2 % (c) The University of Glasgow 2006
3 % (c) The AQUA Project, Glasgow University, 1996-1998
6 TcHsSyn: Specialisations of the @HsSyn@ syntax for the typechecker
8 This module is an extension of @HsSyn@ syntax, for use in the type
13 mkHsConApp, mkHsDictLet, mkHsApp,
14 hsLitType, hsLPatType, hsPatType,
15 mkHsAppTy, mkSimpleHsAlt,
16 nlHsIntLit, mkVanillaTuplePat,
17 shortCutLit, hsOverLitName,
19 mkArbitraryType, -- Put this elsewhere?
21 -- re-exported from TcMonad
22 TcId, TcIdSet, TcDictBinds,
24 zonkTopDecls, zonkTopExpr, zonkTopLExpr,
28 #include "HsVersions.h"
31 import HsSyn -- oodles of it
60 thenM :: Monad a => a b -> (b -> a c) -> a c
63 thenM_ :: Monad a => a b -> a c -> a c
66 returnM :: Monad m => a -> m a
69 mappM :: (Monad m) => (a -> m b) -> [a] -> m [b]
74 %************************************************************************
76 \subsection[mkFailurePair]{Code for pattern-matching and other failures}
78 %************************************************************************
80 Note: If @hsLPatType@ doesn't bear a strong resemblance to @exprType@,
81 then something is wrong.
83 mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
84 -- A vanilla tuple pattern simply gets its type from its sub-patterns
85 mkVanillaTuplePat pats box
86 = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
88 hsLPatType :: OutPat Id -> Type
89 hsLPatType (L _ pat) = hsPatType pat
91 hsPatType :: Pat Id -> Type
92 hsPatType (ParPat pat) = hsLPatType pat
93 hsPatType (WildPat ty) = ty
94 hsPatType (VarPat var) = idType var
95 hsPatType (VarPatOut var _) = idType var
96 hsPatType (BangPat pat) = hsLPatType pat
97 hsPatType (LazyPat pat) = hsLPatType pat
98 hsPatType (LitPat lit) = hsLitType lit
99 hsPatType (AsPat var _) = idType (unLoc var)
100 hsPatType (ViewPat _ _ ty) = ty
101 hsPatType (ListPat _ ty) = mkListTy ty
102 hsPatType (PArrPat _ ty) = mkPArrTy ty
103 hsPatType (TuplePat _ _ ty) = ty
104 hsPatType (ConPatOut { pat_ty = ty }) = ty
105 hsPatType (SigPatOut _ ty) = ty
106 hsPatType (NPat lit _ _) = overLitType lit
107 hsPatType (NPlusKPat id _ _ _) = idType (unLoc id)
108 hsPatType (CoPat _ _ ty) = ty
109 hsPatType p = pprPanic "hsPatType" (ppr p)
111 hsLitType :: HsLit -> TcType
112 hsLitType (HsChar _) = charTy
113 hsLitType (HsCharPrim _) = charPrimTy
114 hsLitType (HsString _) = stringTy
115 hsLitType (HsStringPrim _) = addrPrimTy
116 hsLitType (HsInt _) = intTy
117 hsLitType (HsIntPrim _) = intPrimTy
118 hsLitType (HsWordPrim _) = wordPrimTy
119 hsLitType (HsInteger _ ty) = ty
120 hsLitType (HsRat _ ty) = ty
121 hsLitType (HsFloatPrim _) = floatPrimTy
122 hsLitType (HsDoublePrim _) = doublePrimTy
125 Overloaded literals. Here mainly becuase it uses isIntTy etc
128 shortCutLit :: OverLitVal -> TcType -> Maybe (HsExpr TcId)
129 shortCutLit (HsIntegral i) ty
130 | isIntTy ty && inIntRange i = Just (HsLit (HsInt i))
131 | isWordTy ty && inWordRange i = Just (mkLit wordDataCon (HsWordPrim i))
132 | isIntegerTy ty = Just (HsLit (HsInteger i ty))
133 | otherwise = shortCutLit (HsFractional (fromInteger i)) ty
134 -- The 'otherwise' case is important
135 -- Consider (3 :: Float). Syntactically it looks like an IntLit,
136 -- so we'll call shortCutIntLit, but of course it's a float
137 -- This can make a big difference for programs with a lot of
138 -- literals, compiled without -O
140 shortCutLit (HsFractional f) ty
141 | isFloatTy ty = Just (mkLit floatDataCon (HsFloatPrim f))
142 | isDoubleTy ty = Just (mkLit doubleDataCon (HsDoublePrim f))
143 | otherwise = Nothing
145 shortCutLit (HsIsString s) ty
146 | isStringTy ty = Just (HsLit (HsString s))
147 | otherwise = Nothing
149 mkLit :: DataCon -> HsLit -> HsExpr Id
150 mkLit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit)
152 ------------------------------
153 hsOverLitName :: OverLitVal -> Name
154 -- Get the canonical 'fromX' name for a particular OverLitVal
155 hsOverLitName (HsIntegral {}) = fromIntegerName
156 hsOverLitName (HsFractional {}) = fromRationalName
157 hsOverLitName (HsIsString {}) = fromStringName
160 %************************************************************************
162 \subsection[BackSubst-HsBinds]{Running a substitution over @HsBinds@}
164 %************************************************************************
167 -- zonkId is used *during* typechecking just to zonk the Id's type
168 zonkId :: TcId -> TcM TcId
170 = zonkTcType (idType id) `thenM` \ ty' ->
171 returnM (Id.setIdType id ty')
174 The rest of the zonking is done *after* typechecking.
175 The main zonking pass runs over the bindings
177 a) to convert TcTyVars to TyVars etc, dereferencing any bindings etc
178 b) convert unbound TcTyVar to Void
179 c) convert each TcId to an Id by zonking its type
181 The type variables are converted by binding mutable tyvars to immutable ones
182 and then zonking as normal.
184 The Ids are converted by binding them in the normal Tc envt; that
185 way we maintain sharing; eg an Id is zonked at its binding site and they
186 all occurrences of that Id point to the common zonked copy
188 It's all pretty boring stuff, because HsSyn is such a large type, and
189 the environment manipulation is tiresome.
