2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[TcHsSyn]{Specialisations of the @HsSyn@ syntax for the typechecker}
6 This module is an extension of @HsSyn@ syntax, for use in the type
11 mkHsConApp, mkHsDictLet, mkHsApp,
12 hsLitType, hsLPatType, hsPatType,
13 mkHsAppTy, mkSimpleHsAlt,
14 nlHsIntLit, mkVanillaTuplePat,
17 -- re-exported from TcMonad
18 TcId, TcIdSet, TcDictBinds,
20 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
24 #include "HsVersions.h"
27 import HsSyn -- oodles of it
30 import Id ( idType, setIdType, Id )
33 import Type ( Type, isLiftedTypeKind, liftedTypeKind, isSubKind, eqKind )
34 import TcType ( TcType, TcTyVar, mkTyVarTy, mkTyConApp, isImmutableTyVar )
36 import TcMType ( zonkQuantifiedTyVar, zonkType, zonkTcType, writeMetaTyVar )
37 import TysPrim ( charPrimTy, intPrimTy, floatPrimTy,
38 doublePrimTy, addrPrimTy
40 import TysWiredIn ( charTy, stringTy, intTy,
41 mkListTy, mkPArrTy, mkTupleTy, unitTy,
42 voidTy, listTyCon, tupleTyCon )
43 import TyCon ( mkPrimTyCon, tyConKind, PrimRep(..) )
44 import {- Kind parts of -} Type ( splitKindFunTys )
45 import Name ( Name, getOccName, mkInternalName, mkDerivedTyConOcc )
46 import Var ( Var, isId, isLocalVar, tyVarKind )
49 import BasicTypes ( Boxity(..), IPName(..), ipNameName, mapIPName )
50 import Maybes ( orElse )
51 import Unique ( Uniquable(..) )
52 import SrcLoc ( noSrcLoc, noLoc, Located(..), unLoc )
53 import Util ( mapSnd )
59 %************************************************************************
61 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
63 %************************************************************************
65 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
66 then something is wrong.
68 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
69 -- A vanilla tuple pattern simply gets its type from its sub-patterns
70 mkVanillaTuplePat pats box
71 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
73 hsLPatType :: OutPat Id -> Type
74 hsLPatType (L _ pat) = hsPatType pat
76 hsPatType (ParPat pat) = hsLPatType pat
77 hsPatType (WildPat ty) = ty
78 hsPatType (VarPat var) = idType var
79 hsPatType (VarPatOut var _) = idType var
80 hsPatType (BangPat pat) = hsLPatType pat
81 hsPatType (LazyPat pat) = hsLPatType pat
82 hsPatType (LitPat lit) = hsLitType lit
83 hsPatType (AsPat var pat) = idType (unLoc var)
84 hsPatType (ListPat _ ty) = mkListTy ty
85 hsPatType (PArrPat _ ty) = mkPArrTy ty
86 hsPatType (TuplePat pats box ty) = ty
87 hsPatType (ConPatOut{ pat_ty = ty })= ty
88 hsPatType (SigPatOut pat ty) = ty
89 hsPatType (NPat lit _ _ ty) = ty
90 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
91 hsPatType (CoPat _ _ ty) = ty
92 hsPatType (DictPat ds ms) = case (ds ++ ms) of
95 ds -> mkTupleTy Boxed (length ds) (map idType ds)
98 hsLitType :: HsLit -> TcType
99 hsLitType (HsChar c) = charTy
100 hsLitType (HsCharPrim c) = charPrimTy
101 hsLitType (HsString str) = stringTy
102 hsLitType (HsStringPrim s) = addrPrimTy
103 hsLitType (HsInt i) = intTy
104 hsLitType (HsIntPrim i) = intPrimTy
105 hsLitType (HsInteger i ty) = ty
106 hsLitType (HsRat _ ty) = ty
107 hsLitType (HsFloatPrim f) = floatPrimTy
108 hsLitType (HsDoublePrim d) = doublePrimTy
112 %************************************************************************
114 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
116 %************************************************************************
119 -- zonkId is used *during* typechecking just to zonk the Id's type
120 zonkId :: TcId -> TcM TcId
122 = zonkTcType (idType id) `thenM` \ ty' ->
123 returnM (setIdType id ty')
126 The rest of the zonking is done *after* typechecking.
127 The main zonking pass runs over the bindings
129 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
130 b) convert unbound TcTyVar to Void
131 c) convert each TcId to an Id by zonking its type
133 The type variables are converted by binding mutable tyvars to immutable ones
134 and then zonking as normal.
