\begin{code}
module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
- matchCtxt, TcMatchCtxt(..),
+ TcMatchCtxt(..),
tcStmts, tcDoStmts, tcBody,
tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
+import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRhoNC,
+ tcMonoExpr, tcMonoExprNC, tcPolyExpr )
import HsSyn
import TcRnMonad
import FastString
import Control.Monad
+
+#include "HsVersions.h"
\end{code}
%************************************************************************
-- 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 ->
+ ; subFunTys doc n_pats exp_ty (Just (FunSigCtxt fun_name)) $ \ pat_tys rhs_ty ->
tcMatches match_ctxt pat_tys rhs_ty matches
}
where
-> 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')) }
+
+ | otherwise
= tcMatches ctxt [scrut_ty] res_ty matches
tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (HsWrapper, MatchGroup TcId)
tcMatchLambda match res_ty
- = subFunTys doc n_pats res_ty $ \ pat_tys rhs_ty ->
+ = subFunTys doc n_pats res_ty Nothing $ \ 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),
+ <+> 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"))]
match_ctxt = MC { mc_what = LambdaExpr,
-> 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)) }
-------------
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 $
+ do { (pats', grhss') <- tcPats (mc_what ctxt) pats pat_tys rhs_ty $
tc_grhss ctxt maybe_rhs_sig grhss
; return (Match pats' Nothing grhss') }
= 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
tcBody :: LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr TcId)
tcBody body res_ty
= do { traceTc (text "tcBody" <+> ppr res_ty)
- ; body' <- tcPolyExpr body res_ty
+ ; body' <- tcMonoExpr body res_ty
; return body'
}
\end{code}
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' $
; thing <- thing_inside res_ty
; return (ExprStmt guard' noSyntaxExpr boolTy, thing) }
-tcGuardStmt _ (BindStmt pat rhs _ _) res_ty thing_inside
- = do { (rhs', rhs_ty) <- tcInferRho rhs
- ; (pat', thing) <- tcLamPat pat rhs_ty res_ty thing_inside
+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
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
tcGuardStmt _ stmt _ _
-> TcStmtChecker
-- A generator, pat <- rhs
-tcLcStmt m_tc _ (BindStmt pat rhs _ _) res_ty thing_inside
+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
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
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
+ (byExpr', tTy) <- tcInferRhoNC byExpr
usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar ((alphaTy `mkFunTy` tTy) `mkFunTy` (alphaListTy `mkFunTy` alphaListTy)))
return (usingExpr', Just byExpr')
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
+ (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))
tcDoStmt :: TcStmtChecker
-tcDoStmt _ (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.
+tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+ = 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)
- ; (pat', thing) <- tcLamPat pat pat_ty new_res_ty thing_inside
+ -- 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) <- tcInferRho 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
tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
-> TcStmtChecker
-tcMDoStmt tc_rhs _ (BindStmt pat rhs _ _) 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 res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
tcMDoStmt tc_rhs _ (ExprStmt rhs _ _) res_ty thing_inside
; 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
checkArgs _ _ = panic "TcPat.checkArgs" -- Matches always non-empty
\end{code}
-\begin{code}
-matchCtxt :: HsMatchContext Name -> Match Name -> SDoc
-matchCtxt ctxt match = hang (ptext (sLit "In") <+> pprMatchContext ctxt <> colon)
- 4 (pprMatch ctxt match)
-
-stmtCtxt :: HsStmtContext Name -> StmtLR Name Name -> SDoc
-stmtCtxt ctxt stmt = hang (ptext (sLit "In a stmt of") <+> pprStmtContext ctxt <> colon)
- 4 (ppr stmt)
-\end{code}
projects / ghc-hetmet.git / blobdiff