%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[TcMatches]{Typecheck some @Matches@}
+
+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(..),
tcStmts, tcDoStmts, tcBody,
import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
-import HsSyn ( HsExpr(..), LHsExpr, MatchGroup(..),
- Match(..), LMatch, GRHSs(..), GRHS(..),
- Stmt(..), LStmt, HsMatchContext(..),
- HsStmtContext(..),
- pprMatch, isIrrefutableHsPat, mkHsCoerce,
- mkLHsCoerce, pprMatchContext, pprStmtContext,
- noSyntaxExpr, matchGroupArity, pprMatches,
- ExprCoFn )
-
+import HsSyn
import TcRnMonad
-import TcGadt ( Refinement, emptyRefinement, refineResType )
-import Inst ( newMethodFromName )
-import TcEnv ( TcId, tcLookupLocalIds, tcLookupId, tcExtendIdEnv )
-import TcPat ( tcLamPats, tcLamPat )
-import TcMType ( newFlexiTyVarTy, newFlexiTyVarTys )
-import TcType ( TcType, TcRhoType,
- BoxySigmaType, BoxyRhoType,
- mkFunTys, mkFunTy, mkAppTy, mkTyConApp,
- liftedTypeKind )
-import TcBinds ( tcLocalBinds )
-import TcUnify ( boxySplitAppTy, boxySplitTyConApp, boxySplitListTy,
- subFunTys, tcSubExp, withBox )
-import TcSimplify ( bindInstsOfLocalFuns )
-import Name ( Name )
-import TysWiredIn ( stringTy, boolTy, parrTyCon, listTyCon, mkListTy, mkPArrTy )
-import PrelNames ( bindMName, returnMName, mfixName, thenMName, failMName )
-import Id ( idType, mkLocalId )
-import TyCon ( TyCon )
+import TcGadt
+import Inst
+import TcEnv
+import TcPat
+import TcMType
+import TcType
+import TcBinds
+import TcUnify
+import TcSimplify
+import Name
+import TysWiredIn
+import PrelNames
+import Id
+import TyCon
+import TysPrim
import Outputable
-import SrcLoc ( Located(..), getLoc )
+import Util
+import SrcLoc
+
+import Control.Monad( liftM )
\end{code}
%************************************************************************
same number of arguments before using @tcMatches@ to do the work.
\begin{code}
-tcMatchesFun :: Name
+tcMatchesFun :: Name -> Bool
-> MatchGroup Name
-> BoxyRhoType -- Expected type of function
- -> TcM (ExprCoFn, MatchGroup TcId) -- Returns type of body
+ -> TcM (HsWrapper, MatchGroup TcId) -- Returns type of body
-tcMatchesFun fun_name matches exp_ty
+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
-- any inter-equation error messages get some vaguely
doc = ptext SLIT("The equation(s) for") <+> quotes (ppr fun_name)
<+> ptext SLIT("have") <+> speakNOf n_pats (ptext SLIT("argument"))
n_pats = matchGroupArity matches
- match_ctxt = MC { mc_what = FunRhs fun_name, mc_body = tcBody }
+ match_ctxt = MC { mc_what = FunRhs fun_name inf, mc_body = tcBody }
\end{code}
@tcMatchesCase@ doesn't do the argument-count check because the
tcMatchesCase ctxt scrut_ty matches res_ty
= tcMatches ctxt [scrut_ty] res_ty matches
-tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (ExprCoFn, MatchGroup TcId)
+tcMatchLambda :: MatchGroup Name -> BoxyRhoType -> TcM (HsWrapper, MatchGroup TcId)
tcMatchLambda match res_ty
= subFunTys 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 match),
+ <+> quotes (pprSetDepth 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,
= wrapLocM (tc_match ctxt pat_tys rhs_ty) match
where
tc_match ctxt pat_tys rhs_ty match@(Match pats maybe_rhs_sig grhss)
- = addErrCtxt (matchCtxt (mc_what ctxt) match) $
+ = add_match_ctxt match $
do { (pats', grhss') <- tcLamPats 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 (co,rhs_ty)
+ tc_grhss ctxt (Just res_sig) grhss (co, rhs_ty)
= do { addErr (ptext SLIT("Ignoring (deprecated) result type signature")
<+> ppr res_sig)
- tcGRHSs ctxt grhss (co, inner_ty) }
+ ; tcGRHSs ctxt grhss (co, rhs_ty) }
+
+ -- 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
-------------
tcGRHSs :: TcMatchCtxt -> GRHSs Name -> (Refinement, BoxyRhoType)
-> BoxyRhoType
-> TcM (HsExpr TcId) -- Returns a HsDo
tcDoStmts ListComp stmts body res_ty
- = do { elt_ty <- boxySplitListTy res_ty
+ = do { (elt_ty, coi) <- boxySplitListTy res_ty
; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts
(emptyRefinement,elt_ty) $
tcBody body
- ; return (HsDo ListComp stmts' body' (mkListTy elt_ty)) }
+ ; return $ mkHsWrapCoI coi
+ (HsDo ListComp stmts' body' (mkListTy elt_ty)) }
tcDoStmts PArrComp stmts body res_ty
- = do { [elt_ty] <- boxySplitTyConApp parrTyCon res_ty
+ = do { (elt_ty, coi) <- boxySplitPArrTy res_ty
; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts
(emptyRefinement, elt_ty) $
tcBody body
- ; return (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
+ ; return $ mkHsWrapCoI coi
+ (HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
tcDoStmts DoExpr stmts body res_ty
- = do { (m_ty, elt_ty) <- boxySplitAppTy res_ty
