tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC,
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC, tcCheckId,
tcMonoExpr, tcMonoExprNC, tcPolyExpr )
import HsSyn
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 VarSet
+import BasicTypes ( Arity )
import Util
import SrcLoc
import FastString
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...
- traceTc (text "tcMatchesFun" <+> (ppr fun_name $$ ppr exp_ty))
+ traceTc "tcMatchesFun" (ppr fun_name $$ ppr exp_ty)
; checkArgs fun_name matches
- -- ToDo: Don't use "expected" stuff if there ain't a type signature
- -- because inconsistency between branches
- -- 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 (Just (FunSigCtxt fun_name)) $ \ pat_tys rhs_ty ->
- tcMatches match_ctxt pat_tys rhs_ty matches
- }
+ ; (wrap_gen, (wrap_fun, group))
+ <- tcGen (SigSkol (FunSigCtxt fun_name)) emptyVarSet 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
- do { -- Make sure we follow the invariant that res_ty is filled in
- res_ty' <- refineBoxToTau res_ty
- ; return (MatchGroup [] (mkFunTys [scrut_ty] 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 Nothing $ \ 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
@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 _)
-------------
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)
tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss)
= add_match_ctxt match $
do { (pats', grhss') <- tcPats (mc_what ctxt) pats pat_tys rhs_ty $
- tc_grhss ctxt maybe_rhs_sig grhss
+ tc_grhss ctxt maybe_rhs_sig grhss rhs_ty
; return (Match pats' Nothing grhss') }
tc_grhss ctxt Nothing grhss rhs_ty
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
; 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 _ _ _ = 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)
+ = do { traceTc "tcBody" (ppr res_ty)
; body' <- tcMonoExpr body res_ty
; return body'
}
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
tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRhoNC rhs -- Stmt has a context already
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat rhs_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat rhs_ty res_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
tcGuardStmt _ stmt _ _
-- 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) <- tcPat (StmtCtxt ctxt) pat pat_ty 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 res_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
-- | ... ; 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
-- (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
-
- ; ((bind_op', new_res_ty), pat_ty) <-
- withBox liftedTypeKind $ \ pat_ty ->
- withBox liftedTypeKind $ \ new_res_ty ->
- tcSyntaxOp DoOrigin bind_op
+ 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,
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
+ ; rhs' <- tcMonoExprNC rhs rhs_ty
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty new_res_ty $
+ thing_inside new_res_ty
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
= 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
+ 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
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
+ { 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_op', mfix_res_ty) <- withBox liftedTypeKind $ \ mfix_res_ty ->
- tcSyntaxOp DoOrigin mfix_op
- (mkFunTy (mkFunTy tup_ty stmts_ty) mfix_res_ty)
+ ; mfix_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; mfix_op' <- 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)
+ ; new_res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; bind_op' <- 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
+ ; 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 (text "tcdo" <+> vcat [ppr rec_ids <+> ppr (map idType rec_ids),
- ppr later_ids <+> ppr (map idType later_ids)])
+ ; 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 = lie_binds }, thing)
+ , recS_rec_rets = tup_rets, recS_dicts = emptyTcEvBinds }, 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)
-> TcStmtChecker
tcMDoStmt tc_rhs ctxt (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_rhs rhs
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty res_ty thing_inside
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty res_ty $
+ thing_inside res_ty
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
tcMDoStmt tc_rhs _ (ExprStmt rhs _ _) res_ty thing_inside
{ (stmts', (later_ids, rec_rets))
<- 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 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 _ _ stmt _ _
= pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
-
\end{code}
projects / ghc-hetmet.git / blobdiff