TcMatches: Typecheck some @Matches@
\begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
- matchCtxt, TcMatchCtxt(..),
+ TcMatchCtxt(..),
tcStmts, tcDoStmts, tcBody,
tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-#include "HsVersions.h"
-
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC, tcCheckId,
+ tcMonoExpr, tcMonoExprNC, tcPolyExpr )
import HsSyn
import TcRnMonad
-import TcGadt
import Inst
import TcEnv
import TcPat
import TcType
import TcBinds
import TcUnify
-import TcSimplify
import Name
import TysWiredIn
import PrelNames
import Id
import TyCon
import TysPrim
+import Coercion ( mkSymCoI )
import Outputable
+import BasicTypes ( Arity )
import Util
import SrcLoc
+import FastString
import Control.Monad
+
+#include "HsVersions.h"
\end{code}
%************************************************************************
is used in error messages. It checks that all the equations have the
same number of arguments before using @tcMatches@ to do the work.
+Note [Polymorphic expected type for tcMatchesFun]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+tcMatchesFun may be given a *sigma* (polymorphic) type
+so it must be prepared to use tcGen to skolemise it.
+See Note [sig_tau may be polymorphic] in TcPat.
+
\begin{code}
tcMatchesFun :: Name -> Bool
-> MatchGroup Name
- -> BoxyRhoType -- Expected type of function
- -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body
-
+ -> TcSigmaType -- Expected type of function
+ -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body
tcMatchesFun fun_name inf matches exp_ty
= do { -- Check that they all have the same no of arguments
-- Location is in the monad, set the caller so that
-- 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
-
- -- ToDo: Don't use "expected" stuff if there ain't a type signature
- -- because inconsistency between branches
- -- may show up as something wrong with the (non-existent) type signature
-
- -- This is one of two places places we call subFunTys
- -- The point is that if expected_y is a "hole", we want
- -- to make pat_tys and rhs_ty as "holes" too.
- ; subFunTys doc n_pats exp_ty $ \ pat_tys rhs_ty ->
- tcMatches match_ctxt pat_tys rhs_ty matches
- }
+ traceTc "tcMatchesFun" (ppr fun_name $$ ppr exp_ty)
+ ; checkArgs fun_name matches
+
+ ; (wrap_gen, (wrap_fun, group))
+ <- tcGen (SigSkol (FunSigCtxt fun_name)) exp_ty $ \ _ exp_rho ->
+ -- Note [Polymorphic expected type for tcMatchesFun]
+ matchFunTys herald arity exp_rho $ \ pat_tys rhs_ty ->
+ tcMatches match_ctxt pat_tys rhs_ty matches
+ ; return (wrap_gen <.> wrap_fun, group) }
where
- doc = ptext SLIT("The equation(s) for") <+> quotes (ppr fun_name)
- <+> ptext SLIT("have") <+> speakNOf n_pats (ptext SLIT("argument"))
- n_pats = matchGroupArity matches
+ arity = matchGroupArity matches
+ herald = ptext (sLit "The equation(s) for")
+ <+> quotes (ppr fun_name) <+> ptext (sLit "have")
match_ctxt = MC { mc_what = FunRhs fun_name inf, mc_body = tcBody }
\end{code}
tcMatchesCase :: TcMatchCtxt -- Case context
-> TcRhoType -- Type of scrutinee
-> MatchGroup Name -- The case alternatives
- -> BoxyRhoType -- Type of whole case expressions
+ -> TcRhoType -- Type of whole case expressions
