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
22 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
26 #include "HsVersions.h"
29 import HsSyn -- oodles of it
50 import DynFlags( DynFlag(..) )
58 thenM :: Monad a => a b -> (b -> a c) -> a c
61 returnM :: Monad m => a -> m a
64 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
69 %************************************************************************
71 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
73 %************************************************************************
75 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
76 then something is wrong.
78 hsLPatType :: OutPat Id -> Type
79 hsLPatType (L _ pat) = hsPatType pat
81 hsPatType :: Pat Id -> Type
82 hsPatType (ParPat pat) = hsLPatType pat
83 hsPatType (WildPat ty) = ty
84 hsPatType (VarPat var) = idType var
85 hsPatType (BangPat pat) = hsLPatType pat
86 hsPatType (LazyPat pat) = hsLPatType pat
87 hsPatType (LitPat lit) = hsLitType lit
88 hsPatType (AsPat var _) = idType (unLoc var)
89 hsPatType (ViewPat _ _ ty) = ty
90 hsPatType (ListPat _ ty) = mkListTy ty
91 hsPatType (PArrPat _ ty) = mkPArrTy ty
92 hsPatType (TuplePat _ _ ty) = ty
93 hsPatType (ConPatOut { pat_ty = ty }) = ty
94 hsPatType (SigPatOut _ ty) = ty
95 hsPatType (NPat lit _ _) = overLitType lit
96 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
97 hsPatType (CoPat _ _ ty) = ty
98 hsPatType p = pprPanic "hsPatType" (ppr p)
100 hsLitType :: HsLit -> TcType
101 hsLitType (HsChar _) = charTy
102 hsLitType (HsCharPrim _) = charPrimTy
103 hsLitType (HsString _) = stringTy
104 hsLitType (HsStringPrim _) = addrPrimTy
105 hsLitType (HsInt _) = intTy
106 hsLitType (HsIntPrim _) = intPrimTy
107 hsLitType (HsWordPrim _) = wordPrimTy
108 hsLitType (HsInteger _ ty) = ty
109 hsLitType (HsRat _ ty) = ty
110 hsLitType (HsFloatPrim _) = floatPrimTy
111 hsLitType (HsDoublePrim _) = doublePrimTy
114 Overloaded literals. Here mainly becuase it uses isIntTy etc
117 shortCutLit :: OverLitVal -> TcType -> Maybe (HsExpr TcId)
118 shortCutLit (HsIntegral i) ty
119 | isIntTy ty && inIntRange i = Just (HsLit (HsInt i))
120 | isWordTy ty && inWordRange i = Just (mkLit wordDataCon (HsWordPrim i))
121 | isIntegerTy ty = Just (HsLit (HsInteger i ty))
122 | otherwise = shortCutLit (HsFractional (fromInteger i)) ty
123 -- The 'otherwise' case is important
124 -- Consider (3 :: Float). Syntactically it looks like an IntLit,
125 -- so we'll call shortCutIntLit, but of course it's a float
126 -- This can make a big difference for programs with a lot of
127 -- literals, compiled without -O
129 shortCutLit (HsFractional f) ty
130 | isFloatTy ty = Just (mkLit floatDataCon (HsFloatPrim f))
131 | isDoubleTy ty = Just (mkLit doubleDataCon (HsDoublePrim f))
132 | otherwise = Nothing
134 shortCutLit (HsIsString s) ty
135 | isStringTy ty = Just (HsLit (HsString s))
136 | otherwise = Nothing
138 mkLit :: DataCon -> HsLit -> HsExpr Id
139 mkLit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit)
141 ------------------------------
142 hsOverLitName :: OverLitVal -> Name
143 -- Get the canonical 'fromX' name for a particular OverLitVal
144 hsOverLitName (HsIntegral {}) = fromIntegerName
145 hsOverLitName (HsFractional {}) = fromRationalName
146 hsOverLitName (HsIsString {}) = fromStringName
149 %************************************************************************
151 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
153 %************************************************************************
156 -- zonkId is used *during* typechecking just to zonk the Id's type
157 zonkId :: TcId -> TcM TcId
159 = zonkTcType (idType id) `thenM` \ ty' ->
160 returnM (Id.setIdType id ty')
163 The rest of the zonking is done *after* typechecking.
164 The main zonking pass runs over the bindings
166 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
167 b) convert unbound TcTyVar to Void
168 c) convert each TcId to an Id by zonking its type
170 The type variables are converted by binding mutable tyvars to immutable ones
171 and then zonking as normal.
173 The Ids are converted by binding them in the normal Tc envt; that
174 way we maintain sharing; eg an Id is zonked at its binding site and they
175 all occurrences of that Id point to the common zonked copy
177 It's all pretty boring stuff, because HsSyn is such a large type, and
178 the environment manipulation is tiresome.
181 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
182 (VarEnv Var) -- What variables are in scope
183 -- Maps an Id or EvVar to its zonked version; both have the same Name
184 -- Note that all evidence (coercion variables as well as dictionaries)
185 -- are kept in the ZonkEnv
186 -- Only *type* abstraction is done by side effect
187 -- Is only consulted lazily; hence knot-tying
189 emptyZonkEnv :: ZonkEnv
190 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
192 extendZonkEnv :: ZonkEnv -> [Var] -> ZonkEnv
193 extendZonkEnv (ZonkEnv zonk_ty env) ids
194 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
196 extendZonkEnv1 :: ZonkEnv -> Var -> ZonkEnv
197 extendZonkEnv1 (ZonkEnv zonk_ty env) id
198 = ZonkEnv zonk_ty (extendVarEnv env id id)
200 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
201 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
203 zonkEnvIds :: ZonkEnv -> [Id]
204 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
206 zonkIdOcc :: ZonkEnv -> TcId -> Id
207 -- Ids defined in this module should be in the envt;
208 -- ignore others. (Actually, data constructors are also
209 -- not LocalVars, even when locally defined, but that is fine.)