192 data ZonkEnv = ZonkEnv (TcType -> TcM Type) -- How to zonk a type
193 (IdEnv Id) -- What variables are in scope
194 -- Maps an Id to its zonked version; both have the same Name
195 -- Is only consulted lazily; hence knot-tying
197 emptyZonkEnv :: ZonkEnv
198 emptyZonkEnv = ZonkEnv zonkTypeZapping emptyVarEnv
200 extendZonkEnv :: ZonkEnv -> [Id] -> ZonkEnv
201 extendZonkEnv (ZonkEnv zonk_ty env) ids
202 = ZonkEnv zonk_ty (extendVarEnvList env [(id,id) | id <- ids])
204 extendZonkEnv1 :: ZonkEnv -> Id -> ZonkEnv
205 extendZonkEnv1 (ZonkEnv zonk_ty env) id
206 = ZonkEnv zonk_ty (extendVarEnv env id id)
208 setZonkType :: ZonkEnv -> (TcType -> TcM Type) -> ZonkEnv
209 setZonkType (ZonkEnv _ env) zonk_ty = ZonkEnv zonk_ty env
211 zonkEnvIds :: ZonkEnv -> [Id]
212 zonkEnvIds (ZonkEnv _ env) = varEnvElts env
214 zonkIdOcc :: ZonkEnv -> TcId -> Id
215 -- Ids defined in this module should be in the envt;
216 -- ignore others. (Actually, data constructors are also
217 -- not LocalVars, even when locally defined, but that is fine.)
218 -- (Also foreign-imported things aren't currently in the ZonkEnv;
219 -- that's ok because they don't need zonking.)
221 -- Actually, Template Haskell works in 'chunks' of declarations, and
222 -- an earlier chunk won't be in the 'env' that the zonking phase
223 -- carries around. Instead it'll be in the tcg_gbl_env, already fully
224 -- zonked. There's no point in looking it up there (except for error
225 -- checking), and it's not conveniently to hand; hence the simple
226 -- 'orElse' case in the LocalVar branch.
228 -- Even without template splices, in module Main, the checking of
229 -- 'main' is done as a separate chunk.
230 zonkIdOcc (ZonkEnv _zonk_ty env) id
231 | isLocalVar id = lookupVarEnv env id `orElse` id
234 zonkIdOccs :: ZonkEnv -> [TcId] -> [Id]
235 zonkIdOccs env ids = map (zonkIdOcc env) ids
237 -- zonkIdBndr is used *after* typechecking to get the Id's type
238 -- to its final form. The TyVarEnv give
239 zonkIdBndr :: ZonkEnv -> TcId -> TcM Id
241 = zonkTcTypeToType env (idType id) `thenM` \ ty' ->
242 returnM (Id.setIdType id ty')
244 zonkIdBndrs :: ZonkEnv -> [TcId] -> TcM [Id]
245 zonkIdBndrs env ids = mappM (zonkIdBndr env) ids
247 zonkDictBndrs :: ZonkEnv -> [Var] -> TcM [Var]
248 -- "Dictionary" binders can be coercion variables or dictionary variables
249 zonkDictBndrs env ids = mappM (zonkDictBndr env) ids
251 zonkDictBndr :: ZonkEnv -> Var -> TcM Var
252 zonkDictBndr env var | isTyVar var = zonkTyVarBndr env var
253 | otherwise = zonkIdBndr env var
255 zonkTopBndrs :: [TcId] -> TcM [Id]
256 zonkTopBndrs ids = zonkIdBndrs emptyZonkEnv ids
258 -- Zonk the kind of a non-TC tyvar in case it is a coercion variable (their
259 -- kind contains types).
261 zonkTyVarBndr :: ZonkEnv -> TyVar -> TcM TyVar
264 = do { kind <- zonkTcTypeToType env (tyVarKind tv)
265 ; return $ setTyVarKind tv kind
267 | otherwise = return tv
272 zonkTopExpr :: HsExpr TcId -> TcM (HsExpr Id)
273 zonkTopExpr e = zonkExpr emptyZonkEnv e
275 zonkTopLExpr :: LHsExpr TcId -> TcM (LHsExpr Id)
276 zonkTopLExpr e = zonkLExpr emptyZonkEnv e
278 zonkTopDecls :: LHsBinds TcId -> [LRuleDecl TcId] -> [LForeignDecl TcId]
283 zonkTopDecls binds rules fords
284 = do { (env, binds') <- zonkRecMonoBinds emptyZonkEnv binds
285 -- Top level is implicitly recursive
286 ; rules' <- zonkRules env rules
287 ; fords' <- zonkForeignExports env fords
288 ; return (zonkEnvIds env, binds', fords', rules') }
290 ---------------------------------------------
291 zonkLocalBinds :: ZonkEnv -> HsLocalBinds TcId -> TcM (ZonkEnv, HsLocalBinds Id)
292 zonkLocalBinds env EmptyLocalBinds
293 = return (env, EmptyLocalBinds)
295 zonkLocalBinds env (HsValBinds binds)
296 = do { (env1, new_binds) <- zonkValBinds env binds
297 ; return (env1, HsValBinds new_binds) }
299 zonkLocalBinds env (HsIPBinds (IPBinds binds dict_binds))
300 = mappM (wrapLocM zonk_ip_bind) binds `thenM` \ new_binds ->
302 env1 = extendZonkEnv env [ipNameName n | L _ (IPBind n _) <- new_binds]
304 zonkRecMonoBinds env1 dict_binds `thenM` \ (env2, new_dict_binds) ->
305 returnM (env2, HsIPBinds (IPBinds new_binds new_dict_binds))
307 zonk_ip_bind (IPBind n e)
308 = mapIPNameTc (zonkIdBndr env) n `thenM` \ n' ->
309 zonkLExpr env e `thenM` \ e' ->
310 returnM (IPBind n' e')
313 ---------------------------------------------
314 zonkValBinds :: ZonkEnv -> HsValBinds TcId -> TcM (ZonkEnv, HsValBinds Id)
315 zonkValBinds _ (ValBindsIn _ _)
316 = panic "zonkValBinds" -- Not in typechecker output
317 zonkValBinds env (ValBindsOut binds sigs)
318 = do { (env1, new_binds) <- go env binds
319 ; return (env1, ValBindsOut new_binds sigs) }
321 go env [] = return (env, [])