-> TcM (MatchGroup TcId) -- Translated alternatives
tcMatchesCase ctxt scrut_ty matches res_ty
+ | isEmptyMatchGroup matches -- Allow empty case expressions
+ = return (MatchGroup [] (mkFunTys [scrut_ty] res_ty))
+
+ | otherwise
= tcMatches ctxt [scrut_ty] res_ty matches
-tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (HsWrapper, MatchGroup TcId)
+tcMatchLambda :: MatchGroup Name -> TcRhoType -> TcM (HsWrapper, MatchGroup TcId)
tcMatchLambda match res_ty
- = subFunTys doc n_pats res_ty $ \ pat_tys rhs_ty ->
+ = matchFunTys doc n_pats res_ty $ \ pat_tys rhs_ty ->
tcMatches match_ctxt pat_tys rhs_ty match
where
n_pats = matchGroupArity match
- doc = sep [ ptext SLIT("The lambda expression")
- <+> quotes (pprSetDepth 1 $ pprMatches (LambdaExpr :: HsMatchContext Name) match),
+ doc = sep [ ptext (sLit "The lambda expression")
+ <+> quotes (pprSetDepth (PartWay 1) $
+ pprMatches (LambdaExpr :: HsMatchContext Name) match),
-- The pprSetDepth makes the abstraction print briefly
- ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("argument"))]
+ ptext (sLit "has") <+> speakNOf n_pats (ptext (sLit "argument"))]
match_ctxt = MC { mc_what = LambdaExpr,
mc_body = tcBody }
\end{code}
@tcGRHSsPat@ typechecks @[GRHSs]@ that occur in a @PatMonoBind@.
\begin{code}
-tcGRHSsPat :: GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId)
+tcGRHSsPat :: GRHSs Name -> TcRhoType -> TcM (GRHSs TcId)
-- Used for pattern bindings
tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss res_ty
where
\end{code}
+\begin{code}
+matchFunTys
+ :: SDoc -- See Note [Herald for matchExpecteFunTys] in TcUnify
+ -> Arity
+ -> TcRhoType
+ -> ([TcSigmaType] -> TcRhoType -> TcM a)
+ -> TcM (HsWrapper, a)
+
+-- Written in CPS style for historical reasons;
+-- could probably be un-CPSd, like matchExpectedTyConApp
+
+matchFunTys herald arity res_ty thing_inside
+ = do { (coi, pat_tys, res_ty) <- matchExpectedFunTys herald arity res_ty
+ ; res <- thing_inside pat_tys res_ty
+ ; return (coiToHsWrapper (mkSymCoI coi), res) }
+\end{code}
+
%************************************************************************
%* *
\subsection{tcMatch}
\begin{code}
tcMatches :: TcMatchCtxt
- -> [BoxySigmaType] -- Expected pattern types
- -> BoxyRhoType -- Expected result-type of the Match.
+ -> [TcSigmaType] -- Expected pattern types
+ -> TcRhoType -- Expected result-type of the Match.
-> MatchGroup Name
-> TcM (MatchGroup TcId)
= MC { mc_what :: HsMatchContext Name, -- What kind of thing this is
mc_body :: LHsExpr Name -- Type checker for a body of
-- an alternative
- -> BoxyRhoType
+ -> TcRhoType
-> TcM (LHsExpr TcId) }
tcMatches ctxt pat_tys rhs_ty (MatchGroup matches _)
- = do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches
+ = ASSERT( not (null matches) ) -- Ensure that rhs_ty is filled in
+ do { matches' <- mapM (tcMatch ctxt pat_tys rhs_ty) matches
; return (MatchGroup matches' (mkFunTys pat_tys rhs_ty)) }
-------------
tcMatch :: TcMatchCtxt
- -> [BoxySigmaType] -- Expected pattern types
- -> BoxyRhoType -- Expected result-type of the Match.
+ -> [TcSigmaType] -- Expected pattern types
+ -> TcRhoType -- Expected result-type of the Match.