136 The Ids are converted by binding them in the normal Tc envt; that
137 way we maintain sharing; eg an Id is zonked at its binding site and they
138 all occurrences of that Id point to the common zonked copy
140 It's all pretty boring stuff, because HsSyn is such a large type, and
141 the environment manipulation is tiresome.
144 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
145 (IdEnv Id) -- What variables are in scope
146 -- Maps an Id to its zonked version; both have the same Name
147 -- Is only consulted lazily; hence knot-tying
149 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
151 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
152 extendZonkEnv (ZonkEnv zonk_ty env) ids
153 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
155 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
156 extendZonkEnv1 (ZonkEnv zonk_ty env) id
157 = ZonkEnv zonk_ty (extendVarEnv env id id)
159 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
160 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
162 zonkEnvIds :: ZonkEnv -> [Id]
163 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
165 zonkIdOcc :: ZonkEnv -> TcId -> Id
166 -- Ids defined in this module should be in the envt;
167 -- ignore others. (Actually, data constructors are also
168 -- not LocalVars, even when locally defined, but that is fine.)
169 -- (Also foreign-imported things aren't currently in the ZonkEnv;
170 -- that's ok because they don't need zonking.)
172 -- Actually, Template Haskell works in 'chunks' of declarations, and
173 -- an earlier chunk won't be in the 'env' that the zonking phase
174 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
175 -- zonked. There's no point in looking it up there (except for error
176 -- checking), and it's not conveniently to hand; hence the simple
177 -- 'orElse' case in the LocalVar branch.
179 -- Even without template splices, in module Main, the checking of
180 -- 'main' is done as a separate chunk.
181 zonkIdOcc (ZonkEnv zonk_ty env) id
182 | isLocalVar id = lookupVarEnv env id `orElse` id
185 zonkIdOccs env ids = map (zonkIdOcc env) ids
187 -- zonkIdBndr is used *after* typechecking to get the Id's type
188 -- to its final form. The TyVarEnv give
189 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
191 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
192 returnM (setIdType id ty')
194 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
195 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
197 zonkTopBndrs :: [TcId] -> TcM [Id]
198 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
203 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
204 zonkTopExpr e = zonkExpr emptyZonkEnv e
206 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
207 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
209 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
214 zonkTopDecls binds rules fords
215 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
216 -- Top level is implicitly recursive
217 ; rules' <- zonkRules env rules
218 ; fords' <- zonkForeignExports env fords
219 ; return (zonkEnvIds env, binds', fords', rules') }
221 ---------------------------------------------
222 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
223 zonkLocalBinds env EmptyLocalBinds
224 = return (env, EmptyLocalBinds)
226 zonkLocalBinds env (HsValBinds binds)
227 = do { (env1, new_binds) <- zonkValBinds env binds
228 ; return (env1, HsValBinds new_binds) }
230 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
231 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
233 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
235 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
236 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
238 zonk_ip_bind (IPBind n e)
239 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
240 zonkLExpr env e `thenM` \ e' ->
241 returnM (IPBind n' e')
244 ---------------------------------------------
245 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
246 zonkValBinds env bs@(ValBindsIn _ _)
247 = panic "zonkValBinds" -- Not in typechecker output