322 go env ((r,b):bs) = do { (env1, b') <- zonkRecMonoBinds env b
323 ; (env2, bs') <- go env1 bs
324 ; return (env2, (r,b'):bs') }
326 ---------------------------------------------
327 zonkRecMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (ZonkEnv, LHsBinds Id)
328 zonkRecMonoBinds env binds
329 = fixM (\ ~(_, new_binds) -> do
330 { let env1 = extendZonkEnv env (collectHsBindBinders new_binds)
331 ; binds' <- zonkMonoBinds env1 binds
332 ; return (env1, binds') })
334 ---------------------------------------------
335 zonkMonoBinds :: ZonkEnv -> LHsBinds TcId -> TcM (LHsBinds Id)
336 zonkMonoBinds env binds = mapBagM (wrapLocM (zonk_bind env)) binds
338 zonk_bind :: ZonkEnv -> HsBind TcId -> TcM (HsBind Id)
339 zonk_bind env bind@(PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty = ty})
340 = do { (_env, new_pat) <- zonkPat env pat -- Env already extended
341 ; new_grhss <- zonkGRHSs env grhss
342 ; new_ty <- zonkTcTypeToType env ty
343 ; return (bind { pat_lhs = new_pat, pat_rhs = new_grhss, pat_rhs_ty = new_ty }) }
345 zonk_bind env (VarBind { var_id = var, var_rhs = expr })
346 = zonkIdBndr env var `thenM` \ new_var ->
347 zonkLExpr env expr `thenM` \ new_expr ->
348 returnM (VarBind { var_id = new_var, var_rhs = new_expr })
350 zonk_bind env bind@(FunBind { fun_id = var, fun_matches = ms, fun_co_fn = co_fn })
351 = wrapLocM (zonkIdBndr env) var `thenM` \ new_var ->
352 zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
353 zonkMatchGroup env1 ms `thenM` \ new_ms ->
354 returnM (bind { fun_id = new_var, fun_matches = new_ms, fun_co_fn = new_co_fn })
356 zonk_bind env (AbsBinds { abs_tvs = tyvars, abs_dicts = dicts,
357 abs_exports = exports, abs_binds = val_binds })
358 = ASSERT( all isImmutableTyVar tyvars )
359 zonkDictBndrs env dicts `thenM` \ new_dicts ->
360 fixM (\ ~(new_val_binds, _) ->
362 env1 = extendZonkEnv env new_dicts
363 env2 = extendZonkEnv env1 (collectHsBindBinders new_val_binds)
365 zonkMonoBinds env2 val_binds `thenM` \ new_val_binds ->
366 mappM (zonkExport env2) exports `thenM` \ new_exports ->
367 returnM (new_val_binds, new_exports)
368 ) `thenM` \ (new_val_bind, new_exports) ->
369 returnM (AbsBinds { abs_tvs = tyvars, abs_dicts = new_dicts,
370 abs_exports = new_exports, abs_binds = new_val_bind })
372 zonkExport env (tyvars, global, local, prags)
373 -- The tyvars are already zonked
374 = zonkIdBndr env global `thenM` \ new_global ->
375 mapM zonk_prag prags `thenM` \ new_prags ->
376 returnM (tyvars, new_global, zonkIdOcc env local, new_prags)
377 zonk_prag prag@(L _ (InlinePrag {})) = return prag
378 zonk_prag (L loc (SpecPrag expr ty inl))
379 = do { expr' <- zonkExpr env expr
380 ; ty' <- zonkTcTypeToType env ty
381 ; return (L loc (SpecPrag expr' ty' inl)) }
384 %************************************************************************
386 \subsection[BackSubst-Match-GRHSs]{Match and GRHSs}
388 %************************************************************************
391 zonkMatchGroup :: ZonkEnv -> MatchGroup TcId-> TcM (MatchGroup Id)
392 zonkMatchGroup env (MatchGroup ms ty)
393 = do { ms' <- mapM (zonkMatch env) ms
394 ; ty' <- zonkTcTypeToType env ty
395 ; return (MatchGroup ms' ty') }
397 zonkMatch :: ZonkEnv -> LMatch TcId-> TcM (LMatch Id)
398 zonkMatch env (L loc (Match pats _ grhss))
399 = do { (env1, new_pats) <- zonkPats env pats
400 ; new_grhss <- zonkGRHSs env1 grhss
401 ; return (L loc (Match new_pats Nothing new_grhss)) }
403 -------------------------------------------------------------------------
404 zonkGRHSs :: ZonkEnv -> GRHSs TcId -> TcM (GRHSs Id)
406 zonkGRHSs env (GRHSs grhss binds)
407 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
409 zonk_grhs (GRHS guarded rhs)
410 = zonkStmts new_env guarded `thenM` \ (env2, new_guarded) ->
411 zonkLExpr env2 rhs `thenM` \ new_rhs ->
412 returnM (GRHS new_guarded new_rhs)
414 mappM (wrapLocM zonk_grhs) grhss `thenM` \ new_grhss ->
415 returnM (GRHSs new_grhss new_binds)
418 %************************************************************************
420 \subsection[BackSubst-HsExpr]{Running a zonkitution over a TypeCheckedExpr}
422 %************************************************************************
425 zonkLExprs :: ZonkEnv -> [LHsExpr TcId] -> TcM [LHsExpr Id]
426 zonkLExpr :: ZonkEnv -> LHsExpr TcId -> TcM (LHsExpr Id)
427 zonkExpr :: ZonkEnv -> HsExpr TcId -> TcM (HsExpr Id)
429 zonkLExprs env exprs = mappM (zonkLExpr env) exprs
430 zonkLExpr env expr = wrapLocM (zonkExpr env) expr
432 zonkExpr env (HsVar id)
433 = returnM (HsVar (zonkIdOcc env id))
435 zonkExpr env (HsIPVar id)
436 = returnM (HsIPVar (mapIPName (zonkIdOcc env) id))
438 zonkExpr env (HsLit (HsRat f ty))
439 = zonkTcTypeToType env ty `thenM` \ new_ty ->