-> LMatch Name
-> TcM (LMatch TcId)
where
tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss)
= add_match_ctxt match $
- do { (pats', grhss') <- tcLamPats pats pat_tys rhs_ty $
- tc_grhss ctxt maybe_rhs_sig grhss
+ do { (pats', grhss') <- tcPats (mc_what ctxt) pats pat_tys $
+ tc_grhss ctxt maybe_rhs_sig grhss rhs_ty
; return (Match pats' Nothing grhss') }
tc_grhss ctxt Nothing grhss rhs_ty
= tcGRHSs ctxt grhss rhs_ty -- No result signature
-- Result type sigs are no longer supported
- tc_grhss ctxt (Just res_sig) grhss rhs_ty
- = do { addErr (ptext SLIT("Ignoring (deprecated) result type signature")
- <+> ppr res_sig)
- ; tcGRHSs ctxt grhss rhs_ty }
+ tc_grhss _ (Just {}) _ _
+ = panic "tc_ghrss" -- Rejected by renamer
-- For (\x -> e), tcExpr has already said "In the expresssion \x->e"
-- so we don't want to add "In the lambda abstraction \x->e"
add_match_ctxt match thing_inside
= case mc_what ctxt of
LambdaExpr -> thing_inside
- m_ctxt -> addErrCtxt (matchCtxt m_ctxt match) thing_inside
+ m_ctxt -> addErrCtxt (pprMatchInCtxt m_ctxt match) thing_inside
-------------
-tcGRHSs :: TcMatchCtxt -> GRHSs Name -> BoxyRhoType
+tcGRHSs :: TcMatchCtxt -> GRHSs Name -> TcRhoType
-> TcM (GRHSs TcId)
-- Notice that we pass in the full res_ty, so that we get
; return (GRHSs grhss' binds') }
-------------
-tcGRHS :: TcMatchCtxt -> BoxyRhoType -> GRHS Name -> TcM (GRHS TcId)
+tcGRHS :: TcMatchCtxt -> TcRhoType -> GRHS Name -> TcM (GRHS TcId)
tcGRHS ctxt res_ty (GRHS guards rhs)
= do { (guards', rhs') <- tcStmts stmt_ctxt tcGuardStmt guards res_ty $
tcDoStmts :: HsStmtContext Name
-> [LStmt Name]
-> LHsExpr Name
- -> BoxyRhoType
+ -> TcRhoType
-> TcM (HsExpr TcId) -- Returns a HsDo
tcDoStmts ListComp stmts body res_ty
- = do { (elt_ty, coi) <- boxySplitListTy res_ty
+ = do { (coi, elt_ty) <- matchExpectedListTy res_ty
; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts
elt_ty $
tcBody body
(HsDo ListComp stmts' body' (mkListTy elt_ty)) }
tcDoStmts PArrComp stmts body res_ty
- = do { (elt_ty, coi) <- boxySplitPArrTy res_ty
+ = do { (coi, elt_ty) <- matchExpectedPArrTy res_ty
; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts
elt_ty $
tcBody body
(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) }
tcDoStmts ctxt@(MDoExpr _) stmts body res_ty
- = do { ((m_ty, elt_ty), coi) <- boxySplitAppTy res_ty
- ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty
- tc_rhs rhs = withBox liftedTypeKind $ \ pat_ty ->
+ = do { (coi, (m_ty, elt_ty)) <- matchExpectedAppTy res_ty
+ ; let res_ty' = mkAppTy m_ty elt_ty -- The matchExpected consumes res_ty
+ tc_rhs rhs = tcInfer $ \ pat_ty ->
tcMonoExpr rhs (mkAppTy m_ty pat_ty)
- ; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts
- res_ty' $
+ ; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty' $
tcBody body
; let names = [mfixName, bindMName, thenMName, returnMName, failMName]
- ; insts <- mapM (newMethodFromName DoOrigin m_ty) names
- ; return $
- mkHsWrapCoI coi
- (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') }
+ ; insts <- mapM (\name -> newMethodFromName DoOrigin name m_ty) names
+ ; return $ mkHsWrapCoI coi $
+ HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty' }
-tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt)
