
658 zonkLExpr env e2 `thenM` \ new_e2 ->
659 zonkLExpr env e3 `thenM` \ new_e3 ->
660 returnM (FromThenTo new_e1 new_e2 new_e3)
663 -------------------------------------------------------------------------
664 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
665 zonkStmts env [] = return (env, [])
666 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
667 ; (env2, ss') <- zonkStmts env1 ss
668 ; return (env2, s' : ss') }
670 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
671 zonkStmt env (ParStmt stmts_w_bndrs)
672 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
674 new_binders = concat (map snd new_stmts_w_bndrs)
675 env1 = extendZonkEnv env new_binders
677 return (env1, ParStmt new_stmts_w_bndrs)
679 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
680 returnM (new_stmts, zonkIdOccs env1 bndrs)
682 zonkStmt env (RecStmt { recS_stmts = segStmts, recS_later_ids = lvs, recS_rec_ids = rvs
683 , recS_ret_fn = ret_id, recS_mfix_fn = mfix_id, recS_bind_fn = bind_id
684 , recS_rec_rets = rets, recS_dicts = binds })
685 = do { new_rvs <- zonkIdBndrs env rvs
686 ; new_lvs <- zonkIdBndrs env lvs
687 ; new_ret_id <- zonkExpr env ret_id
688 ; new_mfix_id <- zonkExpr env mfix_id
689 ; new_bind_id <- zonkExpr env bind_id
690 ; let env1 = extendZonkEnv env new_rvs
691 ; (env2, new_segStmts) <- zonkStmts env1 segStmts
692 -- Zonk the ret-expressions in an envt that
693 -- has the polymorphic bindings in the envt
694 ; new_rets <- mapM (zonkExpr env2) rets
695 ; let env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
696 ; (env4, new_binds) <- zonkRecMonoBinds env3 binds
698 RecStmt { recS_stmts = new_segStmts, recS_later_ids = new_lvs
699 , recS_rec_ids = new_rvs, recS_ret_fn = new_ret_id
700 , recS_mfix_fn = new_mfix_id, recS_bind_fn = new_bind_id
701 , recS_rec_rets = new_rets, recS_dicts = new_binds }) }
703 zonkStmt env (ExprStmt expr then_op ty)
704 = zonkLExpr env expr `thenM` \ new_expr ->
705 zonkExpr env then_op `thenM` \ new_then ->
706 zonkTcTypeToType env ty `thenM` \ new_ty ->
707 returnM (env, ExprStmt new_expr new_then new_ty)
709 zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
710 = do { (env', stmts') <- zonkStmts env stmts
711 ; let binders' = zonkIdOccs env' binders
712 ; usingExpr' <- zonkLExpr env' usingExpr
713 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
714 ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
716 zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
717 = do { (env', stmts') <- zonkStmts env stmts
718 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
720 case groupByClause of
721 GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
722 GroupBySomething eitherUsingExpr byExpr -> do
723 eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
724 byExpr' <- zonkLExpr env' byExpr
725 return $ GroupBySomething eitherUsingExpr' byExpr'
727 ; let env'' = extendZonkEnv env' (map snd binderMap')
728 ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
730 mapEitherM f g x = do
732 Left a -> f a >>= (return . Left)
733 Right b -> g b >>= (return . Right)
735 zonkBinderMapEntry env (oldBinder, newBinder) = do
736 let oldBinder' = zonkIdOcc env oldBinder
737 newBinder' <- zonkIdBndr env newBinder
738 return (oldBinder', newBinder')
740 zonkStmt env (LetStmt binds)
741 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
742 returnM (env1, LetStmt new_binds)
744 zonkStmt env (BindStmt pat expr bind_op fail_op)
745 = do { new_expr <- zonkLExpr env expr
746 ; (env1, new_pat) <- zonkPat env pat
747 ; new_bind <- zonkExpr env bind_op
748 ; new_fail <- zonkExpr env fail_op
749 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
751 zonkMaybeLExpr :: ZonkEnv -> Maybe (LHsExpr TcId) -> TcM (Maybe (LHsExpr Id))
752 zonkMaybeLExpr _ Nothing = return Nothing
753 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
756 -------------------------------------------------------------------------
757 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
758 zonkRecFields env (HsRecFields flds dd)
759 = do { flds' <- mappM zonk_rbind flds
760 ; return (HsRecFields flds' dd) }
763 = do { new_id <- wrapLocM (zonkIdBndr env) (hsRecFieldId fld)
764 ; new_expr <- zonkLExpr env (hsRecFieldArg fld)
765 ; return (fld { hsRecFieldId = new_id, hsRecFieldArg = new_expr }) }
767 -------------------------------------------------------------------------