210 -- (Also foreign-imported things aren't currently in the ZonkEnv;
211 -- that's ok because they don't need zonking.)
213 -- Actually, Template Haskell works in 'chunks' of declarations, and
214 -- an earlier chunk won't be in the 'env' that the zonking phase
215 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
216 -- zonked. There's no point in looking it up there (except for error
217 -- checking), and it's not conveniently to hand; hence the simple
218 -- 'orElse' case in the LocalVar branch.
220 -- Even without template splices, in module Main, the checking of
221 -- 'main' is done as a separate chunk.
222 zonkIdOcc (ZonkEnv _zonk_ty env) id
223 | isLocalVar id = lookupVarEnv env id `orElse` id
226 zonkIdOccs :: ZonkEnv -> [TcId] -> [Id]
227 zonkIdOccs env ids = map (zonkIdOcc env) ids
229 -- zonkIdBndr is used *after* typechecking to get the Id's type
230 -- to its final form. The TyVarEnv give
231 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
233 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
234 returnM (Id.setIdType id ty')
236 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
237 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
239 zonkTopBndrs :: [TcId] -> TcM [Id]
240 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
242 zonkEvBndrsX :: ZonkEnv -> [EvVar] -> TcM (ZonkEnv, [Var])
243 zonkEvBndrsX = mapAccumLM zonkEvBndrX
245 zonkEvBndrX :: ZonkEnv -> EvVar -> TcM (ZonkEnv, EvVar)
246 -- Works for dictionaries and coercions
248 = do { var' <- zonkEvBndr env var
249 ; return (extendZonkEnv1 env var', var') }
251 zonkEvBndr :: ZonkEnv -> EvVar -> TcM EvVar
252 -- Works for dictionaries and coercions
253 -- Does not extend the ZonkEnv
255 = do { ty' <- zonkTcTypeToType env (varType var)
256 ; return (setVarType var ty') }
258 zonkEvVarOcc :: ZonkEnv -> EvVar -> EvVar
259 zonkEvVarOcc env v = zonkIdOcc env v
264 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
265 zonkTopExpr e = zonkExpr emptyZonkEnv e
267 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
268 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
270 zonkTopDecls :: Bag EvBind
271 -> LHsBinds TcId -> NameSet
272 -> [LRuleDecl TcId] -> [LTcSpecPrag] -> [LForeignDecl TcId]
279 zonkTopDecls ev_binds binds sig_ns rules imp_specs fords
280 = do { (env1, ev_binds') <- zonkEvBinds emptyZonkEnv ev_binds
282 -- Warn about missing signatures
283 -- Do this only when we we have a type to offer
284 ; warn_missing_sigs <- doptM Opt_WarnMissingSigs
285 ; let sig_warn | warn_missing_sigs = topSigWarn sig_ns
286 | otherwise = noSigWarn
288 ; (env2, binds') <- zonkRecMonoBinds env1 sig_warn binds
289 -- Top level is implicitly recursive
290 ; rules' <- zonkRules env2 rules
291 ; specs' <- zonkLTcSpecPrags env2 imp_specs
292 ; fords' <- zonkForeignExports env2 fords
293 ; return (zonkEnvIds env2, ev_binds', binds', fords', specs', rules') }
295 ---------------------------------------------
296 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
297 zonkLocalBinds env EmptyLocalBinds
298 = return (env, EmptyLocalBinds)
300 zonkLocalBinds _ (HsValBinds (ValBindsIn {}))
301 = panic "zonkLocalBinds" -- Not in typechecker output
303 zonkLocalBinds env (HsValBinds vb@(ValBindsOut binds sigs))
304 = do { warn_missing_sigs <- doptM Opt_WarnMissingLocalSigs
305 ; let sig_warn | not warn_missing_sigs = noSigWarn
306 | otherwise = localSigWarn sig_ns
307 sig_ns = getTypeSigNames vb
308 ; (env1, new_binds) <- go env sig_warn binds
309 ; return (env1, HsValBinds (ValBindsOut new_binds sigs)) }
313 go env sig_warn ((r,b):bs)
314 = do { (env1, b') <- zonkRecMonoBinds env sig_warn b
315 ; (env2, bs') <- go env1 sig_warn bs
316 ; return (env2, (r,b'):bs') }
318 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
319 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
321 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
323 zonkTcEvBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
324 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
326 zonk_ip_bind (IPBind n e)
327 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
328 zonkLExpr env e `thenM` \ e' ->
329 returnM (IPBind n' e')
331 ---------------------------------------------
332 zonkRecMonoBinds :: ZonkEnv -> SigWarn -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
333 zonkRecMonoBinds env sig_warn binds
334 = fixM (\ ~(_, new_binds) -> do
335 { let env1 = extendZonkEnv env (collectHsBindsBinders new_binds)
336 ; binds' <- zonkMonoBinds env1 sig_warn binds
337 ; return (env1, binds') })
339 ---------------------------------------------
340 type SigWarn = Bool -> [Id] -> TcM ()
341 -- Missing-signature warning
342 -- The Bool is True for an AbsBinds, False otherwise
345 noSigWarn _ _ = return ()
347 topSigWarn :: NameSet -> SigWarn