+tcDoStmts ctxt _ _ _ = pprPanic "tcDoStmts" (pprStmtContext ctxt)
-tcBody :: LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr TcId)
+tcBody :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
tcBody body res_ty
- = do { traceTc (text "tcBody" <+> ppr res_ty)
- ; body' <- tcPolyExpr body res_ty
+ = do { traceTc "tcBody" (ppr res_ty)
+ ; body' <- tcMonoExpr body res_ty
; return body'
}
\end{code}
type TcStmtChecker
= forall thing. HsStmtContext Name
-> Stmt Name
- -> BoxyRhoType -- Result type for comprehension
- -> (BoxyRhoType -> TcM thing) -- Checker for what follows the stmt
+ -> TcRhoType -- Result type for comprehension
+ -> (TcRhoType -> TcM thing) -- Checker for what follows the stmt
-> TcM (Stmt TcId, thing)
tcStmts :: HsStmtContext Name
-> TcStmtChecker -- NB: higher-rank type
-> [LStmt Name]
- -> BoxyRhoType
- -> (BoxyRhoType -> TcM thing)
+ -> TcRhoType
+ -> (TcRhoType -> TcM thing)
-> TcM ([LStmt TcId], thing)
-- Note the higher-rank type. stmt_chk is applied at different
-- types in the equations for tcStmts
-tcStmts ctxt stmt_chk [] res_ty thing_inside
+tcStmts _ _ [] res_ty thing_inside
= do { thing <- thing_inside res_ty
; return ([], thing) }
tcStmts ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside
= do { (stmt', (stmts', thing)) <-
setSrcSpan loc $
- addErrCtxt (stmtCtxt ctxt stmt) $
+ addErrCtxt (pprStmtInCtxt ctxt stmt) $
stmt_chk ctxt stmt res_ty $ \ res_ty' ->
popErrCtxt $
tcStmts ctxt stmt_chk stmts res_ty' $
--------------------------------
-- Pattern guards
tcGuardStmt :: TcStmtChecker
-tcGuardStmt ctxt (ExprStmt guard _ _) res_ty thing_inside
+tcGuardStmt _ (ExprStmt guard _ _) res_ty thing_inside
= do { guard' <- tcMonoExpr guard boolTy
; thing <- thing_inside res_ty
; return (ExprStmt guard' noSyntaxExpr boolTy, thing) }
tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRho rhs
- ; (pat', thing) <- tcLamPat pat rhs_ty res_ty thing_inside
+ = do { (rhs', rhs_ty) <- tcInferRhoNC rhs -- Stmt has a context already
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat rhs_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcGuardStmt ctxt stmt res_ty thing_inside
+tcGuardStmt _ stmt _ _
= pprPanic "tcGuardStmt: unexpected Stmt" (ppr stmt)
-> TcStmtChecker
-- A generator, pat <- rhs
-tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) res_ty thing_inside
- = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ ty ->
- tcMonoExpr rhs (mkTyConApp m_tc [ty])
- ; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
+tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) res_ty thing_inside
+ = do { pat_ty <- newFlexiTyVarTy liftedTypeKind
+ ; rhs' <- tcMonoExpr rhs (mkTyConApp m_tc [pat_ty])
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
-tcLcStmt m_tc ctxt (ExprStmt rhs _ _) res_ty thing_inside
+tcLcStmt _ _ (ExprStmt rhs _ _) res_ty thing_inside
= do { rhs' <- tcMonoExpr rhs boolTy
; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr boolTy, thing) }
-- | ... ; let h v = ... ]
--
-- It's possible that g,h are overloaded, so we need to feed the LIE from the
--- (g x, h x) up through both lots of bindings (so we get the bindInstsOfLocalFuns).
+-- (g x, h x) up through both lots of bindings (so we get the bindLocalMethods).