768 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
769 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
773 %************************************************************************
775 \subsection[BackSubst-Pats]{Patterns}
777 %************************************************************************
780 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
781 -- Extend the environment as we go, because it's possible for one
782 -- pattern to bind something that is used in another (inside or
784 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
786 zonk_pat :: ZonkEnv -> Pat TcId -> TcM (ZonkEnv, Pat Id)
787 zonk_pat env (ParPat p)
788 = do { (env', p') <- zonkPat env p
789 ; return (env', ParPat p') }
791 zonk_pat env (WildPat ty)
792 = do { ty' <- zonkTcTypeToType env ty
793 ; return (env, WildPat ty') }
795 zonk_pat env (VarPat v)
796 = do { v' <- zonkIdBndr env v
797 ; return (extendZonkEnv1 env v', VarPat v') }
799 zonk_pat env (VarPatOut v binds)
800 = do { v' <- zonkIdBndr env v
801 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
802 ; returnM (env', VarPatOut v' binds') }
804 zonk_pat env (LazyPat pat)
805 = do { (env', pat') <- zonkPat env pat
806 ; return (env', LazyPat pat') }
808 zonk_pat env (BangPat pat)
809 = do { (env', pat') <- zonkPat env pat
810 ; return (env', BangPat pat') }
812 zonk_pat env (AsPat (L loc v) pat)
813 = do { v' <- zonkIdBndr env v
814 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
815 ; return (env', AsPat (L loc v') pat') }
817 zonk_pat env (ViewPat expr pat ty)
818 = do { expr' <- zonkLExpr env expr
819 ; (env', pat') <- zonkPat env pat
820 ; ty' <- zonkTcTypeToType env ty
821 ; return (env', ViewPat expr' pat' ty') }
823 zonk_pat env (ListPat pats ty)
824 = do { ty' <- zonkTcTypeToType env ty
825 ; (env', pats') <- zonkPats env pats
826 ; return (env', ListPat pats' ty') }
828 zonk_pat env (PArrPat pats ty)
829 = do { ty' <- zonkTcTypeToType env ty
830 ; (env', pats') <- zonkPats env pats
831 ; return (env', PArrPat pats' ty') }
833 zonk_pat env (TuplePat pats boxed ty)
834 = do { ty' <- zonkTcTypeToType env ty
835 ; (env', pats') <- zonkPats env pats
836 ; return (env', TuplePat pats' boxed ty') }
838 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
839 = ASSERT( all isImmutableTyVar (pat_tvs p) )
840 do { new_ty <- zonkTcTypeToType env ty
841 ; new_dicts <- zonkDictBndrs env dicts
842 ; let env1 = extendZonkEnv env new_dicts
843 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
844 ; (env', new_args) <- zonkConStuff env2 args
845 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
846 pat_binds = new_binds, pat_args = new_args }) }
848 zonk_pat env (LitPat lit) = return (env, LitPat lit)
850 zonk_pat env (SigPatOut pat ty)
851 = do { ty' <- zonkTcTypeToType env ty
852 ; (env', pat') <- zonkPat env pat
853 ; return (env', SigPatOut pat' ty') }
855 zonk_pat env (NPat lit mb_neg eq_expr)
856 = do { lit' <- zonkOverLit env lit
857 ; mb_neg' <- case mb_neg of
858 Nothing -> return Nothing
859 Just neg -> do { neg' <- zonkExpr env neg
860 ; return (Just neg') }
861 ; eq_expr' <- zonkExpr env eq_expr
862 ; return (env, NPat lit' mb_neg' eq_expr') }
864 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
865 = do { n' <- zonkIdBndr env n
866 ; lit' <- zonkOverLit env lit
867 ; e1' <- zonkExpr env e1
868 ; e2' <- zonkExpr env e2
869 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
871 zonk_pat env (CoPat co_fn pat ty)
872 = do { (env', co_fn') <- zonkCoFn env co_fn
873 ; (env'', pat') <- zonkPat env' (noLoc pat)
874 ; ty' <- zonkTcTypeToType env'' ty
875 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
877 zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat)
879 ---------------------------
880 zonkConStuff :: ZonkEnv
881 -> HsConDetails (OutPat TcId) (HsRecFields id (OutPat TcId))
883 HsConDetails (OutPat Id) (HsRecFields id (OutPat Id)))
884 zonkConStuff env (PrefixCon pats)
885 = do { (env', pats') <- zonkPats env pats
886 ; return (env', PrefixCon pats') }
888 zonkConStuff env (InfixCon p1 p2)
889 = do { (env1, p1') <- zonkPat env p1
890 ; (env', p2') <- zonkPat env1 p2
891 ; return (env', InfixCon p1' p2') }
893 zonkConStuff env (RecCon (HsRecFields rpats dd))
894 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
895 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