348 topSigWarn sig_ns _ ids = mapM_ (topSigWarnId sig_ns) ids
350 topSigWarnId :: NameSet -> Id -> TcM ()
351 -- The NameSet is the Ids that *lack* a signature
352 -- We have to do it this way round because there are
353 -- lots of top-level bindings that are generated by GHC
354 -- and that don't have signatures
355 topSigWarnId sig_ns id
356 | idName id `elemNameSet` sig_ns = warnMissingSig msg id
357 | otherwise = return ()
359 msg = ptext (sLit "Top-level binding with no type signature:")
361 localSigWarn :: NameSet -> SigWarn
362 localSigWarn sig_ns is_abs_bind ids
363 | not is_abs_bind = return ()
364 | otherwise = mapM_ (localSigWarnId sig_ns) ids
366 localSigWarnId :: NameSet -> Id -> TcM ()
367 -- NameSet are the Ids that *have* type signatures
368 localSigWarnId sig_ns id
369 | not (isSigmaTy (idType id)) = return ()
370 | idName id `elemNameSet` sig_ns = return ()
371 | otherwise = warnMissingSig msg id
373 msg = ptext (sLit "Polymophic local binding with no type signature:")
375 warnMissingSig :: SDoc -> Id -> TcM ()
376 warnMissingSig msg id
377 = do { env0 <- tcInitTidyEnv
378 ; let (env1, tidy_ty) = tidyOpenType env0 (idType id)
379 ; addWarnTcM (env1, mk_msg tidy_ty) }
381 mk_msg ty = sep [ msg, nest 2 $ pprHsVar (idName id) <+> dcolon <+> ppr ty ]
383 ---------------------------------------------
384 zonkMonoBinds :: ZonkEnv -> SigWarn -> LHsBinds TcId -> TcM (LHsBinds Id)
385 zonkMonoBinds env sig_warn binds = mapBagM (wrapLocM (zonk_bind env sig_warn)) binds
387 zonk_bind :: ZonkEnv -> SigWarn -> HsBind TcId -> TcM (HsBind Id)
388 zonk_bind env sig_warn bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
389 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
390 ; sig_warn False (collectPatBinders new_pat)
391 ; new_grhss <- zonkGRHSs env grhss
392 ; new_ty <- zonkTcTypeToType env ty
393 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
395 zonk_bind env sig_warn (VarBind { var_id = var, var_rhs = expr, var_inline = inl })
396 = do { new_var <- zonkIdBndr env var
397 ; sig_warn False [new_var]
398 ; new_expr <- zonkLExpr env expr
399 ; return (VarBind { var_id = new_var, var_rhs = new_expr, var_inline = inl }) }
401 zonk_bind env sig_warn bind@(FunBind { fun_id = L loc var, fun_matches = ms
402 , fun_co_fn = co_fn })
403 = do { new_var <- zonkIdBndr env var
404 ; sig_warn False [new_var]
405 ; (env1, new_co_fn) <- zonkCoFn env co_fn
406 ; new_ms <- zonkMatchGroup env1 ms
407 ; return (bind { fun_id = L loc new_var, fun_matches = new_ms
408 , fun_co_fn = new_co_fn }) }
410 zonk_bind env sig_warn (AbsBinds { abs_tvs = tyvars, abs_ev_vars = evs
411 , abs_ev_binds = ev_binds
412 , abs_exports = exports
413 , abs_binds = val_binds })
414 = ASSERT( all isImmutableTyVar tyvars )
415 do { (env1, new_evs) <- zonkEvBndrsX env evs
416 ; (env2, new_ev_binds) <- zonkTcEvBinds env1 ev_binds
417 ; (new_val_bind, new_exports) <- fixM $ \ ~(new_val_binds, _) ->
418 do { let env3 = extendZonkEnv env2 (collectHsBindsBinders new_val_binds)
419 ; new_val_binds <- zonkMonoBinds env3 noSigWarn val_binds
420 ; new_exports <- mapM (zonkExport env3) exports
421 ; return (new_val_binds, new_exports) }
422 ; sig_warn True [b | (_,b,_,_) <- new_exports]
423 ; return (AbsBinds { abs_tvs = tyvars, abs_ev_vars = new_evs, abs_ev_binds = new_ev_binds
424 , abs_exports = new_exports, abs_binds = new_val_bind }) }
426 zonkExport env (tyvars, global, local, prags)
427 -- The tyvars are already zonked
428 = zonkIdBndr env global `thenM` \ new_global ->
429 zonkSpecPrags env prags `thenM` \ new_prags ->
430 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
432 zonkSpecPrags :: ZonkEnv -> TcSpecPrags -> TcM TcSpecPrags
433 zonkSpecPrags _ IsDefaultMethod = return IsDefaultMethod
434 zonkSpecPrags env (SpecPrags ps) = do { ps' <- zonkLTcSpecPrags env ps
435 ; return (SpecPrags ps') }
437 zonkLTcSpecPrags :: ZonkEnv -> [LTcSpecPrag] -> TcM [LTcSpecPrag]
438 zonkLTcSpecPrags env ps
441 zonk_prag (L loc (SpecPrag id co_fn inl))
442 = do { (_, co_fn') <- zonkCoFn env co_fn
443 ; return (L loc (SpecPrag (zonkIdOcc env id) co_fn' inl)) }
446 %************************************************************************
448 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
450 %************************************************************************
453 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
454 zonkMatchGroup env (MatchGroup ms ty)
455 = do { ms' <- mapM (zonkMatch env) ms
456 ; ty' <- zonkTcTypeToType env ty
457 ; return (MatchGroup ms' ty') }
459 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
460 zonkMatch env (L loc (Match pats _ grhss))
461 = do { (env1, new_pats) <- zonkPats env pats
462 ; new_grhss <- zonkGRHSs env1 grhss
463 ; return (L loc (Match new_pats Nothing new_grhss)) }