440 returnM (HsLit (HsRat f new_ty))
442 zonkExpr _ (HsLit lit)
443 = returnM (HsLit lit)
445 zonkExpr env (HsOverLit lit)
446 = do { lit' <- zonkOverLit env lit
447 ; return (HsOverLit lit') }
449 zonkExpr env (HsLam matches)
450 = zonkMatchGroup env matches `thenM` \ new_matches ->
451 returnM (HsLam new_matches)
453 zonkExpr env (HsApp e1 e2)
454 = zonkLExpr env e1 `thenM` \ new_e1 ->
455 zonkLExpr env e2 `thenM` \ new_e2 ->
456 returnM (HsApp new_e1 new_e2)
458 zonkExpr env (HsBracketOut body bs)
459 = mappM zonk_b bs `thenM` \ bs' ->
460 returnM (HsBracketOut body bs')
462 zonk_b (n,e) = zonkLExpr env e `thenM` \ e' ->
465 zonkExpr _ (HsSpliceE s) = WARN( True, ppr s ) -- Should not happen
466 returnM (HsSpliceE s)
468 zonkExpr env (OpApp e1 op fixity e2)
469 = zonkLExpr env e1 `thenM` \ new_e1 ->
470 zonkLExpr env op `thenM` \ new_op ->
471 zonkLExpr env e2 `thenM` \ new_e2 ->
472 returnM (OpApp new_e1 new_op fixity new_e2)
474 zonkExpr env (NegApp expr op)
475 = zonkLExpr env expr `thenM` \ new_expr ->
476 zonkExpr env op `thenM` \ new_op ->
477 returnM (NegApp new_expr new_op)
479 zonkExpr env (HsPar e)
480 = zonkLExpr env e `thenM` \new_e ->
481 returnM (HsPar new_e)
483 zonkExpr env (SectionL expr op)
484 = zonkLExpr env expr `thenM` \ new_expr ->
485 zonkLExpr env op `thenM` \ new_op ->
486 returnM (SectionL new_expr new_op)
488 zonkExpr env (SectionR op expr)
489 = zonkLExpr env op `thenM` \ new_op ->
490 zonkLExpr env expr `thenM` \ new_expr ->
491 returnM (SectionR new_op new_expr)
493 zonkExpr env (HsCase expr ms)
494 = zonkLExpr env expr `thenM` \ new_expr ->
495 zonkMatchGroup env ms `thenM` \ new_ms ->
496 returnM (HsCase new_expr new_ms)
498 zonkExpr env (HsIf e1 e2 e3)
499 = zonkLExpr env e1 `thenM` \ new_e1 ->
500 zonkLExpr env e2 `thenM` \ new_e2 ->
501 zonkLExpr env e3 `thenM` \ new_e3 ->
502 returnM (HsIf new_e1 new_e2 new_e3)
504 zonkExpr env (HsLet binds expr)
505 = zonkLocalBinds env binds `thenM` \ (new_env, new_binds) ->
506 zonkLExpr new_env expr `thenM` \ new_expr ->
507 returnM (HsLet new_binds new_expr)
509 zonkExpr env (HsDo do_or_lc stmts body ty)
510 = zonkStmts env stmts `thenM` \ (new_env, new_stmts) ->
511 zonkLExpr new_env body `thenM` \ new_body ->
512 zonkTcTypeToType env ty `thenM` \ new_ty ->
513 returnM (HsDo (zonkDo env do_or_lc)
514 new_stmts new_body new_ty)
516 zonkExpr env (ExplicitList ty exprs)
517 = zonkTcTypeToType env ty `thenM` \ new_ty ->
518 zonkLExprs env exprs `thenM` \ new_exprs ->
519 returnM (ExplicitList new_ty new_exprs)
521 zonkExpr env (ExplicitPArr ty exprs)
522 = zonkTcTypeToType env ty `thenM` \ new_ty ->
523 zonkLExprs env exprs `thenM` \ new_exprs ->
524 returnM (ExplicitPArr new_ty new_exprs)
526 zonkExpr env (ExplicitTuple exprs boxed)
527 = zonkLExprs env exprs `thenM` \ new_exprs ->
528 returnM (ExplicitTuple new_exprs boxed)
530 zonkExpr env (RecordCon data_con con_expr rbinds)
531 = do { new_con_expr <- zonkExpr env con_expr
532 ; new_rbinds <- zonkRecFields env rbinds
533 ; return (RecordCon data_con new_con_expr new_rbinds) }
535 zonkExpr env (RecordUpd expr rbinds cons in_tys out_tys)
536 = do { new_expr <- zonkLExpr env expr
537 ; new_in_tys <- mapM (zonkTcTypeToType env) in_tys
538 ; new_out_tys <- mapM (zonkTcTypeToType env) out_tys
539 ; new_rbinds <- zonkRecFields env rbinds
540 ; return (RecordUpd new_expr new_rbinds cons new_in_tys new_out_tys) }
542 zonkExpr env (ExprWithTySigOut e ty)
543 = do { e' <- zonkLExpr env e
544 ; return (ExprWithTySigOut e' ty) }
546 zonkExpr _ (ExprWithTySig _ _) = panic "zonkExpr env:ExprWithTySig"
548 zonkExpr env (ArithSeq expr info)
549 = zonkExpr env expr `thenM` \ new_expr ->
550 zonkArithSeq env info `thenM` \ new_info ->
551 returnM (ArithSeq new_expr new_info)
553 zonkExpr env (PArrSeq expr info)
554 = zonkExpr env expr `thenM` \ new_expr ->
555 zonkArithSeq env info `thenM` \ new_info ->
556 returnM (PArrSeq new_expr new_info)
558 zonkExpr env (HsSCC lbl expr)
559 = zonkLExpr env expr `thenM` \ new_expr ->
560 returnM (HsSCC lbl new_expr)
562 zonkExpr env (HsTickPragma info expr)
563 = zonkLExpr env expr `thenM` \ new_expr ->
564 returnM (HsTickPragma info new_expr)
566 -- hdaume: core annotations
567 zonkExpr env (HsCoreAnn lbl expr)
568 = zonkLExpr env expr `thenM` \ new_expr ->
569 returnM (HsCoreAnn lbl new_expr)
571 -- arrow notation extensions
572 zonkExpr env (HsProc pat body)
573 = do { (env1, new_pat) <- zonkPat env pat
574 ; new_body <- zonkCmdTop env1 body
575 ; return (HsProc new_pat new_body) }
577 zonkExpr env (HsArrApp e1 e2 ty ho rl)
578 = zonkLExpr env e1 `thenM` \ new_e1 ->
579 zonkLExpr env e2 `thenM` \ new_e2 ->
580 zonkTcTypeToType env ty `thenM` \ new_ty ->
581 returnM (HsArrApp new_e1 new_e2 new_ty ho rl)