248 zonkValBinds env (ValBindsOut binds sigs)
249 = do { (env1, new_binds) <- go env binds
250 ; return (env1, ValBindsOut new_binds sigs) }
252 go env [] = return (env, [])
253 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
254 ; (env2, bs') <- go env1 bs
255 ; return (env2, (r,b'):bs') }
257 ---------------------------------------------
258 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
259 zonkRecMonoBinds env binds
260 = fixM (\ ~(_, new_binds) -> do
261 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
262 ; binds' <- zonkMonoBinds env1 binds
263 ; return (env1, binds') })
265 ---------------------------------------------
266 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
267 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
269 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
270 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
271 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
272 ; new_grhss <- zonkGRHSs env grhss
273 ; new_ty <- zonkTcTypeToType env ty
274 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
276 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
277 = zonkIdBndr env var `thenM` \ new_var ->
278 zonkLExpr env expr `thenM` \ new_expr ->
279 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
281 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
282 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
283 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
284 zonkMatchGroup env1 ms `thenM` \ new_ms ->
285 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
287 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
288 abs_exports = exports, abs_binds = val_binds })
289 = ASSERT( all isImmutableTyVar tyvars )
290 zonkIdBndrs env dicts `thenM` \ new_dicts ->
291 fixM (\ ~(new_val_binds, _) ->
293 env1 = extendZonkEnv env new_dicts
294 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
296 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
297 mappM (zonkExport env2) exports `thenM` \ new_exports ->
298 returnM (new_val_binds, new_exports)
299 ) `thenM` \ (new_val_bind, new_exports) ->
300 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
301 abs_exports = new_exports, abs_binds = new_val_bind })
303 zonkExport env (tyvars, global, local, prags)
304 -- The tyvars are already zonked
305 = zonkIdBndr env global `thenM` \ new_global ->
306 mapM zonk_prag prags `thenM` \ new_prags ->
307 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
308 zonk_prag prag@(InlinePrag {}) = return prag
309 zonk_prag (SpecPrag expr ty ds inl) = do { expr' <- zonkExpr env expr
310 ; ty' <- zonkTcTypeToType env ty
311 ; let ds' = zonkIdOccs env ds
312 ; return (SpecPrag expr' ty' ds' inl) }
315 %************************************************************************
317 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
319 %************************************************************************
322 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
323 zonkMatchGroup env (MatchGroup ms ty)
324 = do { ms' <- mapM (zonkMatch env) ms
325 ; ty' <- zonkTcTypeToType env ty
326 ; return (MatchGroup ms' ty') }
328 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
329 zonkMatch env (L loc (Match pats _ grhss))
330 = do { (env1, new_pats) <- zonkPats env pats
331 ; new_grhss <- zonkGRHSs env1 grhss
332 ; return (L loc (Match new_pats Nothing new_grhss)) }
334 -------------------------------------------------------------------------
335 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
337 zonkGRHSs env (GRHSs grhss binds)
338 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
340 zonk_grhs (GRHS guarded rhs)
341 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
342 zonkLExpr env2 rhs `thenM` \ new_rhs ->
343 returnM (GRHS new_guarded new_rhs)
345 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
346 returnM (GRHSs new_grhss new_binds)
349 %************************************************************************
351 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
353 %************************************************************************