465 -------------------------------------------------------------------------
466 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
468 zonkGRHSs env (GRHSs grhss binds)
469 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
471 zonk_grhs (GRHS guarded rhs)
472 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
473 zonkLExpr env2 rhs `thenM` \ new_rhs ->
474 returnM (GRHS new_guarded new_rhs)
476 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
477 returnM (GRHSs new_grhss new_binds)
480 %************************************************************************
482 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
484 %************************************************************************
487 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
488 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
489 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
491 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
492 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
494 zonkExpr env (HsVar id)
495 = returnM (HsVar (zonkIdOcc env id))
497 zonkExpr env (HsIPVar id)
498 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
500 zonkExpr env (HsLit (HsRat f ty))
501 = zonkTcTypeToType env ty `thenM` \ new_ty ->
502 returnM (HsLit (HsRat f new_ty))
504 zonkExpr _ (HsLit lit)
505 = returnM (HsLit lit)
507 zonkExpr env (HsOverLit lit)
508 = do { lit' <- zonkOverLit env lit
509 ; return (HsOverLit lit') }
511 zonkExpr env (HsLam matches)
512 = zonkMatchGroup env matches `thenM` \ new_matches ->
513 returnM (HsLam new_matches)
515 zonkExpr env (HsApp e1 e2)
516 = zonkLExpr env e1 `thenM` \ new_e1 ->
517 zonkLExpr env e2 `thenM` \ new_e2 ->
518 returnM (HsApp new_e1 new_e2)
520 zonkExpr env (HsBracketOut body bs)
521 = mappM zonk_b bs `thenM` \ bs' ->
522 returnM (HsBracketOut body bs')
524 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
527 zonkExpr _ (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
528 returnM (HsSpliceE s)
530 zonkExpr env (OpApp e1 op fixity e2)
531 = zonkLExpr env e1 `thenM` \ new_e1 ->
532 zonkLExpr env op `thenM` \ new_op ->
533 zonkLExpr env e2 `thenM` \ new_e2 ->
534 returnM (OpApp new_e1 new_op fixity new_e2)
536 zonkExpr env (NegApp expr op)
537 = zonkLExpr env expr `thenM` \ new_expr ->
538 zonkExpr env op `thenM` \ new_op ->
539 returnM (NegApp new_expr new_op)
541 zonkExpr env (HsPar e)
542 = zonkLExpr env e `thenM` \new_e ->
543 returnM (HsPar new_e)
545 zonkExpr env (SectionL expr op)
546 = zonkLExpr env expr `thenM` \ new_expr ->
547 zonkLExpr env op `thenM` \ new_op ->
548 returnM (SectionL new_expr new_op)
550 zonkExpr env (SectionR op expr)
551 = zonkLExpr env op `thenM` \ new_op ->
552 zonkLExpr env expr `thenM` \ new_expr ->
553 returnM (SectionR new_op new_expr)
555 zonkExpr env (ExplicitTuple tup_args boxed)
556 = do { new_tup_args <- mapM zonk_tup_arg tup_args
557 ; return (ExplicitTuple new_tup_args boxed) }
559 zonk_tup_arg (Present e) = do { e' <- zonkLExpr env e; return (Present e') }
560 zonk_tup_arg (Missing t) = do { t' <- zonkTcTypeToType env t; return (Missing t') }
562 zonkExpr env (HsCase expr ms)
563 = zonkLExpr env expr `thenM` \ new_expr ->
564 zonkMatchGroup env ms `thenM` \ new_ms ->
565 returnM (HsCase new_expr new_ms)
567 zonkExpr env (HsIf e0 e1 e2 e3)
568 = do { new_e0 <- fmapMaybeM (zonkExpr env) e0
569 ; new_e1 <- zonkLExpr env e1
570 ; new_e2 <- zonkLExpr env e2
571 ; new_e3 <- zonkLExpr env e3
572 ; returnM (HsIf new_e0 new_e1 new_e2 new_e3) }
574 zonkExpr env (HsLet binds expr)
575 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
576 zonkLExpr new_env expr `thenM` \ new_expr ->
577 returnM (HsLet new_binds new_expr)
579 zonkExpr env (HsDo do_or_lc stmts body ty)
580 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
581 zonkLExpr new_env body `thenM` \ new_body ->
582 zonkTcTypeToType env ty `thenM` \ new_ty ->
583 returnM (HsDo do_or_lc new_stmts new_body new_ty)
585 zonkExpr env (ExplicitList ty exprs)
586 = zonkTcTypeToType env ty `thenM` \ new_ty ->
587 zonkLExprs env exprs `thenM` \ new_exprs ->
588 returnM (ExplicitList new_ty new_exprs)
590 zonkExpr env (ExplicitPArr ty exprs)
591 = zonkTcTypeToType env ty `thenM` \ new_ty ->
592 zonkLExprs env exprs `thenM` \ new_exprs ->
593 returnM (ExplicitPArr new_ty new_exprs)
595 zonkExpr env (RecordCon data_con con_expr rbinds)
596 = do { new_con_expr <- zonkExpr env con_expr
597 ; new_rbinds <- zonkRecFields env rbinds
598 ; return (RecordCon data_con new_con_expr new_rbinds) }
600 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
601 = do { new_expr <- zonkLExpr env expr
602 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
603 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
604 ; new_rbinds <- zonkRecFields env rbinds