583 zonkExpr env (HsArrForm op fixity args)
584 = zonkLExpr env op `thenM` \ new_op ->
585 mappM (zonkCmdTop env) args `thenM` \ new_args ->
586 returnM (HsArrForm new_op fixity new_args)
588 zonkExpr env (HsWrap co_fn expr)
589 = zonkCoFn env co_fn `thenM` \ (env1, new_co_fn) ->
590 zonkExpr env1 expr `thenM` \ new_expr ->
591 return (HsWrap new_co_fn new_expr)
593 zonkExpr _ expr = pprPanic "zonkExpr" (ppr expr)
595 zonkCmdTop :: ZonkEnv -> LHsCmdTop TcId -> TcM (LHsCmdTop Id)
596 zonkCmdTop env cmd = wrapLocM (zonk_cmd_top env) cmd
598 zonk_cmd_top :: ZonkEnv -> HsCmdTop TcId -> TcM (HsCmdTop Id)
599 zonk_cmd_top env (HsCmdTop cmd stack_tys ty ids)
600 = zonkLExpr env cmd `thenM` \ new_cmd ->
601 zonkTcTypeToTypes env stack_tys `thenM` \ new_stack_tys ->
602 zonkTcTypeToType env ty `thenM` \ new_ty ->
603 mapSndM (zonkExpr env) ids `thenM` \ new_ids ->
604 returnM (HsCmdTop new_cmd new_stack_tys new_ty new_ids)
606 -------------------------------------------------------------------------
607 zonkCoFn :: ZonkEnv -> HsWrapper -> TcM (ZonkEnv, HsWrapper)
608 zonkCoFn env WpHole = return (env, WpHole)
609 zonkCoFn env WpInline = return (env, WpInline)
610 zonkCoFn env (WpCompose c1 c2) = do { (env1, c1') <- zonkCoFn env c1
611 ; (env2, c2') <- zonkCoFn env1 c2
612 ; return (env2, WpCompose c1' c2') }
613 zonkCoFn env (WpCast co) = do { co' <- zonkTcTypeToType env co
614 ; return (env, WpCast co') }
615 zonkCoFn env (WpLam id) = do { id' <- zonkDictBndr env id
616 ; let env1 = extendZonkEnv1 env id'
617 ; return (env1, WpLam id') }
618 zonkCoFn env (WpTyLam tv) = ASSERT( isImmutableTyVar tv )
619 do { tv' <- zonkTyVarBndr env tv
620 ; return (env, WpTyLam tv') }
621 zonkCoFn env (WpApp v)
622 | isTcTyVar v = do { co <- zonkTcTyVar v
623 ; return (env, WpTyApp co) }
624 -- Yuk! A mutable coercion variable is a TcTyVar
625 -- not a CoVar, so don't use isCoVar!
626 -- Yuk! A WpApp can't hold the zonked type,
627 -- so we switch to WpTyApp
628 | otherwise = return (env, WpApp (zonkIdOcc env v))
629 zonkCoFn env (WpTyApp ty) = do { ty' <- zonkTcTypeToType env ty
630 ; return (env, WpTyApp ty') }
631 zonkCoFn env (WpLet bs) = do { (env1, bs') <- zonkRecMonoBinds env bs
632 ; return (env1, WpLet bs') }
635 -------------------------------------------------------------------------
636 zonkDo :: ZonkEnv -> HsStmtContext Name -> HsStmtContext Name
637 -- Only used for 'do', so the only Ids are in a MDoExpr table
638 zonkDo env (MDoExpr tbl) = MDoExpr (mapSnd (zonkIdOcc env) tbl)
639 zonkDo _ do_or_lc = do_or_lc
641 -------------------------------------------------------------------------
642 zonkOverLit :: ZonkEnv -> HsOverLit TcId -> TcM (HsOverLit Id)
643 zonkOverLit env lit@(OverLit { ol_witness = e, ol_type = ty })
644 = do { ty' <- zonkTcTypeToType env ty
645 ; e' <- zonkExpr env e
646 ; return (lit { ol_witness = e', ol_type = ty' }) }
648 -------------------------------------------------------------------------
649 zonkArithSeq :: ZonkEnv -> ArithSeqInfo TcId -> TcM (ArithSeqInfo Id)
651 zonkArithSeq env (From e)
652 = zonkLExpr env e `thenM` \ new_e ->
655 zonkArithSeq env (FromThen e1 e2)
656 = zonkLExpr env e1 `thenM` \ new_e1 ->
657 zonkLExpr env e2 `thenM` \ new_e2 ->
658 returnM (FromThen new_e1 new_e2)
660 zonkArithSeq env (FromTo e1 e2)
661 = zonkLExpr env e1 `thenM` \ new_e1 ->
662 zonkLExpr env e2 `thenM` \ new_e2 ->
663 returnM (FromTo new_e1 new_e2)
665 zonkArithSeq env (FromThenTo e1 e2 e3)
666 = zonkLExpr env e1 `thenM` \ new_e1 ->
667 zonkLExpr env e2 `thenM` \ new_e2 ->
668 zonkLExpr env e3 `thenM` \ new_e3 ->
669 returnM (FromThenTo new_e1 new_e2 new_e3)
672 -------------------------------------------------------------------------
673 zonkStmts :: ZonkEnv -> [LStmt TcId] -> TcM (ZonkEnv, [LStmt Id])
674 zonkStmts env [] = return (env, [])
675 zonkStmts env (s:ss) = do { (env1, s') <- wrapLocSndM (zonkStmt env) s
676 ; (env2, ss') <- zonkStmts env1 ss
677 ; return (env2, s' : ss') }
679 zonkStmt :: ZonkEnv -> Stmt TcId -> TcM (ZonkEnv, Stmt Id)
680 zonkStmt env (ParStmt stmts_w_bndrs)
681 = mappM zonk_branch stmts_w_bndrs `thenM` \ new_stmts_w_bndrs ->
683 new_binders = concat (map snd new_stmts_w_bndrs)
684 env1 = extendZonkEnv env new_binders
686 return (env1, ParStmt new_stmts_w_bndrs)
688 zonk_branch (stmts, bndrs) = zonkStmts env stmts `thenM` \ (env1, new_stmts) ->
689 returnM (new_stmts, zonkIdOccs env1 bndrs)
691 zonkStmt env (RecStmt segStmts lvs rvs rets binds)
692 = zonkIdBndrs env rvs `thenM` \ new_rvs ->
694 env1 = extendZonkEnv env new_rvs
696 zonkStmts env1 segStmts `thenM` \ (env2, new_segStmts) ->
697 -- Zonk the ret-expressions in an envt that
698 -- has the polymorphic bindings in the envt
