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 PrelNames
import Id
import TyCon
+import TysPrim
import Outputable
+import Util
import SrcLoc
+
+import Control.Monad
\end{code}
%************************************************************************
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,
tcGRHSs ctxt (GRHSs grhss binds) res_ty
= do { (binds', grhss') <- tcLocalBinds binds $
- mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss
+ mapM (wrapLocM (tcGRHS ctxt res_ty)) grhss
- ; returnM (GRHSs grhss' binds') }
+ ; return (GRHSs grhss' binds') }
-------------
tcGRHS :: TcMatchCtxt -> (Refinement, BoxyRhoType) -> GRHS Name -> TcM (GRHS TcId)
-> 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)
; 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) 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 -> (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)
- -- 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)
+ else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy new_res_ty)
+
+ ; (pat', thing) <- tcLamPat pat pat_ty (reft, new_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
- ; thing <- thing_inside reft_res_ty
+tcDoStmt ctxt (ExprStmt rhs then_op _) (reft,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
+ (mkFunTys [rhs_ty, new_res_ty] res_ty)
+
+ ; thing <- thing_inside (reft, new_res_ty)
; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt m_ty ctxt stmt res_ty thing_inside
+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
= 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
+ ; 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
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