605 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
607 zonkExpr env (ExprWithTySigOut e ty)
608 = do { e' <- zonkLExpr env e
609 ; return (ExprWithTySigOut e' ty) }
611 zonkExpr _ (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
613 zonkExpr env (ArithSeq expr info)
614 = zonkExpr env expr `thenM` \ new_expr ->
615 zonkArithSeq env info `thenM` \ new_info ->
616 returnM (ArithSeq new_expr new_info)
618 zonkExpr env (PArrSeq expr info)
619 = zonkExpr env expr `thenM` \ new_expr ->
620 zonkArithSeq env info `thenM` \ new_info ->
621 returnM (PArrSeq new_expr new_info)
623 zonkExpr env (HsSCC lbl expr)
624 = zonkLExpr env expr `thenM` \ new_expr ->
625 returnM (HsSCC lbl new_expr)
627 zonkExpr env (HsTickPragma info expr)
628 = zonkLExpr env expr `thenM` \ new_expr ->
629 returnM (HsTickPragma info new_expr)
631 -- hdaume: core annotations
632 zonkExpr env (HsCoreAnn lbl expr)
633 = zonkLExpr env expr `thenM` \ new_expr ->
634 returnM (HsCoreAnn lbl new_expr)
636 -- arrow notation extensions
637 zonkExpr env (HsProc pat body)
638 = do { (env1, new_pat) <- zonkPat env pat
639 ; new_body <- zonkCmdTop env1 body
640 ; return (HsProc new_pat new_body) }
642 zonkExpr env (HsArrApp e1 e2 ty ho rl)
643 = zonkLExpr env e1 `thenM` \ new_e1 ->
644 zonkLExpr env e2 `thenM` \ new_e2 ->
645 zonkTcTypeToType env ty `thenM` \ new_ty ->
646 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
648 zonkExpr env (HsArrForm op fixity args)
649 = zonkLExpr env op `thenM` \ new_op ->
650 mappM (zonkCmdTop env) args `thenM` \ new_args ->
651 returnM (HsArrForm new_op fixity new_args)
653 zonkExpr env (HsWrap co_fn expr)
654 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
655 zonkExpr env1 expr `thenM` \ new_expr ->
656 return (HsWrap new_co_fn new_expr)
658 zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr)
660 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
661 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
663 zonk_cmd_top :: ZonkEnv -> HsCmdTop TcId -> TcM (HsCmdTop Id)
664 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
665 = zonkLExpr env cmd `thenM` \ new_cmd ->
666 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
667 zonkTcTypeToType env ty `thenM` \ new_ty ->
668 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
669 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
671 -------------------------------------------------------------------------
672 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
673 zonkCoFn env WpHole = return (env, WpHole)
674 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
675 ; (env2, c2') <- zonkCoFn env1 c2
676 ; return (env2, WpCompose c1' c2') }
677 zonkCoFn env (WpCast co) = do { co' <- zonkTcTypeToType env co
678 ; return (env, WpCast co') }
679 zonkCoFn env (WpEvLam ev) = do { (env', ev') <- zonkEvBndrX env ev
680 ; return (env', WpEvLam ev') }
681 zonkCoFn env (WpEvApp arg) = do { arg' <- zonkEvTerm env arg
682 ; return (env, WpEvApp arg') }
683 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
684 return (env, WpTyLam tv)
685 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
686 ; return (env, WpTyApp ty') }
687 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkTcEvBinds env bs
688 ; return (env1, WpLet bs') }
690 -------------------------------------------------------------------------
691 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
692 zonkOverLit env lit@(OverLit { ol_witness = e, ol_type = ty })
693 = do { ty' <- zonkTcTypeToType env ty
694 ; e' <- zonkExpr env e
695 ; return (lit { ol_witness = e', ol_type = ty' }) }
697 -------------------------------------------------------------------------
698 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
700 zonkArithSeq env (From e)
701 = zonkLExpr env e `thenM` \ new_e ->
704 zonkArithSeq env (FromThen e1 e2)
705 = zonkLExpr env e1 `thenM` \ new_e1 ->
706 zonkLExpr env e2 `thenM` \ new_e2 ->
707 returnM (FromThen new_e1 new_e2)
709 zonkArithSeq env (FromTo e1 e2)
710 = zonkLExpr env e1 `thenM` \ new_e1 ->
711 zonkLExpr env e2 `thenM` \ new_e2 ->
712 returnM (FromTo new_e1 new_e2)
714 zonkArithSeq env (FromThenTo e1 e2 e3)
715 = zonkLExpr env e1 `thenM` \ new_e1 ->
716 zonkLExpr env e2 `thenM` \ new_e2 ->
717 zonkLExpr env e3 `thenM` \ new_e3 ->
718 returnM (FromThenTo new_e1 new_e2 new_e3)
721 -------------------------------------------------------------------------
722 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
723 zonkStmts env [] = return (env, [])
724 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
725 ; (env2, ss') <- zonkStmts env1 ss
726 ; return (env2, s' : ss') }
728 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
729 zonkStmt env (ParStmt stmts_w_bndrs)
730 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