699 mapM (zonkExpr env2) rets `thenM` \ new_rets ->
701 new_lvs = zonkIdOccs env2 lvs
702 env3 = extendZonkEnv env new_lvs -- Only the lvs are needed
704 zonkRecMonoBinds env3 binds `thenM` \ (env4, new_binds) ->
705 returnM (env4, RecStmt new_segStmts new_lvs new_rvs new_rets new_binds)
707 zonkStmt env (ExprStmt expr then_op ty)
708 = zonkLExpr env expr `thenM` \ new_expr ->
709 zonkExpr env then_op `thenM` \ new_then ->
710 zonkTcTypeToType env ty `thenM` \ new_ty ->
711 returnM (env, ExprStmt new_expr new_then new_ty)
713 zonkStmt env (TransformStmt (stmts, binders) usingExpr maybeByExpr)
714 = do { (env', stmts') <- zonkStmts env stmts
715 ; let binders' = zonkIdOccs env' binders
716 ; usingExpr' <- zonkLExpr env' usingExpr
717 ; maybeByExpr' <- zonkMaybeLExpr env' maybeByExpr
718 ; return (env', TransformStmt (stmts', binders') usingExpr' maybeByExpr') }
720 zonkStmt env (GroupStmt (stmts, binderMap) groupByClause)
721 = do { (env', stmts') <- zonkStmts env stmts
722 ; binderMap' <- mappM (zonkBinderMapEntry env') binderMap
724 case groupByClause of
725 GroupByNothing usingExpr -> (zonkLExpr env' usingExpr) >>= (return . GroupByNothing)
726 GroupBySomething eitherUsingExpr byExpr -> do
727 eitherUsingExpr' <- mapEitherM (zonkLExpr env') (zonkExpr env') eitherUsingExpr
728 byExpr' <- zonkLExpr env' byExpr
729 return $ GroupBySomething eitherUsingExpr' byExpr'
731 ; let env'' = extendZonkEnv env' (map snd binderMap')
732 ; return (env'', GroupStmt (stmts', binderMap') groupByClause') }
734 mapEitherM f g x = do
736 Left a -> f a >>= (return . Left)
737 Right b -> g b >>= (return . Right)
739 zonkBinderMapEntry env (oldBinder, newBinder) = do
740 let oldBinder' = zonkIdOcc env oldBinder
741 newBinder' <- zonkIdBndr env newBinder
742 return (oldBinder', newBinder')
744 zonkStmt env (LetStmt binds)
745 = zonkLocalBinds env binds `thenM` \ (env1, new_binds) ->
746 returnM (env1, LetStmt new_binds)
748 zonkStmt env (BindStmt pat expr bind_op fail_op)
749 = do { new_expr <- zonkLExpr env expr
750 ; (env1, new_pat) <- zonkPat env pat
751 ; new_bind <- zonkExpr env bind_op
752 ; new_fail <- zonkExpr env fail_op
753 ; return (env1, BindStmt new_pat new_expr new_bind new_fail) }
755 zonkMaybeLExpr :: ZonkEnv -> Maybe (LHsExpr TcId) -> TcM (Maybe (LHsExpr Id))
756 zonkMaybeLExpr _ Nothing = return Nothing
757 zonkMaybeLExpr env (Just e) = (zonkLExpr env e) >>= (return . Just)
760 -------------------------------------------------------------------------
761 zonkRecFields :: ZonkEnv -> HsRecordBinds TcId -> TcM (HsRecordBinds TcId)
762 zonkRecFields env (HsRecFields flds dd)
763 = do { flds' <- mappM zonk_rbind flds
764 ; return (HsRecFields flds' dd) }
767 = do { new_id <- wrapLocM (zonkIdBndr env) (hsRecFieldId fld)
768 ; new_expr <- zonkLExpr env (hsRecFieldArg fld)
769 ; return (fld { hsRecFieldId = new_id, hsRecFieldArg = new_expr }) }
771 -------------------------------------------------------------------------
772 mapIPNameTc :: (a -> TcM b) -> IPName a -> TcM (IPName b)
773 mapIPNameTc f (IPName n) = f n `thenM` \ r -> returnM (IPName r)
777 %************************************************************************
779 \subsection[BackSubst-Pats]{Patterns}
781 %************************************************************************
784 zonkPat :: ZonkEnv -> OutPat TcId -> TcM (ZonkEnv, OutPat Id)
785 -- Extend the environment as we go, because it's possible for one
786 -- pattern to bind something that is used in another (inside or
788 zonkPat env pat = wrapLocSndM (zonk_pat env) pat
790 zonk_pat :: ZonkEnv -> Pat TcId -> TcM (ZonkEnv, Pat Id)
791 zonk_pat env (ParPat p)
792 = do { (env', p') <- zonkPat env p
793 ; return (env', ParPat p') }
795 zonk_pat env (WildPat ty)
796 = do { ty' <- zonkTcTypeToType env ty
797 ; return (env, WildPat ty') }
799 zonk_pat env (VarPat v)
800 = do { v' <- zonkIdBndr env v
801 ; return (extendZonkEnv1 env v', VarPat v') }
803 zonk_pat env (VarPatOut v binds)
804 = do { v' <- zonkIdBndr env v
805 ; (env', binds') <- zonkRecMonoBinds (extendZonkEnv1 env v') binds
806 ; returnM (env', VarPatOut v' binds') }
808 zonk_pat env (LazyPat pat)
809 = do { (env', pat') <- zonkPat env pat
810 ; return (env', LazyPat pat') }
812 zonk_pat env (BangPat pat)
813 = do { (env', pat') <- zonkPat env pat
814 ; return (env', BangPat pat') }
816 zonk_pat env (AsPat (L loc v) pat)
817 = do { v' <- zonkIdBndr env v
818 ; (env', pat') <- zonkPat (extendZonkEnv1 env v') pat
819 ; return (env', AsPat (L loc v') pat') }
821 zonk_pat env (ViewPat expr pat ty)
822 = do { expr' <- zonkLExpr env expr
823 ; (env', pat') <- zonkPat env pat
824 ; ty' <- zonkTcTypeToType env ty
825 ; return (env', ViewPat expr' pat' ty') }
827 zonk_pat env (ListPat pats ty)
