tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC, tcMonoExpr, tcPolyExpr )
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC,
+ tcMonoExpr, tcMonoExprNC, tcPolyExpr )
import HsSyn
import TcRnMonad
-- sensible location. Note: we have to do this odd
-- ann-grabbing, because we don't always have annotations in
-- hand when we call tcMatchesFun...
- checkArgs fun_name matches
+ traceTc (text "tcMatchesFun" <+> (ppr fun_name $$ ppr exp_ty))
+ ; checkArgs fun_name matches
-- ToDo: Don't use "expected" stuff if there ain't a type signature
-- because inconsistency between branches
(HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
tcDoStmts DoExpr stmts body res_ty
- = do { (stmts', body') <- tcStmts DoExpr tcDoStmt stmts
- res_ty $
+ = do { (stmts', body') <- tcStmts DoExpr tcDoStmt stmts res_ty $
tcBody body
; return (HsDo DoExpr stmts' body' res_ty) }
; return (ids, pairs', thing) }
; return ( (stmts', ids) : pairs', thing ) }
-tcLcStmt m_tc ctxt (TransformStmt (stmts, binders) usingExpr maybeByExpr) elt_ty thing_inside = do
+tcLcStmt m_tc ctxt (TransformStmt stmts binders usingExpr maybeByExpr) elt_ty thing_inside = do
(stmts', (binders', usingExpr', maybeByExpr', thing)) <-
tcStmts (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do
let alphaListTy = mkTyConApp m_tc [alphaTy]
return (binders', usingExpr', maybeByExpr', thing)
- return (TransformStmt (stmts', binders') usingExpr' maybeByExpr', thing)
+ return (TransformStmt stmts' binders' usingExpr' maybeByExpr', thing)
-tcLcStmt m_tc ctxt (GroupStmt (stmts, bindersMap) groupByClause) elt_ty thing_inside = do
- (stmts', (bindersMap', groupByClause', thing)) <-
+tcLcStmt m_tc ctxt (GroupStmt stmts bindersMap by using) elt_ty thing_inside
+ = do { let (bndr_names, list_bndr_names) = unzip bindersMap
+
+ ; (stmts', (bndr_ids, by', using_ty, elt_ty')) <-
tcStmts (TransformStmtCtxt ctxt) (tcLcStmt m_tc) stmts elt_ty $ \elt_ty' -> do
- let alphaListTy = mkTyConApp m_tc [alphaTy]
- alphaListListTy = mkTyConApp m_tc [alphaListTy]
-
- groupByClause' <-
- case groupByClause of
- GroupByNothing usingExpr ->
- -- We must validate that usingExpr :: forall a. [a] -> [[a]]
- tcPolyExpr usingExpr (mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListListTy)) >>= (return . GroupByNothing)
- GroupBySomething eitherUsingExpr byExpr -> do
- -- We must infer a type such that byExpr :: t
- (byExpr', tTy) <- tcInferRhoNC byExpr
-
- -- If it exists, we then check that usingExpr :: forall a. (a -> t) -> [a] -> [[a]]
- let expectedUsingType = mkForAllTy alphaTyVar ((alphaTy `mkFunTy` tTy) `mkFunTy` (alphaListTy `mkFunTy` alphaListListTy))
- eitherUsingExpr' <-
- case eitherUsingExpr of
- Left usingExpr -> (tcPolyExpr usingExpr expectedUsingType) >>= (return . Left)
- Right usingExpr -> (tcPolyExpr (noLoc usingExpr) expectedUsingType) >>= (return . Right . unLoc)
- return $ GroupBySomething eitherUsingExpr' byExpr'
-
- -- Find the IDs and types of all old binders
- let (oldBinders, newBinders) = unzip bindersMap
- oldBinders' <- tcLookupLocalIds oldBinders
+ (by', using_ty) <- case by of
+ Nothing -> -- check that using :: forall a. [a] -> [[a]]
+ return (Nothing, mkForAllTy alphaTyVar $
+ alphaListTy `mkFunTy` alphaListListTy)
+
+ Just by_e -> -- check that using :: forall a. (a -> t) -> [a] -> [[a]]
+ -- where by :: t
+ do { (by_e', t_ty) <- tcInferRhoNC by_e
+ ; return (Just by_e', mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` t_ty)
+ `mkFunTy` alphaListTy