732 new_binders = concat (map snd new_stmts_w_bndrs)
733 env1 = extendZonkEnv env new_binders
735 return (env1, ParStmt new_stmts_w_bndrs)
737 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
738 returnM (new_stmts, zonkIdOccs env1 bndrs)
740 zonkStmt env (RecStmt { recS_stmts = segStmts, recS_later_ids = lvs, recS_rec_ids = rvs
741 , recS_ret_fn = ret_id, recS_mfix_fn = mfix_id, recS_bind_fn = bind_id
742 , recS_rec_rets = rets })
743 = do { new_rvs <- zonkIdBndrs env rvs
744 ; new_lvs <- zonkIdBndrs env lvs
745 ; new_ret_id <- zonkExpr env ret_id
746 ; new_mfix_id <- zonkExpr env mfix_id
747 ; new_bind_id <- zonkExpr env bind_id
748 ; let env1 = extendZonkEnv env new_rvs
749 ; (env2, new_segStmts) <- zonkStmts env1 segStmts
750 -- Zonk the ret-expressions in an envt that
751 -- has the polymorphic bindings in the envt
752 ; new_rets <- mapM (zonkExpr env2) rets
753 ; return (extendZonkEnv env new_lvs, -- Only the lvs are needed
754 RecStmt { recS_stmts = new_segStmts, recS_later_ids = new_lvs
755 , recS_rec_ids = new_rvs, recS_ret_fn = new_ret_id
756 , recS_mfix_fn = new_mfix_id, recS_bind_fn = new_bind_id
757 , recS_rec_rets = new_rets }) }
759 zonkStmt env (ExprStmt expr then_op ty)
760 = zonkLExpr env expr `thenM` \ new_expr ->
761 zonkExpr env then_op `thenM` \ new_then ->
762 zonkTcTypeToType env ty `thenM` \ new_ty ->
763 returnM (env, ExprStmt new_expr new_then new_ty)
765 zonkStmt env (TransformStmt stmts binders usingExpr maybeByExpr)
766 = do { (env', stmts') <- zonkStmts env stmts
767 ; let binders' = zonkIdOccs env' binders
768 ; usingExpr' <- zonkLExpr env' usingExpr
769 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
770 ; return (env', TransformStmt stmts' binders' usingExpr' maybeByExpr') }
772 zonkStmt env (GroupStmt stmts binderMap by using)
773 = do { (env', stmts') <- zonkStmts env stmts
774 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
775 ; by' <- fmapMaybeM (zonkLExpr env') by
776 ; using' <- fmapEitherM (zonkLExpr env) (zonkExpr env) using
777 ; let env'' = extendZonkEnv env' (map snd binderMap')
778 ; return (env'', GroupStmt stmts' binderMap' by' using') }
780 zonkBinderMapEntry env (oldBinder, newBinder) = do
781 let oldBinder' = zonkIdOcc env oldBinder
782 newBinder' <- zonkIdBndr env newBinder
783 return (oldBinder', newBinder')
785 zonkStmt env (LetStmt binds)
786 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
787 returnM (env1, LetStmt new_binds)
789 zonkStmt env (BindStmt pat expr bind_op fail_op)
790 = do { new_expr <- zonkLExpr env expr
791 ; (env1, new_pat) <- zonkPat env pat
792 ; new_bind <- zonkExpr env bind_op
793 ; new_fail <- zonkExpr env fail_op
794 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
796 zonkMaybeLExpr :: ZonkEnv -> Maybe (LHsExpr TcId) -> TcM (Maybe (LHsExpr Id))
797 zonkMaybeLExpr _ Nothing = return Nothing
798 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
801 -------------------------------------------------------------------------
802 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
803 zonkRecFields env (HsRecFields flds dd)
804 = do { flds' <- mappM zonk_rbind flds
805 ; return (HsRecFields flds' dd) }
808 = do { new_id <- wrapLocM (zonkIdBndr env) (hsRecFieldId fld)
809 ; new_expr <- zonkLExpr env (hsRecFieldArg fld)
810 ; return (fld { hsRecFieldId = new_id, hsRecFieldArg = new_expr }) }
812 -------------------------------------------------------------------------
813 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
814 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
818 %************************************************************************
820 \subsection[BackSubst-Pats]{Patterns}
822 %************************************************************************
825 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
826 -- Extend the environment as we go, because it's possible for one
827 -- pattern to bind something that is used in another (inside or
829 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
831 zonk_pat :: ZonkEnv -> Pat TcId -> TcM (ZonkEnv, Pat Id)
832 zonk_pat env (ParPat p)
833 = do { (env', p') <- zonkPat env p
834 ; return (env', ParPat p') }
836 zonk_pat env (WildPat ty)
837 = do { ty' <- zonkTcTypeToType env ty
838 ; return (env, WildPat ty') }
840 zonk_pat env (VarPat v)
841 = do { v' <- zonkIdBndr env v
842 ; return (extendZonkEnv1 env v', VarPat v') }
844 zonk_pat env (LazyPat pat)
845 = do { (env', pat') <- zonkPat env pat
846 ; return (env', LazyPat pat') }
848 zonk_pat env (BangPat pat)
849 = do { (env', pat') <- zonkPat env pat
850 ; return (env', BangPat pat') }
852 zonk_pat env (AsPat (L loc v) pat)
853 = do { v' <- zonkIdBndr env v
854 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