-- Similarly if we had an existential pattern match:
--
-- data T = forall a. Show a => C a
loop ((stmts, names) : pairs)
= do { (stmts', (ids, pairs', thing))
- <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ elt_ty' ->
+ <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ _elt_ty' ->
do { ids <- tcLookupLocalIds names
; (pairs', thing) <- loop pairs
; 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]
case maybeByExpr of
Nothing -> do
-- We must validate that usingExpr :: forall a. [a] -> [a]
- usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListTy))
+ let using_ty = mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListTy)
+ usingExpr' <- tcPolyExpr usingExpr using_ty
return (usingExpr', Nothing)
Just byExpr -> do
- -- We must infer a type such that e :: t and then check that usingExpr :: forall a. (a -> t) -> [a] -> [a]
- (byExpr', tTy) <- tcInferRho byExpr
- usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar ((alphaTy `mkFunTy` tTy) `mkFunTy` (alphaListTy `mkFunTy` alphaListTy)))
+ -- We must infer a type such that e :: t and then check that
+ -- usingExpr :: forall a. (a -> t) -> [a] -> [a]
+ (byExpr', tTy) <- tcInferRhoNC byExpr
+ let using_ty = mkForAllTy alphaTyVar $
+ (alphaTy `mkFunTy` tTy)
+ `mkFunTy` alphaListTy `mkFunTy` alphaListTy
+ usingExpr' <- tcPolyExpr usingExpr using_ty
return (usingExpr', Just byExpr')
binders' <- tcLookupLocalIds binders
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 by using) elt_ty thing_inside
+ = do { let (bndr_names, list_bndr_names) = unzip bindersMap
-tcLcStmt m_tc ctxt (GroupStmt (stmts, bindersMap) groupByClause) elt_ty thing_inside = do
- (stmts', (bindersMap', groupByClause', thing)) <-
+ ; (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) <- tcInferRho 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
- -- 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
-
- -- 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 (bndr_ids, by', using_ty, elt_ty')
- return (GroupStmt (stmts', bindersMap') groupByClause', thing)
- where
- associateNewBinder :: TcId -> Name -> TcId
- associateNewBinder oldBinder newBinder = mkLocalId newBinder (mkTyConApp m_tc [idType oldBinder])
+ -- Ensure that every old binder of type b is linked up with
+ -- its new binder which should have type [b]
+ ; 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
+
+ ; 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 m_tc ctxt stmt elt_ty thing_inside
+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) <- tcInferRho 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.
-
- -- 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)
+ = 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_ty <- newFlexiTyVarTy liftedTypeKind
+ ; pat_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; bind_op' <- tcSyntaxOp DoOrigin bind_op
+ (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)
- ; (pat', thing) <- tcLamPat pat pat_ty new_res_ty thing_inside
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside new_res_ty
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
-tcDoStmt ctxt (ExprStmt rhs then_op _) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRho rhs
-
- -- Deal with rebindable syntax; (>>) :: rhs_ty -> new_res_ty -> res_ty
- ; (then_op', new_res_ty) <-
- withBox liftedTypeKind $ \ new_res_ty ->
- tcSyntaxOp DoOrigin then_op
+tcDoStmt _ (ExprStmt rhs then_op _) res_ty thing_inside
+ = do { -- Deal with rebindable syntax;
+ -- (>>) :: rhs_ty -> new_res_ty -> res_ty
+ -- See also Note [Treat rebindable syntax first]
+ rhs_ty <- newFlexiTyVarTy liftedTypeKind
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; then_op' <- 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 {}) res_ty thing_inside
- = failWithTc (ptext SLIT("Illegal 'rec' stmt in") <+> pprStmtContext ctxt)
- -- This case can't be caught in the renamer