+ `mkFunTy` alphaListListTy) }
+ -- Find the Ids (and hence types) of all old binders
+ bndr_ids <- tcLookupLocalIds bndr_names
+ return (bndr_ids, by', using_ty, elt_ty')
+
-- Ensure that every old binder of type b is linked up with its new binder which should have type [b]
- let newBinders' = zipWith associateNewBinder oldBinders' newBinders
+ ; let list_bndr_ids = zipWith mk_list_bndr list_bndr_names bndr_ids
+ bindersMap' = bndr_ids `zip` list_bndr_ids
+ -- See Note [GroupStmt binder map] in HsExpr
- -- Type check the thing in the environment with these new binders and return the result
- thing <- tcExtendIdEnv newBinders' (thing_inside elt_ty')
- return (zipEqual "tcLcStmt: Old and new binder lists were not of the same length" oldBinders' newBinders', groupByClause', thing)
-
- return (GroupStmt (stmts', bindersMap') groupByClause', thing)
- where
- associateNewBinder :: TcId -> Name -> TcId
- associateNewBinder oldBinder newBinder = mkLocalId newBinder (mkTyConApp m_tc [idType oldBinder])
+ ; using' <- case using of
+ Left e -> do { e' <- tcPolyExpr e using_ty; return (Left e') }
+ Right e -> do { e' <- tcPolyExpr (noLoc e) using_ty; return (Right (unLoc e')) }
+
+ -- Type check the thing in the environment with these new binders and return the result
+ ; thing <- tcExtendIdEnv list_bndr_ids (thing_inside elt_ty')
+ ; return (GroupStmt stmts' bindersMap' by' using', thing) }
+ where
+ alphaListTy = mkTyConApp m_tc [alphaTy]
+ alphaListListTy = mkTyConApp m_tc [alphaListTy]
+
+ mk_list_bndr :: Name -> TcId -> TcId
+ mk_list_bndr list_bndr_name bndr_id = mkLocalId list_bndr_name (mkTyConApp m_tc [idType bndr_id])
tcLcStmt _ _ stmt _ _
= pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt)
tcDoStmt :: TcStmtChecker
tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRhoNC rhs
- -- We should use type *inference* for the RHS computations,
- -- becuase of GADTs.
- -- do { pat <- rhs; <rest> }
- -- is rather like
- -- case rhs of { pat -> <rest> }
- -- We do inference on rhs, so that information about its type
- -- can be refined when type-checking the pattern.
+ = do { -- Deal with rebindable syntax:
+ -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty
+ -- This level of generality is needed for using do-notation
+ -- in full generality; see Trac #1537
+
+ -- I'd like to put this *after* the tcSyntaxOp
+ -- (see Note [Treat rebindable syntax first], but that breaks
+ -- the rigidity info for GADTs. When we move to the new story
+ -- for GADTs, we can move this after tcSyntaxOp
+ (rhs', rhs_ty) <- tcInferRhoNC rhs
- -- Deal with rebindable syntax:
- -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty
- -- This level of generality is needed for using do-notation
- -- in full generality; see Trac #1537
; ((bind_op', new_res_ty), pat_ty) <-
withBox liftedTypeKind $ \ pat_ty ->
withBox liftedTypeKind $ \ new_res_ty ->
tcSyntaxOp DoOrigin bind_op
- (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty)
+ (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty)
-- If (but only if) the pattern can fail,
-- typecheck the 'fail' operator
then return noSyntaxExpr
else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy new_res_ty)
+ -- We should typecheck the RHS *before* the pattern,
+ -- because of GADTs.
+ -- do { pat <- rhs; <rest> }
+ -- is rather like
+ -- case rhs of { pat -> <rest> }
+ -- We do inference on rhs, so that information about its type
+ -- can be refined when type-checking the pattern.