356 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
357 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
358 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
360 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
361 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
363 zonkExpr env (HsVar id)
364 = returnM (HsVar (zonkIdOcc env id))
366 zonkExpr env (HsIPVar id)
367 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
369 zonkExpr env (HsLit (HsRat f ty))
370 = zonkTcTypeToType env ty `thenM` \ new_ty ->
371 returnM (HsLit (HsRat f new_ty))
373 zonkExpr env (HsLit lit)
374 = returnM (HsLit lit)
376 zonkExpr env (HsOverLit lit)
377 = do { lit' <- zonkOverLit env lit
378 ; return (HsOverLit lit') }
380 zonkExpr env (HsLam matches)
381 = zonkMatchGroup env matches `thenM` \ new_matches ->
382 returnM (HsLam new_matches)
384 zonkExpr env (HsApp e1 e2)
385 = zonkLExpr env e1 `thenM` \ new_e1 ->
386 zonkLExpr env e2 `thenM` \ new_e2 ->
387 returnM (HsApp new_e1 new_e2)
389 zonkExpr env (HsBracketOut body bs)
390 = mappM zonk_b bs `thenM` \ bs' ->
391 returnM (HsBracketOut body bs')
393 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
396 zonkExpr env (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
397 returnM (HsSpliceE s)
399 zonkExpr env (OpApp e1 op fixity e2)
400 = zonkLExpr env e1 `thenM` \ new_e1 ->
401 zonkLExpr env op `thenM` \ new_op ->
402 zonkLExpr env e2 `thenM` \ new_e2 ->
403 returnM (OpApp new_e1 new_op fixity new_e2)
405 zonkExpr env (NegApp expr op)
406 = zonkLExpr env expr `thenM` \ new_expr ->
407 zonkExpr env op `thenM` \ new_op ->
408 returnM (NegApp new_expr new_op)
410 zonkExpr env (HsPar e)
411 = zonkLExpr env e `thenM` \new_e ->
412 returnM (HsPar new_e)
414 zonkExpr env (SectionL expr op)
415 = zonkLExpr env expr `thenM` \ new_expr ->
416 zonkLExpr env op `thenM` \ new_op ->
417 returnM (SectionL new_expr new_op)
419 zonkExpr env (SectionR op expr)
420 = zonkLExpr env op `thenM` \ new_op ->
421 zonkLExpr env expr `thenM` \ new_expr ->
422 returnM (SectionR new_op new_expr)
424 zonkExpr env (HsCase expr ms)
425 = zonkLExpr env expr `thenM` \ new_expr ->
426 zonkMatchGroup env ms `thenM` \ new_ms ->
427 returnM (HsCase new_expr new_ms)
429 zonkExpr env (HsIf e1 e2 e3)
430 = zonkLExpr env e1 `thenM` \ new_e1 ->
431 zonkLExpr env e2 `thenM` \ new_e2 ->
432 zonkLExpr env e3 `thenM` \ new_e3 ->
433 returnM (HsIf new_e1 new_e2 new_e3)
435 zonkExpr env (HsLet binds expr)
436 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
437 zonkLExpr new_env expr `thenM` \ new_expr ->
438 returnM (HsLet new_binds new_expr)
440 zonkExpr env (HsDo do_or_lc stmts body ty)
441 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
442 zonkLExpr new_env body `thenM` \ new_body ->
443 zonkTcTypeToType env ty `thenM` \ new_ty ->
444 returnM (HsDo (zonkDo env do_or_lc)
445 new_stmts new_body new_ty)
447 zonkExpr env (ExplicitList ty exprs)
448 = zonkTcTypeToType env ty `thenM` \ new_ty ->
449 zonkLExprs env exprs `thenM` \ new_exprs ->
450 returnM (ExplicitList new_ty new_exprs)
452 zonkExpr env (ExplicitPArr ty exprs)
453 = zonkTcTypeToType env ty `thenM` \ new_ty ->
454 zonkLExprs env exprs `thenM` \ new_exprs ->
455 returnM (ExplicitPArr new_ty new_exprs)
457 zonkExpr env (ExplicitTuple exprs boxed)
458 = zonkLExprs env exprs `thenM` \ new_exprs ->
459 returnM (ExplicitTuple new_exprs boxed)
461 zonkExpr env (RecordCon data_con con_expr rbinds)
462 = zonkExpr env con_expr `thenM` \ new_con_expr ->
463 zonkRbinds env rbinds `thenM` \ new_rbinds ->
464 returnM (RecordCon data_con new_con_expr new_rbinds)
466 zonkExpr env (RecordUpd expr rbinds in_ty out_ty)
467 = zonkLExpr env expr `thenM` \ new_expr ->
468 zonkTcTypeToType env in_ty `thenM` \ new_in_ty ->
469 zonkTcTypeToType env out_ty `thenM` \ new_out_ty ->
470 zonkRbinds env rbinds `thenM` \ new_rbinds ->
471 returnM (RecordUpd new_expr new_rbinds new_in_ty new_out_ty)
473 zonkExpr env (ExprWithTySigOut e ty)
474 = do { e' <- zonkLExpr env e
475 ; return (ExprWithTySigOut e' ty) }
477 zonkExpr env (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
479 zonkExpr env (ArithSeq expr info)