- -- see RnExpr.checkRecStmt
-
-tcDoStmt ctxt stmt res_ty thing_inside
+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_ty <- newFlexiTyVarTy liftedTypeKind
+ ; (stmts', (ret_op', tup_rets))
+ <- tcStmts ctxt tcDoStmt stmts stmts_ty $ \ inner_res_ty ->
+ do { tup_rets <- zipWithM tcCheckId tup_names tup_elt_tys
+ -- Unify the types of the "final" Ids (which may
+ -- be polymorphic) with those of "knot-tied" Ids
+ ; ret_op' <- tcSyntaxOp DoOrigin ret_op (mkFunTy tup_ty inner_res_ty)
+ ; return (ret_op', tup_rets) }
+
+ ; mfix_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; mfix_op' <- tcSyntaxOp DoOrigin mfix_op
+ (mkFunTy (mkFunTy tup_ty stmts_ty) mfix_res_ty)
+
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; bind_op' <- tcSyntaxOp DoOrigin bind_op
+ (mkFunTys [mfix_res_ty, mkFunTy tup_ty new_res_ty] res_ty)
+
+ ; thing <- thing_inside new_res_ty
+-- ; lie_binds <- bindLocalMethods lie tup_ids
+
+ ; let rec_ids = takeList rec_names tup_ids
+ ; later_ids <- tcLookupLocalIds later_names
+ ; traceTc "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 = emptyTcEvBinds }, thing)
+ }}
+
+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
tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
-> TcStmtChecker
-tcMDoStmt tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+tcMDoStmt tc_rhs ctxt (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_rhs rhs
- ; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcMDoStmt tc_rhs ctxt (ExprStmt rhs then_op _) res_ty thing_inside
+tcMDoStmt tc_rhs _ (ExprStmt rhs _ _) res_ty thing_inside
= do { (rhs', elt_ty) <- tc_rhs rhs
; 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
{ (stmts', (later_ids, rec_rets))
- <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ res_ty' ->
+ <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ _res_ty' ->
-- ToDo: res_ty not really right
- do { rec_rets <- zipWithM tc_ret recNames rec_tys
+ do { rec_rets <- zipWithM tcCheckId recNames rec_tys
; later_ids <- tcLookupLocalIds laterNames
; return (later_ids, rec_rets) }
- ; (thing,lie) <- tcExtendIdEnv later_ids (getLIE (thing_inside res_ty))
+ ; thing <- tcExtendIdEnv later_ids (thing_inside res_ty)
-- NB: The rec_ids for the recursive things
-- already scope over this part. This binding may shadow
-- some of them with polymorphic things with the same Name
-- (see note [RecStmt] in HsExpr)
- ; lie_binds <- bindInstsOfLocalFuns lie later_ids
+
+-- Need the bindLocalMethods if we re-add Method constraints
+-- ; lie_binds <- bindLocalMethods lie later_ids
+ ; let lie_binds = emptyTcEvBinds
- ; 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
- 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)) }
-
-tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside
- = pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
+tcMDoStmt _ _ stmt _ _
+ = pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
\end{code}
checkArgs fun (MatchGroup (match1:matches) _)
| null bad_matches = return ()
| otherwise
- = failWithTc (vcat [ptext SLIT("Equations for") <+> quotes (ppr fun) <+>
- ptext SLIT("have different numbers of arguments"),
+ = failWithTc (vcat [ptext (sLit "Equations for") <+> quotes (ppr fun) <+>
+ ptext (sLit "have different numbers of arguments"),
nest 2 (ppr (getLoc match1)),
nest 2 (ppr (getLoc (head bad_matches)))])
where
args_in_match :: LMatch Name -> Int
args_in_match (L _ (Match pats _ _)) = length pats
-checkArgs fun other = panic "TcPat.checkArgs" -- Matches always non-empty
+checkArgs fun _ = pprPanic "TcPat.checkArgs" (ppr fun) -- Matches always non-empty
\end{code}
-\begin{code}
-matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon)
- 4 (pprMatch ctxt match)
-
-stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pprStmtContext ctxt <> colon)
- 4 (ppr stmt)
-\end{code}
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