828 = do { ty' <- zonkTcTypeToType env ty
829 ; (env', pats') <- zonkPats env pats
830 ; return (env', ListPat pats' ty') }
832 zonk_pat env (PArrPat pats ty)
833 = do { ty' <- zonkTcTypeToType env ty
834 ; (env', pats') <- zonkPats env pats
835 ; return (env', PArrPat pats' ty') }
837 zonk_pat env (TuplePat pats boxed ty)
838 = do { ty' <- zonkTcTypeToType env ty
839 ; (env', pats') <- zonkPats env pats
840 ; return (env', TuplePat pats' boxed ty') }
842 zonk_pat env p@(ConPatOut { pat_ty = ty, pat_dicts = dicts, pat_binds = binds, pat_args = args })
843 = ASSERT( all isImmutableTyVar (pat_tvs p) )
844 do { new_ty <- zonkTcTypeToType env ty
845 ; new_dicts <- zonkDictBndrs env dicts
846 ; let env1 = extendZonkEnv env new_dicts
847 ; (env2, new_binds) <- zonkRecMonoBinds env1 binds
848 ; (env', new_args) <- zonkConStuff env2 args
849 ; returnM (env', p { pat_ty = new_ty, pat_dicts = new_dicts,
850 pat_binds = new_binds, pat_args = new_args }) }
852 zonk_pat env (LitPat lit) = return (env, LitPat lit)
854 zonk_pat env (SigPatOut pat ty)
855 = do { ty' <- zonkTcTypeToType env ty
856 ; (env', pat') <- zonkPat env pat
857 ; return (env', SigPatOut pat' ty') }
859 zonk_pat env (NPat lit mb_neg eq_expr)
860 = do { lit' <- zonkOverLit env lit
861 ; mb_neg' <- case mb_neg of
862 Nothing -> return Nothing
863 Just neg -> do { neg' <- zonkExpr env neg
864 ; return (Just neg') }
865 ; eq_expr' <- zonkExpr env eq_expr
866 ; return (env, NPat lit' mb_neg' eq_expr') }
868 zonk_pat env (NPlusKPat (L loc n) lit e1 e2)
869 = do { n' <- zonkIdBndr env n
870 ; lit' <- zonkOverLit env lit
871 ; e1' <- zonkExpr env e1
872 ; e2' <- zonkExpr env e2
873 ; return (extendZonkEnv1 env n', NPlusKPat (L loc n') lit' e1' e2') }
875 zonk_pat env (CoPat co_fn pat ty)
876 = do { (env', co_fn') <- zonkCoFn env co_fn
877 ; (env'', pat') <- zonkPat env' (noLoc pat)
878 ; ty' <- zonkTcTypeToType env'' ty
879 ; return (env'', CoPat co_fn' (unLoc pat') ty') }
881 zonk_pat _ pat = pprPanic "zonk_pat" (ppr pat)
883 ---------------------------
884 zonkConStuff :: ZonkEnv
885 -> HsConDetails (OutPat TcId) (HsRecFields id (OutPat TcId))
887 HsConDetails (OutPat Id) (HsRecFields id (OutPat Id)))
888 zonkConStuff env (PrefixCon pats)
889 = do { (env', pats') <- zonkPats env pats
890 ; return (env', PrefixCon pats') }
892 zonkConStuff env (InfixCon p1 p2)
893 = do { (env1, p1') <- zonkPat env p1
894 ; (env', p2') <- zonkPat env1 p2
895 ; return (env', InfixCon p1' p2') }
897 zonkConStuff env (RecCon (HsRecFields rpats dd))
898 = do { (env', pats') <- zonkPats env (map hsRecFieldArg rpats)
899 ; let rpats' = zipWith (\rp p' -> rp { hsRecFieldArg = p' }) rpats pats'
900 ; returnM (env', RecCon (HsRecFields rpats' dd)) }
901 -- Field selectors have declared types; hence no zonking
903 ---------------------------
904 zonkPats :: ZonkEnv -> [OutPat TcId] -> TcM (ZonkEnv, [OutPat Id])
905 zonkPats env [] = return (env, [])
906 zonkPats env (pat:pats) = do { (env1, pat') <- zonkPat env pat
907 ; (env', pats') <- zonkPats env1 pats
908 ; return (env', pat':pats') }
911 %************************************************************************
913 \subsection[BackSubst-Foreign]{Foreign exports}
915 %************************************************************************
919 zonkForeignExports :: ZonkEnv -> [LForeignDecl TcId] -> TcM [LForeignDecl Id]
920 zonkForeignExports env ls = mappM (wrapLocM (zonkForeignExport env)) ls
922 zonkForeignExport :: ZonkEnv -> ForeignDecl TcId -> TcM (ForeignDecl Id)
923 zonkForeignExport env (ForeignExport i _hs_ty spec) =
924 returnM (ForeignExport (fmap (zonkIdOcc env) i) undefined spec)
925 zonkForeignExport _ for_imp
926 = returnM for_imp -- Foreign imports don't need zonking
930 zonkRules :: ZonkEnv -> [LRuleDecl TcId] -> TcM [LRuleDecl Id]
931 zonkRules env rs = mappM (wrapLocM (zonkRule env)) rs
933 zonkRule :: ZonkEnv -> RuleDecl TcId -> TcM (RuleDecl Id)
934 zonkRule env (HsRule name act (vars{-::[RuleBndr TcId]-}) lhs fv_lhs rhs fv_rhs)
935 = mappM zonk_bndr vars `thenM` \ new_bndrs ->
936 newMutVar emptyVarSet `thenM` \ unbound_tv_set ->
938 env_rhs = extendZonkEnv env [id | b <- new_bndrs, let id = unLoc b, isId id]
939 -- Type variables don't need an envt
940 -- They are bound through the mutable mechanism
942 env_lhs = setZonkType env_rhs (zonkTypeCollecting unbound_tv_set)
943 -- We need to gather the type variables mentioned on the LHS so we can
944 -- quantify over them. Example:
950 -- {-# RULES "myrule" foo C = 1 #-}
952 -- After type checking the LHS becomes (foo a (C a))
953 -- and we do not want to zap the unbound tyvar 'a' to (), because
954 -- that limits the applicability of the rule. Instead, we
955 -- want to quantify over it!