480 = zonkExpr env expr `thenM` \ new_expr ->
481 zonkArithSeq env info `thenM` \ new_info ->
482 returnM (ArithSeq new_expr new_info)
484 zonkExpr env (PArrSeq expr info)
485 = zonkExpr env expr `thenM` \ new_expr ->
486 zonkArithSeq env info `thenM` \ new_info ->
487 returnM (PArrSeq new_expr new_info)
489 zonkExpr env (HsSCC lbl expr)
490 = zonkLExpr env expr `thenM` \ new_expr ->
491 returnM (HsSCC lbl new_expr)
493 -- hdaume: core annotations
494 zonkExpr env (HsCoreAnn lbl expr)
495 = zonkLExpr env expr `thenM` \ new_expr ->
496 returnM (HsCoreAnn lbl new_expr)
498 -- arrow notation extensions
499 zonkExpr env (HsProc pat body)
500 = do { (env1, new_pat) <- zonkPat env pat
501 ; new_body <- zonkCmdTop env1 body
502 ; return (HsProc new_pat new_body) }
504 zonkExpr env (HsArrApp e1 e2 ty ho rl)
505 = zonkLExpr env e1 `thenM` \ new_e1 ->
506 zonkLExpr env e2 `thenM` \ new_e2 ->
507 zonkTcTypeToType env ty `thenM` \ new_ty ->
508 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
510 zonkExpr env (HsArrForm op fixity args)
511 = zonkLExpr env op `thenM` \ new_op ->
512 mappM (zonkCmdTop env) args `thenM` \ new_args ->
513 returnM (HsArrForm new_op fixity new_args)
515 zonkExpr env (HsWrap co_fn expr)
516 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
517 zonkExpr env1 expr `thenM` \ new_expr ->
518 return (HsWrap new_co_fn new_expr)
520 zonkExpr env other = pprPanic "zonkExpr" (ppr other)
522 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
523 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
525 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
526 = zonkLExpr env cmd `thenM` \ new_cmd ->
527 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
528 zonkTcTypeToType env ty `thenM` \ new_ty ->
529 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
530 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
532 -------------------------------------------------------------------------
533 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
534 zonkCoFn env WpHole = return (env, WpHole)
535 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
536 ; (env2, c2') <- zonkCoFn env1 c2
537 ; return (env2, WpCompose c1' c2') }
538 zonkCoFn env (WpCo co) = do { co' <- zonkTcTypeToType env co
539 ; return (env, WpCo co') }
540 zonkCoFn env (WpLam id) = do { id' <- zonkIdBndr env id
541 ; let env1 = extendZonkEnv1 env id'
542 ; return (env1, WpLam id') }
543 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
544 do { return (env, WpTyLam tv) }
545 zonkCoFn env (WpApp id) = do { return (env, WpApp (zonkIdOcc env id)) }
546 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
547 ; return (env, WpTyApp ty') }
548 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
549 ; return (env1, WpLet bs') }
552 -------------------------------------------------------------------------
553 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
554 -- Only used for 'do', so the only Ids are in a MDoExpr table
555 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
556 zonkDo env do_or_lc = do_or_lc
558 -------------------------------------------------------------------------
559 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
560 zonkOverLit env (HsIntegral i e)
561 = do { e' <- zonkExpr env e; return (HsIntegral i e') }
562 zonkOverLit env (HsFractional r e)
563 = do { e' <- zonkExpr env e; return (HsFractional r e') }
565 -------------------------------------------------------------------------
566 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
568 zonkArithSeq env (From e)
569 = zonkLExpr env e `thenM` \ new_e ->
572 zonkArithSeq env (FromThen e1 e2)
573 = zonkLExpr env e1 `thenM` \ new_e1 ->
574 zonkLExpr env e2 `thenM` \ new_e2 ->
575 returnM (FromThen new_e1 new_e2)
577 zonkArithSeq env (FromTo e1 e2)
578 = zonkLExpr env e1 `thenM` \ new_e1 ->
579 zonkLExpr env e2 `thenM` \ new_e2 ->
580 returnM (FromTo new_e1 new_e2)
582 zonkArithSeq env (FromThenTo e1 e2 e3)
583 = zonkLExpr env e1 `thenM` \ new_e1 ->
584 zonkLExpr env e2 `thenM` \ new_e2 ->
585 zonkLExpr env e3 `thenM` \ new_e3 ->
586 returnM (FromThenTo new_e1 new_e2 new_e3)