+
; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty new_res_ty thing_inside
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
tcDoStmt _ (ExprStmt rhs then_op _) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRhoNC rhs
-
- -- Deal with rebindable syntax; (>>) :: rhs_ty -> new_res_ty -> res_ty
- ; (then_op', new_res_ty) <-
+ = do { -- Deal with rebindable syntax;
+ -- (>>) :: rhs_ty -> new_res_ty -> res_ty
+ -- See also Note [Treat rebindable syntax first]
+ ((then_op', rhs_ty), new_res_ty) <-
withBox liftedTypeKind $ \ new_res_ty ->
+ withBox liftedTypeKind $ \ rhs_ty ->
tcSyntaxOp DoOrigin then_op
(mkFunTys [rhs_ty, new_res_ty] res_ty)
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
; thing <- thing_inside new_res_ty
; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt ctxt (RecStmt {}) _ _
- = failWithTc (ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt)
- -- This case can't be caught in the renamer
- -- see RnExpr.checkRecStmt
+tcDoStmt ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = later_names
+ , recS_rec_ids = rec_names, recS_ret_fn = ret_op
+ , recS_mfix_fn = mfix_op, recS_bind_fn = bind_op })
+ res_ty thing_inside
+ = do { let tup_names = rec_names ++ filterOut (`elem` rec_names) later_names
+ ; tup_elt_tys <- newFlexiTyVarTys (length tup_names) liftedTypeKind
+ ; let tup_ids = zipWith mkLocalId tup_names tup_elt_tys
+ tup_ty = mkBoxedTupleTy tup_elt_tys
+
+ ; tcExtendIdEnv tup_ids $ do
+ { ((stmts', (ret_op', tup_rets)), stmts_ty)
+ <- withBox liftedTypeKind $ \ stmts_ty ->
+ tcStmts ctxt tcDoStmt stmts stmts_ty $ \ inner_res_ty ->
+ do { tup_rets <- zipWithM tc_ret tup_names tup_elt_tys
+ ; ret_op' <- tcSyntaxOp DoOrigin ret_op (mkFunTy tup_ty inner_res_ty)
+ ; return (ret_op', tup_rets) }
+
+ ; (mfix_op', mfix_res_ty) <- withBox liftedTypeKind $ \ mfix_res_ty ->
+ tcSyntaxOp DoOrigin mfix_op
+ (mkFunTy (mkFunTy tup_ty stmts_ty) mfix_res_ty)
+
+ ; (bind_op', new_res_ty) <- withBox liftedTypeKind $ \ new_res_ty ->
+ tcSyntaxOp DoOrigin bind_op
+ (mkFunTys [mfix_res_ty, mkFunTy tup_ty new_res_ty] res_ty)
+
+ ; (thing,lie) <- getLIE (thing_inside new_res_ty)
+ ; lie_binds <- bindInstsOfLocalFuns lie tup_ids
+
+ ; let rec_ids = takeList rec_names tup_ids
+ ; later_ids <- tcLookupLocalIds later_names
+ ; traceTc (text "tcdo" <+> vcat [ppr rec_ids <+> ppr (map idType rec_ids),
+ ppr later_ids <+> ppr (map idType later_ids)])
+ ; return (RecStmt { recS_stmts = stmts', recS_later_ids = later_ids
+ , recS_rec_ids = rec_ids, recS_ret_fn = ret_op'
+ , recS_mfix_fn = mfix_op', recS_bind_fn = bind_op'
+ , recS_rec_rets = tup_rets, recS_dicts = lie_binds }, thing)
+ }}
+ where
+ -- Unify the types of the "final" Ids with those of "knot-tied" Ids
+ tc_ret rec_name mono_ty
+ = do { poly_id <- tcLookupId rec_name
+ -- poly_id may have a polymorphic type
+ -- but mono_ty is just a monomorphic type variable
+ ; co_fn <- tcSubExp DoOrigin (idType poly_id) mono_ty
+ ; return (mkHsWrap co_fn (HsVar poly_id)) }
tcDoStmt _ stmt _ _
= pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt)
+\end{code}
+
+Note [Treat rebindable syntax first]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+When typechecking
+ do { bar; ... } :: IO ()
+we want to typecheck 'bar' in the knowledge that it should be an IO thing,
+pushing info from the context into the RHS. To do this, we check the
+rebindable syntax first, and push that information into (tcMonoExprNC rhs).
+Otherwise the error shows up when cheking the rebindable syntax, and
+the expected/inferred stuff is back to front (see Trac #3613).
+\begin{code}
--------------------------------
-- Mdo-notation
-- The distinctive features here are
; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr elt_ty, thing) }
-tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _) res_ty thing_inside
+tcMDoStmt tc_rhs ctxt (RecStmt stmts laterNames recNames _ _ _ _ _) res_ty thing_inside
= do { rec_tys <- newFlexiTyVarTys (length recNames) liftedTypeKind
; let rec_ids = zipWith mkLocalId recNames rec_tys
; tcExtendIdEnv rec_ids $ do
-- (see note [RecStmt] in HsExpr)
; lie_binds <- bindInstsOfLocalFuns lie later_ids
- ; return (RecStmt stmts' later_ids rec_ids rec_rets lie_binds, thing)
+ ; return (RecStmt stmts' later_ids rec_ids noSyntaxExpr noSyntaxExpr noSyntaxExpr rec_rets lie_binds, thing)
}}
where
-- Unify the types of the "final" Ids with those of "knot-tied" Ids
projects / ghc-hetmet.git / blobdiff