896 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
897 -- Field selectors have declared types; hence no zonking
899 ---------------------------
900 zonkPats :: ZonkEnv -> [OutPat TcId] -> TcM (ZonkEnv, [OutPat Id])
901 zonkPats env [] = return (env, [])
902 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
903 ; (env', pats') <- zonkPats env1 pats
904 ; return (env', pat':pats') }
907 %************************************************************************
909 \subsection[BackSubst-Foreign]{Foreign exports}
911 %************************************************************************
915 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
916 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
918 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
919 zonkForeignExport env (ForeignExport i _hs_ty spec) =
920 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
921 zonkForeignExport _ for_imp
922 = returnM for_imp -- Foreign imports don't need zonking
926 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
927 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
929 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
930 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
931 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
932 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
934 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
935 -- Type variables don't need an envt
936 -- They are bound through the mutable mechanism
938 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
939 -- We need to gather the type variables mentioned on the LHS so we can
940 -- quantify over them. Example:
946 -- {-# RULES "myrule" foo C = 1 #-}
948 -- After type checking the LHS becomes (foo a (C a))
949 -- and we do not want to zap the unbound tyvar 'a' to (), because
950 -- that limits the applicability of the rule. Instead, we
951 -- want to quantify over it!
953 -- It's easiest to find the free tyvars here. Attempts to do so earlier
954 -- are tiresome, because (a) the data type is big and (b) finding the
955 -- free type vars of an expression is necessarily monadic operation.
956 -- (consider /\a -> f @ b, where b is side-effected to a)
958 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
959 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
961 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
963 final_bndrs :: [Located Var]
964 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
966 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
967 -- I hate this map RuleBndr stuff
969 zonk_bndr (RuleBndr v)
970 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
971 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
973 zonk_bndr (RuleBndrSig {}) = panic "zonk_bndr RuleBndrSig"
977 %************************************************************************
979 \subsection[BackSubst-Foreign]{Foreign exports}
981 %************************************************************************
984 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
985 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
987 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
988 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
990 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
991 -- This variant collects unbound type variables in a mutable variable
992 zonkTypeCollecting unbound_tv_set
993 = zonkType zonk_unbound_tyvar
995 zonk_unbound_tyvar tv
996 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
997 readMutVar unbound_tv_set `thenM` \ tv_set ->
998 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
999 return (mkTyVarTy tv')
1001 zonkTypeZapping :: TcType -> TcM Type
1002 -- This variant is used for everything except the LHS of rules
1003 -- It zaps unbound type variables to (), or some other arbitrary type
1005 = zonkType zonk_unbound_tyvar ty
1007 -- Zonk a mutable but unbound type variable to an arbitrary type
1008 -- We know it's unbound even though we don't carry an environment,
1009 -- because at the binding site for a type variable we bind the
1010 -- mutable tyvar to a fresh immutable one. So the mutable store
1011 -- plays the role of an environment. If we come across a mutable
1012 -- type variable that isn't so bound, it must be completely free.
1013 zonk_unbound_tyvar tv = do { let ty = anyTypeOfKind (tyVarKind tv)
1014 ; writeMetaTyVar tv ty