589 -------------------------------------------------------------------------
590 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
591 zonkStmts env [] = return (env, [])
592 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
593 ; (env2, ss') <- zonkStmts env1 ss
594 ; return (env2, s' : ss') }
596 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
597 zonkStmt env (ParStmt stmts_w_bndrs)
598 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
600 new_binders = concat (map snd new_stmts_w_bndrs)
601 env1 = extendZonkEnv env new_binders
603 return (env1, ParStmt new_stmts_w_bndrs)
605 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
606 returnM (new_stmts, zonkIdOccs env1 bndrs)
608 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
609 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
611 env1 = extendZonkEnv env new_rvs
613 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
614 -- Zonk the ret-expressions in an envt that
615 -- has the polymorphic bindings in the envt
616 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
618 new_lvs = zonkIdOccs env2 lvs
619 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
621 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
622 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
624 zonkStmt env (ExprStmt expr then_op ty)
625 = zonkLExpr env expr `thenM` \ new_expr ->
626 zonkExpr env then_op `thenM` \ new_then ->
627 zonkTcTypeToType env ty `thenM` \ new_ty ->
628 returnM (env, ExprStmt new_expr new_then new_ty)
630 zonkStmt env (LetStmt binds)
631 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
632 returnM (env1, LetStmt new_binds)
634 zonkStmt env (BindStmt pat expr bind_op fail_op)
635 = do { new_expr <- zonkLExpr env expr
636 ; (env1, new_pat) <- zonkPat env pat
637 ; new_bind <- zonkExpr env bind_op
638 ; new_fail <- zonkExpr env fail_op
639 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
642 -------------------------------------------------------------------------
643 zonkRbinds :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds Id)
645 zonkRbinds env rbinds
646 = mappM zonk_rbind rbinds
648 zonk_rbind (field, expr)
649 = zonkLExpr env expr `thenM` \ new_expr ->
650 returnM (fmap (zonkIdOcc env) field, new_expr)
652 -------------------------------------------------------------------------
653 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
654 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
658 %************************************************************************
660 \subsection[BackSubst-Pats]{Patterns}
662 %************************************************************************
665 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
666 -- Extend the environment as we go, because it's possible for one
667 -- pattern to bind something that is used in another (inside or
669 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
671 zonk_pat env (ParPat p)
672 = do { (env', p') <- zonkPat env p
673 ; return (env', ParPat p') }
675 zonk_pat env (WildPat ty)
676 = do { ty' <- zonkTcTypeToType env ty
677 ; return (env, WildPat ty') }
679 zonk_pat env (VarPat v)
680 = do { v' <- zonkIdBndr env v
681 ; return (extendZonkEnv1 env v', VarPat v') }
683 zonk_pat env (VarPatOut v binds)
684 = do { v' <- zonkIdBndr env v
685 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
686 ; returnM (env', VarPatOut v' binds') }
688 zonk_pat env (LazyPat pat)
689 = do { (env', pat') <- zonkPat env pat
690 ; return (env', LazyPat pat') }
692 zonk_pat env (BangPat pat)
693 = do { (env', pat') <- zonkPat env pat
694 ; return (env', BangPat pat') }
696 zonk_pat env (AsPat (L loc v) pat)
697 = do { v' <- zonkIdBndr env v
698 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
699 ; return (env', AsPat (L loc v') pat') }
701 zonk_pat env (ListPat pats ty)
702 = do { ty' <- zonkTcTypeToType env ty
703 ; (env', pats') <- zonkPats env pats
704 ; return (env', ListPat pats' ty') }
706 zonk_pat env (PArrPat pats ty)
707 = do { ty' <- zonkTcTypeToType env ty
708 ; (env', pats') <- zonkPats env pats
709 ; return (env', PArrPat pats' ty') }