855 ; return (env', AsPat (L loc v') pat') }
857 zonk_pat env (ViewPat expr pat ty)
858 = do { expr' <- zonkLExpr env expr
859 ; (env', pat') <- zonkPat env pat
860 ; ty' <- zonkTcTypeToType env ty
861 ; return (env', ViewPat expr' pat' ty') }
863 zonk_pat env (ListPat pats ty)
864 = do { ty' <- zonkTcTypeToType env ty
865 ; (env', pats') <- zonkPats env pats
866 ; return (env', ListPat pats' ty') }
868 zonk_pat env (PArrPat pats ty)
869 = do { ty' <- zonkTcTypeToType env ty
870 ; (env', pats') <- zonkPats env pats
871 ; return (env', PArrPat pats' ty') }
873 zonk_pat env (TuplePat pats boxed ty)
874 = do { ty' <- zonkTcTypeToType env ty
875 ; (env', pats') <- zonkPats env pats
876 ; return (env', TuplePat pats' boxed ty') }
878 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = evs, pat_binds = binds, pat_args = args })
879 = ASSERT( all isImmutableTyVar (pat_tvs p) )
880 do { new_ty <- zonkTcTypeToType env ty
881 ; (env1, new_evs) <- zonkEvBndrsX env evs
882 ; (env2, new_binds) <- zonkTcEvBinds env1 binds
883 ; (env', new_args) <- zonkConStuff env2 args
884 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_evs,
885 pat_binds = new_binds, pat_args = new_args }) }
887 zonk_pat env (LitPat lit) = return (env, LitPat lit)
889 zonk_pat env (SigPatOut pat ty)
890 = do { ty' <- zonkTcTypeToType env ty
891 ; (env', pat') <- zonkPat env pat
892 ; return (env', SigPatOut pat' ty') }
894 zonk_pat env (NPat lit mb_neg eq_expr)
895 = do { lit' <- zonkOverLit env lit
896 ; mb_neg' <- fmapMaybeM (zonkExpr env) mb_neg
897 ; eq_expr' <- zonkExpr env eq_expr
898 ; return (env, NPat lit' mb_neg' eq_expr') }
900 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
901 = do { n' <- zonkIdBndr env n
902 ; lit' <- zonkOverLit env lit
903 ; e1' <- zonkExpr env e1
904 ; e2' <- zonkExpr env e2
905 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
907 zonk_pat env (CoPat co_fn pat ty)
908 = do { (env', co_fn') <- zonkCoFn env co_fn
909 ; (env'', pat') <- zonkPat env' (noLoc pat)
910 ; ty' <- zonkTcTypeToType env'' ty
911 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
913 zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat)
915 ---------------------------
916 zonkConStuff :: ZonkEnv
917 -> HsConDetails (OutPat TcId) (HsRecFields id (OutPat TcId))
919 HsConDetails (OutPat Id) (HsRecFields id (OutPat Id)))
920 zonkConStuff env (PrefixCon pats)
921 = do { (env', pats') <- zonkPats env pats
922 ; return (env', PrefixCon pats') }
924 zonkConStuff env (InfixCon p1 p2)
925 = do { (env1, p1') <- zonkPat env p1
926 ; (env', p2') <- zonkPat env1 p2
927 ; return (env', InfixCon p1' p2') }
929 zonkConStuff env (RecCon (HsRecFields rpats dd))
930 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
931 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
932 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
933 -- Field selectors have declared types; hence no zonking
935 ---------------------------
936 zonkPats :: ZonkEnv -> [OutPat TcId] -> TcM (ZonkEnv, [OutPat Id])
937 zonkPats env [] = return (env, [])
938 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
939 ; (env', pats') <- zonkPats env1 pats
940 ; return (env', pat':pats') }
943 %************************************************************************
945 \subsection[BackSubst-Foreign]{Foreign exports}
947 %************************************************************************
951 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
952 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
954 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
955 zonkForeignExport env (ForeignExport i _hs_ty spec) =
956 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
957 zonkForeignExport _ for_imp
958 = returnM for_imp -- Foreign imports don't need zonking
962 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
963 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
965 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
966 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
967 = do { (env_rhs, new_bndrs) <- mapAccumLM zonk_bndr env vars
969 ; unbound_tv_set <- newMutVar emptyVarSet
970 ; let env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
971 -- We need to gather the type variables mentioned on the LHS so we can
972 -- quantify over them. Example:
978 -- {-# RULES "myrule" foo C = 1 #-}
980 -- After type checking the LHS becomes (foo a (C a))
981 -- and we do not want to zap the unbound tyvar 'a' to (), because
982 -- that limits the applicability of the rule. Instead, we
983 -- want to quantify over it!
985 -- It's easiest to find the free tyvars here. Attempts to do so earlier
986 -- are tiresome, because (a) the data type is big and (b) finding the
987 -- free type vars of an expression is necessarily monadic operation.