- ; let res_ty' = mkAppTy m_ty elt_ty -- The boxySplit consumes res_ty
- ; (stmts', body') <- tcStmts DoExpr (tcDoStmt m_ty) stmts
- (emptyRefinement, res_ty') $
+ = do { (stmts', body') <- tcStmts DoExpr tcDoStmt stmts
+ (emptyRefinement, res_ty) $
tcBody body
- ; return (HsDo DoExpr stmts' body' res_ty') }
+ ; return (HsDo DoExpr stmts' body' res_ty) }
tcDoStmts ctxt@(MDoExpr _) stmts body res_ty
- = do { (m_ty, elt_ty) <- boxySplitAppTy 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 ->
tcMonoExpr rhs (mkAppTy m_ty pat_ty)
; let names = [mfixName, bindMName, thenMName, returnMName, failMName]
; insts <- mapM (newMethodFromName DoOrigin m_ty) names
- ; return (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') }
+ ; return $
+ mkHsWrapCoI coi
+ (HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') }
tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt)
= do { traceTc (text "tcBody" <+> ppr res_ty <+> ppr reft)
; let (co, res_ty') = refineResType reft res_ty
; body' <- tcPolyExpr body res_ty'
- ; return (mkLHsCoerce co body') }
+ ; return (mkLHsWrap co body') }
\end{code}
; return (ids, pairs', thing) }
; return ( (stmts', ids) : pairs', thing ) }
+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]
+
+ (usingExpr', maybeByExpr') <-
+ case maybeByExpr of
+ Nothing -> do
+ -- We must validate that usingExpr :: forall a. [a] -> [a]
+ usingExpr' <- tcPolyExpr usingExpr (mkForAllTy alphaTyVar (alphaListTy `mkFunTy` alphaListTy))
+ 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)))
+ return (usingExpr', Just byExpr')
+
+ binders' <- tcLookupLocalIds binders
+ thing <- thing_inside elt_ty'
+
+ return (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)) <-
+ 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
+
+ -- 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 (GroupStmt (stmts', bindersMap') groupByClause', thing)
+ where
+ associateNewBinder :: TcId -> Name -> TcId
+ associateNewBinder oldBinder newBinder = mkLocalId newBinder (mkTyConApp m_tc [idType oldBinder])
+
tcLcStmt m_tc ctxt stmt elt_ty thing_inside
= pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt)
-
+
--------------------------------
-- Do-notation
-- The main excitement here is dealing with rebindable syntax
-tcDoStmt :: TcType -- Monad type, m
- -> TcStmtChecker
+tcDoStmt :: TcStmtChecker
-tcDoStmt m_ty ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,res_ty) thing_inside
- = do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ pat_ty ->
- tcMonoExpr rhs (mkAppTy m_ty pat_ty)
+tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,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
-- We do inference on rhs, so that information about its type can be refined
-- when type-checking the pattern.
- ; (pat', thing) <- tcLamPat pat pat_ty reft_res_ty thing_inside
+ -- Deal with rebindable syntax; (>>=) :: rhs_ty -> (a -> res_ty) -> res_ty
+ ; (bind_op', pat_ty) <-
+ withBox liftedTypeKind $ \ pat_ty ->
+ tcSyntaxOp DoOrigin bind_op
+ (mkFunTys [rhs_ty, mkFunTy pat_ty res_ty] res_ty)
- -- Deal with rebindable syntax; (>>=) :: m a -> (a -> m b) -> m b
- ; let bind_ty = mkFunTys [mkAppTy m_ty pat_ty,
- mkFunTy pat_ty res_ty] res_ty
- ; bind_op' <- tcSyntaxOp DoOrigin bind_op bind_ty
-- If (but only if) the pattern can fail,
-- typecheck the 'fail' operator
- ; fail_op' <- if isIrrefutableHsPat pat'
+ ; fail_op' <- if isIrrefutableHsPat pat
then return noSyntaxExpr
else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy res_ty)
+
+ ; (pat', thing) <- tcLamPat pat pat_ty reft_res_ty thing_inside
+
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
-tcDoStmt m_ty ctxt (ExprStmt rhs then_op _) reft_res_ty@(_,res_ty) thing_inside
- = do { -- Deal with rebindable syntax; (>>) :: m a -> m b -> m b
- a_ty <- newFlexiTyVarTy liftedTypeKind
- ; let rhs_ty = mkAppTy m_ty a_ty
- then_ty = mkFunTys [rhs_ty, res_ty] res_ty
- ; then_op' <- tcSyntaxOp DoOrigin then_op then_ty
- ; rhs' <- tcPolyExpr rhs rhs_ty
+tcDoStmt ctxt (ExprStmt rhs then_op _) reft_res_ty@(_,res_ty) thing_inside
+ = do { (rhs', rhs_ty) <- tcInferRho rhs
+
+ -- Deal with rebindable syntax; (>>) :: rhs_ty -> res_ty -> res_ty
+ ; then_op' <- tcSyntaxOp DoOrigin then_op
+ (mkFunTys [rhs_ty, res_ty] res_ty)
+
; thing <- thing_inside reft_res_ty
; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt m_ty ctxt stmt res_ty thing_inside
+tcDoStmt ctxt stmt res_ty thing_inside
= pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt)
--------------------------------
= 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 (idType poly_id) mono_ty
- ; return (mkHsCoerce co_fn (HsVar poly_id)) }
+ ; 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)