711 zonk_pat env (TuplePat pats boxed ty)
712 = do { ty' <- zonkTcTypeToType env ty
713 ; (env', pats') <- zonkPats env pats
714 ; return (env', TuplePat pats' boxed ty') }
716 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
717 = ASSERT( all isImmutableTyVar (pat_tvs p) )
718 do { new_ty <- zonkTcTypeToType env ty
719 ; new_dicts <- zonkIdBndrs env dicts
720 ; let env1 = extendZonkEnv env new_dicts
721 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
722 ; (env', new_args) <- zonkConStuff env2 args
723 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
724 pat_binds = new_binds, pat_args = new_args }) }
726 zonk_pat env (LitPat lit) = return (env, LitPat lit)
728 zonk_pat env (SigPatOut pat ty)
729 = do { ty' <- zonkTcTypeToType env ty
730 ; (env', pat') <- zonkPat env pat
731 ; return (env', SigPatOut pat' ty') }
733 zonk_pat env (NPat lit mb_neg eq_expr ty)
734 = do { lit' <- zonkOverLit env lit
735 ; mb_neg' <- case mb_neg of
736 Nothing -> return Nothing
737 Just neg -> do { neg' <- zonkExpr env neg
738 ; return (Just neg') }
739 ; eq_expr' <- zonkExpr env eq_expr
740 ; ty' <- zonkTcTypeToType env ty
741 ; return (env, NPat lit' mb_neg' eq_expr' ty') }
743 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
744 = do { n' <- zonkIdBndr env n
745 ; lit' <- zonkOverLit env lit
746 ; e1' <- zonkExpr env e1
747 ; e2' <- zonkExpr env e2
748 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
750 zonk_pat env (DictPat ds ms)
751 = do { ds' <- zonkIdBndrs env ds
752 ; ms' <- zonkIdBndrs env ms
753 ; return (extendZonkEnv env (ds' ++ ms'), DictPat ds' ms') }
755 zonk_pat env (CoPat co_fn pat ty)
756 = do { (env', co_fn') <- zonkCoFn env co_fn
757 ; (env'', pat') <- zonkPat env' (noLoc pat)
758 ; ty' <- zonkTcTypeToType env'' ty
759 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
761 zonk_pat env pat = pprPanic "zonk_pat" (ppr pat)
763 ---------------------------
764 zonkConStuff env (PrefixCon pats)
765 = do { (env', pats') <- zonkPats env pats
766 ; return (env', PrefixCon pats') }
768 zonkConStuff env (InfixCon p1 p2)
769 = do { (env1, p1') <- zonkPat env p1
770 ; (env', p2') <- zonkPat env1 p2
771 ; return (env', InfixCon p1' p2') }
773 zonkConStuff env (RecCon rpats)
774 = do { (env', pats') <- zonkPats env pats
775 ; returnM (env', RecCon (fields `zip` pats')) }
777 (fields, pats) = unzip rpats
779 ---------------------------
780 zonkPats env [] = return (env, [])
781 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
782 ; (env', pats') <- zonkPats env1 pats
783 ; return (env', pat':pats') }
786 %************************************************************************
788 \subsection[BackSubst-Foreign]{Foreign exports}
790 %************************************************************************
794 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
795 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
797 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
798 zonkForeignExport env (ForeignExport i hs_ty spec) =
799 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
800 zonkForeignExport env for_imp
801 = returnM for_imp -- Foreign imports don't need zonking
805 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
806 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
808 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
809 zonkRule env (HsRule name act (vars::[RuleBndr TcId]) lhs fv_lhs rhs fv_rhs)
810 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
811 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
813 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
814 -- Type variables don't need an envt
815 -- They are bound through the mutable mechanism
817 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
818 -- We need to gather the type variables mentioned on the LHS so we can
819 -- quantify over them. Example:
825 -- {-# RULES "myrule" foo C = 1 #-}
827 -- After type checking the LHS becomes (foo a (C a))
828 -- and we do not want to zap the unbound tyvar 'a' to (), because
829 -- that limits the applicability of the rule. Instead, we
830 -- want to quantify over it!