988 -- (consider /\a -> f @ b, where b is side-effected to a)
990 ; new_lhs <- zonkLExpr env_lhs lhs
991 ; new_rhs <- zonkLExpr env_rhs rhs
993 ; unbound_tvs <- readMutVar unbound_tv_set
994 ; let final_bndrs :: [RuleBndr Var]
995 final_bndrs = map (RuleBndr . noLoc) (varSetElems unbound_tvs) ++ new_bndrs
997 ; return (HsRule name act final_bndrs new_lhs fv_lhs new_rhs fv_rhs) }
999 zonk_bndr env (RuleBndr (L loc v))
1000 = do { (env', v') <- zonk_it env v; return (env', RuleBndr (L loc v')) }
1001 zonk_bndr _ (RuleBndrSig {}) = panic "zonk_bndr RuleBndrSig"
1004 | isId v = do { v' <- zonkIdBndr env v; return (extendZonkEnv1 env v', v') }
1005 | isCoVar v = do { v' <- zonkEvBndr env v; return (extendZonkEnv1 env v', v') }
1006 | otherwise = ASSERT( isImmutableTyVar v) return (env, v)
1010 %************************************************************************
1012 Constraints and evidence
1014 %************************************************************************
1017 zonkEvTerm :: ZonkEnv -> EvTerm -> TcM EvTerm
1018 zonkEvTerm env (EvId v) = ASSERT2( isId v, ppr v )
1019 return (EvId (zonkIdOcc env v))
1020 zonkEvTerm env (EvCoercion co) = do { co' <- zonkTcTypeToType env co
1021 ; return (EvCoercion co') }
1022 zonkEvTerm env (EvCast v co) = ASSERT( isId v)
1023 do { co' <- zonkTcTypeToType env co
1024 ; return (EvCast (zonkIdOcc env v) co') }
1025 zonkEvTerm env (EvSuperClass d n) = return (EvSuperClass (zonkIdOcc env d) n)
1026 zonkEvTerm env (EvDFunApp df tys tms)
1027 = do { tys' <- zonkTcTypeToTypes env tys
1028 ; let tms' = map (zonkEvVarOcc env) tms
1029 ; return (EvDFunApp (zonkIdOcc env df) tys' tms') }
1031 zonkTcEvBinds :: ZonkEnv -> TcEvBinds -> TcM (ZonkEnv, TcEvBinds)
1032 zonkTcEvBinds env (TcEvBinds var) = do { (env', bs') <- zonkEvBindsVar env var
1033 ; return (env', EvBinds bs') }
1034 zonkTcEvBinds env (EvBinds bs) = do { (env', bs') <- zonkEvBinds env bs
1035 ; return (env', EvBinds bs') }
1037 zonkEvBindsVar :: ZonkEnv -> EvBindsVar -> TcM (ZonkEnv, Bag EvBind)
1038 zonkEvBindsVar env (EvBindsVar ref _) = do { bs <- readMutVar ref
1039 ; zonkEvBinds env (evBindMapBinds bs) }
1041 zonkEvBinds :: ZonkEnv -> Bag EvBind -> TcM (ZonkEnv, Bag EvBind)
1042 zonkEvBinds env binds
1043 = fixM (\ ~( _, new_binds) -> do
1044 { let env1 = extendZonkEnv env (collect_ev_bndrs new_binds)
1045 ; binds' <- mapBagM (zonkEvBind env1) binds
1046 ; return (env1, binds') })
1048 collect_ev_bndrs :: Bag EvBind -> [EvVar]
1049 collect_ev_bndrs = foldrBag add []
1050 add (EvBind var _) vars = var : vars
1052 zonkEvBind :: ZonkEnv -> EvBind -> TcM EvBind
1053 zonkEvBind env (EvBind var term)
1054 = do { var' <- zonkEvBndr env var
1055 ; term' <- zonkEvTerm env term
1056 ; return (EvBind var' term') }
1059 %************************************************************************
1063 %************************************************************************
1066 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
1067 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
1069 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
1070 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
1072 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
1073 -- This variant collects unbound type variables in a mutable variable
1074 zonkTypeCollecting unbound_tv_set
1075 = zonkType (mkZonkTcTyVar zonk_unbound_tyvar)
1077 zonk_unbound_tyvar tv
1078 = do { tv' <- zonkQuantifiedTyVar tv
1079 ; tv_set <- readMutVar unbound_tv_set
1080 ; writeMutVar unbound_tv_set (extendVarSet tv_set tv')
1081 ; return (mkTyVarTy tv') }
1083 zonkTypeZapping :: TcType -> TcM Type
1084 -- This variant is used for everything except the LHS of rules
1085 -- It zaps unbound type variables to (), or some other arbitrary type
1087 = zonkType (mkZonkTcTyVar zonk_unbound_tyvar) ty
1089 -- Zonk a mutable but unbound type variable to an arbitrary type
1090 -- We know it's unbound even though we don't carry an environment,
1091 -- because at the binding site for a type variable we bind the
1092 -- mutable tyvar to a fresh immutable one. So the mutable store
1093 -- plays the role of an environment. If we come across a mutable
1094 -- type variable that isn't so bound, it must be completely free.
1095 zonk_unbound_tyvar tv = do { let ty = anyTypeOfKind (tyVarKind tv)
1096 ; writeMetaTyVar tv ty