957 -- It's easiest to find the free tyvars here. Attempts to do so earlier
958 -- are tiresome, because (a) the data type is big and (b) finding the
959 -- free type vars of an expression is necessarily monadic operation.
960 -- (consider /\a -> f @ b, where b is side-effected to a)
962 zonkLExpr env_lhs lhs `thenM` \ new_lhs ->
963 zonkLExpr env_rhs rhs `thenM` \ new_rhs ->
965 readMutVar unbound_tv_set `thenM` \ unbound_tvs ->
967 final_bndrs :: [Located Var]
968 final_bndrs = map noLoc (varSetElems unbound_tvs) ++ new_bndrs
970 returnM (HsRule name act (map RuleBndr final_bndrs) new_lhs fv_lhs new_rhs fv_rhs)
971 -- I hate this map RuleBndr stuff
973 zonk_bndr (RuleBndr v)
974 | isId (unLoc v) = wrapLocM (zonkIdBndr env) v
975 | otherwise = ASSERT( isImmutableTyVar (unLoc v) )
977 zonk_bndr (RuleBndrSig {}) = panic "zonk_bndr RuleBndrSig"
981 %************************************************************************
983 \subsection[BackSubst-Foreign]{Foreign exports}
985 %************************************************************************
988 zonkTcTypeToType :: ZonkEnv -> TcType -> TcM Type
989 zonkTcTypeToType (ZonkEnv zonk_ty _) ty = zonk_ty ty
991 zonkTcTypeToTypes :: ZonkEnv -> [TcType] -> TcM [Type]
992 zonkTcTypeToTypes env tys = mapM (zonkTcTypeToType env) tys
994 zonkTypeCollecting :: TcRef TyVarSet -> TcType -> TcM Type
995 -- This variant collects unbound type variables in a mutable variable
996 zonkTypeCollecting unbound_tv_set
997 = zonkType zonk_unbound_tyvar
999 zonk_unbound_tyvar tv
1000 = zonkQuantifiedTyVar tv `thenM` \ tv' ->
1001 readMutVar unbound_tv_set `thenM` \ tv_set ->
1002 writeMutVar unbound_tv_set (extendVarSet tv_set tv') `thenM_`
1003 return (mkTyVarTy tv')
1005 zonkTypeZapping :: TcType -> TcM Type
1006 -- This variant is used for everything except the LHS of rules
1007 -- It zaps unbound type variables to (), or some other arbitrary type
1009 = zonkType zonk_unbound_tyvar ty
1011 -- Zonk a mutable but unbound type variable to an arbitrary type
1012 -- We know it's unbound even though we don't carry an environment,
1013 -- because at the binding site for a type variable we bind the
1014 -- mutable tyvar to a fresh immutable one. So the mutable store
1015 -- plays the role of an environment. If we come across a mutable
1016 -- type variable that isn't so bound, it must be completely free.
1017 zonk_unbound_tyvar tv = do { ty <- mkArbitraryType warn tv
1018 ; writeMetaTyVar tv ty
1021 warn span msg = setSrcSpan span (addWarnTc msg)
1024 {- Note [Strangely-kinded void TyCons]
1025 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1026 See Trac #959 for more examples
1028 When the type checker finds a type variable with no binding, which
1029 means it can be instantiated with an arbitrary type, it usually
1030 instantiates it to Void. Eg.
1034 length Void (Nil Void)
1036 But in really obscure programs, the type variable might have a kind
1037 other than *, so we need to invent a suitably-kinded type.
1042 Tuple for kind *->...*->*
1044 which deals with most cases. (Previously, it only dealt with
1047 In the other cases, it just makes up a TyCon with a suitable kind. If
1048 this gets into an interface file, anyone reading that file won't
1049 understand it. This is fixable (by making the client of the interface
1050 file make up a TyCon too) but it is tiresome and never happens, so I
1053 Meanwhile I have now fixed GHC to emit a civilized warning.
1056 mkArbitraryType :: (SrcSpan -> SDoc -> TcRnIf g l a) -- How to complain
1058 -> TcRnIf g l Type -- Used by desugarer too
1059 -- Make up an arbitrary type whose kind is the same as the tyvar.
1060 -- We'll use this to instantiate the (unbound) tyvar.
1062 -- Also used by the desugarer; hence the (tiresome) parameter
1063 -- to use when generating a warning
1064 mkArbitraryType warn tv
1065 | liftedTypeKind `isSubKind` kind -- The vastly common case
1067 | eqKind kind (tyConKind anyPrimTyCon1) -- @*->*@
1068 = return (mkTyConApp anyPrimTyCon1 []) -- No tuples this size
1069 | all isLiftedTypeKind args -- @*-> ... ->*->*@
1070 , isLiftedTypeKind res -- Horrible hack to make less use
1071 = return (mkTyConApp tup_tc []) -- of mkAnyPrimTyCon
1073 = do { _ <- warn (getSrcSpan tv) msg
1074 ; return (mkTyConApp (mkAnyPrimTyCon (getUnique tv) kind) []) }
1075 -- Same name as the tyvar, apart from making it start with a colon (sigh)
1076 -- I dread to think what will happen if this gets out into an
1077 -- interface file. Catastrophe likely. Major sigh.
1080 (args,res) = splitKindFunTys kind
1081 tup_tc = tupleTyCon Boxed (length args)
1083 msg = vcat [ hang (ptext (sLit "Inventing strangely-kinded Any TyCon"))
1084 2 (ptext (sLit "of kind") <+> quotes (ppr kind))
1085 , nest 2 (ptext (sLit "from an instantiation of type variable") <+> quotes (ppr tv))
1086 , ptext (sLit "This warning can be suppressed by a type signature fixing") <+> quotes (ppr tv)
1087 , nest 2 (ptext (sLit "but is harmless without -O (and usually harmless anyway)."))
1088 , ptext (sLit "See http://hackage.haskell.org/trac/ghc/ticket/959 for details") ]