832 -- It's easiest to find the free tyvars here. Attempts to do so earlier
833 -- are tiresome, because (a) the data type is big and (b) finding the
834 -- free type vars of an expression is necessarily monadic operation.
835 -- (consider /\a -> f @ b, where b is side-effected to a)
837 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
838 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
840 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
842 final_bndrs :: [Located Var]
843 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
845 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
846 -- I hate this map RuleBndr stuff
848 zonk_bndr (RuleBndr v)
849 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
850 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
855 %************************************************************************
857 \subsection[BackSubst-Foreign]{Foreign exports}
859 %************************************************************************
862 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
863 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
865 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
866 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
868 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
869 -- This variant collects unbound type variables in a mutable variable
870 zonkTypeCollecting unbound_tv_set
871 = zonkType zonk_unbound_tyvar
873 zonk_unbound_tyvar tv
874 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
875 readMutVar unbound_tv_set `thenM` \ tv_set ->
876 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
877 return (mkTyVarTy tv')
879 zonkTypeZapping :: TcType -> TcM Type
880 -- This variant is used for everything except the LHS of rules
881 -- It zaps unbound type variables to (), or some other arbitrary type
883 = zonkType zonk_unbound_tyvar ty
885 -- Zonk a mutable but unbound type variable to an arbitrary type
886 -- We know it's unbound even though we don't carry an environment,
887 -- because at the binding site for a type variable we bind the
888 -- mutable tyvar to a fresh immutable one. So the mutable store
889 -- plays the role of an environment. If we come across a mutable
890 -- type variable that isn't so bound, it must be completely free.
891 zonk_unbound_tyvar tv = do { writeMetaTyVar tv ty; return ty }
893 ty = mkArbitraryType tv
896 -- When the type checker finds a type variable with no binding,
897 -- which means it can be instantiated with an arbitrary type, it
898 -- usually instantiates it to Void. Eg.
902 -- length Void (Nil Void)
904 -- But in really obscure programs, the type variable might have
905 -- a kind other than *, so we need to invent a suitably-kinded type.
909 -- List for kind *->*
910 -- Tuple for kind *->...*->*
912 -- which deals with most cases. (Previously, it only dealt with
915 -- In the other cases, it just makes up a TyCon with a suitable
916 -- kind. If this gets into an interface file, anyone reading that
917 -- file won't understand it. This is fixable (by making the client
918 -- of the interface file make up a TyCon too) but it is tiresome and
919 -- never happens, so I am leaving it
921 mkArbitraryType :: TcTyVar -> Type
922 -- Make up an arbitrary type whose kind is the same as the tyvar.
923 -- We'll use this to instantiate the (unbound) tyvar.
925 | liftedTypeKind `isSubKind` kind = voidTy -- The vastly common case
926 | otherwise = mkTyConApp tycon []
929 (args,res) = splitKindFunTys kind
931 tycon | eqKind kind (tyConKind listTyCon) -- *->*
932 = listTyCon -- No tuples this size
934 | all isLiftedTypeKind args && isLiftedTypeKind res
935 = tupleTyCon Boxed (length args) -- *-> ... ->*->*
938 = pprTrace "Urk! Inventing strangely-kinded void TyCon:" (ppr tc_name $$ ppr kind) $
939 mkPrimTyCon tc_name kind 0 VoidRep
940 -- Same name as the tyvar, apart from making it start with a colon (sigh)
941 -- I dread to think what will happen if this gets out into an
942 -- interface file. Catastrophe likely. Major sigh.
944 tc_name = mkInternalName (getUnique tv) (mkDerivedTyConOcc (getOccName tv)) noSrcLoc